What does one bring to Jupiter's neighborhood?
May 26, 2015 3:45 PM Subscribe
Well, if you're going to Europa, you definitely want to pack a magnetometer, among other neat tools.
Not yet selected for flight, SPace Environmental and Composition Investigation near the Europan Surface (SPECIES) has been selected for furhter technology development. The instrument blends neutral mass spectrometer and grass chromatograph, and may be developed for other, future mission opportunities.
It's high time this was funded. The search for dank matter is really, really, super really important.
posted by bonehead at 3:58 PM on May 26, 2015 [11 favorites]
It's high time this was funded. The search for dank matter is really, really, super really important.
posted by bonehead at 3:58 PM on May 26, 2015 [11 favorites]
PIMS
1) It's Pimm's
2) All the instruments should be named after various alcoholic drinks. Make it so, NASA. Make it so.
posted by eriko at 4:06 PM on May 26, 2015 [3 favorites]
1) It's Pimm's
2) All the instruments should be named after various alcoholic drinks. Make it so, NASA. Make it so.
posted by eriko at 4:06 PM on May 26, 2015 [3 favorites]
OK SO I GUESS YOURE GOING TO IGNORE WHAT WE SAID ABOUT EUROPA EARLIER
SO AS LONG AS YOURE COMING ANYWAY CAN YOU STOP BY THE STORE AND PICK UP SOME TONIC WATER AND DORITOS
COOL RANCH WOULD BE GREAT THANKS
posted by Halloween Jack at 4:06 PM on May 26, 2015 [12 favorites]
SO AS LONG AS YOURE COMING ANYWAY CAN YOU STOP BY THE STORE AND PICK UP SOME TONIC WATER AND DORITOS
COOL RANCH WOULD BE GREAT THANKS
posted by Halloween Jack at 4:06 PM on May 26, 2015 [12 favorites]
Who's idea was it to make it solar powered? At that range from the Sun, there just isn't all that much light. (Have they finally run completely out of Pu238?)
posted by Chocolate Pickle at 4:26 PM on May 26, 2015
posted by Chocolate Pickle at 4:26 PM on May 26, 2015
It's actually solar powered for a pretty good reason, which I can't recall at the moment, just putting it out there.
posted by Brandon Blatcher at 4:37 PM on May 26, 2015
posted by Brandon Blatcher at 4:37 PM on May 26, 2015
Yeah, politics is a factor with RTGs, but 238Pu stocks are low right now. And, if that changes, it's pretty easy to retrofit the design. It may be, though, that a planned instrument can't handled the radiation noise of an RTG. Anyway, right now, you design solar for anything short of the Kuiper Belt, and if come build time the world has changed, you might be able to swap to an RTG. The Voyagers used RTGs because they were going well beyond Jupiter, Galileo used a pair of RTGs because solar panels back then meant it would have needed 65 square meters (700 square feet) of solar panels to power the probe. That's a lot of mass, and a lot of not-fun unfolding it all, and it had enough problems unfolding things.
Solar panels are a *lot* better these days. Ditto boosters, which means you can spend an extra hundred kilograms on solar panels as well. If we guess that the high gain antenna is the same size as New Horizons, 2.1m, then the solar array they're showing has 4 square panels that are 2.5x2.5m and two smaller ones, call them half the size, so about 31 square meters of solar panel. Even with 70's era solar panels, that's 250W, but 2015 solar panels put out much more power, so I feel confident in saying that if they're hanging out 30 square meters of solar panels, they're getting at least a kilowatt out of them, probably closer to two.
An issue, though (and the reason Curiositywent with an RTG) is that an RTG gives you both electricity and heat, where a solar panel gives you just electricity, and you're going to need to use some of that for heat. But heck, if you're getting a couple of kilowatts, you can afford it (Galileo's RTGs launched with 570W. )
posted by eriko at 6:45 PM on May 26, 2015 [1 favorite]
Solar panels are a *lot* better these days. Ditto boosters, which means you can spend an extra hundred kilograms on solar panels as well. If we guess that the high gain antenna is the same size as New Horizons, 2.1m, then the solar array they're showing has 4 square panels that are 2.5x2.5m and two smaller ones, call them half the size, so about 31 square meters of solar panel. Even with 70's era solar panels, that's 250W, but 2015 solar panels put out much more power, so I feel confident in saying that if they're hanging out 30 square meters of solar panels, they're getting at least a kilowatt out of them, probably closer to two.
