I had planned to do a "week in review" post, a somewhat in-depth report on Spirit's first week on Mars. I'm not going to have time to turn out the article that I'd intended to but I'm not gonna let that stop me from posting the first segment. If you all are ineterested in this kind of "original" content, let me know and I'll try to do more of it. It's something more than the notes I've been posting but also something less than an "article".
On November 7th, 1996, a one ton satellite named Mars Global Surveyor began its ten month journey to the red planet. Apon arrival, it would settle into orbit at an altitude of about 235 miles and begin recording and beaming back to Earth some of the most detailed photographic, spectral, and elevation data ever collected of the Martian surface. In addition to the science payload, MGS carried an instrument called Mars Relay, a communications link between the Earth and future Mars surface landers.
Three and a half years after MGS's Martian arrival, the 2001 Mars Odyssey was launched. Odyssey, one half of the Mars Surveyor 2001 project (the lander/rover half of the project was canceled) carried alongside of its science package a second communications relay into orbit around the red planet.
On January 3rd, 2004, just one week ago today, both MGS and Odyssey phoned home with data from the most recent Martian arrival, Spirit, first of two Mars Explorer Rovers to arrive at the red planet. Spirit would be sending telemetry and other data through MGS's Mars Relay during entry, descent, and landing - the final phases of its 200 day voyage. It was scheduled to transmit about 250 kilobits worth of descent-specific data and when the EDL team at JPL announced that it had received more than the expected 250 kilobits of decent data from MGS, that was the first clear indication that Spirit was alive on the surface.
Soon, the data beamed from Spirit's UHF antenna to MGS and then to the deep-space communications facility (a DSN component) near Canberra, Australia, was coming in fast and furious. We learned within minutes that the lander had settled "base petal down" meaning that it wouldn't have to flip itself over to open up. Seconds later we learned that the airbag retraction was in process and that if all went well with that retraction, Spirit might be able to take advantage of an evening Odyssey flyover to relay photographs of the Martian surface that same night. Everything went well and we got back an amazing 24 megabits of data through Odyssey's relay. That data included first the engineering data reporting "all systems green", then thumbnail images, and then full-frame images.
Three hours after Spirit jettisoned her cruise stage, she was sitting on the Martian surface and the science and engineering teams (and the public, via NASA TV, CNN, the MER website, and other outlets) were pouring over dozens of images from the Descent Image Motion Estimation System, the MER's Hazard Avoidance Cameras, Navigation Cameras, and Panoramic Cameras, along with enough EDL telemetry and atmospheric data to keep them busy for days.
There are many lessons to be learned from Spirit's first days on Mars. One of them should be obvious the next time someone mentions to you "all of the failed Mars missions". Our Mars program is solid and the pieces are all working well together. Thanks to the hard work at NASA, the JPL and elsewhere over the last decade, we have satellites in orbit around another planet, ready and quite capable of adding amazing value to current and future missions.
