OCTOBER 11,1976 MISSION STATUS BULLETIN SUPPLEMENT

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Mars OrbitersPiloted by O-PAG

NO SUBSTITUTEFOR EXPERIENCE

Nobody on the Project would deny that the Vikingspotlight is rightfully on the Landers and their excitingsurface missions on Mars. But think about the critical space-craft events that had to be accomplished before the landedmissions could begin, and you might be surprised (andimpressed) by the number of times your mind will have toreturn to the subject of Orbiter performance. Add to thesecredentials the post landing orbital achievements of the two

Orbiters,

in support of the two Landers and on their own,and the sum total of Orbiter value to the Viking storybecomes impressively large — larger in fact in severalrespects not anticipated or planned. The performance oithese remarkable planetary "mariners" has been in thecompetent hands of the Orbiter Performance and AnalysisGroup (O-PAG).

The use of the term "mariner" is not for value of effect.The Viking Orbiters are in fact the latest generation of theMariner spacecraft family — a line of planetary vehicles thatspans nearly fifteen years of inner solar system exploration.Mariners have contributed significant new knowledge, andprovided important new avenues of understanding, aboutour nearest planetary neighbors — Mercury, Venus andMars. Three Mariners have flown past Mars on scienceobservation missions, and one has orbited and mapped thered planet — and still orbits in silence having exhausted itspower supply.

This review isn't intended as a recognition of earlierMariner accomplishments, for they have already receivedtheir tributes. It is intended instead to illustrate that theOrbiter spacecraft concept represents outstanding planetaryexperience in terms of both evolving spacecraft technologyand human technological participation. These spacecraft arethe product of long-term, state-of-the-artevolution, and theFlight Team Orbiter-associated personnel reflect the degreeof conditioning and responsive skill that bespeak a wellseasoned and historically involved team of human minds.

These qualities of spacecraft performance and humantechnical skill have — in combination — served as an invalu-able tool during the construction of the fantastic Vikingsuccess story. O-PAG personnel, from their energeticchief — Ron Ploszaj — down through their organizationalranks, represent Mariner and other programs totalling manyyears of experience. But to understand the importance ofthis experience, one must first comprehend and appreciatethe remarkable performance capabilities of the spacecraftitself.

The Viking Orbiters traveled more than 400 millionmiles through space to intercept a planet that has — duringthe prime mission — been in excess of 200 million milesfrom Earth. Mars is never more than a pinpoint of reddishlight when visible in the night sky. The Orbiters had totransport and maneuver the additional burden of Landercapsules more than 1 1 feet across and weighing more than aton, and they had to be sufficiently larger and heavierthemselves in order to manage the increased burden and tocarry the additional fuel needed to accomplish the task.Together, the Viking Orbiter/Lander configuration weighednearly four tons — by far the largest unmanned planetarypayload ever launched by NASA.

Two distinct propulsion systems are used to maneuverthe Orbiters. The first is represented by small attitude con-trol jets which use pressurized nitrogen to provide pitch/yaw/roll control and pointing accuracy. The secondincorporates a propulsion system and engine that generates300 pounds of thrust to provide the energy needed for £>Gene Hanover, left, Walt Havens andMike Hill - GuidanceControl & Power analysts -observe orbit insertionmaneuvers. -^

VIKING PROJECT OFFICELangley Research Center

VIKING MISSION OPERATIONSNASA Jet Propulsion LaboratoryHampton, Virginia Pasadena, CaliforniaRecorded Mission Status (213) 354-7237 Status Bulletin Editor (213) 354-7873

