The Space Congress® Proceedings 1981 (18th) The Year of the Shuttle

Apr 1st, 8:00 AM

Experiences In Delta Mission Planning

Jyri Kork Delta Mission Analysis Manager

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Scholarly Commons Citation Kork, Jyri, "Experiences In Delta Mission Planning" (1981). The Space Congress® Proceedings. 5. https://commons.erau.edu/space-congress-proceedings/proceedings-1981-18th/session-6/5

This Event is brought to you for free and open access by the Conferences at Scholarly Commons. It has been accepted for inclusion in The Space Congress® Proceedings by an authorized administrator of Scholarly Commons. For more information, please contact [email protected]. EXPERIENCES IN DELTA MISSION PLANNING

Mr. Jyri Kork Delta Mission Analysis Manager Goddard Space Flight Center, NASA

solve its initial problems in only three ABSTRACT months and to score 22 successive successes in the next 3 1/2 years, establishing a new In 1959 NASA decided to develop Delta as an early dawn of for medium payloads reliability record for the interim launch vehicle the Space Age. The pattern of surmounting until more sophisticated vehicles reached hardships became In the twenty years difficulties and mastering operational status. somewhat of a Delta trademark, reflecting that have followed, Delta has matured into such as the launch vehicle, in the news media headlines a versatile all-purpose "Space Transportation Workhorse 11 and "The being utilized by various US government Delta. 11 agencies, domestic industry, and a number Indomitable as well. of foreign governments, The philosophy of the Delta launch vehicle cir­ was unorthodox in its inherent simplicity: Delta's 153 launches have included low up-to-date technology sun-synchronous, earth-syn­ to utilize the latest cular orbits, and flight proven hardware, to minimize the chronous, polar, lunar, and interplanetary totally new flight 'firsts' include the necessity of developing missions. Delta's components, while aiming for optimum per­ first international satellite, the first and cost effective­ orbit, the first polar formance, reliability, synchronous transfer ness. Especially the stress on the cost launch from ETR, and the first lunar orbiter spectac­ correction. effectiveness accounted for the without a midcourse velocity ular popularity of the early Delta launch vehicles among the 'poor people of outer Typical Delta mission analysis methods and missions, the feasibility studies, space 1 — non-government results are reviewed: reimbursable launches. In this respect — trajectory shaping, payload, orbit and Delta has range safety without any .false modesty — launch window optimizations, probably been one of the best United States studies, orbit injection error analyses, numerous widely and vehicle sepa­ good will ambassadors in radar tracking coverage, separated areas of our common world. ration dynamics. A number of more pictur­ esque cases of the above missions analyses philosophy was to 'please the past 153 missions, Another basic Delta are highlighted among the customer 1 . It involved many extra week­ as well as among the approximately 40 future not spelled out for the Delta ends of studies in the area.s missions presently scheduled in the formal contract: alternate launch launch vehicle. windows, orbit optimizations over and beyond the call of duty, celestial mechanics lec­ tures to foreign scientists just starting out 1) INTRODUCTION on their road to the stars. In the beginning the Delta launch vehicle was placed The first launch But above all the Delta launch vehicle modest and unassuming, versatility. Missions to be attempt on Friday the 13th, May 1960 ended a premium on an un­ considered covered the whole spectrum of the like the first launch of Vanguard; ranged from the low failure. There was but one basic space studies. Orbits qualified based circular ETR to the high circular WTR difference: Delta — using a design coast on the Vanguard second stage — was able to launches, geosynchronous transfer

