A Microprocessor-Controlled Data Acquisition System for the Federal Scientific Model UA-500-1 Ubiquitous Spectrum Analyzer

DTIC Science & Technology

1976-09-01

Model AN/ UGC -59A teletype and paper-tape punch console. This unit is connected with the Intellec 8 computer and punching operations are controlled by...order to use this program, the microprocessor would have to be one of the many types on the market that make use of the INTEL 8008-1 CPD chip. The use

The use of LANDSAT DCS and imagery in reservoir management and operation. [New England and Alaska

NASA Technical Reports Server (NTRS)

Cooper, S. (Principal Investigator)

1975-01-01

The author has identified the following significant results. The local user terminal has proven the hypothesis that a relatively inexpensive, automatic, and easily maintained ground receive station for satellite relayed data is practical for operational use. Data acquisition activities were expanded to include both the teletype-relayed information as well as that received directly from local user terminals.

Development of New Instructional Uses of the Computer in an Inner-City Comprehensive High School. Final Report.

ERIC Educational Resources Information Center

Lichten, William

A three-part program investigated the use of computers at an inner-city high school. An attempt was made to introduce a digital computer for instructional purposes at the high school. A single portable teletype terminal and a simple programing language, BASIC, were used. It was found that a wide variety of students could benefit from this…

A Prototype System for a Computer-Based Statewide Film Library Network: A Model for Operation. Statewide Film Library Network: System-1 Specifications - Files.

ERIC Educational Resources Information Center

Sullivan, Todd

Using an IBM System/360 Model 50 computer, the New York Statewide Film Library Network schedules film use, reports on materials handling and statistics, and provides for interlibrary loan of films. Communications between the film libraries and the computer are maintained by Teletype model 33 ASR Teletypewriter terminals operating on TWX…

Soviet Seismographic Stations and Seismic Instruments. Part 2

DTIC Science & Technology

1975-06-01

seismograph consisting of a modified Ostrovskiy tiltmeter was tested and Installed at the Obninsk station sometime in the late 1960s. The tiltmeter ...curves of 1 - Ostrovskiy tiltmeter 2 - Press-Ewing seismograph 3 - SMD seismograph [60] signal coil (C1) is now used for calibration and for remote...multichannel teletype seismograph network in Armenia that is suitable for earthquake prediction investigations. It includes up to 70 prognostic sensors and

SPAR reference manual. [for stress analysis

NASA Technical Reports Server (NTRS)

Whetstone, W. D.

1974-01-01

SPAR is a system of related programs which may be operated either in batch or demand (teletype) mode. Information exchange between programs is automatically accomplished through one or more direct access libraries, known collectively as the data complex. Card input is command-oriented, in free-field form. Capabilities available in the first production release of the system are fully documented, and include linear stress analysis, linear bifurcation buckling analysis, and linear vibrational analysis.

Second Report of the Multirate Processor (MRP) for Digital Voice Communications.

DTIC Science & Technology

1982-09-30

machine are: * two arithmetic logic units (ALUs)-one for data processing, and the other for address generation, * two memorys -6144 words (70 bits per word...of program memory , and 6094 words (16 bits per word) of data memory , q * input/output through modem and teletype, -15 .9 S-;. KANG AND FRANSEN Table...provides a measure of intelligibility and allows one to evaluate the discriminability of six distinctive features: voicing, nasality, sustention

Compendium of Applications Technology Satellite user experiments

NASA Technical Reports Server (NTRS)

Engler, N. A.; Strange, J. D.; Hein, G. F.

1976-01-01

The achievements of the user experiments performed with ATS satellites from 1967 to 1973 are summarized. Included are fixed and mobile point to point communications experiments involving voice, teletype and facsimile transmissions. Particular emphasis is given to the Alaska and Hawaii satellite communications experiments. The use of the ATS satellites for ranging and position fixing of ships and aircraft is also covered. The structure and operating characteristics of the various ATS satellite are briefly described.

MAGTF (Marine Air Ground Task Force) Data Transfer Alternatives (1986-1996).

DTIC Science & Technology

1986-04-01

Devices currently on the market offer circuit conditioning and access control as well as the required dial-up connectivity. A program to provide dial... UGC -74A(V)3 Communication Terminal (Teletype Writer (TTY) CV-3591 Advanced Narrowband Digital Voice Terminal (ANDVT) AN/TGC-46 TTY Central (part of AN...interface directly with both AN/ UGC -74 TTY and ADPE-FMF/EUC equipment over serial circuits. 5.5.2.2 Switching Equipment. Switching equipments perform the

ETL History Update, 1968-1978

DTIC Science & Technology

1979-02-01

I ser light source, a 250 x 500-mm. X-Y input table, optics, and a 500 x 1,000-mm, output drum mounted on a 3-ton granite base. As the input...computer via the teletype. The printer unit is installed in a clean-room environment, part of which is a darkroom containing-E the output drum . Since... drum -type. UNAMACE elevation data will that are repetitive, tedious, and very demanding with respect to be converted to contour line format by

Determination of Selected Properties of Teletype Parts.

DTIC Science & Technology

1985-10-01

THtS REPORT IS NOT TO BC USED IN WHOLE OR IN PART rOR ADVERTISING OR SALES PROMOTION PURPOSES ASD $1 64 PNCVIOus COTION OF THIS FORM MAY at useo...REPoRT 1s NOT TO BE USED IN WHOLE of IN PART FOa AOvCRTsINO oR SALES PROMoTIoN PuRPW-- PR S* P0gwSOUS -oD ION Of .. . , FOM MAY O uSTm. AI-W---,AT AS ?M 57

A Transportable VLF/LF Repeater Terminal - A Design Study,

DTIC Science & Technology

1986-07-01

Corporation and marketed commercially as the ROLM 1602B, is expected to be used on the Airborne Command Post (ABNCP) fleet for MMPM processing. The basic...A suitable keyboard/printer for this application is a solid state teletype, the AN/ UGC -120. This device can also function as an AFSATCOM terminal...and as the VLF output device in the event of CPU failure. The AN/ UGC -120 is an Air Force inventory item. 20 INTERSITE COW4UNICATIONS SUBSYSTEM A single

Communications satellite system for Africa

NASA Astrophysics Data System (ADS)

Kriegl, W.; Laufenberg, W.

1980-09-01

Earlier established requirement estimations were improved upon by contacting African administrations and organizations. An enormous demand is shown to exist for telephony and teletype services in rural areas. It is shown that educational television broadcasting should be realized in the current African transport and communications decade (1978-1987). Radio broadcasting is proposed in order to overcome illiteracy and to improve educational levels. The technical and commercial feasibility of the system is provided by computer simulations which demonstrate how the required objectives can be fulfilled in conjunction with ground networks.

Solution of nonlinear multivariable constrained systems using a gradient projection digital algorithm that is insensitive to the initial state

NASA Technical Reports Server (NTRS)

Hargrove, A.

1982-01-01

Optimal digital control of nonlinear multivariable constrained systems was studied. The optimal controller in the form of an algorithm was improved and refined by reducing running time and storage requirements. A particularly difficult system of nine nonlinear state variable equations was chosen as a test problem for analyzing and improving the controller. Lengthy analysis, modeling, computing and optimization were accomplished. A remote interactive teletype terminal was installed. Analysis requiring computer usage of short duration was accomplished using Tuskegee's VAX 11/750 system.

A PDP-15 to industrial-14 interface at the Lewis Research Center's cyclotron

NASA Technical Reports Server (NTRS)

Kebberly, F. R.; Leonard, R. F.

1977-01-01

An interface (hardware and software) was built which permits the loading, monitoring, and control of a digital equipment industrial-14/30 programmable controller by a PDP-15 computer. The interface utilizes the serial mode for data transfer to and from the controller, so that the required hardware is essentially that of a teletype unit except for the speed of transmission. Software described here permits the user to load binary paper tape, read or load individual controller memory locations, and if desired turn controller outputs on and off directly from the computer.

