Magellan

Chronology

Mission timeline

1. May 4, 1989, 18:46:59 UTC

   Launch

   Launch aboard Space Shuttle Atlantis (STS-30R) from LC-39B

   NSSDCA's launch/orbital record gives the launch epoch as 1989-05-04T18:46:59Z; NASA's STS-30 mission page gives 2:46:59 p.m. EDT, the same instant. The NASA Science Magellan page states 18:47:00 UT, one second later.

   Earth
2. May 5, 1989, 01:01 UTC

   Deployment

   Released from Atlantis payload bay; IUS ignition one hour later

   NASA Science: released at 01:01 UT on 5 May 1989 from the payload bay, with the two-stage Inertial Upper Stage firing one hour later. NASA's STS-30 page states the payload "was deployed six hours, 14 minutes into flight", consistent with an 18:46:59 UT liftoff.

   Earth
3. August 10, 1990

   Orbit insertion

   Venus orbit insertion

   Arrived in a near-polar Venus orbit of 297 x 8,463 km at 85.5 degrees inclination. No primary source fetched gave a time of day for the insertion burn.

   Venus
4. September 15, 1990

   Milestone

   Radar mapping Cycle 1 begins

   Magellan began returning high-resolution radar images showing volcanism, tectonic movement, lava channels and pancake-shaped domes.

   Venus
5. May 15, 1991

   Milestone

   Cycle 1 complete: 83.7 percent of Venus imaged

   The first 243-day mapping cycle ended on 15 May 1991, providing the first clear views of 83.7 percent of the surface (NSSDCA rounds this to about 84 percent).

   Venus
6. January 1992

   Milestone

   Cycle 2 complete: coverage raised to 96 percent

   Cycle 2 filled gaps left by Cycle 1 and imaged the southern polar region. Recorded at month precision because sources disagree on the closing day of the cycle.

   Venus
7. September 1992

   Milestone

   Cycle 3 complete: stereo imaging, coverage 98 percent

   Recorded at month precision because primary sources disagree on the day: NASA Science states the third cycle ended 13 September 1992, while NSSDCA states Cycle 3 "began on 24 Jan. 1992 and lasted until 15 Sept. 1992".

   Venus
8. May 1993

   Milestone

   Cycle 4 complete: gravity data from the elliptical orbit

   Cycle 4 acquired gravity-field data rather than radar images, with Magellan transmitting a constant radio signal for Doppler tracking. Recorded at month precision because sources disagree on the closing day of the cycle.

   Venus
9. May 1993

   Milestone

   Aerobraking campaign begins, circularizing the orbit

   NSSDCA states aerobraking was "performed from 24 May until 02 August 1993", ending with a 180 x 540 km orbit and a 94-minute period. The JPL Magellan Summary Sheet instead states aerobraking "was completed between May 25 and August 3, 1993", giving 180 x 541 km. First use of aerobraking at a planet. Recorded at month precision because sources disagree on the start day.

   Venus
10. August 1994

    Milestone

    Cycle 5 complete: high-resolution gravity data for about 95 percent of Venus

    Cycle 5 acquired gravity data from the circularized orbit, giving high-resolution gravity data for about 95 percent of the planet. The cycle boundaries are disputed between sources, so no day is asserted.

    Venus
11. September 1994

    Milestone

    Windmill experiment begins

    JPL's 7 September 1994 release states only that Magellan "has begun a unique experiment" and that it "is scheduled to last until September 14". No source dates the start, so the event is held at month precision.

    Venus
12. October 1994

    Impact

    Predicted destruction in the Venusian atmosphere (never observed)

    The destruction was predicted, not observed. JPL's 13 October weekly report states "The spacecraft should land on Venus by 1:00 PM PDT Thursday, October 13, 1994"; the 12 October release said Magellan "is expected to burn up in the planet's upper atmosphere within two days"; NSSDCA states it "presumably burned up in the atmosphere on 13 or 14 October 1994". No day can be asserted, so month precision is recorded.

    Venus
13. October 11, 1994

    Milestone

    Final orbit trim maneuvers lower periapsis to 139.7 km

    NSSDCA: "Magellan began its final descent into the Venus atmosphere on 11 October 1994." JPL's 12 October release says the thrusters "were fired in four sequences on Tuesday, Oct. 11", while JPL's 13 October weekly report describes "an aggressive series of five Orbit Trim Maneuvers (OTMs) on Tuesday, October 11".

    Venus
14. October 12, 1994

    Mission end

    JPL declares the Magellan mission ended

    JPL's release of 12 October 1994 states the mission "ended today when ground controllers lost contact with the spacecraft", after mapping 98 percent of the surface and compiling gravity data for 95 percent of the planet.

    Venus
15. October 12, 1994, 10:02 UTC

    Loss of contact

    Loss of signal on orbit 15032

    Tracking stations lost the radio signal at 10:02 UT (3:02 a.m. PDT) as Magellan was about to enter Earth occultation on orbit 15032, with the spacecraft power-starved. NSSDCA agrees on 12 October at 10:02 UT and lists a decay date of 1994-10-12. The NASA Science mission page instead states "Contact was lost after 10:05 UT Oct. 13, 1994", which the two contemporaneous JPL reports contradict.

    Venus

Mission architecture

Vehicles

• Magellan · Orbiter · completed

  Destinations: Venus