6-32 orbits, highly elliptic probes, to lunar, propel"!ant rocket X-258, developed for Scout. and even interplanetary missions. Quite properly, it was called Delta C. Both configurations were popular at their time: Delta's 153 launches and 40 presently sched­ 9 Delta B-s and 12 Delta C-s were launched. uled future missions will be discussed in the following technical review paper. The trend of Delta performance improvements developed into a genuine trademark. An exasperated aerospace engineer (not totally 2) LAUNCH HISTORY sympathetic to Delta) once explained that launch vehicle statistics can only be cal­ A direct outcome of the agreement of the culated if configurations remain identical, United States in 1955 to participate in the which "is true for all of the vehicles but International Geophysical Year (IGY) was Delta, for which some wag has remarked that the development of the Vanguard three-stage 'no two Delta flights have used identical vehicle. In 1959 NASA decided to develop configurations 1 . 11 Delta as an interim launch vehicle for medium-class payloads until more sophisti­ Aerospace engineers have been known to occa­ cated vehicles (such as Scout and Agena, sionally exaggerate. Actually, there have then under development) reached operational been many Delta launches using the same status. The Vanguard second stage and the configuration. Of the sum total of 32 Delta Vanguard third stage X-248 were adapted to flight configurations (ref. 2, 3, 4) two the Thor booster to become the original and were used definitely more than once: Delta the first Delta configuration. E was flown on 22 missions and Delta 2914 on 30 missions. On the other hand, among the The Douglas Aircraft Company (presently 32 development steps, four were used only McDonnell Douglas Astronautics Company - once (Delta J, 1900, 1410, and 1913), while MDAC) was and still is the prime contractor two became true space age collectors' items. for the Delta launch vehicle program. In Delta M6 and Delta 2314 were possible config­ the past 21 years this has been one of the urations that were never flown. Both, of most fruitful government/private industry course, were designed at the time when Delta cooperations. A considerable number of the came with three sets of interchangeable con­ members of the original Delta team are still figurations -- 3, 6, and 9 solids. The operational at both outfits. spacecraft managers, as experience clearly shows, are in these cases apt to "get there The Delta development program involved 12 fastest with the mostest" and pick the highest vehicles of the DM-19 configuration, 11 l of available payload... ' which were successful. No history is complete without the "firsts" In 1962, characteristically, the Delta first that the newspapers used to list in their stage was uprated (utilizing an Air Force "scorebox" when outerspace was young. Thor DM-21 first stage) and named Delta A. After changes in the vehicle control system The honor roll of these early satellite and a fairly extensive ground-qualification "firsts" for the Delta vehicle includes: program. Delta 13 and 14 were successfully 1) First passive communications sattelite launched in October 1962. Only two Delta A (ECHO I) configurations were ever launched. The (handwriting of the Delta was on the wall. 2) First international satellite (ARIEL) ( A long history of the state-of-the-art per­ 3) First privately owned satellite (TELSTAR) formance improvements had just begun. 4) First geosynchronous satellite (SYNCOM I) Delta B was improved by lengthening the 5) First equatorial geosynchronous satellite second stage propel!ant tanks by three feet (SYNCOM III) and changing the oxidizer from white inhib­ ited fuming nitric acid (WIFNA) to inhibited 6) First polar orbiter from ETR (TIROS I) red fuming nitric acid (IRFNA). It added 7) First commercial comsat (EARLY BIRD) roughly 100 Ibs. to a 200 n. mi. circular orbit payload capability. In today's numbers 8) First operational weather satellite it may look like a bag of peanuts, but let (ESSA I) us remember that Vanguard I (still in orbit) 9) First lunar orbiter without midcourse was a whole total of 3.25 Ibs. velocity correction (AIMP-E) Having weathered successfully the improve­ But more than the "firsts", three points ments of its first and second stages, it was evolve from the past Delta history: only logical that the Delta management, in its orderly one-two-three punch sequence, 1) The cumulative launch success ratios next incorporated a new third stage solid have remained in the 92% to 95% region

