Dawn approaches Ceres, From opnav images to first orbit |
Dawn approaches Ceres, From opnav images to first orbit |
Jan 12 2015, 12:10 AM
Post
#1
|
||
Solar System Cartographer Group: Members Posts: 10189 Joined: 5-April 05 From: Canada Member No.: 227 |
On Tuesday (two days from now, for visitors from the future), the first optical navigation image will be taken... hopefully we'll have it in our hands soon after that. So it's time for a new topic. Over the next few months we'll have progressively closer images and full orbit characterization sequences, no doubt including multispectral image sets.
A new world... This is a bit of reprocessing I have been doing with the Hubble images from a few years ago. Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PD: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
|
|
||
Jan 23 2015, 02:55 PM
Post
#2
|
|
Solar System Cartographer Group: Members Posts: 10189 Joined: 5-April 05 From: Canada Member No.: 227 |
I don't know if that was discussed as a vague possibility, but it's not been a realistic plan for a long time, if ever. Ceres is big - 4 times the surface area of Vesta, so needing 4 times the number of images to cover it at any given resolution. Any extended mission which might be possible with the current limitations of the spacecraft will be most productively used adding data for Ceres, not starting off on a long cruise to some other destination.
Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PD: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
|
|
Jan 23 2015, 03:12 PM
Post
#3
|
|
Member Group: Members Posts: 207 Joined: 6-March 07 From: houston, texas Member No.: 1828 |
I don't know if that was discussed as a vague possibility, but it's not been a realistic plan for a long time, if ever. Ceres is big - 4 times the surface area of Vesta, so needing 4 times the number of images to cover it at any given resolution. Any extended mission which might be possible with the current limitations of the spacecraft will be most productively used adding data for Ceres, not starting off on a long cruise to some other destination. Phil That is quite right. more area requires more time. also the shift to using hydrazine removes any margin that we might have had for a hypothetical transfer to another object, if it ever was seriously an option (which i don't know). the other factor is that the GRAND gamma ray instrument requires really long integration times to accumulate enough signal to confidently detect elements on the surface. the final orbit is not as low as they would like so getting extra time to fully map out Ceres composition would be a logical and compelling justification for extending the mission. any exciting discoveries like volcanoes or well, who knows, would also be a compelling reason. -------------------- Dr. Paul Schenk, Lunar and Planetary Institute, Houston TX
http://stereomoons.blogspot.com; http://www.youtube.com/galsat400; http://www.lpi.usra.edu/science/schenk/ |
|
|
Jan 23 2015, 04:16 PM
Post
#4
|
|
Member Group: Members Posts: 495 Joined: 12-February 12 Member No.: 6336 |
also the shift to using hydrazine removes any margin that we might have had for a hypothetical transfer to another object, if it ever was seriously an option (which i don't know). Yes a colleague of yours stated in a blog that any transfer to any third object was now no longer even considered due to the flywheel problem. Getting good data from GRAND is better science than just a snapshot from a quick flyby. So the third lowest orbit is out of the question now then? I tried to find any information about that, since I figured that would indeed be more costly on hydrazine? So as for algorimancer's question I know Pallas have been mentioned, but have no idea if that was ever on any extended planning or just ideas that were tossed around. [I toss 14 ideas or more around daily, something that have taken years for some people to getting used to not to take too seriously.] =) One ancient ice volcano would be really cool, and could provide some information about both history and perhaps even the interior of Ceres. But only if it have survived large impacts since the early days of Ceres. That artwork vikingmars posted is actually very close to my hopes for a best case scenario, even a polar cap, of what Ceres would provide for us. Hmm arcuate structures, like Miranda? Temporary melting after one impact, who knows..... |
|
|
Jan 23 2015, 04:28 PM
Post
#5
|
|
Member Group: Members Posts: 423 Joined: 13-November 14 From: Norway Member No.: 7310 |
So the third lowest orbit is out of the question now then? I tried to find any information about that, since I figured that would indeed be more costly on hydrazine? I guess the information you are looking for can be found in this blog entry from last year (which also mentions why a landing is impossible, cf. debate above): QUOTE What fate awaits our stalwart adventurer following the completion of its primary assignment? There are several possibilities, but they all conclude the same way. If hydrazine remains at the end, and if the spacecraft is still healthy, NASA will decide whether to invest further in Dawn. NASA has many exciting and important activities to choose among — after all, there’s a vast universe to explore! If it provides further funds, Dawn will perform further investigations in LAMO, making GRaND’s gamma ray and neutron pictures even sharper, refining the gravitational measurements, collecting still more photos of the expansive surface, and acquiring even more spectra with VIR.
There is no intention to fly to a lower orbit. Even if the two remaining reaction wheels operate, hydrazine will be running very low, so time will be short. Following another spiral to a different altitude would not be wise. There will be no below-LAMO (BLAMO) or super low altitude mapping orbit (SLAMO) phase of the mission. -------------------- |
|
|
Lo-Fi Version | Time is now: 8th June 2024 - 05:59 AM |
RULES AND GUIDELINES Please read the Forum Rules and Guidelines before posting. IMAGE COPYRIGHT |
OPINIONS AND MODERATION Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators. |
SUPPORT THE FORUM Unmannedspaceflight.com is funded by the Planetary Society. Please consider supporting our work and many other projects by donating to the Society or becoming a member. |