Jonathan's Space Report No. 310 1997 Jan 12 Toronto, Ontario ------------------------------------------------------------------------------- Shuttle and Mir --------------- Atlantis was launched at 0928 UTC on Jan 12 from pad 39B. Solid rocket booster came at 0930 UTC. The orbiter entered a 51.6 degree inclination orbit around the Earth at 0936 UTC. Atlantis will dock with the Mir orbital station, and NASA astronaut Jerry Linenger will replace John Blaha. Russian astronauts Valeriy Korzun and Aleksandr Kaleri will remain on the station. Recent Launches --------------- The Bion No. 11 spacecraft landed near Kustanai on Jan 7. One of the two monkeys, Multik, died a day later from unspecified causes. Geostationary Transfer Orbits ----------------------------- Some recent comsat launches have used an extremely high apogee transfer orbit with subsequent apogee lowering to reach their final orbits. The following article is an attempt to put this new orbital technique in context. The first geostationary satellite was Syncom 3, launched in August 1964 into a 1113 x 38084 km x 16.80 deg, 694.5 min transfer orbit. A solid motor was used to circularize the orbit at 36000 km. The perigee of Syncom 3's transfer orbit was unusually high; between 1970 and 1990, almost all geostationary satellites used transfer orbits with perigees between 150 and 600 km, and apogees from 34000 to 41000 km. During the 1980s the use of liquid propellant apogee engines (LAEs) began to supersede the older solid rocket apogee motors (AKMs), but it was not until the 1990s that the greater flexibility of the LAE was fully exploited, most notably in Atlas Centaur launches. A number of transfer orbit techniques are now in use. To classify transfer orbits, I consider the first orbit entered by the spacecraft with an apogee above 5000 km (i.e. the first burn after any initial low parking orbit). Thus, the Astra 1F Proton launch in 1996 used a standard GTO of 220 x 36131 x 51.6 for its initial transfer orbit, but the final stage made an extra burn leaving the payload in a 11970 x 35936 x 7.0 orbit. In similar Ariane missions, the final stage would separate in the standard GTO orbit and the LAE first burn would leave the payload in the 12000 km perigee orbit. I don't care whether this extra burn is made by the launch vehicle or the payload, I am focussing on the initial transfeer orbit which in this case is the 220 km perigee one. With this proviso, the different transfer orbits in use can be usefully grouped as follows (names and arbitrary dividing lines are my invention:) (1) Standard GTO: 150-700 x 34000-41000. Still used by almost all Ariane, H-II and Chang Zheng launches. (2) High perigee GTO (HP-GTO): 700-4000 x 34000-41000. This type of orbit was used by Syncom 3 and Early Bird and then abandoned in favour of lower perigees. It appears to have been used by some Titan 34D/Transtage classified missions beginning in 1984, and came back into regular use with the first flight of the Delta 7925 in 1991. All Delta 7925 geostationary missions have had transfer orbit perigees between 700 and 3000 km. Three Atlas launches have also used a high perigee GTO: Galaxy V (1992-13), Inmarsat III F-1 (1996-20) and F-3 (1996-70). (3) Low-GTO: Apogees below 30000 km. For these missions, a perigee motor places the spacecraft in an orbit with an intermediate apogee well below geostationary, and subsequent LAE burns are used to reach GEO. Introduced by the LEASAT/SYNCOM IV spacecraft in 1984, they have also been used by a Titan JCSAT launch and the UHF and Galaxy missions with HS-601 satellites: (UHF F/O F1 was also intended for this orbit but failed). 1984-93 Leasat 2 316 15213 27.2 278.7 Low-GTO 1984-113 Leasat 1 317 15227 27.1 278.95 Low-GTO 1985-28 Leasat 3 317 15877 27.0 288.59 Low-GTO 1985-76 Leasat 4 374 15556 27.5 284.66 Low-GTO 1990-01 Titan/JCSAT 299 19294 26.79 340.91 Low-GTO 1990-02 STS/Leasat 320 15076 27.21 276.73 Low-GTO 1992-072 Galaxy VII 199 29834 6.95 518.52 Low-GTO 1993-015 UHF F/O F1 215 9134 27.28 192.75 Failure 1993-039 HS601-Galaxy 4H 211 27551 6.97 478.28 Low-GTO 1993-056 UHF F/O F2 222 14928 27.00 273.39 Low-GTO 1994-035 UHF F/O F3 225 15596 26.95 283.30 Low-GTO 1995-003 UHF F/O F4 297 27437 26.74 477.79 Low-GTO 1995-027 UHF F/O F5 290 26514 26.93 461.43 Low-GTO 1995-057 UHF F/O F6 260 27482 26.97 477.94 Low-GTO 1996-042 UHF F/O F7 276 27198 26.88 473.21 Low-GTO (4) Sub-GTO: Apogees between 30000 and 34000 km. A different compromise between final stage and LAE fuel loading, I treat these missions as different from the Low-GTO ones since only a small burn is needed to reach final altitude, although it could be argued that 25000 km would be a better dividing line. The only such mission launched to date is DBS 3 in 1995, although two earlier non-GEO science satellites used such orbits as their final mission orbits. 