[X] My Assistant

[vikingmars]

Now, it's time to open a new section devoted to the landing of the Philae lander itself on the nucleus of Comet 67P C-G.

Also to answer better the earlier post,
http://www.unmannedspaceflight.com/index.p...st&p=212943
and for your information, here is the quick summary (as a "pdf" file) of the events that are expected to occur during landing on the nucleus and after : it's the timeschedule on which we are working to set up our EPO event in Paris.
 Sequence_ATTERRISSAGE10_UMSF.pdf ( 263.81K ) Number of downloads: 4707

The landing itself should occur around November 11th.

We'll keep you informed

[blake]

Questions from an interested non-expert:

I have read that Philae may still partly function if it lands in the wrong orientation (lying on its side, or similar). Is there the possibility that Philae may bounce off the surface, or even not contact the surface? In either of these scenarios, would Philae still be able to transmit back whatever data or images it has already taken?

Is there a scenario other than spacecraft system failure where Philae would not be able to transmit data back (like landing upside down, perhaps)?

Thanks.

[Gerald]

In either of these scenarios, would Philae still be able to transmit back whatever data or images it has already taken?
Is there a scenario other than spacecraft system failure where Philae would not be able to transmit data back (like landing upside down, perhaps)?

NSSDC about Philae:

The lander will communicate with the Rosetta spacecraft via a 1 W S-band transmitter.

S-band communication usually is rather tolerant in terms of pointing.
Although I didn't find reliable information about whether the (two?) Philae S-band antennas (at least taken together) are omnidirectional.
The other instruments may shield the radio waves in some directions. But if Philae doesn't vanish in some deep gap, I'm optimistic, that communication will be possible in some directions, at least, as long as the batteries are charged.

Most descent data will be transmitted before touchdown; thus we'll get some infos of the descent phase, at least.

[djellison]

S-band communication usually is rather tolerant in terms of pointing.

Whilst the lower frequencies are less fussy regarding pointing - the predominant factor in required pointing accuracy is antenna design - NOT frequency.

The S-Band relay from Huygens to Cassini had a beamwidth of only 2.3-2.4 degrees because it used Cassini's HGA.
http://descanso.jpl.nasa.gov/DPSummary/Des...3--Cassini2.pdf ( page 8 )

Whereas Deep Impact's probe-flyby relay used S-Band but patch-antennas that were in essence omnidirectional and managed 64kbps downlink at 8,000km range.