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The Planetary Society Blog

By Emily Lakdawalla

Mars Reconnaissance Orbiter's big day

Mar. 10, 2006 | 07:43 PST | 15:43 UTC

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After launching successfully, the scariest moment in any mission is the moment when it must autonomously execute a series of commands flawlessly in order to land or enter orbit at a planet. There is little room for error at this moment; an under-burn (or failure to burn at all) would send the spacecraft flying past the planet, never to return, and an over-burn would crash the spacecraft too deeply into its atmosphere or even into the planet (which is what happened to Mars Climate Orbiter). But because everything is happening millions of kilometers away, there's no possibility for humans to monitor and intervene if anything appears to be going wrong. It's all up to the spacecraft to do this right.

Mars Reconnaissance Orbiter should begin its orbit insertion burn at 1:24 p.m. this afternoon, my time (21:24 UTC). Here is the full timeline of events:

PST	UTC	Event
7:24 AM	15:24	Final trajectory correction maneuver (if needed)
9:00 AM	17:00	NASA TV: Pre-Arrival News Briefing (1 hour)
12:30 PM	20:30	NASA TV: JPL Mission Coverage (2+ hours)
1:07 PM	21:07	Start of turn to orbit-insertion attitude
1:19 PM	21:19	End of turn to orbit-insertion attitude
1:24 PM	21:24	Start of orbit-insertion burn by main thrusters
1:43 PM	21:43	Closest approach to Mars during Insertion
1:45 PM	21:45	Entry into shadow of Mars, shift from solar to battery power
1:47 PM	21:47	Loss of signal as spacecraft goes behind Mars
1:51 PM	21:51	End of orbit-insertion burn (though still out of contact)
2:13 PM	22:13	End of turn toward Earth pointing (still out of contact)
2:16 PM	22:16	Reacquisition of signal as orbiter emerges from behind Mars
4:30 PM	0:30	NASA TV: Post-Arrival - JPL News Briefing
The times of all events at Marsare listed in Earth-received time, the time at which the radio signalsfrom the spacecraft reach Earth. The distance between the two planetson March 10 will be 215 million kilometers (134 million miles). Travelingat the speed of light, radio signals take 12 minutes to travel fromMars to Earth.

You should be able to watch this on NASA TV. The mission has also made available some other fun things to watch, including a live-updated Doppler plot which shows you how the workers at the Deep Space Network can tell when things are going right -- or wrong -- on a mission. There are also some pretty animations of the orbit insertion. I, unfortunately, will be traveling much of the day and on a plane during the most critical time period of MOI, so I'll miss the fun. But A. J. S. Rayl will be watching and reporting for The Planetary Society, and I'll catch up on what happened after I land tonight!

Good luck, Mars Reconnaissance Orbiter!