


Mars 98 Mission Status Report

June 29, 1999

Late last week, flight controllers for NASA's Mars Climate Orbiter commanded the spacecraft to begin flying in an "all- stellar" mode. This configuration means that the spacecraft's auto-pilot is operating by only using star sightings from its star camera, allowing its gyroscopes to be turned off so that their operating life can be preserved for future uses. With this transition to "all-stellar" mode, all of the engineering objectives for the phase of the mission during cruise from Earth to Mars are complete.

Mars Climate Orbiter is now 90 days from Mars arrival on September 23. Today, the spacecraft is 95.6 million kilometers (59.4 million miles) from Earth and 24.6 million kilometers (15.3 million miles) from Mars, approaching the planet at a speed of 13,933 kilometers per hour (8,658 miles per hour).

Meanwhile the other Mars '98 spacecraft, Mars Polar Lander, is undergoing preparation for its landing December 3. The master sequence of computer commands that will control the spacecraft during its critical entry, descent and landing was tested last week in a simulator facility at Lockheed Martin Astronautics, Denver, CO. The test was largely successful and identified a few minor issues that are being worked this week. The flight team is now conducting its first operational readiness test for entry, descent and landing. In this readiness test, the team uses the updated sequence of computer commands to practice all activities leading up to landing.

The Mars Polar Lander team will spend the summer poring over the latest images of the south pole taken by the currently orbiting Mars Global Surveyor spacecraft in order to fine-tune the landing site selection. Final selection of Mars Polar Lander's landing site will take place later this summer.

The lander is now is 74.3 million kilometers (46.2 million miles) from Earth and 48.6 million kilometers (30.2 million miles) away from Mars, traveling at a speed of 5,384 kilometers per hour (3,346 miles per hour).

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