trajectory corrections enroute, the "no tomorrow" orbit From their central configuration, flanked by the Flightinsertion burns, and the orbital trim maneuvers needed Path Analysis Group (F-PAG) and the Lander Performanceonce in orbit. The state-of-the-art of these propulsion and Analysis Group (L-PAG), O-PAG teams share thesystems allows a degree of performance precision that is responsibility and accomplishments of the major spacecrafttruly hard to imagine - thrust values predictable to a 10th performance events. But, just at those associate groups haveof a meter-per-second, burn times to within fractions of a specific areas of responsibility and can point to the high-second, and attitude accuracies to less than a degree. But lights of their achievements within the scope of that partici-what the spacecraft is capable of doingand what it actually pation, O-PAG has theirs. The Orbiter really belongs todoes is two different things unless. . . unless the prepro- them.grammed software sequences, the Earth-based ground What that means is that once O-PAG has assisted thesystems, and the personnel "minding the store" have all other two groups in their primary tasks, such as supportingbeen tuned to a level of readiness and skill that allows the the major events mentioned and aiding in landing sitespacecraft capability to be utilized to its fullest potential. search programs, Lander relay communication links and inFor Viking -the Deep Space Network was ready, the anomaly investigations, O-PAG is -in turn - the keyground systems and computers were ready, and so was element in all events that tend to pertain only to OrbiterO-PAG! The Orbiters performed so well that percentagesof operations and not to orbital characteristics and Landererror were fractional — only once exceeding 1% for the performance. While this involves many onboard systemsmajor orbit-insertion or landing-preseparation maneuvers. and activities, perhaps the most vital and interesting has toMore recent orbital trim maneuvers have been so precise do with Viking orbital science. O-PAG is responsible forthat errors are difficult to detect. most of the command loads prepared for the Orbiter

regarding the performance of the science scan platform andits instruments, and the pointing of the S/X-band antenna.While most operational subroutines were part of the initialcomputer load, regular uplinks are needed to update thecomputer to execute sequences in reaction to uniquemission requirements under unusual circumstances. Thiswas particularly important during landing site certificationexercises performed by both

Orbiters,

because verydemanding circumstances wereencountered which requiredsignificant changes in the orbital plans and the supporting

ORBITERPILOT

With experience as the key to O-PAG success, it isn'tsurprising to learn that the group's

Chief,

Ron Ploszaj(pronounced Plo-zay) has participated in some manner inevery Mars mission successfully flown — Mariner 5 (1965flyby), Mariners 6 and 7 (1969 dual flyby), Mariner 9(1971-72 orbital) and of course two current Viking Orbiters(1976-7?).

Having that kind of concentrated, high-technologybackground makes Ron sound a little like some kind ofhighbrow engineer who prefers to be buried — with hissliderule — in a mountain of calculations. Not so! Themountains this amiable, aggressive engineer prefers are thegeological type, and even his home is high on a LaCrescenta hillside overlooking the L.A. basin. The O-PAGteams have worked some long, grueling hours during thisViking-dominated summer — keeping Ron and his peopleinside JPL's control center behind their consoles or in worksessions, but Ron is the type who would as soon trade hissliderule for a backpack and his office for a tent when thespacecraft business allows.

The southern California life style and planetaryexploration business have only been part of his youngcareer since he joined JPL in 1967. Like so many of theresidents of this part of the country, Ron is a midwesttransplant. A Chicago product, he developed his technicalexpertisewith a BS in electrical engineering at Valparaiso inIndiana. He later acquired a masters degree at Purdue whilecompleting a hitch in the Navy, but his naval duties werenot those of a "seafarin' man" ... his assignment was atIndianapolis a long way from any seagoing adventure.

Ron shares both his Viking career and his campinginterests with his wife Joanne, his ten-year-old daughter

Susan,

and his seven-year-old son Brian. One would expectthat their camping enthusiasm makes our pictures of theMartian landscape all the more intriguing — what outdoors-man can resist the desire to see what lies beyond thatdistant ridge!?

Watching carefully the Orbiter relay of Lander touchdowndata are, left to right, Deputy ChiefJack Harris, ChiefRonPloszaj, and systems analyst leads Bill Irace and Bob Kocsis.

