1989-033B
The Venus Radar Mapper, Magellan, was deployed from orbiter Atlantis at 0102 on 1989 May 5 (?) into a 90.5 min, 295 x 303 km x 28.9 deg orbit. The SRM-1 stage of IUS-18 was fired at 0201:33 to place the stack in a 271 x 25790 km x 28.0 deg transfer orbit; at 0206:28 the SRM-2 ignited, cutting off at 0208:13 and separating at 0227:22 to placed Magellan in solar orbit. IUS delta-V was 4.8 km/s.
Three course corrections were made on the way to Venus: TCM-1 at 0200 on 1989 May 22, TCM-2 on 1990 Mar 13, and TCM-3 on 1990 Jul 25. Magellan's perihelion was on 1989 Oct 7.
At 1900 on 1990 Aug 9, Magellan was 387000 km from Venus; by 1600 on Aug 10, the range had dropped to 20000 km. The probe's Star 48B solid motor ignited for an 83s burn at 1632 on Aug 10, and at 1634 Magellan was inserted into a 294 x 8472 km x 85.5 deg orbit around Venus, reaching periapsis at 1637. The Star 48 separated at about 0130 on 1990 Aug 11. Mapping of Venus would take several months.
The nominal mission was complete by 1991 Apr 28, with the spacecraft in a 290 x 8460 km x 85 deg orbit. At 1833 on 1991 May 17, a 33 min orbit trim changed the ascending node, and Cycle 2 radar mapping began. From Jun 27 to Jul 10 the probe filled in gaps in the Cycle 1 survey. Cycle 3 began in 1992 Jan, and was interrupted from 1992 Apr 22 to May 11 for X-band doppler data used for gravity field mapping. Radar operations were also suspended in June and abandoned on 1992 Sep 13.
On 1992 Sep 14, a 54 min OTM (Orbit Trim Maneuver) lowered the orbit from 258 x 8450 km to 182.5 x 8450 km for Cycle 4's gravity mapping program. At 1731 on 1993 May 25 a 10 min OTM lowered the orbit from 170 x 8450 km to 147 x 8450 km beginning the Transition Experiment (TEX). This would be the first use of aerobraking by an American spacecraft. At 1900 Magellan entered the Venusian atmosphere for 36 minutes; a second pass was made at 2214. Precise control of the orbit was now necessary to ensure that Magellan's orbit was changed in the desired manner without burning the spacecraft up. The first Corridor Orbit Trim Maneuver (COTM) at 1246 on 1993 May 26 lowered periapsis to 146.2km, a double burn at 2107 on May 27 put it at 143 km. COTM 3 at 1757 on May 29 left the orbit at 141.1 x 8200 km. By Jun 2 it was 140.6 x 7900 and the apogee was dropping 100 km a day. The solar panel temperatures increased by 40 degrees during atmospheric passes, to 337K. COTM 4 at 1724 on 1993 Jun 4 raised the perigee slightly, to 141.1 x 7700 km. By Jun 14 the apogee was down to 6600 km. Upward perigee maneuvers COTM 5,6, and 7 were due on Jun 16, 20 and 24. On Jun 25 the orbit was 139 x 5300 km. COTM 8 was due in late June, COTM 9 was at 0007 on Jul 1. The process continued through July; by Jul 23 apogee was only 1800 km. A new series of 5 EOTMs (Exit OTMs) began at 1140 on Aug 3 when perigee was raised by 14 km, and at Aug 5 the TEX was complete with Magellan in a 197 x 540 km orbit. A new phase of gravity mapping, Cycle 5, now began.
The end of Cycle 5 was marked by 2 OTMs on 1994 Mar 10 which lowered the periapsis by 24 km. On Apr 4-5 and Apr 11-12 a further series of burns lowered the orbit from 184 x 530 km to 212 x 384 km. Cycle 6 began on Apr 15.
The final phase of Magellan's mission began on 1994 Aug 25 with 2 OTMs to lower the orbit to 172 x 390 km. From 1994 Sep 6 to Sep 9 controllers carried out the Windmill Experiment, in which Magellan's solar panels were turned into the wind and the torque on them was measured. Another OTM on around Sep 28 lowered the orbit again; on Oct 11 the orbit was lowered into the atmosphere. Two-way communications with Magellan were lost at 1002 on Oct 12, but intermittent signals were detected from the spacecraft until around 1800 on Oct 12.