6-33 2) The probability of on-time liftoff has similar previous Delta mission. remained unbelievably high: 70% for a one second window Preliminary Mission Analysis (PMA). Today 90% for a five minute window the first step of the mission planning that is 'tailor-made 1 for a particular space­ 3) Reimbursable missions have become a craft is the Preliminary Mission Analysis, mainstay of the Delta launch schedule. published usually 8 months before the launch. PMA uses all mission requirements and S/C characteristics (weight, moments of inertia, 3) MISSION PLANNING etc.) in order to generate a trajectory se­ quence and profile. At this time the payload For the purposes of this paper the mission capability is fixed within a few pounds. PMA hardware coordination schedules are not also includes range safety and vehicle dis­ discussed and only mission analysis docu­ persion analyses. Tables, probability dis­ mentation is reviewed. tribution curves, and covariance matrices present predicted dispersions of all space­ Spacecraft Restraints Manual. Whether a craft injection conditions and classical mission falls into the class of the Delta orbital elements. A complete and detailed vehicle capabilities, can be approximately trajectory printout is included in the PMA. estimated from parametric performance curves maintained by Delta mission analysis engi­ Detailed Test Objectives (DTP). Approximately neers and published in the Delta Spacecraft 5 months before the launch a DTO presents the Restraints Manuals (such as ref. 5). Delta total description of all flight objectives, Restraints Manuals include a considerable the nominal trajectory printout, a sequence amount of data besides performance capabil­ of events, a detailed weight breakdown, ities, such as spacecraft design restraints, guidance times and rates, spacecraft and safety considerations, hardware integration vehicle radar tracking data, physical flight schedules and field operations reviews. Such conditions, and other pertinent information. manuals are freely distributed among pro­ DTO is used by MDAC to develop guidance tar­ spective customers and spacecraft agencies geting constants. already committed to a Delta launch. Range Safety (R/S) Studies. In the early Feasibility Study. For a totally new type of days of Delta, roughly 2200 man-hours and mission or a new vehicle configuration, a over 700 IBM runs were needed for the R/S feasibility study must be conducted 2-3 years studies of a typical mission. As impacting before the launch date. The feasibility study an empty stage on Africa or Cuba is consid­ utilizes the best estimate of the physical ered totally taboo, severe limitations on model of the Delta launch vehicle, including the payload capabilities can occur. For possible future improvements. In incorpo­ example, several hundreds of trajectories rates a complete trajectory profile for sun- were run for the P-14 mission, before it was angle, radar tracking, and heat transfer decided to change P-14 from a lunar to a studies, fixing the payload estimates within highly elliptical mission, in order to move 50-100 Ibs. the second stage impact point off the African coast. Reference Trajectory. Historically, the next step for a new type of a mission was a ref­ Guided Nominal Trajectory. As the weights of erence trajectory (roughly one year before all the components of the spacecraft and the the launch). It involved a parametric study particular launch vehicle become finalized, required to define optimum performance capa­ updated, and weighed in, roughly 4-6 weeks bilities for a particular set of mission before the liftoff, a guided nominal trajec­ requirements, such as apogee and perigee tory is generated. It basically verifies altitudes, orbit inclination, argument of that the Delta Inertia! Guidance System perigee, nodal drift rate, etc. As all (DIGS) targeting constants actually result trajectories must satisfy numerous vehicle in all required mission specifications. The constraints, the generation of a reference first stage portion of the flight is based trajectory used to take 128 trajectory simu­ on a five-degrees-of-freedom (5D) trajectory lations and 10 IBM machine hours, back in simulation, incorporating the effects of 1962. (ref. 1). Today, using computerized vehicle rotational dynamics and control trajectory shaping models and the combined system responses during the high aerodynamic Delta experience of the past 21 years, such loading portion of flight. The remainder of a reference trajectory can be obtained in the trajectory is based on a three-degrees- just a couple of machine runs. Even better, of-freedom (3D) trajectory simulation. as the Delta experience includes almost all Engine deflections, guidance steering his­ possible mission profiles, the new customer, tories, and in certain cases even seasonal at this stage, will usually receive the wind altitude profiles are incorporated and already flown trajectory printout of a analyzed in the guided nominal.