Ron is assisted in his duties by O-PAG Deputy ChiefJack Harris, who came to the Viking Flight Team fromViking's home base at NASA's Langley Research Center inHampton, Virginia. Jack served as the Orbiter Systemsmanager prior to launch in 1975. John Slonski ofJPL - O-PAG's "Guru" -is Deputy Chief for SystemAnalysis, and Steve Weiner — a Martin Marietta contribu-tion — is Deputy Chief for Operations.

ORBITERPERFORMANCEAND ANALYSIS GROUP PERSONNEL

The Orbiter Performance and Analysis Group (OPAG) and itssecondary teams include the following personnel, with theirhome organizations indicated in parentheses. OPAG CentralResponsibility: Ron Ploszaj, Chief (JPL); Jack Harris, DeputyChief (LRC); John Slonski, Deputy Chief for System Analysis(JPL); Steve Weiner, Deputy Chief for Operations (MMC); JohnRyciak, Documentarian (JPL); Joe Stockemer, Documentarian(JPL); Chuck Williams, Documentarian (JPL); Carolie Raines,Secretary (MMC). Orbiter Systems Analysis Team: JackSchwartz, Team Leader (JPL); Bill Irace, VO-1 (JPL); BobKocsis, VO-2 (JPL). Orbiter Command & Sequencing Team: LewButler, Team Leader (MMC); Nick Medici, Deputy Lead (JPL);Dennis Page, Deputy Lead (JPL); Joe Goudy (LRC); Mac Grant(MMC); Larry Meyer (MMC); Herb Phillips (JPL); Burt Sharpe(LRC); Pete Kobele (JPL); Mike Carter (MMC); Dave Clough(MMC); Mac Jackson (LRC); Gary Ryczek (MMC); Joe Tsai(JPL). Science Payload Analysis Unit - IRTM Team: DonSchofield, Lead Analyst (JPL); Howard Eyerly (JPL); ClaudeMichaux (MMC). Science Payload Analysis Unit - MAWD Team:Don Langford, Lead Analyst (JPL); Rudy Killiam (JPL); DonRupnik (JPL). Sciene Payload Analysis Unit - VIS Team:Maurice Clary, Lead Analyst (JPL); Jim Johnson (Ball Brothers);Clayton Laßaw (JPL). Telecommunications Analysis Unit: JimTaylor, Unit Lead (JPL); George Barbani (JPL); Bill Berkley(Motorola); Bob Faust (LRC); Don Hersey (JPL); Dick Horttor(JPL); Bob Hughes (JPL); Bryan Huneycutt (JPL); Ralph Kanitz(JPL); Tim Kaufman (JPL); Tom Komarek (JPL); Bill Jackson(JPL); Nigel Lambert (JPL); Kermit Pederson (Motorola); FredStolarik (JPL); Ernie Stone (Motorola); Fred Stuhr (JPL); MilesSue (JPL); Ted Talbot (Motorola); Walt Tisdale (JPL); NeilYarnell (JPL); Sam Zingales (JPL). Guidance, Control & PowerAnalysis Unit: Walt Havens, Unit Lead (JPL); Jim Alexander(JPL); Bill Breckenridge (JPL); Phil Brisendine (JPL); DennisCarpenter (JPL); Mike Donovan (Boeing); Ranee Edmunds(JPL); Pat Fitzgerald (GE); John Fowler (GE); Gene Hanover(GE); Mike Hill (JPL); Bob Hughes (JPL); John Kent (JPL); JimLeisenring (Boeing); Howard Marderness (GE); Ed Morgan (GE);Hiroshi Ohtakay (JPL); Phil Pierce (XEOS); Ray Reska (GE);Jack Rhoads (JPL); Don Ritchie (JPL); Doug Roberts (XEOS);Guillermo Rodriquez (JPL); Larry Schumacher (JPL); BobShrake (JPL); Tom Smith (C&D); Fernando Tolivar (JPL); AlTreder (JPL); George Troup (XEOS); Chuck Wong (JPL); RonYoshida (JPL). Thermal & Mechanical Devices Analysis Unit:Jim Stultz, Unit Lead (JPL); Bill Carmines (LRC); Ken Curry(JPL); John Kievit (JPL); Joe Plamondon (JPL); Dan Porter(JPL); Yi-Chien Wu (JPL). Data Systems Analysis Unit: BrianLarman, Unit Lead (JPL); Olen Adams (JPL); Dave Bell (JPL);Carl Bode (JPL); Barbara Brown (JPL); John Buchok (JPL);Glen Bullock (JPL); Ben Dysart (Empire Engrg); Bob Edmonds(JPL); Dave Eisenman (GE); Jerry Erickson (Tl); Carl Geoy(JPL); Dwight Geer (GE); Henry Harper (Tl); Larry Koga (JPL);Wayne Kohl (JPL); Al Lepis (Motorola); Terry Loar (JPL); TomLoesch (GE); Ed Imlay (JPL); Bill Magoon (GE); Maury McEvoy(JPL); Ken McGraw (ATE Associates); George Milligan (JPL);Carl Pearson (LRC); George Reeves (Tl); Dave Rubin (JPL); AlShain (JPL); Al Silliman (JPL); Don Smith (Trend Western); JimStoker (Boeing); Sorkie Tatian (Motorola); Neil Thomas (JPL);Larry Watson (GE); Regina Wong (JPL); Larry Zottarelli (JPL).Propulsion & Pyrotechnic Analysis Unit: Darrell Schmit, UnitLead (JPL); Bob Anderson (JPL); Bob French (JPL); Mike Leeds(JPL); Jack Patzold (JPL); Jack Quinn (JPL); Fred Vote (JPL).