Design of a command, communications, and control van (surrogate)

NASA Astrophysics Data System (ADS)

Holder, J. Darryl; Fishback, Jerome

1989-03-01

This report describes the design, construction, and checkout of a radio and telephone multi-mode communications hub. This unit is to serve as a surrogate for a command, control, and communications van which is to be used in support of a special series of testing at a remote site. This unit is assembled in a military four-wheel van and has a crew of a commander and three operators. Radio communications monitoring can be performed in all popular modes of transmission from 50 KHz to 2 GHz and transmission can be performed on selected frequencies in the 40-meter, 6-meter, and 2-meter bands. Both voice and digital (teletype, packet, facsimile, etc.) communications are supported.

Use of graphics in the design office at the Military Aircraft Division of the British Aircraft Corporation

NASA Technical Reports Server (NTRS)

Coles, W. A.

1975-01-01

The CAD/CAM interactive computer graphics system was described; uses to which it has been put were shown, and current developments of the system were outlined. The system supports batch, time sharing, and fully interactive graphic processing. Engineers using the system may switch between these methods of data processing and problem solving to make the best use of the available resources. It is concluded that the introduction of on-line computing in the form of teletypes, storage tubes, and fully interactive graphics has resulted in large increases in productivity and reduced timescales in the geometric computing, numerical lofting and part programming areas, together with a greater utilization of the system in the technical departments.

Historical data recording for process computers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hale, J.C.; Sellars, H.L.

1981-11-01

Computers have been used to monitor and control chemical and refining processes for more than 15 years. During this time, there has been a steady growth in the variety and sophistication of the functions performed by these process computers. Early systems were limited to maintaining only current operating measurements, available through crude operator's consoles or noisy teletypes. The value of retaining a process history, that is, a collection of measurements over time, became apparent, and early efforts produced shift and daily summary reports. The need for improved process historians which record, retrieve and display process information has grown as processmore » computers assume larger responsibilities in plant operations. This paper describes newly developed process historian functions that have been used on several of its in-house process monitoring and control systems in Du Pont factories. 3 refs.« less

The minitrack tracking function description, volume 1

NASA Technical Reports Server (NTRS)

Englar, T. S., Jr.; Mango, S. A.; Roettcher, C. A.; Watters, D. L.

1973-01-01

The treatment of tracking data by the Minitrack system is described from the transmission of the nominal 136-MHz radio beacon energy from a satellite and the reception of this signal by the interferometer network through the ultimate derivation of the direction cosines (the angular coordinates of the vector from the tracking station to the spacecraft) as a function of time. Descriptions of some of the lesser-known functions operating on the system, such as the computer preprocessing program, are included. A large part of the report is devoted to the preprocessor, which provides for the data compression, smoothing, calibration correction, and ambiguity resolution of the raw interferometer phase tracking measurements teletyped from each of the worldwide Minitrack tracking stations to the central computer facility at Goddard Space Flight Center. An extensive bibliography of Minitrack hardware and theory is presented.

Studies on hand-held visual communication device for the deaf and speech-impaired I. Visual display window size.

PubMed

Thurlow, W R

1980-01-01

Messages were presented which moved from right to left along an electronic alphabetic display which was varied in "window" size from 4 through 32 letter spaces. Deaf subjects signed the messages they perceived. Relatively few errors were made even at the highest rate of presentation, which corresponded to a typing rate of 60 words/min. It is concluded that many deaf persons can make effective use of a small visual display. A reduced cost is then possible for visual communication instruments for these people through reduced display size. Deaf subjects who can profit from a small display can be located by a sentence test administered by tape recorder which drives the display of the communication device by means of the standard code of the deaf teletype network.

Simulation of Clinical Diagnosis: A Comparative Study

PubMed Central

de Dombal, F. T.; Horrocks, Jane C.; Staniland, J. R.; Gill, P. W.

1971-01-01

This paper presents a comparison between three different modes of simulation of the diagnostic process—a computer-based system, a verbal mode, and a further mode in which cards were selected from a large board. A total of 34 subjects worked through a series of 444 diagnostic simulations. The verbal mode was found to be most enjoyable and realistic. At the board, considerable amounts of extra irrelevant data were selected. At the computer, the users asked the same questions every time, whether or not they were relevant to the particular diagnosis. They also found the teletype distracting, noisy, and slow. The need for an acceptable simulation system remains, and at present our Minisim and verbal modes are proving useful in training junior clinical students. Future simulators should be flexible, economical, and acceptably realistic—and to us this latter criterion implies the two-way use of speech. We are currently developing and testing such a system. PMID:5579197

Evolution of the intelligent telecommunications network

NASA Astrophysics Data System (ADS)

Mayo, J. S.

1982-02-01

The development of the U.S. telecommunications network is described and traced from the invention of the telephone by Bell in 1876 to the use of integrated circuits and the UNIX system for interactive computers. The dialing system was introduced in the 19th century, and amplifiers were invented to permit coast to coast communication by 1914. Hierarchical switching was installed in the 1930s, along with telephoto and teletype services. PCM was invented in the 1930s, but was limited to military applications until the transistorized computer was fabricated in 1958, which coincided with spaceflight and the Telstar satellite in 1962. Fiber optics systems with laser pulse transmission are now entering widespread application, following the 1976 introduction of superfast digital switches controlled by a computer and capable of handling 1/2 million calls per hour. Projected advances are in increased teleconferencing, electronic mail, and full computer terminal services.

Continuous water sampling and water analysis in estuaries

USGS Publications Warehouse

Schemel, L.E.; Dedini, L.A.

1982-01-01

Salinity, temperature, light transmission, oxygen saturation, pH, pCO2, chlorophyll a fluorescence, and the concentrations of nitrate, nitrite, dissolved silica, orthophosphate, and ammonia are continuously measured with a system designed primarily for estuarine studies. Near-surface water (2-m depth) is sampled continuously while the vessel is underway; on station, water to depths of 100 m is sampled with a submersible pump. The system is comprised of commercially available instruments, equipment, and components, and of specialized items designed and fabricated by the authors. Data are read from digital displays, analog strip-chart recorders, and a teletype printout, and can be logged in disc storage for subsequent plotting. Data records made in San Francisco Bay illustrate physical, biological, and chemical estuarine processes, such as mixing and phytoplankton net production. The system resolves large- and small-scale events, which contributes to its reliability and usefulness.

Design and implementation of a medium speed communications interface and protocol for a low cost, refreshed display computer

NASA Technical Reports Server (NTRS)

Phyne, J. R.; Nelson, M. D.

1975-01-01

The design and implementation of hardware and software systems involved in using a 40,000 bit/second communication line as the connecting link between an IMLAC PDS 1-D display computer and a Univac 1108 computer system were described. The IMLAC consists of two independent processors sharing a common memory. The display processor generates the deflection and beam control currents as it interprets a program contained in the memory; the minicomputer has a general instruction set and is responsible for starting and stopping the display processor and for communicating with the outside world through the keyboard, teletype, light pen, and communication line. The processing time associated with each data byte was minimized by designing the input and output processes as finite state machines which automatically sequence from each state to the next. Several tests of the communication link and the IMLAC software were made using a special low capacity computer grade cable between the IMLAC and the Univac.

Toward The Goal Of Video Deaf Communication Over Public Telephone Lines

NASA Astrophysics Data System (ADS)

Healy, Donald J.; Clements, Mark A.

1986-11-01

At least 500,000 profoundly deaf persons in the United States communicate primarily by American Sign Language (ASL), a language quite distinct from English and not well suited to writing. Currently, telephone communication for an ASL user is basically limited to use of a teletype machine, which requires both typing skills and proficiency in English. This paper reviews recent research relevant to the development of techniques which would allow manual communication across existing telephone channels using video imagery. Two possibilities for such manual communication are ASL and cued speech. The latter technique uses hand signals to aid lip reading. In either case, conventional television video transmission would require a bandwidth many times that available on a telephone channel. The achievement of visual communication using sign language or cued speech at data rates below 10 kbps, low enough to be transmitted over a public telephone line, will require the development of new data reducing algorithms. Avenues for future research toward this goal are presented.

