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phaishazamkhan
2006-Jul-27, 01:13 AM
Would it have been cost-prohibitive for the space agencies involved with the Cassini mission to wait until the probe arrived at Saturn and performed a few flybys of Titan before dropping Huygens to choose the best place?

Hamlet
2006-Jul-27, 02:05 AM
Would it have been cost-prohibitive for the space agencies involved with the Cassini mission to wait until the probe arrived at Saturn and performed a few flybys of Titan before dropping Huygens to choose the best place?

The Huygens probe was not desiged as a lander so there was no real idea of a "landing site". The probe was designed to be on the parachutes for up to 2.5 hours and was expected to be blown around by the winds. Huygens had no way of manuevering so it was going to come down wherever the winds took it.

From an interview with the Huygens Project Scientist Dr. Jean-Pierre Lebreton (http://www.universetoday.com/am/publish/interview_dr_lebreton.html?31122004):


Huygens is not a lander. So I prefer to talk about impact or touchdown site. The impact site was not specifically chosen. The main drivers were: i) the entry angle in the atmosphere, ii) the need to descend in the sunlit side of Titan, iii) a low to medium latitude descent, but away from the equator for best wind measurements, and iv) an optimized geometry for the radio link with the orbiter.


Also from here (http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=34956):

The spin-stabilized Probe was targeted for a southern-latitude landing site on the dayside of Titan. In order to meet the probe dynamic entry conditions, minimize trajectory dispersion and thus enhance data relay link performance, the probe entry angle into the atmosphere was set at a relatively steep at -65° + 3° (99% certainty). This entry angle would also give the Huygens probe the best opportunity to reach the surface.

There was a general region they were aiming for but this was driven by the needs and limitations of the mission. The need to keep a good radio link with Cassini is probably one of the bigger considerations.

Ufonaut99
2006-Jul-27, 02:09 AM
Also, titan is covered in "cloud", so you couldn't see the surface to decide a good place.

01101001
2006-Jul-27, 02:48 AM
Also, titan is covered in "cloud", so you couldn't see the surface to decide a good place.
Clouds which not quite opaque at all frequencies:
http://photojournal.jpl.nasa.gov/thumb/PIA08630.jpg (http://photojournal.jpl.nasa.gov/catalog/PIA08630)

But, I don't think the availability of impact targets that can be seen is of enough value to delay Huygens' descent.