O-PAG is divided into two primary teams — theCommand and Sequencing Team (OCAST) and the SystemAnalysis Team (OSAT). These two teams have been hard atwork with the Viking spacecraft since the launches inAugust and September of 1975, monitoring and controllingtheir progress. While the 1976 June/August Mars orbitinsertions (MOIs) stand out as the highlights of their partici-pation, the O-PAG teams have made other valuable contri-butions beyond what was required of them. One suchcontribution, that could yield extremely dramatic resultsduring the extended mission in 1977, was made by theOCAST team. A technique was devised to slew the scanplatform to provide motion-compensation photography.Close-range pictures of Mars or its natural satellites wouldbe smeared because of the rapid velocity of the spacecraft,and minimum distances were considerable using conven-tional platform positioning. The slewing technique,which islike camera panning from a moving car, has now beentested with exciting results on Phobos (Mars' nearest moon)and is now being refined in preparation for futureapplications.

O-PAG has left a dramaticsignature on the documentofthat story. Years of experience and long hours of intenseViking Flight Team activity have paid rich dividends, andO-PAG personnel don't feel short changed by having toyield Viking limelight to the Landers. In theirwords — ". . . happiness is the successful orbiting of bothspacecraft and the sharing of Lander touchdowns." Thesuccess belongs to them as well, and their pride shows thatthey know it. We know it, too.

Orbiter monitoring is a job of concentration and paperwork — expressed in the activities of analysts Al Lepis,lirian Larrnan, Larry Watson, Ed Imlay and Al Shain. \j

Orbiter propulsion maneuvers must be monitored very care-fully to be certain that performance characteristics arenominal as illustrated in the faces of (back row left toright): unit lead Darrell

Schmit,

propulsion subsystemanalysts Jack Patzold and Mike Leeds, andpyrotechnic sub-system analyst Bob Anderson; and by (front row left toright) temperature control analysts Bill Carmines and JoePlamondon. -W-

\L\/Bill Irace, left, and Deputy Chief John Slonski keep trackof Viking-1 MOI events.

"wfc- In uniform for a VIKING MOI are power analysts PhilBresendine, left, andDon Ritchie.

■^ Analyst GeorgeBarbani Analysts Glen Bullock, left, and Bob Edmondsevaluates Orbiter data, monitor tape recorder data.

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