HYDES: A generalized hybrid computer program for studying turbojet or turbofan engine dynamics

NASA Technical Reports Server (NTRS)

Szuch, J. R.

1974-01-01

This report describes HYDES, a hybrid computer program capable of simulating one-spool turbojet, two-spool turbojet, or two-spool turbofan engine dynamics. HYDES is also capable of simulating two- or three-stream turbofans with or without mixing of the exhaust streams. The program is intended to reduce the time required for implementing dynamic engine simulations. HYDES was developed for running on the Lewis Research Center's Electronic Associates (EAI) 690 Hybrid Computing System and satisfies the 16384-word core-size and hybrid-interface limits of that machine. The program could be modified for running on other computing systems. The use of HYDES to simulate a single-spool turbojet and a two-spool, two-stream turbofan engine is demonstrated. The form of the required input data is shown and samples of output listings (teletype) and transient plots (x-y plotter) are provided. HYDES is shown to be capable of performing both steady-state design and off-design analyses and transient analyses.

For whom the bell tolls: Silver Alerts raise concerns regarding individual rights and governmental interests.

PubMed

Wasser, Tobias D; Fox, Patrick K

2013-01-01

The Silver Alert system was initially created to help protect missing persons who have cognitive impairments, particularly the elderly. The Silver Alert is modeled after the Amber Alert, created to help locate and safeguard missing children. Unlike the Amber Alert, however, in most states the Silver Alert applies to the elderly, adults with a mental impairment, or both, depending on the state. The goal of the Silver Alert system is the quick dissemination of information about missing persons to law enforcement personnel as well as to the general public. Previously, states notified law enforcement personnel of missing persons through teletype to other public safety jurisdictions to enlist their assistance in the retrieval of the missing person. Silver Alert programs substantially expand the notification to include the general public, who receive information through radio and television broadcasts as well as highway billboards. The programs serve a legitimate governmental interest by protecting a vulnerable population from possible harm. Yet, the implementation of these alerts can have unintended consequences, including the possible violation of an individual's right to privacy. Such consequences require careful consideration.

ERTS operations and data processing

NASA Technical Reports Server (NTRS)

Gonzales, L.; Sos, J. Y.

1974-01-01

The overall communications and data flow between the ERTS spacecraft and the ground stations and processing centers are generally described. Data from the multispectral scanner and the return beam vidicon are telemetered to a primary ground station where they are demodulated, processed, and recorded. The tapes are then transferred to the NASA Data Processing Facility (NDPF) at Goddard. Housekeeping data are relayed from the prime ground stations to the Operations Control Center at Goddard. Tracking data are processed at the ground stations, and the calculated parameters are transmitted by teletype to the orbit determination group at Goddard. The ERTS orbit has been designed so that the same swaths of the ground coverage pattern viewed during one 18-day coverage cycle are repeated by the swaths viewed on all subsequent cycles. The Operations Control Center is the focal point for all communications with the spacecraft. NDPF is a job-oriented facility which processes and stores all sensor data, and which disseminates large quantities of these data to users in the form of films, computer-compatible tapes, and data collection system data.

In-harbor and at-sea electromagnetic compatibility survey for maritime satellite L-band shipboard terminal

NASA Technical Reports Server (NTRS)

1974-01-01

Geostationary maritime satellites, one over the Pacific and one over the Atlantic Ocean, are planned to make available high-speed communications and navigation (position determination) services to ships at sea. A shipboard satellite terminal, operating within the authorized maritime L-band, 1636.5 to 1645.0 MHz, will allow ships to pass voice, teletype, facsimile, and data messages to shore communication facilities with a high degree of reliability. The shore-to-ship link will also operate in the maritime L-band from 1535.0 to 1543.5 MHz. A significant number or maritime/commercial ships are expected to be equipped with an L-band satellite terminal by the year 1980, and so consequently, there is an interest in determining electromagnetic compatibility between the proposed L-band shipboard terminal and existing, on-board, shipboard communications/electronics and electrical systems, as well as determining the influence of shore-based interference sources. The shipboard electromagnetic interference survey described was conducted on-board the United States Line's American Leader class (15,690 tons) commercial container ship, the "American Alliance" from June 16 to 20, 1974. Details of the test plan and measurements are given.

Interoperability through standardization: Electronic mail, and X Window systems

NASA Technical Reports Server (NTRS)

Amin, Ashok T.

1993-01-01

Since the introduction of computing machines, there has been continual advances in computer and communication technologies and approaching limits. The user interface has evolved from a row of switches, character based interface using teletype terminals and then video terminals, to present day graphical user interface. It is expected that next significant advances will come in the availability of services, such as electronic mail and directory services, as the standards for applications are developed and in the 'easy to use' interfaces, such as Graphical User Interface for example Window and X Window, which are being standardized. Various proprietary electronic mail (email) systems are in use within organizations at each center of NASA. Each system provides email services to users within an organization, however the support for email services across organizations and across centers exists at centers to a varying degree and is often easy to use. A recent NASA email initiative is intended 'to provide a simple way to send email across organizational boundaries without disruption of installed base.' The initiative calls for integration of existing organizational email systems through gateways connected by a message switch, supporting X.400 and SMTP protocols, to create a NASA wide email system and for implementation of NASA wide email directory services based on OSI standard X.500. A brief overview of MSFC efforts as a part of this initiative are described. Window based graphical user interfaces make computers easy to use. X window protocol has been developed at Massachusetts Institute of Technology in 1984/1985 to provide uniform window based interface in a distributed computing environment with heterogenous computers. It has since become a standard supported by a number of major manufacturers. Z Windows systems, terminals and workstations, and X Window applications are becoming available. However impact of its use in the Local Area Network environment on the network traffic are not well understood. It is expected that the use of X Windows systems will increase at MSFC especially for Unix based systems. An overview of X Window protocol is presented and its impact on the network traffic is examined. It is proposed that an analytical model of X Window systems in the network environment be developed and validated through the use of measurements to generate application and user profiles.

