SSC00-XI-3 Universal Small Payload Interface – An Assessment of US Piggyback Launch Capability Shahed Aziz AeroAstro, Inc. 327 A Street, 5th Floor Boston, MA 02210 (617) 451-8630 [email protected] Paul Gloyer AeroAstro, Inc. Bldg 8201, Room 209 Stennis Space Center, MS 39529 (228) 688-2790 [email protected] Joel Pedlikin AeroAstro, Inc. 327 A Street, 5th Floor Boston, MA 02210 (617) 451-8630 [email protected] Kimberly Kohlhepp AeroAstro, Inc. 327 A Street, 5th Floor Boston, MA 02210 (617) 451-8630 [email protected] Abstract. Small satellites are becoming the solution of choice for planners trying to reduce space mission costs and shorten schedules. Secondary launches are a quick, frequent, low-cost, reliable solution for small satellites. Most international small spacecraft are launched as secondary piggyback payloads, aboard larger more efficient rockets. However, piggyback accommodations in the US are rare, done only on a case-by-case basis, and far from low cost. AeroAstro is presently developing the Universal Small Payload Interface (USPI), a standardized template for integrating and launching small spacecraft. It is designed so that mission developers can design to its requirements in order to be compatible on demand with a number of different secondary launch vehicle slots. The ‘Phase A’ USPI, based exclusively on existing secondary opportunities, will be complete by August 2000. Phases B and C, based on potential modifications of existing launch vehicles, will be complete by the end of the year. Missions will be quickly designed to a common interface standard, decreasing their dependence on a specific launch. When the spacecraft is ready, the next USPI launch available will be used, bringing ‘launch on-demand’ closer to reality. Introduction assessment is a part of the Universal Small Payload Interface (USPI) project sponsored by This paper discusses an assessment of US the US National Reconnaissance Office capability to launch small or micro-satellites (NRO) Office of Space Launch (OSL). using secondary or "piggyback" launches on large commercial or military launch systems. The motivation for the USPI project is to Secondary launches are payloads that foster US small satellite development by constitute less than 40% of the overall payload allowing cheaper access to space for small, being launched into orbits dependent upon the micro, and pico-satellites. Per-kilogram orbit of the larger – primary – payload. The launch costs for small launchers are roughly Shahed Aziz 1 14th Annual AIAA/USU Conference on Small Satellites three times higher than for large capacity piggyback payloads tend to skew the launchers, while the larger launchers tend to piggyback launch data, they are considered have unused payload mass at launch. shared or co-manifested payloads. Multiple Therefore, exploiting that extra mass capacity payload launches (like Iridium and Orbcomm) for small satellites with standard piggyback also are not considered, as they control the payload adapters would allow cheaper access insertion orbit and are basically treated as to space for these satellites. Anecdotal primary payloads. evidence suggests that US government policy – as the major launch systems customer – has Piggyback capabilities can be assessed by: not fostered piggyback launches for small · The launcher’s historical record of satellites in the US. This paper examines that piggyback launches issue with historical data on piggyback · The consistency of the launcher’s launches and current and future piggyback piggyback payload attachment (i.e. is there accommodations. The assessment used the a standard attachment interface) European Ariane 4 launcher and its ASAP 4 · The provider’s policy regarding piggyback adapter as a benchmark to highlight the payloads opportunities available for small satellites with · The transparency and ease of the process standard piggyback payload adapters and for getting a piggyback payload on a proactive launch policies. launcher The following section describes the criteria Assessments should not be made in isolation, used in the assessment of US piggyback so US piggyback launch capabilities need to launch capabilities. Following the assessment be assessed vis-à-vis the strongest competition criteria is the assessment of historical, present, – a benchmark. Historically, the Soviet Union and planned US piggyback capabilities and a – and now Russia – has been the US’ major discussion of the conclusions based on the competitor in space. However, the assessment. geopolitical competition between the two powers has always overshadowed and strongly Assessment Criteria influenced their competition in space. On the other hand, the Ariane 4 launcher, A launcher’s ability to launch small secondary commercially offered as a launch service by payloads with a much larger primary payload Arianespace SA, has become the dominant is the primary criterion of assessment. commercial satellite launch system over the last two decades. The Ariane 4 – with the To qualify as a piggyback, a payload has to: Ariane Structure for Auxiliary Payloads · Be less than 100 kg (ASAP 4) – is also the major adapter for · Be launched with a much larger payload – piggyback launches to Low Earth Orbit (LEO) the piggyback payload should be less than and Geo-stationary Transfer Orbit (GTO). 