An issue, though (and the reason Curiositywent with an RTG) is that an RTG gives you both electricity and heat, where a solar panel gives you just electricity, and you're going to need to use some of that for heat. But heck, if you're getting a couple of kilowatts, you can afford it (Galileo's RTGs launched with 570W. )
posted by eriko at 6:45 PM on May 26, 2015 [1 favorite]
It's actually solar powered for a pretty good reason, which I can't recall at the moment, just putting it out there.
Money, or the lack thereof. That, and the shortage of Pu-238.
I thought launching nuclear-powered stuff was a no-go these days for political and legal reasons, so if RTGs are out, what are you left with but solar?
Pu-238 RTGs do get launched, like Curiosity's MMRTG. There's apparently enough fuel left for three MMRTGs, one of which is reserved for the Mars 2020 rover.
posted by zamboni at 6:55 PM on May 26, 2015
Money, or the lack thereof. That, and the shortage of Pu-238.
I thought launching nuclear-powered stuff was a no-go these days for political and legal reasons, so if RTGs are out, what are you left with but solar?
Pu-238 RTGs do get launched, like Curiosity's MMRTG. There's apparently enough fuel left for three MMRTGs, one of which is reserved for the Mars 2020 rover.
posted by zamboni at 6:55 PM on May 26, 2015
I should mention that going solar does reduce risk and simplify paperwork- it's not just economics.
If we guess that the high gain antenna is the same size as New Horizons, 2.1m, then the solar array they're showing has 4 square panels that are 2.5x2.5m and two smaller ones, call them half the size, so about 31 square meters of solar panel. Even with 70's era solar panels, that's 250W, but 2015 solar panels put out much more power, so I feel confident in saying that if they're hanging out 30 square meters of solar panels, they're getting at least a kilowatt out of them, probably closer to two.
The figure that gets bandied around is 50 sq m, but there's a lot that can change there, since they're still deciding whether to reuse Juno style panels, or try something new. (A mint Juno should get 486W from 60 sq m, declining with rad exposure.) If they do go with new tech, I suspect they'll pull an Apple and use power gains to make the panels smaller.
posted by zamboni at 7:29 PM on May 26, 2015
If we guess that the high gain antenna is the same size as New Horizons, 2.1m, then the solar array they're showing has 4 square panels that are 2.5x2.5m and two smaller ones, call them half the size, so about 31 square meters of solar panel. Even with 70's era solar panels, that's 250W, but 2015 solar panels put out much more power, so I feel confident in saying that if they're hanging out 30 square meters of solar panels, they're getting at least a kilowatt out of them, probably closer to two.
The figure that gets bandied around is 50 sq m, but there's a lot that can change there, since they're still deciding whether to reuse Juno style panels, or try something new. (A mint Juno should get 486W from 60 sq m, declining with rad exposure.) If they do go with new tech, I suspect they'll pull an Apple and use power gains to make the panels smaller.
posted by zamboni at 7:29 PM on May 26, 2015
All I care about are the cameras. Bring back pretty pictures!
The science is nice too, of course.
posted by bondcliff at 6:15 AM on May 27, 2015
The science is nice too, of course.
posted by bondcliff at 6:15 AM on May 27, 2015
I should mention that going solar does reduce risk and simplify paperwork
I have to deal with a few sources at work. These are sealed and much much simpler than an RTG in terms of licensing. They are still a significant pain in the ass and require a few person-days/yr to manage, and all the staff need training in rad safety.
We're always debating their worth given the admin burden they create. In a couple of cases we've abandoned them going to tube sources, where we only need x-rays, but for certain applications, nothing else works. They're quite frustrating to actually employ, as we have to leave them behind frequently anyway when we go to field sites as there are transportation and import/export controls on even the smallest non-weaponizable sources.
posted by bonehead at 7:14 AM on May 27, 2015
I have to deal with a few sources at work. These are sealed and much much simpler than an RTG in terms of licensing. They are still a significant pain in the ass and require a few person-days/yr to manage, and all the staff need training in rad safety.
We're always debating their worth given the admin burden they create. In a couple of cases we've abandoned them going to tube sources, where we only need x-rays, but for certain applications, nothing else works. They're quite frustrating to actually employ, as we have to leave them behind frequently anyway when we go to field sites as there are transportation and import/export controls on even the smallest non-weaponizable sources.
posted by bonehead at 7:14 AM on May 27, 2015
All I care about are the cameras. Bring back pretty pictures!