hwhap_Ep26_Can You Hear Me Now

NASA Image and Video Library

2018-01-05

Production Transcript for Ep26_Can You Hear Me Now.mp3 [00:00:00] >> Houston, We Have a Podcast. Welcome to the official podcast of the NASA Johnson Space Center, Episode 26, Can You Hear Me Now? I'm Gary Jordan and I'll be your host for the very first episode in 2018! Happy New Year! So on this podcast, this is where we bring in the experts, NASA scientists, engineers, astronauts, flight controllers, all the coolest people! We bring them right here on the show to tell you all the coolest stuff about what you want to know, about what's going on here at NASA. So, today, we're talking about space communications and communication networks with Bill Foster. He's a ground controller in mission control Houston, and we had a great discussion about how space communication works, what it'll look like in the future, and why it's so important to make missions successful. So with no further delay, let's go lightspeed and jump right ahead to our talk with Mr. Bill Foster. Enjoy! [00:00:45] [ Music & Radio Transmissions ] [00:01:09] >> Touch on this later if you want to, but one thing that I always wondered about, you know, the Apollo 13, the movie, you see them entering the blackout, and then there's this big tension because they're not talking after they're supposed to be out of the blackout. [00:01:22] >> This is after reentry, right? [00:01:24] >> Yep. Reentry, and everybody's worried and a minute goes back and, you know, the blackout is pretty predictable. You know when you're going to lose contact, you know when you should get it, so, there's no contact. Two minutes later or so, they make contact. [00:01:40] >> Yeah. But that's a tense two minutes! [00:01:42] >> So I went over -- I was at the space center Houston the other night when they premiered the mission control film. [00:01:49] >> That's right! [00:01:50] >> Which included that aspect of it, and afterwards, Krafton and Kranz and Lonny [phonetic] were all in front taking questions. Somebody asked them, why was the blackout longer than expected? And Kranz's answer was, we were so happy to hear them, we didn't really care. [Laughing] Then somebody finally answered the question. [00:02:12] >> Yeah. [00:02:13] >> For reentry over water, there was no ground station nearby, and they used what's called an ARIA, a-r-i-a aircraft. [00:02:23] >> Okay. [00:02:23] >> And what they said was, probably the, you know, the areas were always somewhat unreliable in a quarrying contact. They just may have been pointing -- looking the wrong way or they may have had an equipment issue onboard, but, you know, they came out of the blackout right when they should have, but it just took a couple of minutes for the aircraft to lock up on them. [00:02:45] >> Oh, wow! [00:02:46] >> So that was interesting. [00:02:47] >> Yeah! Well, how about that? Did -- are we recording? Yeah! [Laughter] We got it! Awesome! Well, that's great! Okay, so for those, yeah, we are -- I have Bill Foster here with me. He is a ground controller in mission control, and he did -- he's ground control -- at the ground control console in the mission control center in Houston for the International Space Station. I got to ask him, to start off, how's Major Tom? [00:03:13] >> We're still looking for him. [00:03:14] >> Oh, okay. [00:03:14] >> And we had a big setback early last year, we think we may have lost all hope of finding him when David Bowie passed away. [00:03:22] >> [Laughing] Yeah. Oh, that's an oldie, but I had -- I mean, how often can you do that, right? [00:03:27] >> I bring that up frequently when I'm talking to people, and that's one of the first things, we're still looking for Major Tom. It's not quite as good as it used to be. [00:03:37] >> [Laughing] I don't know, I think it's pretty good. I was dying to say that for -- for this podcast. But, so today we're going to be talking about space communication, how that works. You know, when you think about mission control Houston, you know, the center of talking with people in space and other centers, really, how does that work? You know, that's -- that's really the main question, and the thing I really want to answer. So, first of all, if you had to describe a ground controller in one or two sentences, what does a ground controller do? [00:04:06] >> TDRSto toilets. [Laughter] Three simple words. [00:04:10] >> Yeah! TDRS to toilets, okay. [00:04:12] >> Ground control is responsible for making sure our communications with the space station and any other human spacecraft is maintained, and that's the [inaudible] part of it, tracking and data relay satellite. That's the geosynchronous communication satellites we use to -- to talk to spacecraft today. And the toilet reference is just we also are responsible for anything to do with the mission control center facility itself. [00:04:37] >> Oh, I see. [00:04:38] >> I have grabbed a mop and headed into the ladies room one time many years ago. [00:04:42] >> Really? [00:04:43] >> Yeah, so. [00:04:43] >> Wow, okay, so that's -- I like that! So your control of the satellites, the TDRS satellites, and we'll talk about those later, but those -- those are the satellites that are way out in space, right? 23-ish... [00:04:52] >> 22,300 miles up. [00:04:54] >> That's it. Yeah, okay, all the way out there, down to the toilets that are right next to you in mission control? Wow. [00:05:01] >> We had a, coincidentally, had a power hit that affected pretty much all of JSC today. [00:05:05] >> Yeah, we just had it here too! [00:05:07] >> Yeah, so that was a big thing in the control center this morning, you know? Fortunately, our -- our backup battery systems and our diesel generators out back all kicked in and there was virtually no disruption to operations in the control center. So the ISS mission, they lost air conditioning in their room for about half an hour, you know, that wasn't enough time for it to heat up appreciably, but, beyond that, there were no notable impact. Some of the simulations, like the one that I was on, and the ISS simulation, they were affected, because the simulator building does not have the backup power. So, yeah, that took about an hour, hour and a half hit to the simulations, but the MCC stayed up. [00:05:51] >> Alright, all part of your day-to-day jobs, right? Is maintaining the power. So you do the -- are you in charge of the backup power too? [00:05:58] >> We -- we have to be aware of it. The Center of Operations Director here at JSC provides that power to us. They -- they maintain and -- and operate all of the systems, the diesel generators, the -- the large banks of batteries that are always online, but if we have a power issue, like we did today, then the GC is the first person that the flight director goes to to find out what's happening, and we'd have to make sure that our backroom support personnel are working with the center ops personnel to understand what happened, and to take whatever steps are necessary to ensure it's no impact, or minimal impact, operations. [00:06:38] >> Nice. Okay, well, okay, so, another, you know, a big thing that we really want to talk about today is -- is your responsibility, as ground controller, is the communication networks that gets us, you know, you in mission control, and -- and everyone there, especially CAPCOM oht, talking with the folks in space. That's really the thing. So, how is that set up? How do you go from the headset down in mission control to, you know, whatever the, I forget what the device is called, but where the astronauts talk into? [00:07:05] >> Well, it's -- it's a complicated system, but, as you said... [00:07:09] >> It's a loaded question, I guess. [00:07:10] >> Everyone in the control center has a headset all, you know, our biggest tool is communications, whether it's looking at data coming down to us, being able to send commands up, talking to the crew, or talking to each other. So we have our voice system that we call, DVICE, Digital Voice Interface Communications Equipment, say that a bunch of times. [00:07:30] >> Oh, yeah. Yeah, is it -- you pronounce it device or is it d-vice? You just do device? [00:07:35] >> I do device, but some people say, d-vice. [00:07:37] >> Okay. [00:07:37] >> But it's just, d-v-i-c-e. [00:07:39] >> Oh, okay, so, I boxed out the E, there it is. [00:07:42] >> Sort of stutter into it. So DVICE is a digital voice communication system. So when you put on your headset and you plug it into the console, the jacket that connects it to DVICE, and then you log into your DVICE, that's establishing a connection into a computer in another part of the building, and once you pull up a given voice conference, or we call them loops to talk on, when you talk, the DVICE system turns that into -- to bits, 1's and 0's, sends it over a fiber optic cable down to the computer system in the bottom. Sends it back out to anybody else that's listening on that loop, turns it back into audio. When CAPCOM talks on it, on the -- the space-to-ground loops, it goes down to DVICE, gets turned into audio, gets sent over to what we call air-to-ground voice equipment, or AGVE, that equipment takes it and modulates it, adds it to the command link that we have going up to the space station. [00:08:46] So it produces a combined 32 kilobit link that goes up to the station that has two voice channels, and, I'm sorry, 72 kilobit link, has two 32 kilobit voice channels and a 6 kilobit command channel in it. And onboard the station, the voice is pulled out, turned back into audio that the crew can hear, when they respond, the reverse process happens. It gets digitized, sent down on the link, sent over to AGVE, turned back into a voice signal, goes into DVICE where it's digitized again. Goes out on the fiber optic cables back up to the CAPCOM or anybody else that's listening to the space-to-ground and turned back into audible voice that you can hear. [00:09:30] >> Oh, wow. [00:09:30] >> So whether you're talking to the crew or I'm talking to someone at White Sands, New Mexico, that's the ground station