Live Dust Devil? Options

[azstrummer]

Man, this looks an awful lot like a dust devil in the distance. What do you think?

[edstrick]

tedstryk commented:

"The Viking 1 lander died in a very sad way. A young controller sent an erant command shutting it down in 1982 - it may well have lived into the 1990s had this not happened."

To set the record straight. The Viking Landers were powered by Radioisotope Thermoelectric Generators, but their instantaneous power demands when they were *doing* anything were greater than the RTG's could supply. They had to draw on rechargable batteries when they were transmitting, recording data to the tape recorder, etc.

Also note that the Landers primary communications to Earth was by relay to the Viking Orbiters, and secondarily by direct uplink to Earth. Viking Orbiter 2 died of attitude control gas depletion after 2 years in Mars Orbit, while Viking Orbiter 1 lasted 4 years.

Viking Lander 2 died of battery failure just a few weeks before the loss of Orbiter 1. It would try to do *ANYTHING*, have a brownout, and go into a safemode. I believe they finally sent it a final shutdown command sequence. Lander 2 had both transmitters to Earth fail, and could only communicate through an Obiter, so it would have been silenced by the loss of the last Orbiter.

Viking 1 was put on a 1-transmission-per-week (direct to Earth) "eternal" mission and lasted 2 1/3 more years till it started to show signs of battery failure. They assembled an "impromptu" team to write battery conditioning software and uplinked a command sequence to the Lander. It was never heard from again. They believe the command sequence accidentally overwrote the code that predicted Earth's location in the sky for the antenna pointing. They attempted to uplink corrected code, but either the Lander never received the corrections, or the batteries had in fact failed.

Viking started the sad example of repeat crisises regarding termination of a live mission. After the first "Extended" mission, there was a further "Extended" Mission, (I think), then a "Completion" mission, after which things wouild be shut down. That was averted and Orbiter 1 did a "Survey" Mission of very simple large area contiguous mapping. Finally, with the orbiter's loss, Lander 1 was put on it's "Eternal" (don't recall if there was an official name or not) mission. They were only able to listen sporadically to it's automatic broadcasts: Voyagers and some other missions were doing their things and there was essentially no $ for the effort.