1978-87A EXOS-B 230 30558 31.09 532.9 Sub-GTO 1990-065 CRRES 332 33724 18.07 593.99 Sub-GTO 1995-029 DBS 3 237 32782 6.91 574.33 Sub-GTO (5) High-GTO: super-synchronous transfer orbits with apogees between 41000 km and 50000 km. These orbits have the advantage that, since the apogee velocity is lower, inclination changes take less fuel (the low initial inclination of Ariane launches is presumably the reason that standard GTO is fine for them). Apogee is then lowered after the plane change. Some USAF classified launches in the CANYON and VORTEX programs have used marginally high apogees around 41000 km, but their final orbits were elliptical and no apogee lowering was required. Two scientific satellites in near-geosynchronous orbits, IUE and SCATHA, also used high apogees. The GOES weather satellites were the first operational geostationary satellites to use such transfer orbits, with apogees around 50000 km, starting with GOES 4 in 1980. Since then, three commercial satellites (Eutelsat II F3 and two Apstars, on Atlas and CZ-3) have used such orbits. 1978-12 IUE 173 46081 28.71 840.64 High-GTO 1979-06 SCATHA 185 43905 27.39 794.8 High-GTO 1980-74 GOES 4 167 49610 26.50 917.03 High-GTO 1981-49 GOES 5 167 49645 26.50 917.79 High-GTO 1983-41 GOES 6 263 48017 24.87 884.27 High-GTO 1991-083 Eutelsat II F-3 854 41247 16.93 753.48 High-GTO 1994-022 GOES 8 113 42247 27.41 758.81 High-GTO 1995-025 GOES 9 130 41709 27.12 748.07 High-GTO 1994-43 CZ3/Apstar 210 42039 26.62 756.52 High-GTO 1996-39 CZ3/Apstar 225 42184 26.93 759.84 High-GTO (5) Super-GTO. The truly spectactular super-synchronous transfer orbits used by some recent commercial satellites reach apogees previously only explored by deep space research probes. The first highly eccentric GTO mission was the Intelsat 603 satellite, launched from LEO in May 1992 following its repair by astronauts on mission STS-49. It reached an apogee of over 70000 km. This was followed by the Orion 1 satellite in 1974, which reached a record-breaking 120000 km, almost a third of the way to the Moon. I also include the scientific ISO satellite in the list below. 1990-021 Intelsat 603 9169 71624 7.28 1677.60 Super-GTO 1994-079 Orion 1 379 120929 25.61 2878.61 Super-GTO 1995-043 JCSAT 3 187 79154 22.95 1639.02 Super-GTO 1995-062 ISO 537 72555 5.19 1475.07 Super-GTO 1996-006 Palapa C1 253 89628 21.86 1928.33 Super-GTO 1996-054 GE 1 196 56275 25.03 1068.17 Super-GTO Table of Recent Launches ------------------------ Date UT Name Launch Vehicle Site Mission INTL. DES. Dec 4 0658 Mars Pathfinder Delta 7925 Canaveral LC17B Mars probe 68A Dec 11 1200 Kosmos-2335 Tsiklon-2 Baykonur LC90 Recon 69A Dec 18 0157 Inmarsat III F3 Atlas IIA Canaveral LC36 Comsat 70A Dec 20 0644 Kosmos-2336 Kosmos-3M Plesetsk LC132 Navsat 71A Dec 20 1804 USA 129 Titan 4 Vandenberg SLC4E Recon 72A Dec 24 1350 Bion No. 11 Soyuz-U Plesetsk LC43 Life sci 73A Jan 12 0928 Atlantis Shuttle Kennedy LC39B Spaceship Current Shuttle Processing Status ____________________________________________ Orbiters Location Mission Launch Due OV-102 Columbia OPF Bay 1 STS-80 OV-103 Discovery OPF Bay 2 STS-82 Feb 13 OV-104 Atlantis LEO STS-81 Jan 12 OV-105 Endeavour Palmdale OMDP ML/SRB/ET/OV stacks ML1/RSRM-58/ET-81 VAB Bay 3 STS-82 ML2/ LC39B STS-81 ML3/RSRM-59/ VAB Bay 1 STS-83 .-------------------------------------------------------------------------. | Jonathan McDowell | phone : (617) 495-7176 | | Harvard-Smithsonian Center for | | | Astrophysics | | | 60 Garden St, MS6 | | | Cambridge MA 02138 | inter : jcm@urania.harvard.edu | | USA | jmcdowell@cfa.harvard.edu | | | | JSR: http://hea-www.harvard.edu/QEDT/jcm/space/jsr/jsr.html | | Back issues: ftp://sao-ftp.harvard.edu/pub/jcm/space/news/news.* | '-------------------------------------------------------------------------'