6-34 Mission Specific Studies, Theoretical anal­ yses specific to any particular spacecraft easily have a development cost of several million dollars and be jealously guarded as include in all cases a spring separation and a miss distance analysis. If desired by the priceless private property by the origi­ S/C project, other studies such as para­ nator. This, by the way explains, why the metric orbit optimizations, launch window, best computer programs usually have no sun-angle, shadow, and orbital lifetime written documentation. histories are calculated. Delta mission analyses have included Pioneer spacecraft Optimality of the Trajectory Shaping Method. coning, preliminary Shuttle orbital maneu­ Another complication arises from the apparent vers, Spacelab lifetime, ECHO balloon in­ lack of uniqueness of mathematical trajectory flation, and other sometimes exotic shaping methods: there are many roads to studies. outer space. Some methods are better than others and some completely wasteful. NASA Various new computer programs have been has from developed by the Delta Project Office and the very beginning placed a premium MDAC to solve specific on trajectory shaping elegance. To quote mission related ref. 1: "A non-optimum trajectory is frowned problems. For example, a program calcu­ upon, lating the stability of lunar satellites, even if it satisfies the mission re­ an earth atmospheric quirements." In the beginning of the Delta drag model accounting history, the inherent semi-randomness in for both the diurnal and 11 -year cyclic trajectory solar flux variations, a 6-degree-of-freedom optimization methods was one of spinning body the main reasons for the almost astronomical motion analysis, interstellar number of trajectory runs generated (.up to targeting programs, etc. etc. Alone in the 1600 trajectories per Delta Project Office computer library there mission). are presently more than 200 computer programs for various Eleven years and over eighty launches later, areas of mission analysis. with the advent of the DIGS guidance system, it finally became feasible to utilize an 4) TRAJECTORY SHAPING optimum standardized trajectory-shaping technique. Once again the mission analyst The heart of successful mission analysis is was the master of his own fate and the new in the trajectory shaping. This is the method was appropriately called BOSS (Base­ territory where the clean dreams of a rocket- line Optimum Standardized Shaping). With man meet the muddy, tangled swamp of reality. BOSS a control program could be defined by The main areas involved in this complicated systematically scaled attitude rates that in problem are the vehicle and spacecraft con­ general during the test runs resulted in per­ straints, the optimality of the trajectory formance being within 5 fps of possible shaping methods, and maximizing the payload optimum. It not only added up to consider­ capabilities. able time and cost savings, but also to better and higher payload estimates. Vehicle and Spacecraft Constraints. Obviously a trajectory should not be flown, if it pre­ Maximizing Payload Capabilities. When all sents any dangers to the structural integ­ is said and calculated, the spacecraft rity of either the vehicle or the spacecraft. weights sometimes have been known to grow Furthermore, it is a range safety requirement and surpass the vehicle capabilities. What that no part of the vehicle (solids, first did the desperate Delta mission analysts do stage, fairing nose cone, etc.) can impact in these cases? a land area. From the viewpoint of the vehicle structure the product of total angle In the early years, when the trajectory of attack and dynamic pressure must be mini­ optimization still had a touch of luck and mized during the time spent in the region of magic in it, there was sometimes the option maximum dynamic pressure. The altitude- of running another 100 trajectory shapings velocity profile must be selected so that a and obtaining another optimum solution per­ 400 F internal fairing wall temperature limit haps 5 to 10 fps higher (i.e. 1 to 2 Ibs. will not be exceeded during the atmospheric higher) than the DTO. With the present high flight and the heat flux to the spacecraft powered BOSS program this option does not at the fairing drop time does not exceed the usually exist. solar heat input. Considering also the vehicle attitude rate limitations at all When Delta was young, there was another solid drop and stage separation times, it is option of last-minute performance increases: easy to visualize that the mathematical using Air Force surplus stages and having trajectory shaping becomes a complicated a launch rate of 10-12 vehicles per year, balancing act, accessible only to the most the Delta mission planners were able to grab sophisticated electronic computer programs. 'hot off the shelf stages 1 (i.e. vehicles A good trajectory analysis program (such as already scheduled and tested out for Delta the MDAC old AB60 and the new DVPAT) can that had somewhat higher than average thrust or specific impulse values). Finally,