for our TDRS satellites, or anywhere else in the country, or talking to our counterparts in Japan or Germany, our -- our Marshall Space Flight Center, that same process is happening, converting it into digital signals, sending it through land-based communications lines to other control centers where their voice system converts it back into something that's audible for the controllers on that end of the loop. [00:10:01] >> Wow! Okay, so, I'm imagining when it gets through the fiber optic cable to the part where it actually sends it to space, right, so you get -- you get to that, is that -- is that a dish? I'm imagining a dish. [00:10:12] >> At a certain point, it goes through a couple of dishes. [00:10:15] >> Oh, okay. [00:10:16] >> So -- so from the MCC, it goes out on just commercial T1 lines, basically, just communication lines. It goes to White Sands, New Mexico, it goes through a lot of processing equipment there, and then it goes into this large dish that's communicating with the TDRS satellite. So there -- there's a composite K-band signal, and K-band is a fairly large bandwidth signal that we send up to the -- the satellite. Now the TDRS uplink to the TDRS satellite is much larger because it combines not just ISS for mission control, but potentially other spacecraft users. [00:10:57] >> Hmm, so you share that -- those satellites? [00:10:59] >> Yeah, so that one dish going up to the satellite is going to a TDRS satellite that has two single access dishes, and each of those dishes can be pointing at a different spacecraft. It also has an array of what they call multiaccess dishes that could be going to up to six other additional satellites. So that uplink from the ground could be supporting up to 6 or 7, maybe even 8 different spacecraft. [00:11:26] >> Wow. [00:11:27] >> From the TDRS spacecraft, we always use, for -- for ISS or any human spacecraft, we use a single access dish. So we're the only customer on that particular dish on the TDRS satellite that's pointing at our spacecraft, ISS this case, and it's sending -- it takes that big KU output going up to it, and breaks out just mission control's communications, which contains the command and voice and video signals, because we're going to also send video or other information up to the space station. And sends it out on either S band or K band links to the spacecraft. [00:12:09] >> Wow. [00:12:10] >> So the S band link has just the commands and voice part of it. The K band link has two voice channels, typically does not have command data, although it could under certain circumstances, but it also has file uplinks, video uplinks, we can send video programming up to the crew. Now, the crew was there for six months at a time. [00:12:31] >> Right. [00:12:32] >> They get off work at the end of the day, they can't close the door, go get in their car and drive home. [00:12:36] >> Right. [00:12:37] >> But just like anybody else, it's nice to relax after work. So we have the ability to send up sports programming, news programming, depending on the crew, some of them just want to see video coming up from the control center, see the people that are supporting them. [00:12:52] >> Oh, cool! [00:12:52] >> So we had the ability to send programming up to them. They also had a lot of pre-recorded material onboard, DVDs, Blu-Rays, whatever, they can pick a lot of what they want ahead of time, to take up with them. [00:13:06] >> Very cool! So how -- I'm guessing this whole thing, right, of sending information on the S bands and K bands, all the way to the...is that instantaneous? All of that happening, like, as fast as I can snap my finger, or is it happening [inaudible]? [00:13:19] >> It's happening at the speed of light. [00:13:20] >> Oh, okay. [00:13:21] >> But consider light travels 186,000 miles per second, when you're going from here to White Sands, that's not that far compared to the speed of light, but now you go from White Sands 22,300 miles up into space, now you're getting a little bit of distance there. And then 22,300 miles, maybe 100 miles, back down to the orbiting spacecraft, but, of course, they're not necessarily directly under TDRS, so, you know, it could be a lot further than that. [00:13:51] >> Right. [00:13:52] >> So -- so just consider, it's about a 45,000 mile round trip to get there. Well, now you're talking about a significant fraction of the speed of light, up to a fourth, maybe even a little bit more than a fourth of that, so you are starting to talk about [pause] in the quarter to half a second delay, particularly if it's -- it's roundtrip, we talk to them, and they respond. Well, now you're going 90,000 miles roundtrip, plus the time it takes for the crew to hear what you're saying and respond to it. So, if you're talking to the crew from the ground, I've only done this once, and I've seen other people that don't do it often do the same thing, you talk. They don't respond in what your mind assumes as a normal response time. So you think they didn't hear you, and you start talking again, and about that time, their response is coming in. So it's -- it's real easy to talk over each other. So the -- the experience, CAPCOM, knows, say what you're going to say, wait, the response will be coming, and... [00:14:56] >> Oh, wow. [00:14:57] >> ...continue that way. [00:14:59] >> That's awesome! I didn't know. I mean, that -- I would have -- I would have thought it was instantaneous, but when you talk about, you know, the space station is 250 miles above the earth, that's not that far compared to 23-ish,000 miles for the -- for the satellites to go up and down. So, some recent news, is very soon, I forget how many days, well, at least by the time this comes out, it probably will have already happened, but at the time of this recording, April 13th, it hasn't happened yet, an ultra-high definition video.... [00:15:30] >> April 26th, I think. [00:15:31] >> April 26th, yeah. [00:15:32] >> We saw some words on that today, coming up, making sure our ground controllers that will be on console are ready to support that, to go ahead. [00:15:38] >> Yeah, so does that -- does that use the same network? [00:15:40] >> Yes. [00:15:41] >> Oh, and it can support ultra high definition? [00:15:43] >> Yeah, right -- right now, the -- the Space Station can support up to a 25-megabit uplink to the station using K band. So that's a pretty big pipe. But it can support up to 300 megabits downlink. [00:15:58] >> Oh! [00:15:58] >> You know, so that 4K ultra video, high-definition video, is going to come through that 300 megabit link down, that same link also supports 6 standard definition video channels down, to normal high-definition channels down, plus a lot of telemetry data, all the voice that comes down, so it -- you know, we're still not using all of it. [00:16:24] >> Yeah, wow! [00:16:25] >> However, the purpose of the Space Station is science, and science, sending a lot of the science data down does take a lot of bandwidth, and there are plans in work that are going to upgrade that downlink to a 600 megabit capability. [00:16:38] >> Oh, very cool. [00:16:39] >> Yeah, so. [00:16:39] >> Are you talking about videos for science too? Or -- or mainly, I guess everything, right? [00:16:44] >> Everything. [00:16:44] >> Yeah, like all data and video and audio, everything, so. [00:16:49] >> Everything in that -- that big pipe coming down. [00:16:52] >> That's -- it's got to be a big pipe to support all that stuff. [00:16:55] >> Yes, sir. [00:16:56] >> So let's go -- let's go back 23,000-ish miles above the earth to the TDRS satellites. So, you know, we keep -- we keep saying, TDRS , TDRS , TDRS , but, you know, what is that? What is that network? [00:17:07] >> Yeah, the TDRS network was established back in the early part of the shuttle program. You know, prior to that, and I guess you can take a step back to fully understand it, you know, look back at where we were with Mercury. When the Mercury program came, there was a need to get data from a spacecraft and to communicate to the spacecraft, but nothing existed. And NASA established a manned spaceflight network putting ground stations around the world, they looked at the -- the orbital track that a spacecraft was going to go on its first few orbits, launching due east from Kennedy Space Center, or, at that time, Cape Canaveral. And they placed ground stations to cover a lot of that area, in Africa and Australia, Bermuda, across the United States. So you had ground stations in Corpus Christi, for instance, in California, so when you launched, the spacecraft would go over those ground stations, and -- and if it was a straight overhead pass, it could last as long as eight minutes. [00:18:21] And during that time, you could communicate with it, but for Mercury, they really didn't have a good way to get the data back to the control center at Cape Canaveral. So they... [00:18:29] >> Oh, so this is going to the ground stations, right, not to the...? [00:18:32] >> Right, so they sent people out there and they had teletype communications between the ground stations and the mercury control center, where information could be passed back and forth to the people on the ground or the people back there. Well, they knew, as we were moving into Gemini and beyond, that that wasn't going to work. [00:18:49] >> Right. [00:18:50] >> Mission control in Houston was designed to have an integrated communications network, which was -- became known as the NASA communications network, or NASSCOM, that would connect all of this together, but you still had the limit that the spacecraft had to be over a ground station. And because of the way they were placed, for 2 or 3 orbits, you could have maybe not quite half of the orbit covered by ground stations, maybe less, but you'd have a lot of that where you can communicate with it. And that's how we did Apollo. Now for Apollo, they also used several tracking ships and aircraft to cover areas where there were no ground stations, but they knew there was going to be critical events happening. And those were all tied together, and