[meteorite-list] C/2013 A1, Mars and spacecraft/rover operation

From: Graham Ensor <graham.ensor_at_meteoritecentral.com>
Date: Mon, 4 Mar 2013 21:07:49 +0000
Message-ID: <CAJkn+kbOhjkWG6_FXWS5+tD3obRSU4TT=Rnc++u3UW8dNTnvpA_at_mail.gmail.com>

Thanks for the update Rob....interesting times ahead.

Graham

On Mon, Mar 4, 2013 at 7:51 PM, Matson, Robert D.
<ROBERT.D.MATSON at saic.com> 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
>
Received on Mon 04 Mar 2013 04:07:49 PM PST