From: Jan Wee <jwee@mail.arc.nasa.gov>
Subject: Mars Earth/Sun Rise & Set
Date: Wed, 09 Jul 1997 09:40:36 -0500
Dear discuss-lfm members, Thought you would find this info of interest. It was shared by PTK Live From Mars host (at JPL) David Seidel and relates to today's program and Mars Sol 6! Pretty interesting comparisons! Enjoy. Jan Wee, moderator ************************************************** Mars Sol 6 / Earth July 9 - 10: Earth Rise is at 12:47 PM Pacific Daylight Time, July 9 Sun Rise is at 3:57 PM Pacific Daylight Time, July 9 Earth Set is at 2:28 AM PDT, July 10 Sun Set is at 4:59 AM PDT, July 10 Live From Mars (11:00 AM - 1:00 AM PDT, July 9) takes place between (approximately) 1 and 3 AM local Sagan Memorial Station/Sojourner Truth/Ares Vallis time. In the last 1/4 hour of LFM, Earth will just be rising as a "morning star" at the landing site. At Earth rise it becomes possible to get a line of sight from Pathfinder to Earth. But no commanding or data downlink takes place until Earth gets a bit higher in the sky. The same applies as Earth gets close to the horizon in the Martian afternoon. When the sun comes up then pictures of the surface can be taken. A couple of hours before noon through a couple of hours afternoon is when Sojourner is run. But... the Imager for Mars Pathfinder takes images of stars (at night) and Sojourner has batteries that allow it to operate at times away from noon (including Alpha Proton X-ray Spectrometer measurements which usually take place at night). So... from a terrestrial perspective, Earth rise and set times are pretty significant. David