Thanks for the update Rob....interesting times ahead. Graham
On Mon, Mar 4, 2013 at 7:51 PM, Matson, Robert D. <[email protected]> wrote: > Hi Graham/Jeff/All, > >> New data puts it so strike likelihood increasing. > >> > http://spaceobs.org/en/2013/02/27/new-data-concerning-the-close-approach > -of-comet-c2013-a1-to-mars/ > > This is a rapidly evolving situation. Pre-recovery observations of > C/2013 A1 were > reported late last week that were made by Pan-STARRS 1 at Haleakala in > early October, > extending the observational arc by an additional two months. The nominal > closest > approach distance that NASA/JPL is now predicting is 53500 km. (The > maximum distance > of closest approach is ~317,000 km, giving an indication of the > uncertainty that > still remains.) While an impact is not yet ruled out, the trend is > moving in that > direction. If the five observations with the highest residuals are > excluded from > the computation, the nominal miss distance increases to 73700 km. > >> If not an impact this means the planet will pass through the comet's > coma. Lots >> of dust and gas. Meteor showers at the surface and all the hardware we > have put >> there will be at risk. > > I think the rovers on the surface will be fine; the question is how well > the > three (and eventually four) spacecraft orbiting Mars will hold up > passing > through C/2013 A1's coma. Past interplanetary spacecraft have survived > closer encounters with comets (Giotto, STARDUST), but they were designed > for that mission (and nevertheless sustained damage and sensor > failures). > Mars Odyssey, Mars Express and the Mars Reconnaissance Orbiter may not > do > as well. MAVEN doesn't launch until November of December of this year, > but > coincidentally would arrive at Mars less than a month prior to the > comet. > > Dr. Chris McKay at NASA-Ames is on the Curiosity team, and in his > opinion > the coma density would not be sufficient to have much effect on any of > the > orbiting spacecraft. But he emphasized that this was just his opinion, > and > it was made at a time when the nominal closest approach was 105,000 km. > > Should MRO suffer a failure, Curiosity will lose its fastest link with > earth (2 megabits/second). It would still have a 256 kilobit/sec link > via Odyssey. If both spacecraft should fail, Curiosity can communicate > directly with earth through its X-band transceiver, but only at 32 > kbits/s. > > --Rob > ______________________________________________ Visit the Archives at http://www.meteorite-list-archives.com Meteorite-list mailing list [email protected] http://six.pairlist.net/mailman/listinfo/meteorite-list