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| Magellan |
| |
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| Date | Time | Event | Orbit |
|---|
|
| 1989 May 4 | 1847:00 | Launch from LC39B |
| 1989 May 5 | 0101:32 | Magellan deploy | 294 x 303 x 28.9 |
| | 0110 | Solar array deploy |
| | 0201:33 | IUS SRM-1 burn 149s |
| | 0203:42? | IUS SRM-1 burnout | 292 x 25796 x 28.0 |
| | 0203:42? | IUS SRM-1 sep |
| | 0206:28 | IUS SRM-2 burn 105s |
| | 0208:13? | IUS SRM-2 burnout |
| | 0227:22 | IUS SRM-2 sep |
| | 0756? | Pass EL1:4 |
| 1989 May 7 | 2010? | Solar orbit insertion |
| 1989 May 17 | | 3.12 Mkm from Earth, 2.67 km/s rel |
| 1989 May 18 | | 3.35 Mkm from Earth, 2.65 km/s rel |
| 1989 May 22 | 0200 | TCM-1 3.0m/s |
| 1989 Aug 7 | | 26.0 Mkm from Earth |
| 1989 Oct 7 | | Perihelion |
| 1989 Oct 17 | | 109 Mkm from Earth |
| 1990 Mar 13 | | TCM-2 |
| 1990 Jul 25 | | TCM-3 |
| 1990 Aug 6 | | 4347000 km to Venus |
| 1990 Aug 8 | 0720? | Enter Venus sphere |
| 1990 Aug 9 | 1900 | Range 387000 km |
| 1990 Aug 10 | 1600 | Range 20000 km |
| | 1632 | Vrel = 10.818 km/s |
| 1990 Aug 10 | 1632:09 | Star 48 VOI burn 2.7 km/s Vrel=8.2 km/s |
| | 1633:32 | VOI | 294 x 8472 x 85.5 |
| 1990 Aug 11 | 0130 | Star 48 sep |
| 1991 Apr 28 | | Nominal mission complete | 290 x 8460 x 85 |
| 1991 May 17 | 1833 | OTM 33 min, Cycle 2 |
| 1992 Jan | | Cycle 3 mapping |
| 1992 Apr 22 | | Begin X-band doppler |
| 1992 May 11 | | End X-band dopller |
| 1992 Jun | | Radar ops suspended |
| 1992 Sep 13 | | End of radar ops |
| 1992 Sep 14 | | Cycle 4 gravity mapping | 258 x 8450 |
| | | OTM 54m | 182 x 8450 |
| 1993 May 25 | | Begin Transition Experiment (TEX) | 170 x 8450 |
| | | OTM 10m | 147 x 8450 |
| | 1900 | First aero pass, 36 min |
| | 2214 | Second aero pass |
| 1993 May 26 | 1246 | COTM 1 lower peri | 146 x 8450 |
| 1993 May 27 | 2107 | COTM 2 | 143 x 8400? |
| 1993 May 29 | 1757 | COTM 3 | 141 x 8200 |
| 1993 Jun 2 | | | 141 x 7900 |
| 1993 Jun 3 | | | 141 x 7800 |
| 1993 Jun 4 | 1724 | COTM 4 | 141 x 7700 |
| 1993 Jun 14 | | | 141 x 6600 |
| 1993 Jun 16 |
| COTM 5, raise peri |
| 1993 Jun 20 |
| COTM 6 raise peri |
| 1993 Jun 24 |
| COTM 7 raise peri |
| 1993 Jun 25 | | | 139 x 5300 |
| 1993 Jun |
| COTM 8 |
| 1993 Jul 1 |
| COTM 9 |
| 1993 Jul 23 | | | 140? x 1800 |
| 1993 Aug 3 | 1140 | Exit OTM, EOTM 1 raise peri 14 km |
| 1993 Aug 3 | | EOTM 2 |
| 1993 Aug 4? | | EOTM 3 |
| 1993 Aug 4? | | EOTM 4 |
| 1993 Aug 5 | | EOTM 5, TEX complete |
| 1993 Aug 5 | | OTM | 197 x 540 |
| | | Begin Cycle 5 gravity mapping |
| 1994 Mar 10 | | OTM Lower peri 24 km |
| | | OTM | 184 x 530 |
| 1994 Apr 4 | | OTM |
| 1994 Apr 5 | | OTM |
| 1994 Apr 11 | | OTM |
| 1994 Apr 12 | | OTM | 212 x 384 |
| 1994 Apr 15 | | Cycle 6 |
| 1994 Aug 25 | | OTM |
| | | OTM | 172 x 390 |
| 1994 Sep 6 | | Begin Windmill expt |
| 1994 Sep 28 | | OTM lower |
| 1994 Oct 11 | | OTM lower |
| 1994 Oct 12 | 1002 | Comm lock lost |
| 1994 Oct 12 | 1800 | Venus entry |
Payload:
- S-band SAR Radar mapping antenna, 2.385 GHz
