OPAG Reports, Formal proposals/evaluations of future outer SS missions |
OPAG Reports, Formal proposals/evaluations of future outer SS missions |
Nov 9 2007, 08:28 PM
Post
#1
|
|
Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
http://www.lpi.usra.edu/opag/announcements.html
That's one little URL with a lifetime's worth of reading material. Three detailed studies are available in PDF format. The missing body is Titan, which will be the subject of a forthcoming report. The three focus missions are: Europa Explorer: Fairly detailed description of a mission that is pretty much what Europa Orbiter would have been. Jupiter System Observer: Basically, Galileo 2 (without the antenna mishap!). The craft would start with a 3-year tour of all the Galileans, then spend 1 year in an elliptical Ganymede orbit, then the rest of the mission in a tight, polar Ganymede orbit (like MGS at Mars). That would map the heck out of Ganymede, but also be close enough to the rest of the system to make long-range observations for years. Note that Ganymede would thereby provide a lot of radiation shielding. Enceladus: where three profiles are examined in depth: Enceladus Orbiter only; Enceladus Orbiter with soft lander; Saturn orbiter with Enceladus soft lander. There's more to chew on here than I have had (or may ever have) time for, but I'll throw in my two cents' worth: Seems like a Europa-only mission would only benefit from coming after a JSO. EE would explore Europa much better than JSO would; why even have JSO observations at Europa if EE came first? In many ways, these two missions are competitive. EE would have the big payoff, but JSO seems like basic recon that would prime EE, especially giving specs on radar performance. But if we waited til JSO was 4 years into its mission before completing design of EE, then put EE sometime mid-century. If an Enceladus mission included a Saturn orbiter, then maybe the same orbiter could provide data relay for separate Titan elements. However, a lot of the Enceladus science goals would require an Enceladus orbiter, so I don't think a Saturn orbiter for Enceladus/Titan will win out. Note that Enceladus orbital velocity is low enough that the craft could manage to take lots of hits from ice pellets and survive. Put a bulletproof vest on the craft and let it soar through the plumes endlessly. |
|
|
Mar 25 2008, 11:25 AM
Post
#2
|
|
Member Group: Members Posts: 118 Joined: 18-November 07 Member No.: 3964 |
In general, the LaPlace instruments weigh much less than the Europa orbiter instruments. In general, that means less capable science but lower development and testing costs, lighter spacecraft, cheaper launcher, smaller power supply, cheaper operations, etc... I think that we get outer planets missions so rarely and they are so expensive, that "less capable instruments" would actually be a waste of resources. |
|
|
Mar 25 2008, 11:40 AM
Post
#3
|
|
Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
I think that we get outer planets missions so rarely and they are so expensive, that "less capable instruments" would actually be a waste of resources. This is my opinion as well. I think we should try and cram as much science onto a single spacecraft as possible (similar to what Cassini did), not send "mediocre" instruments. If that requires several international partners, then by all means go for it. Better than sending virtually empty spacecraft buses on billion km voyages just so we can lower the price and be able to say "we've got an orbiter right there". -------------------- |
|
|
Mar 25 2008, 08:55 PM
Post
#4
|
|
Member Group: Members Posts: 220 Joined: 13-October 05 Member No.: 528 |
This is my opinion as well. I think we should try and cram as much science onto a single spacecraft as possible (similar to what Cassini did), not send "mediocre" instruments. I don't think we should send poor instruments, or vehicles with too limited a payload, but let's not fall into the opposite trap: Endlessly desigining the most capable spacecraft but never quite flying it. One of the reasons there were no Mars missions for so many years after Viking was that many planetary scientists and engineers kept holding out for a Sample Return. On several occasions I remember reading comments from other government officials (Administration, mostly) asking essentially: "Isn't there any other cheaper Mars missions you could fly?" After nearly ten years of NASA holding out for a bigger spectacular than Viking, the Reagan Administration approved the Mars Observer orbiter... becsause NASA finally proposed something that was considered affordable. There are many examples of this sort. Take for example the many attempts over the years to get a Pluto mission funded. Undoubtably there were many reasons it took so long, but at one point JPL actually was pushing for a Cassini class flyby spacecraft.... essentially trying to cram as much science onto a single spacecraft as possible. A single, very expensive spacecraft. What finally flew was the relatively modest New Horizons. Which, IMHO, is far better than a drawing of a really fancy Cassini class space probe. There were many political reasons that the Europa Orbiter was killed in 2001 (not the least of which was a bruised ego of the Nasa Administrator), but I keep looking back at the strawman vehicle that was the baseline early in that mission's definition phase. It had visible light cameras, Infrared Mapping spectrometer, ice pentetrating radar, and laser altimeter. Ok, so that's rather on the low end of 'Flagship' ..... but it would have launched by 2008. Instead we are talking about launching next flagship no earlier than 2016. As Alan Stern has commented, (paraphrasing) " sometimes you need to settle for 70 percent of something, instead of holding out for 100 percent of nothing." |
|
|
Lo-Fi Version | Time is now: 21st September 2024 - 11:46 PM |
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. |