Huygens seen by Cassini, Taken two days after lander release |
Huygens seen by Cassini, Taken two days after lander release |
May 14 2018, 02:34 AM
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#1
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Newbie Group: Members Posts: 5 Joined: 20-November 17 From: Brazil Member No.: 8292 |
Cassini took a few pictures of the Huygens lander two days after (Dec. 27) it was released from the main probe on Dec. 25, 2004 to check on its trajectory, which was found to be correct within the expected error range. This is one of them, more exposed on the left and less exposed on the right (click for full res):
It's not too impressive, but I found it neat LMK if this isn't the right place to post this or if it should be posted in an existing thread - sorry if that's the case! -------------------- |
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May 14 2018, 03:20 AM
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#2
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Senior Member Group: Members Posts: 2106 Joined: 13-February 10 From: Ontario Member No.: 5221 |
Almost looks like a disc, not a point! How far away were the two spacecraft at the time?
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May 14 2018, 04:43 AM
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#3
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Member Group: Members Posts: 903 Joined: 30-January 05 Member No.: 162 |
IIRC, the excellent Haynes manual book noted 50 kilometers more or less.
The book also fleshed out the release details. The rails holding Huygens imparted a spin to it, and a slower rotation to Cassini (due it's greater mass) that gave confidence the probe was spinning at the correct rate. Cassini had it's thrusters switched off till Huygens was far enough away plume impingement would not be an issue. Also, the magnetometer instrument noted the combined rotation rates of both and that was in spec too.. I can't recommend the Haynes book enough, it is excellent and a wonderful resource !! [ADMIN NOTE: And was written by UMSF member Ralph Lorenz! ] Happy to have learned of it here. |
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May 14 2018, 06:19 AM
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#4
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Newbie Group: Members Posts: 5 Joined: 20-November 17 From: Brazil Member No.: 8292 |
How far away were the two spacecraft at the time? Going by the NASA's Eyes app, they were just under 81.2 km apart. Going off a measurement I found of 2.7 meters for Huygens' size, that makes it just under 0.002 degrees in angular size. Considering the NAC had an FOV of 0.35°, that is ~0.5% of the 1024 pixel side of the sensor - just over 5 pixels, which is approximately what you can see in the darker photo, so yes, it is a disc rather than a point! Unless I'm doing everything wrong... -------------------- |
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May 15 2018, 06:51 PM
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#5
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Member Group: Members Posts: 613 Joined: 23-February 07 From: Occasionally in Columbia, MD Member No.: 1764 |
If memory serves, there were two imaging sessions. First was a WAC (9x9 ?) mosaic to find the probe, and this was used to cue a NAC image (which is the one that exhibits a disc, with a bit of shadowing, that I show in the Haynes book)
Almost looks like a disc, not a point! How far away were the two spacecraft at the time? |
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