Europa Imaging System (EIS): This pair of wide and narrow angle cameras will provide wide-coverage maps at 50 meter (164 foot) resolution, with selected detailed areas at 100 times that resolution. It is under principal investigator Dr. Elizabeth Turtle of Johns Hopkins University’s Applied Physics Laboratory.posted by Brandon Blatcher at 12:59 PM on May 27, 2015
There's apparently enough fuel left for three MMRTGs, one of which is reserved for the Mars 2020 rover.
I did not know that. Thanks -- but it makes it very clear why they're going solar. For this mission, there are effectively no RTGs available.
The MMRTG puts out 125W new, dropping to 100W after 14 years, so three of them is 375W. If you're looking at something on the order of Galileo's 500W mission budget, there simply aren't enough of them outthere. If you're holding one for the Mars 2020 rover, you're looking at less than 250W mission budget, given that they're already built and decaying, and that it'll take some time to build the probe and get it to Europa.
So, really, turns out they're going solar because they have to -- there aren't any 500W class RTGs, aren't enough smaller ones to get 500Ws, and aren't likely to be any in time for the 2020 launch window.
The figure that gets bandied around is 50 sq m, but there's a lot that can change there, since they're still deciding whether to reuse Juno style panels, or try something new.
They may well just stick with the Juno panels, though, if those works, because flight proven is a really nice thing to have in spaceflight, esp. when your dealing with the outer planets, where there's very little data on what works and what doesn't. The first thing, of course, is going to be figuring out the power budget. But in general, in spaceflight, where the cost of lofting mass is so large, you use the best solar cells you can get your hands on, and the new 4 junction cells with concentrators are hitting 46% percent efficiency -- compared to 34% in 2000 and 17% in 1985. They're not cheap at all, which is why you don't see them on household rooftops (yet) but they're exactly the sort of cells that end up on spacecraft.
And to give you an idea of the distance factor -- As you know, Zamboni-Bob, the Juno Panels, while just missing 500W at Jupiter, get 12-14kW in Earth orbit. Square-Cube law is a *bitch*.
posted by eriko at 6:50 AM on May 28, 2015
I did not know that. Thanks -- but it makes it very clear why they're going solar. For this mission, there are effectively no RTGs available.
The MMRTG puts out 125W new, dropping to 100W after 14 years, so three of them is 375W. If you're looking at something on the order of Galileo's 500W mission budget, there simply aren't enough of them outthere. If you're holding one for the Mars 2020 rover, you're looking at less than 250W mission budget, given that they're already built and decaying, and that it'll take some time to build the probe and get it to Europa.
So, really, turns out they're going solar because they have to -- there aren't any 500W class RTGs, aren't enough smaller ones to get 500Ws, and aren't likely to be any in time for the 2020 launch window.
The figure that gets bandied around is 50 sq m, but there's a lot that can change there, since they're still deciding whether to reuse Juno style panels, or try something new.
They may well just stick with the Juno panels, though, if those works, because flight proven is a really nice thing to have in spaceflight, esp. when your dealing with the outer planets, where there's very little data on what works and what doesn't. The first thing, of course, is going to be figuring out the power budget. But in general, in spaceflight, where the cost of lofting mass is so large, you use the best solar cells you can get your hands on, and the new 4 junction cells with concentrators are hitting 46% percent efficiency -- compared to 34% in 2000 and 17% in 1985. They're not cheap at all, which is why you don't see them on household rooftops (yet) but they're exactly the sort of cells that end up on spacecraft.
And to give you an idea of the distance factor -- As you know, Zamboni-Bob, the Juno Panels, while just missing 500W at Jupiter, get 12-14kW in Earth orbit. Square-Cube law is a *bitch*.
posted by eriko at 6:50 AM on May 28, 2015
And hey, from November 2007, Solar Power for Outer Planet Study. "...a quick look study for who could extend the Juno and Rosetta 5 AU-class mission on solar arrays at Saturn (10 AU) and Uranus (20 AU)".
2008 State of the Arts was cited as triple junction cells with 28-30% efficiency, silicon single junction 16-19%. Near term (by 2010) was 30-33% for multi-junction.
Good stuff, and, of course, that's 7 years ago, and there's been a bunch of research into solar power over the last few years.
posted by eriko at 8:45 AM on May 28, 2015
2008 State of the Arts was cited as triple junction cells with 28-30% efficiency, silicon single junction 16-19%. Near term (by 2010) was 30-33% for multi-junction.
Good stuff, and, of course, that's 7 years ago, and there's been a bunch of research into solar power over the last few years.
posted by eriko at 8:45 AM on May 28, 2015
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posted by GuyZero at 3:55 PM on May 26, 2015 [2 favorites]