all the data did go back to mission control in Houston. So we didn't have to send personnel out to the ground stations for Gemini, Apollo, or beyond, all of that came into the control center. [00:19:48] >> So there were no satellites established at this point, right? All -- all the information from the moon was going to all these different points on the earth? [00:19:54] >> That's correct. When we landed on the moon, when the first steps on the moon, I believe that was coming to us through Australia, through the Canberra, or -- oh, which station? It wasn't Canberra, but one of the stations in Australia. [00:20:07] >> Wow! [00:20:09] >> And all being relayed back to us. So, in fact, there was a -- a big controversy, not sure it's ever been completely settled about what Neil Armstrong actually said when he landed -- when he took his first step on the moon, was that, one small step for man or one small step for a man. And he claims he said a man, but you don't hear it, there's a lot of effort, including someone that had tapes from the Australian ground station in his attic [laughing], which probably about 10, 15 years ago were -- were discovered and sent back and I don't think that's still solved the mystery. The assumption was that it -- it came down clearly to Australia, but it was distorted in the transmission back to the control center. And I don't think we've ever really resolved that. So, officially, it's one small step for man. [00:21:02] >> Right. Oh, wow! How about that? Just a little bit of a -- little bit of a gap there. I remember seeing that, just because I was trying to come up with a name for this podcast, and I was like -- I was looking through like historical quotes and stuff, and I was like, I wonder if I can take like a, you know, one small step for man, or something like that? And I found, like, a little parentheses over a, because I guess there was this controversy around it. [00:21:24] >> And, again, I don't know that it was ever resolved. [00:21:26] >> Wow! [00:21:27] >> But we still, again, we still had these gaps in between ground stations that was a concern. And -- and moving into shuttle, which was going to be a -- a -- it never panned out to be what it was going to be, but a -- a reusable spacecraft that could be launched many times in the same year, you know, 30, 40, 50 flights a year, for the same orbiter. That would have been nice [laughter]. But communications was going to be even more important and -- and that's where they working to the -- the space network, the -- the -- all the ground stations were part of the ground network. There's also a deep space network, and when we went to the moon, we used the deep space network that was -- it's based out of the jet propulsion laboratory. [00:22:11] >> Okay, in California? [00:22:12] >> Right. So when you go above -- too far above low-earth orbit, then ground stations, normal ground stations, and their intent is no longer suffice, and you need the -- the very large ground stations, antennas that the deep space network provides, and instead of an antenna so much tracking a spacecraft, it goes across the horizon, the earth is tracking the spacecraft as it rotates around the world, when it gets far enough out. [00:22:43] >> Yeah. [00:22:43] >> But the antenna is still moving a little bit, but a lot slower for than something in low-earth orbit. [00:22:49] >> Were there -- were there large gaps then? If -- if there were all these [inaudible]? [00:22:52] >> For when you get far enough away, and the moon's far enough away, there are no gaps. You handover between Canberra, Australia to Goldstone to Madrid, and those are the three major, the main ground stations in the deep space network, and we will be using that again when we start flying the Orion missions. [00:23:12] >> Alright! So, yeah, it would have been -- I went out to JPL back in October, as a familiarization visit, to -- to look at the Goldstone location, to look at their operations at JPL and to start learning how the ground controllers here at Houston are going to be scheduling those assets in a similar way that we schedule the space network assets. [00:23:34] >> Oh, so the deep space network, you gotta -- you gotta share too, right? [00:23:37] >> Yeah. And the difference there, when we -- when we schedule a space network assets, which are used by a lot o of other users in low-earth orbit, we have to forecast roughly 17 days ahead of time to -- to schedule what we think we're going to need for a week's worth of -- of passes, so, tomorrow we'll be sending in a schedule request for a week that begins two weeks from Monday. [00:24:09] >> Oh, wow. [00:24:10] >> For the JPL, for the deep space network, you put those types of forecast requests in months in advance. [00:24:16] >> Oh. [00:24:17] >> And, you know, one of the things we look at, well, you know, for Orion missions, you almost certainly going to have a launch slip. So months in advance, we say, we're launching this day, we need this support based on our trajectory here, here, and here, and all of a sudden, we slip a day, and all of that's out the window. [00:24:36] >> So during an Orion mission then, so, I guess, you know, you'll be communicating with Orion, but then there's going to be periods during that mission, whatever -- whatever it may be, where you're going to have to trade off and maybe someone else is going to have to take priority for a little bit? [00:24:51] >> It's very possible. [00:24:52] >> Okay. [00:24:52] >> Yo uknow, for any mission, you've got periods that are higher priority than other periods. So you don't have to maintain constant communications with the spacecraft, and we don't with ISS. You know, we frequently have 20, 30 minute gaps, unless we need to have continuous comm. Same thing with -- with Orion. You know, when you're getting ready for a maneuver or an orbital burn or an inner-planetary burn, then you want to have communications, you want to be able to talk to the crew, you want to be able to look at the data coming from the spacecraft, particularly after the burn to make sure that it actually did what you expected it to do. So, during those periods, we will -- we will have solid communications for as long a period as we need to. But during quiescent periods, it's not as important, you know, you don't have to stay in touch the whole time, and other users, you know, are out there that, you know, you got to program Pluto, well, they want communications too. [00:25:54] >> Yeah! Yeah! Well, yeah, it makes a lot of sense. So I'm thinking, I mean, right now, I was just reading about Cassini. Cassini's going to start making passes on the inner rings and then, you know, make a controlled entry into Saturn to... [00:26:08] >> Suicide. [00:26:09] >> Yeah, suicide dive, kind of, so, you know, it doesn't affect [inaudible] or tighten or anything like that, and can cause contamination, so, you know, not to be -- not to be mean, but that's one less spacecraft we have to worry about on the deep space network [laughing]. [00:26:23] >> Well, and you're right. You know, it's really not a huge issue sharing times, again, for -- for most of the planetary spacecraft that are out there, it's not that difficult for them to plan months ahead of time. You know, they know when we're going to do this burn in a year and a half. You know, so they can plan when they need that communication. [00:26:45] >> Yeah. You guys must be really good at scheduling, if you're planning that far in advance. [00:26:51] >> Well, I got to -- got to admit, I admire the people at JPL, because the detail they go to, particularly if they're doing a -- a course correction, you know, want to sling around a planet and get a gravity assess to go somewhere else, you know, just the planning for when to make that happen is incredible, but then you also want to have that communications to verify that it's doing what you're doing. And, of course, when they do that, you know, when we're talking to the space station, we talked about the delay, it's -- it's near instantaneous, within a -- a quarter to half a second roundtrip. When you're talking something out of Pluto, it's hours. [00:27:33] >> Right. [00:27:33] >> You know, it's literally hours. It -- it was sort of funny watching some of the Mars landings, and you would see the people at JPL and their control center, and they would get data back that, you know, reentry has started, and they're up jumping and cheering, you know, and I'm thinking, we don't do that! Sit down! Behave yourselves! [Laughter] But, be it, there's nothing they can do at that point. That reentry started 20, 30 minutes ago. [00:28:01] >> Right! At that point, it's like -- it's like a replay. [00:28:04] >> Chutes are out! Yeah! Jump and down! You know, it's -- come on, you know, but, you know, for us, when the shuttle landed, chutes were out, you know, we still had work to do, and this was virtually real-time, so it's -- you know, you couldn't jump up and down and shout and whatever, but for JPL, yeah, that's okay. They're watching events that happened. You know, it may have already crashed and burned by that time, but they don't know it yet. [00:28:30] >> Yeah. [00:28:31] >> And, fortunately, in most cases, it didn't, and it lands very nicely and the rovers are wandering Mars, doing great things, years beyond what they were planned to do! So we got to admire those people out there. [00:28:42] >> Oh, yeah! Curiosity... [00:28:43] >> However, if you go to their control center, right in the center of it, they got this little glass, plexiglass plate with an emblem down there that declares they are the center of the universe. I don't know about that [laughter]. [00:28:58] >> A little egotistical, but okay. [00:29:00] >> It's a great place. [00:29:02] >> Oh, yeah. So they were using the deep space network then to watch... [00:29:04] >> Yeah, so they almost exclusively used the deep space network. [00:29:08] >> Okay, but I would say we use for the International Space Station the TDRS satellite. [00:29:13] >> Right, the space network. We -- we use the G and