6-35 reaching for the last payload pound in the Another interesting facet of the Delta im­ totally exhausted performance barrel, lighter provement history is taking a count of the telemetry systems, light batteries, removal "Delta building blocks" that have been or of insulation in relatively less important will be utilized. First stages have come in areas, and even leaving the total vehicle four versions: MB-3, Blocks I, II, III, and unpainted, have come up in the history of RS-27. Second stages come historically in Delta. seven versions: AJ10-118, AJ10-118A, D, E, F, TRW-201, and AJ10-118K. There have been And in cases where nothing helped, Delta was also seven types of third stages: X-248, occasionally known to have an extra card up X-258, FW-4, TE-364-3, TE-364-4, and PAM. the sleeve: sudden vehicle improvements. Last, let us also mention that there have been several Delta improvement proposals 5) VEHICLE IMPROVEMENTS that were never approved. Especially dear HOSS (Hydrogen- and to the old timers was the old The Delta vehicle improvement history Oxygen Second Stage), that was first dreamed philosophy has been treated in several up by Delta mission planners in the mid- papers (e.g. ref. 2 and 3). The first early seventies, and sixties, reproposed in the improvements of uprating the second and finally build just recently — by the third stages, successively, have already been mentioned. Japanese! Delta The basic philosophy of the early & THE REIMBURSABLES stressed flexibility and a "building block" 6) COST HISTORY meant to accomodate a feature. It simply The original Delta vehicle, able to launch wide variety of missions. Delta planners transfer orbit, utilize previously developed 100 Ibs into a geosynchronous felt free to was priced moderately at roughly $2.5 M. improvements, flight proven by other agencies. payload capability improvement, was based on Five years later Delta's Delta D, the next for the same mission had more than tripled, the thrust augmented Thor booster (an Air kept low, at the addition of 3 but the cost was stubbornly Force development) and roughly $3 M. Thirteen years from the be­ Castor I solid boosters, almost doubling the payload had risen to capabilities for low circular ginning of Delta the old DM-19 1590 Ibs (almost by a factor of sixteen), orbits. while the price was slowly rising to $7 M (by less than a factor of 3). Thus the cost The 26 past Delta configurations are all at a rate really in the Delta Restraints per pound was coming down listed and described tempting to the non-government (reimbursable) Manual (ref. 5). An exhaustive narrative of Delta model 2914 is market. A comprehensive history Delta history up to vehicle vs. capability is given in ref. 6. included in the MDAC Thor history (ref. 3). cost They all accounted for more than 140 launches, low cost and successful. The main result of Delta's approximately 92% of them flexible configurations was that certain objectives Delta con­ spacecraft planners sized mission There are four presently available and flight hardware to match available Delta figurations: 3910, 3913, 3914, and 3910/PAM. consider a larger planning are the capabilities, rather than Also available for mission spacecraft requiring a much more expensive four improved second stage versions 3920, 3923, 3924, and 3920/PAM. To get a perspec­ launch vehicle. history, let us tive of the Delta improvement Another factor to be considered was the just tabulate the geosynchronous transfer mission planners to 14 typical Delta philosophy of the Delta orbit capabilities for th'e actually search out interested spacecraft models and the years of their arrival: advertize Delta's 100 Ibs planners and to widely 1960 Delta performance capabilities. A typical example 1962 Delta A 150 Ibs seminar held 150 Ibs was the Delta payload planners 1962 Delta B at Goddard, which was attended by more than 1963 Delta C 180 Ibs both Ameri­ 230 Ibs one hundred spacecraft planners, 1964 Delta D can and international. Another example was 1965 Delta E 330 Ibs presentation trip 580 Ibs a famous Delta management 1968 Delta J through seven European countries in fourteen 1968 Delta M 785 Ibs 1969 Delta M6 1000 Ibs days. 1971 Delta 904 1400 Ibs seemingly 1590 Ibs Both low cost and vigorous selling 1972 Delta 2914 helped. As the Delta old-timers used to 1975 Delta 3914 2100 Ibs the only government 2540 Ibs joke, Delta was probably 1980 Delta 3910/PAM able to show a profit. 1982 Delta 3920/PAM 2890 Ibs operation

