MAGELLAN

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Deployment
To Venus
Orbiting Venus
Mapping the planet
Last status report

May 4, 1989, Magellan was deployed from the shuttle Atlantis. The spacecraft was headed for a mission to Venus. At Venus it would map the surface with sophisticated radar equipment. Radar had to be used because the dense carbon dioxide atmosphere keeps us from seeing the surface. The spacecraft is topped by a 3.7m (12ft) -diameter dish-shaped antenna that was a spare part left over from the Voyager program. The long, white, horn-shaped antenna, attached just to the left of the dish antenna, is the altimeter antenna that gathers data concerning the surface height of features on Venus. Most of the spacecraft is wrapped in reflective white thermal blankets that protect its sensitive instruments from solar radiation.

Deployment

The Magellan spacecraft's deployment from the shuttle Atlantis' cargo bay was captured by an astronaut with a hand-held camera pointed through the shuttle's aft flight deck windows. Deployment occurred in the early evening of May 4, 1989, after Atlantis had carried Magellan and its Inertial Upper Stage (IUS) booster rocket, into low Earth orbit. Once the shuttle was safely away from the spacecraft, the IUS ignited and placed Magellan on course for its 15-month journey to Venus.

Next stop: Venus

Magellan gets a final boost from the second stage of the Inertial Upper Stage in this artist's depiction. This event occurred on May 4, 1989, and signified the beginning of the operational phase of the spacecraft. Magellan entered the orbit of Venus 15 months later on August 10, 1990.

Orbiting Venus

On August 10, 1990, Magellan entered into orbit about Venus, as depicted in this artist's view. During its 243-day primary mission, referred to as Cycle 1, the spacecraft mapped well over 80 percent of the planet with its high-resolution Synthetic Aperture Radar (SAR). By the end of the mission, 99% of the planet had been mapped. The spacecraft returned more digital imaging data in the first cycle than all previous U.S. planetary missions combined.

Mapping Venus

The sequence of events that comprise a Magellan mapping orbit are shown in this artist's conception. For the first 37.2 minutes of each orbit, the Synthetic Aperture Radar measures and records a 20 km (12 mi) -wide swath of the planet's surface. When Magellan reaches the high point of its orbit, the spacecraft turns its antenna toward Earth and transmits the data. After 113.8 minutes of transmitting, the antenna is repositioned for another orbit about Venus. The spacecraft used this orbit to complete three mapping cycles of radar-imaging data and two cycles of gravity and radio science data. In May, 1993, the spacecraft entered its final, aerobraking phase, in which its orbit was gradually lowered and made more circular, allowing Magellan to collect more gravity data and to conduct radar and radio science experiments. The Magellan mission ended when the spacecraft was allowed to plunge into Venus' atmosphere in October, 1994.

Here is the last Magellan Status Report
October 13, 1994

Magellan Significant Events for Week Ending 10/14/94

1. Communication with the Magellan spacecraft was lost early Wednesday morning, following an aggressive series of five Orbit Trim Maneuvers (OTMs) on Tuesday, October 11, which took the orbit down into the upper atmosphere of Venus. The Termination experiment (extension of September "Windmill" experiment) design was expected to result in final loss of the spacecraft due to a negative power margin. This was not a problem since spacecraft power would have been too low to sustain operations in the next few weeks due to continuing solar cell loss.

Thus, a final controlled experiment was designed to maximize mission return. This final, low altitude was necessary to study the effects of a carbon dioxide atmosphere.

2. The final OTM took the periapsis to 139.7 km (86.6 miles) where the sensible drag on the spacecraft was very evident. The solar panel temperatures rose to 126 deg. C. and the attitude control system fired all available Y-axis thrusters to counteract the torques. However, attitude control was maintained to the end.

3. The main bus voltage dropped to 24.7 volts after five orbits, and it was predicted that attitude control would be lost if the power dropped below 24 volts. It was decided to enhance the windmill experiment by changing the panel angles for the remaining orbits. This was also a preplanned experiment option.

At this point, the spacecraft was expected to survive only two orbits.

4. Magellan continued to maintain communication for three more orbits, even though the power continued to drop below 23 volts and eventually reached 20.4 volts. At this time, one battery went off-line, and the spacecraft was defined as power starved.

5. Communication was lost at 3:02 AM PDT just as Magellan was about to enter an Earth occultation on orbit 15032. Contact was not re-established. Tracking operations were continued to 11:00 AM but no signal was seen, and none was expected. The spacecraft should land on Venus by 1:00 PM PDT Thursday, October 13, 1994.

6. The Magellan Project Office received many requests for television and radio interviews relating to the demise of the spacecraft. All requests were very positive in nature, relating to the tremendous success of the Magellan mission.

7. This was the last regular Magellan report.

Here is the last Magellan Status ReportOctober 13, 1994

Here is the last Magellan Status Report
October 13, 1994