the ground network for space station, very rarely we use Wallops and White Sands and Armstrong, they're VHF radio capability as an emergency voice capability for the space station. We don't -- I don't think we've ever had to actually use it in an emergency situation, but we schedule passes several times a year to provide proficiency training for the ground stations, and also for the crew and operating the radios to talk to us. So, you know, we do that, but that's the only time we actually use ground station. For normal communications, it's all space network, TDRS. [00:29:58] >> So, the TDRS satellites, you said, you know, some of them are pointing towards the spacecraft and some of them are pointings out towards other things, and this is -- and this is a communication network that you have to share. But, you know, that -- that's 23,000 miles up, there's -- there's several satellites around the earth, right? [00:30:16] >> Yes. there are. [00:30:17] >> So how many are there, and how do they talk to each other? [00:30:21] >> We're [inaudible], I say our, the space network, I believe, on their 12th satellite on orbit. The first one was launched on STS6, back in the 1983 timeframe, I believe. It had problems getting up there. The -- the booster that was supposed to take into geosynchronous orbit malfunctioned. [00:30:46] >> On the satellite? Or on the...? [00:30:49] >> Yeah, for the TDRS satellite, it had an inertial upper stage booster... [00:30:54] >> Oh, okay. [00:30:54] >> That was attached to it that was going to burn, take into geosynch, then the booster would drop off. [00:30:59] >> Okay. [00:31:00] >> And the burn didn't happen correctly. It ended up in a very elliptical orbit, thousands of miles below where it should have been. [00:31:09] >> Oh, so I guess it's unreliable at that point, right? [00:31:12] >> What they had to do on that one, because each satellite has a certain amount of fuel onboard, propellant to basically keep it in its orbitor, to make slight adjustments if they need to drift it to a different part of the earth. They had to use a fair amount of that propellant to gently boost it up into the right orbit. So that -- that reduced its overall lifetime, it's no longer operational, but it did provide great support for many years. So that first one covered the Atlantic Ocean region. [00:31:46] >> Oh, okay. So, 23,000 miles up, that's -- you get that sliver, and I guess, you know, they used all the propellant to... [00:31:53] >> To get it up there, so you get almost a third of the earth. [00:31:55] >> A third of the earth, okay! That's decent. [00:31:58] >> So, and we use that beginning with STS-8, and -- which, before that point, the shuttles were using ground station just like everything else before it, every other spacecraft before that. So, you know, we had the limitations. You first orbit, you had a good amount of communications, first three orbits, and then you drifted off range of most of the ground stations. You might end up with an 8 minute pass every orbit or every 90 minutes. [00:32:25] >> Wow! [00:32:26] >> So, you know, from a control center standpoint, you know, that gives you a chance for a bit of a break, but we don't want that long of a break. We want to stay in touch with them. [00:32:35] >> That's right. 8 minutes is a long break, but, you know... [00:32:37] >> So when the first TDRS got up, we didn't cover a fair part of the orbit -- of half of the earth. Yeah, so starting somewhere with the Pacific to right before the Indian Ocean, you could cover communications. Then we later put up the next TDRS, and, unfortunately, it was destroyed in the Challenger accident. So the second TDRS never made it into space. STS-26, the return to flight, put up for the third TDRS, which became the second operational one, and that closed most of the orbit. You had a -- a -- sort of a banana-shaped sliver over the Indian Ocean that became known as the zone of exclusion. [00:33:22] >> Oh. [00:33:22] >> Where you didn't have communications. And the biggest problem there is, you've got to, you know, picture the TDRS satellites, they have to communicate through a ground station, and that ground station is in White Sands, New Mexico. So they have to be able to see White Sands. So you -- you put one satellite as far east of White Sands as you can, but still maintain good connection with the ground. You put the other one as far west as you can covering the Pacific Ocean region, but still being able to see the ground. [00:33:55] >> And then the other one on the other side? [00:33:57] >> Well, at -- at that point, that's all we had. [00:34:01] >> Oh! [00:34:01] >> But we did -- I think there was 7 TDRS that went up on shuttles before they started going through the expendables to put them up. [00:34:10] >> Oh, okay. [00:34:11] >> But, you know, we eventually got enough to have spares on orbit and solidly cover the east and west side. In the late 90's, there was a scientific satellite, it may have been TRN, but I forget specifically, they had a spacecraft emergency. And as part of the recovery of that, they really needed to have continuous coverage around the earth. So that zone of exclusion was a big hindrance to them. And they took one of the spare satellites, drifted it over the Indian Ocean, they brought up a ground station in the Canberra, Australia, one of the old deep space network stations, I think we still use it for deep space, but they put a capability there to talk to TDRS. And then sent back that -- sent that back to White Sand, so we -- we were able to close the ZOE. [00:35:03] >> Nice. That happened when? [00:35:07] >> I want to say '99, but it was the late -- it may have been, maybe it was the early 90's. Somewhere in the 1990's. So when I started as a GC, it was already there, and that was '97, so it was before '97. [00:35:22] >> Okay. [00:35:24] >> They -- yeah, we need this, and so they built a permanent ground station on Guam, which is known as the Guam Remote Ground Terminal, GRGT, and so we have that today, there's, you know, and so we have that today, you know, for space station, we have a satellite we call 275, it's -- which is the longitude that it's at. And we use it to cover the gap. For a long time, there were limitations to that, for instance, the ground link between Guam and White Sands didn't have enough bandwidth to cover video. So if we were only 275 satellite, we could cover the -- the telemetry and command and voice gap, but you couldn't get video up or down through that. Last year, I believe it was -- they upgraded the link between there and now we can have full video service, full bandwidth, so regardless of where we are in the world, we can have a full communications with the International Space Station. [00:36:28] >> Nice! [00:36:29] >> There's five satellites that we -- that the ISS uses. There's two over the eastern region, what we call TDRS East and TDRS Spare. There's two over the western region, TDRS West and a TDRS that we just refer to it by longitude, 171. [00:36:47] >> Okay. [00:36:47] >> And then we have 275 over the Indian Ocean. So we'll use three of them, you know, one east, one west, and one in the Indian Ocean to cover the entire orbit, if we need to, for -- for EVAs and spacewalks, for robotics operations where we need to have a good link to the ground. We'll declare a TDRS critical period, and for a period of several hours to maybe a day or more, we will schedule constantly during that period. If we don't have critical activities going on, then we'll schedule around important events. If there's a private conference with the crew, we want to make sure that we have good S band coverage, preferably good K band coverage if it's a private family conference where we're setting up a video teleconference capability, then we want to have that K band covered. So, the -- the ops plan control -- controllers in there that look at what's being planned, one of their backrooms generates the TDRS coverage request that says these are the times we really need to have that coverage, which is given to another position called pointing, which then uses tools that they have that -- that takes in the altitude timeline of the space station. [00:38:10] Which is important, because you need to know how the station is pointing it in a particular side to know whether it has a good -- a good view of a TDRS satellite or whether there's blockage to some of its antennas. And then they design which satellites were used at any given time, and that all goes into a forecast request that's provided to my position, the ground controllers, and then we work with the people out of White Sands to physically schedule those satellites for the time required. [00:38:40] >> I see. And so the ops planner, that's -- that's another flight controller position, right? Your ground control, ops planner, they're the ones planning out and they -- they determine those times and they send the information to you. [00:38:50] >> They take inputs from the increment lead team that says this is what the crew needs to do at any given time, and they pull all the science inputs and the crew inputs and everything into one, big package and have to come up with a plan of what coverage is needed to support that. And then it goes, like I said, to pointing, who determines what works and what doesn't work. You know, we have to be in view of the satellite, but we also have to have good antenna coverage for S band, S band is a lower data rate, and its -- doesn't require as precise pointing. [00:39:29] >> Okay. [00:39:29] >> So, the coverage for S band is a lot better, generally. K band is a very much higher rate signal that has a dish antenna on the space station that has to be precisely pointed at the dish antenna of the TDRS. And depending on the attitude of the space station, there's plenty of times where solar rays, trusses, or other structure of the space station block that. [00:39:54] >> And those are predictable, right? So even though you schedule, you prioritize the schedule for, say, a spacewalk, and you prioritize the schedule, you're