6-36 The first privately built satellite was Delta as a re-entry test vehicle were con­ Tel star I, the AT&T Bell Telephone Labora­ ducted by MDAC and Delta Project in the same tory's TV satellite in 1962, followed by time frame. Plenty of TelstarJI in 1963. interest. No sales. But the noblest moment of the Delta mission Intel sat F-l, first commercial COMSAT space­ analysts was "Operation Kohoutec". In just craft with 240 voice channels came in 1965, one week all tn-house launch-window and per­ to be followed by an ever increasing percent formance capability studies were completed -- of reimbursable launches. Among the private for 16 launch dates and 8 arrival dates. companies, AT&T and COMSAT were followed by Unluckily, the Smithsonian museum was the RCA and Western Union, all using Deltas to proud owner of the only spacecraft (capable launch their own communications satellites. of such a mission), which they did not want to release from the collections. Luckily, Among other United States agencies, Delta was Kohoutec fizzled and there was no great loss used by the USAF and NOAA (National Oceanic for the history of science. and Atmospheric Administration). Before passing from these lighter interludes The following foreign governments and agencies of the Delta mission analysis, let us just have used Delta reimbursable launches: observe that presently we have shown Delta European Space Agency (ESA) payload capabilities for the rendezvous National Space Development Agency (NASDA), mission with Halley's comet to be in the Japan order of 1480 to 1650 Ibs. Puzzlingly, NATO there seems to be a lack of interest in the BMFT, Germany greatest comet of mankind's history. ONES, France Communication Research Center, Canada Returning to a more serious look to the Telesat, Canada future of Delta, it must be noted that we Indonesian Government (Perumtel) presently are experiencing one of the longest Italian Government [CNR) mission lineups in our whole history. There are presently listed 40 Delta missions, A box score of Delta reimbursable launches extending up to the middle of 1985. (in launch blocks of 50 each) tells the story of the Delta vehicle as a 'good will ambas­ The leading customer is RCA with 5 scheduled sador 1 : launches, f.ol.lQwe.d by Telesat (4). Two Launch numbers No. of Reimbursables scheduled launches, each, are lined up by 1 to 50 11 various agencies: Western Electric, AT&T, 51 to 100 27 India, Indonesia, NATO, etc. A number of 101 to 150 34 the 40 launches scheduled for Delta are obviously Shuttle backup and Shuttle over­ There have recently been years where 80% to flow types of missions, still capable of 100% of Delta launches have been reimbursable picking various options. missions, being a clear statement of Delta's continuing vitality on the space market. 8) CONCLUSIONS 7) FUTURE MISSIONS Delta, being initially considered only as an interim launch vehicle, has survived for An important part of the Delta mission plan­ over 21 years and launched over 150 satel­ ning philosophy was an active pursuit of lites. By following the policy of cost future missions. Among the 153 past missions conciousness, aggressive mission/vehicle there were psyloads originally considering a improvement planning, and 'pleasing the higher priced brand of launch vehicle. By customer', the Delta vehicle has through the performing an unsolicited mission analysis, years developed into a flexible launch which included tempting short-cuts and extra system popular not only in the private sector options, a number of these missions were of the United States, but also in numerous switched to the "low-price brand". To avoid foreign countries and their space agencies. any hard feelings about the past, let's not For the past 50 Delta launches, roughly 75% mention any names at this point. have been reimbursables, a trend seen to be continued in the future. Delta's 40 pre­ On the other hand, various mission analyses sently scheduled future missions may well ended up in limbo, some of them rather compli­ raise the total score to 200, proving that cated and ambitious. For example, Delta a flexible, expendable launch vehicle system missions to both Mars and Venus were exten­ can still remain an active, operational sively analyzed by the Delta office both in space transportation alternative -- even in the 1960-s and 1970-s. There were no firm the dawning of the Age of the Shuttle. buyers. Similarly, two studies considering

6-37 REFERENCES 1) Van Winkle, D. D., "What Price A Trajec­ tory? 11 Douglas Memo A2-260-S/AA-62-66, dtd. 1/23/62. 2) Kork, J. and Schindler, W. R., "The Thor- Delta Launch Vehicle: Past and Future," 19th Congress of the International Astro- nautical Federation, N. Y., Oct. 13-19, 1968; IAF Paper SD32, also "Proceedings of the XlXth International Astronautical Congress," Vol. I, Pergamon Press, 1970. 3) "Thor: The Workhorse of Space -- A Narrative History," MDAC Report MDC G3770, dtd. July 31, 1972. 4) "Delta 1960-1979, 150 Missions, Exploring Space," GSFC Publication, 1979. 5) "Delta Spacecraft Design Restraints," MDAC Report DAC 61687D, dtd. July 1980. 6) Bonnett, E. W., "A Cost History of the Thor-Delta Launch Vehicle Family," MDAC Paper WD 2422, Sept. 1974.

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