Thursday, July 15, 2010

Loss of Signal


This is the view you would see looking East from Gusev Crater at local sunrise, 1:14 PM Universal Time. Because of the speed of light, this image will not appear until 1:26 PM UT. Earth is slightly lower in the sky than last week and Venus higher, so they form a cluster with Jupiter between them. Observers on Earth will see Mars between Venus and Saturn, with a crescent Moon nearby. If Earth's Moon were bright enough to be seen from Mars, its orbit would span an angular distance 1/6 the Moon's diameter seen from Earth. All of human history, even the Apollo landings on the Moon, has taken place in a tiny patch of sky.

Mission Control in Houston often deals with loss of signal from spacecraft. More than one day after landing there is no word from Gusev Crater. The Spirit Rover, permanently lodged in Martian regolith, has not been heard from since March 13. The ARES spacecraft launched October 28, 2009 has not been heard from since beginning reentry. Many things could have gone wrong. The inflatable heat shield has never been tested in Martian conditions. The 3 main parachutes, which deploy at a speed over Mach 1, are another possible point of failure. There are many risks in landing a spacecraft on Mars.

Possibly the crew landed safely but the communications dish has not deployed. Signals between Earth and Gusev Crater are limited to the roughly 12 hours that Earth is visible in the sky. The crew's first priority is maintaining her own survival and that of the spacecraft. Possibly she is safely settling on Mars, but unable to communicate. If this ARES mission is not successful, hopefully others willl follow. There is still a possiblity of hearing a human voice from Mars.

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