still going to have little periods of -- of interruptions, and it's because of that? [00:40:06] >> Exactly. And -- and because of that, you know, you have two satellites over the east, two over the west. Sometimes you've got bad KU coverage over one of those satellites, but just because of a slight difference, maybe 3 to 4 degrees difference on orbit, but that's at 23,000 miles up, so that's quite an angular distance. You may have better coverage over the other -- from the other satellites. So pointing, they'll look at their tools and they'll say, well, normally, we would use TDRS East to cover this part of the world, but for this particular request, or requirement, TDRS Spare is going to provide better coverage. :45 Or normally we would take TDRS East until we run out of view of it, and then if we needed 275, hand up to it, or maybe that last portion of the pass is bad coverage, but 275 is good, and since we can do video through that now, then we can move on. They'll say, let's schedule this for that period of time. [00:41:05] >> Right. So there's a lot -- there's a lot going on behind the scenes that creates that clean coverage that we're just not aware of. There's handovers and all kinds... [00:41:13] >> That's all the forecast period. That's saying nothing ever changes, but it does change frequently. So in the real time period, you know, we -- once the forecast is scheduled and set, you enter the real time period about a week before you actually start using that. Which means pointing outcomes and says, well, the trajectory has changed a little bit since we generated that forecast request. Or this spacewalk has been added here, or something else, due to some reason that wasn't predicted ahead of time, and now we need different coverage. So that then comes into a -- a system where they generate a -- what we call a flight note that says, change up our coverage based on this, and the flight director will have to approve that, and then the GC, my position, will go work with White Sands and say, we -- we need to give up this time, but get this time, and White Sands may say, well, another user has that time, so what's the priority? [00:42:16] You know, can we bump the other user or, you know, is it a TDRS critical period that's driving that? In which case, we probably can bump the other use, because human spaceflight has higher priority, in general, than scientific spacecraft. [00:42:31] >> I see. [00:42:32] >> But not always. It -- there's lots... [00:42:35] >> But in -- in times of like a spacewalk or something, then I guess it would take -- it would kind of trump it? [00:42:40] >> Yes. It would -- it would trump it. Sometimes we have to get the management at Goddard involved to go arbitrate or -- or, you know, help us with our request. [00:42:51] >> Oh, you guys got to fight over the....? [00:42:52] >> There are times we do. And we -- we can never know who the other users are. You know, that's -- that's their business, not our business, they don't know who we are when we're asking for their time. So the terminology is a higher priority user needs this. [00:43:08] >> In general, who are some of the other folks that use the TDRS satellites? [00:43:11] >> Most of them are like Hubble space -- space telescope, TRM was a good example, different satellites doing earth sciences. But Department of Defense also uses them. [00:43:23] >> Oh! [00:43:24] >> And sometimes when you get a higher priority user, they really are a higher priority user, and we -- we can tell from the way things are being told to us that we don't need to go fight this battle, we're not going to win [laughter]. But if we have a spacecraft emergency, that bumps us up to the highest priority user. [00:43:43] >> Totally makes sense. So, we're running out of time just a little bit, but I do want to talk about one more thing before I let you go, and that's, I know, you know, we're talking about how the International Space Station has near instantaneous, you're saying quarter of a second-ish, roundtrip communication. I know if we go to Mars, when we go to Mars, that's going to take a long time. We're talking about way longer than just a fraction of a second. Are we -- are we training for what that's going to look like? [00:44:13] >> Yes, we are! That certainly is a consideration, we actually began several years ago with an experiment. I think it's been a while since we've done it, but we've put delay equipment into one of our space-to-ground channels up to the crew. We -- only one of them though. And it was a planned experiment with the crew where we would talk from the ground, and it would sit on the ground for 10 minutes before being sent up. [00:44:42] >> Yeah, right. [00:44:42] >> And the crew would respond, and it would sit on the ground for 10 minutes before being put into our voice system. So you'd have a 20-minute round-time delay. And -- and they would practice with simple tasks. You know, and that's depending on circumstances. You know, a 10 minute or longer one-way trip time is very possible as you head toward Mars. [00:45:04] >> Right. [00:45:05] >> The other day, when I was at that mission control film, Dr. Kraft was asked, you know, what the next step for NASA should be? And he says, I don't know why we're going to Mars? [00:45:16] >> Oh. [00:45:16] >> He said, you go to the moon and explore its resources, you're a 3 second voice time away. If you go to Mars, you're 40 minutes away. [00:45:25] >> Yeah. [00:45:25] >> And, you know, and there's a lot of other reasons on that, but -- but that's a good example. So -- so we're thinking along the lines of, well, right now, we talk to the crew, and we say, they're having a problem, and someone on the ground, well, this procedure says they should go do this, so we tell them that. Then they go do that, and then it doesn't work, and they say, well, that didn't work, what should I do next? And, well, go try this. Well, you can't do that real time when you're a 20 or 40 minute round trip voice path away. [00:45:57] >> Yeah, you have a problem, you're not getting an answer for 40 minutes. So you've got to frame your questions and your directions a lot differently. You know, we -- we want you to try this step, if that doesn't work, go to this part of the procedure, if that doesn't work, go to that part of the procedure. You've got to understand and think of what the problems could be ahead of time, and you want to package that conversation one way to include as much information and as much alternate things that they can do as possible, and they get that and they try it, and they'll have to package their response back in a similar way that says we did this and we did that and we did this, and maybe this worked, or maybe we got this indication, not that indication, you know, and so instead of a quick, 2 second voice uplink, you may have a 2 or 3 minute voice uplink to them, to give them a lot of options, they can go work, and then respond back. [00:46:58] So those types of things are part of the planning process, and -- and how do we handle this obstacle? We can't beat physics. So, how do we work with it to the best of our advantage? [00:47:10] >> Right. So the main thing really you discovered is that talking on Mars is going to be really, really annoying, so. [00:47:16] >> It will be. [00:47:17] >> [Laughing] But you're coming up with all the right techniques to make sure it's... [00:47:20] >> But we go back to the JPL session, you know, when they -- because they send back something say it worked, you can jump up and down and cheer, because, you know, you're not affecting anything real time. [00:47:31] >> Yeah. Very cool! Okay, well, I think that's -- that's about all the time we have. Bill, thank you so much for coming... [00:47:37] >> It's my pleasure. [00:47:38] >> ....and talking about space communication. Learned a lot, I'm sure there's much more to this topic. If there's anything we missed, stay tuned to after the outro music here, and we'll tell you about how to talk to us to see if there's -- if you have any suggestions for questions or topics that we can answer. So, Bill, thanks again for coming on the show, and hopefully we'll see you next time! [00:47:58] >> You bet! Y'all have a great day! [00:47:59] >> Thanks! [00:48:00] [ Music & Radio Transmissions ] Hey, thanks for sticking around! So, today we talked space communication with Bill Foster, and you can learn way more about it if you go on the internet! A great place to go for more information for pretty much everything, including learning about space communication. So I have a website here called, deepspace.jpl.nasa.gov, or you can just go and search for DSNow, that's deep space network now. It's a really cool website where, if you go, you can actually see which satellites are being used for which things in the deep space network. That was one of the main things that Bill and I talked about today. If you want to know more about the International Space Station, where we are sending a lot of our space communication now on a day-to-day basis, you can go to nasa.gov/iss, and learn everything about all the latest updates about the International Space Station. [00:49:13] We have blogs and articles and scientific updates on a day-to-day basis, so make sure you go there. We're also very active on social media for the International Space Station, on Facebook, it's -- the title of the page itself is called, The International Space Station, on Twitter, it's @space_station, and on Instagram, it's @ISS. If you go to any one of those, you can find some great information, but you can also use the hashtag, @asknasa, on any one of those platforms, and we'll take a look and you can submit an idea for a podcast topic or maybe you just have a question, and we'll try to address it later on a podcast, just make sure to mention, Houston, We Have a Podcast, in that hashtag. This podcast was recorded on April 13th, 2017. Thanks to John Stohl, Alex Perryman, and Matt McKinsey for helping with the script, and thanks again for Bill Foster for coming on the show. We'll see you next time!