40% of the total mass launched on that Therefore, Ariane has been chosen as the particular mission benchmark for US piggyback capability · Be listed as an auxiliary payload on the assessment. ASAP 4 has proven the technical launch manifest data and commercial viability of piggyback payloads. It has also demonstrated the For some small launch vehicles (most notably viability of the European Space Agency Pegasus XL), 100 kg payloads are a large (ESA) policy of nurturing small satellite fraction of available capacity. Since these development by supporting standard Shahed Aziz 2 14th Annual AIAA/USU Conference on Small Satellites piggyback accommodations on Ariane 4 has also forced the majority of Ariane 4 launches. For these reasons, Ariane 4 is the launches to GTO, reducing its share of most appropriate benchmark for assessing US piggyback launches (since GTO does not piggyback capability. seem very attractive for small spacecraft users/ designers). The higher proportion of Ariane 4 piggyback launches therefore reflects Historical Piggyback Capability a much weaker historical US position vis-à-vis piggyback payloads. The major reason for Figure 1 shows piggyback payloads as this discrepency between the two sets of data percentages of all payloads launched through is that ESA policy has effectively forced 1999. The raw data are skewed by the launch Arianespace to offer piggyback of Russian and US (Orbcomm) satellite accommodations whenever possible. clusters. These data show small/piggyback payloads accounting for 6% of the global total Figure 3 shows the global distribution of and 8% of the US (i.e., the US piggyback piggyback payloads by mass with the majority payload launch rate is on par with the global in the 40-80 kg ranges. Soviet/Russian rate in overall percentages). However, the US payloads dominated the 60-80 kg range while should have launched more piggyback the only range with predominantly US satellites compared to the benchmark Ariane payloads is the 40-60 kg range. Russian 4, because they had more launches with the predominance in the 60-80 kg range is same or better payload mass margin available. primarily a historical artifact (although there have been a significant number of Figure 2 shows piggyback payloads as a Soviet/former Soviet piggyback launches, a percentage of all payloads launched by each large number of launches in the early years of active US launch vehicle (the high percentage the space age were below 100 kg because of of Pegasus small payloads are co-manifested lesser payload capacities). Ignoring the launches, mostly for the Orbcomm Russian data, there is again a very strong constellation). US vehicles have launched a representation by Ariane piggyback payloads smaller percentage of piggyback payloads across the mass ranges. This highlights ASAP than Ariane 4. Ariane 4’s dominance of the 4’s capability of handling a wide variety of commercial communications satellite market payloads with the standard piggyback adapter. 100-200kg 100-200kg under 2% 2% 100kg under 4% 100kg 6% over 200kg over 200kg 94% World Payloads 92% U.S. Payloads Figure 1. Piggyback Payloads Launched Through 19991 Shahed Aziz 3 14th Annual AIAA/USU Conference on Small Satellites U.S. Payloads by Launch Vehicle 200 180 160 140 120 100 80 60 40 20 0 Ariane Athena Atlas Delta Pegasus Shuttle Taurus Titan (ref.) Total under 100kg 25 0 0 10 29 9 4 4 Total 100-200kg 3 1 0 0 11 3 0 0 Payloads over 200 kg 177 4 107 183 12 182 4 84 Figure 2. Piggyback Payload Launches by Launch Vehicle for US Vehicles1 The majority of payloads under 100 kg are actually co-manifests – mostly for the Orbcomm constellation.. Ariane data provided for reference. 225 200 175 Worldwide Small Payloads 150 125 100 75 50 25 0 0-20 kg 20-40kg 40-60kg 60-80kg 80-100kg 100- 120- 140- 160- 180- 120kg 140kg 160kg 180kg 200kg US Vehicles 5 4 32 13 2 5 2 1 1 6 Ariane 6 4 13 2 0 0 0 2 1 0 Russian 4 6 16 201 1 2 0 0 0 0 Other 4 4 8 4 3 7 3 7 1 4 Figure 3. Distribution of Small Payloads According to Size1 The majority of US piggybacks (45%) are in the 40-60 kg range. Ignoring the Russian payloads in the 60-80 kg range, Ariane piggybacks are generally across the range. Shahed Aziz 4 14th Annual AIAA/USU Conference on Small Satellites Payloads by Orbit Piggyback Payloads by Orbit 300 313 60 59 250 208 50 200 177 40 150 30 100 57 20 18 10 10 8 0 50 Total U.S. 24 Total U.S. 0 2 0 Ariane 3 Ariane GTO GTO Polar Polar LEO LEO Figure 4.