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Unmanned Spaceflight.com _ Exploration Strategy _ The case for more flybys

Posted by: TheAnt Jul 11 2015, 06:17 PM

QUOTE (belleraphon1 @ Jul 11 2015, 07:44 PM) *
I really do not see this as an end to classical exploration. We are opening a new door. It never ends...

Craig


I concur, this is only the later part of a first survey of some of the major stops in the solar system, but not all.

Though all big stops have been covered with a first peek, we cant say we have visited a place after seeing it trough a window of a high speed train. And NH can be compared to that to one amazing degree. =)
Even by a simple flyby we still got Pallas, the Trojans of Jupiter, Chiron, Haumea, Ixion, Makemake, Orcus, Sedna, Quaoar and Varuna before we even will see the end of the first survey.
When all these worlds have had a visit by a lander or one atmospheric probe, then I will agree we've come to the end of 'classical exploration' and start to think about what kind of rovers that would be suitable for Varuna or Io. =)

And thank you for the 2 images fredk, yes I did show those to a friend and we could see the slight difference in size from only 4 minute, that really put some perspective on how fast NH is travelling. =)

Posted by: belleraphon1 Jul 11 2015, 06:38 PM

QUOTE (TheAnt @ Jul 11 2015, 02:17 PM) *
I concur, this is only the later part of a first survey of some of the major stops in the solar system, but not all.


Agree ....first pass ... and what a wonderland has been revealed.

Still want to hear the winds whisper on Mars. What does a human breath sound like there?
What sonorous bells ring in the caverns of Enceladus?
What vapours rise from the hollows on Mercury?
Does a wind stir the anvil plains of Venus?
What electric dreams stir the rad belts of Jupiter and what would a skyfall reveal of the interior?
Do diamonds really rain on Uranus and Neptune?
Do whales sing in the oceans of Europa?
What hydrocarbon magic occurs in the cauldron of Titan seas?

What awaits in the outer dark and across the stygian sky?

We have just started.

Craig.

Posted by: rboerner Jul 11 2015, 06:41 PM

There has been a slightly off-topic sub discussion in the New Horizons Pluto System Encounter about the merits of additional KBO flybys.

Some people seem to think that the age of flybys is over with NH. I don't quite see the logic in that. The diversity of KBOs calls for additional samples. One cheap NH-type craft could encounter Jupiter, Uranus or Neptune and then one or even two KBOs. Explore additional KBOs, get ice giants and perhaps Triton for free.

Given that new ice giant exploration with orbiters may not be happening until the 2040s, this seems like an incredibly good deal for a $700 million mission.

Uranus should count as a "new" planet not previously visited anyway because it is approaching the opposite solstice (2028) than the one Voyager 2 encountered in 1986, so a flyby probe would image the northern hemispheres of the Uranian satellites for the first time.




Posted by: rboerner Jul 11 2015, 06:57 PM

Something to add: I know the idea is quite obvious. Alan Stern proposed it as New Horizons II and it was rejected.

http://blogs.discovermagazine.com/outthere/2015/03/29/alan-stern-on-plutos-wonders/
https://en.wikipedia.org/wiki/New_Horizons_2


Posted by: ZLD Jul 11 2015, 06:58 PM

One of the biggest hurdles for any of these outer planets missions will be in getting enough Plutonium-238 to power the craft. Much of this ceased production as nuclear weaponry slowed in production. http://www.nasa.gov/pdf/636900main_Howe_Presentation.pdf(pdf) link has a good overview of the current situation with powering spacecraft in the outer planets.

It isn't necessarily just that people don't want a flyby mission. It also has some to do with 'wasting' an extremely rare resource for a very limited science return, versus a mission like Cassini which has generated an enormous sum of data for over 11 years.

Don't get me wrong, if Pu-238 was plentiful again, a bunch of NH class missions would be great, so long as it didn't jeopardize the science return for other longer missions.

Posted by: OWW Jul 11 2015, 06:59 PM

QUOTE (belleraphon1 @ Jul 11 2015, 07:38 PM) *
What does a human breath sound like there?

We already https://youtu.be/86scPKqWFvc?t=15.

Less than 2 million miles now!

Posted by: nprev Jul 11 2015, 07:02 PM

Topic moved to the Exploration Strategy section. Please review the Forum http://www.unmannedspaceflight.com/index.php?act=boardrules and keep them firmly in mind before posting.

Posted by: rboerner Jul 11 2015, 07:08 PM

At the risk of derailing my own thread, what are the odds that NASA will try to ease the PU 238 shortage by restarting development of ASRG? The latest news I'm aware of on the subject,

http://spacenews.com/u-s-plutonium-stockpile-good-for-two-more-nuclear-batteries-after-mars-2020/

says that ASRG development isn't truly dead, just on the minimum funding back burner and could be revived.

Posted by: djellison Jul 11 2015, 07:52 PM

QUOTE (rboerner @ Jul 11 2015, 10:41 AM) *
One cheap NH-type craft ....


$650M isn't cheap - New Horizons was New Frontiers class. Only Flagship missions are more expensive. Unless you are actually building them at the same time, there is little to be saved by building any sort of copy.

New Frontiers missions are now in the region of $800M - and given the current budget environment, expecting more than two every decade could be considered highly optimistic.

Posted by: ZLD Jul 11 2015, 08:35 PM

The ASRG is a good concept. I like it because it produces a lot more power for the same fuel supply. I don't like it because moving parts inherently fail eventually without maintenance. Most units will probably be fine (should they go into use) but a few are likely to cripple a mission and that always stings.

Posted by: JRehling Jul 23 2015, 06:49 PM

I'll mention an idea I had 15 years ago and the extension of that idea from the asteroid belt to the Kuiper Belt.

The high concept for the asteroid belt was this: Use a Jupiter gravity assist to put a solar orbiter into retrograde orbit. Use propulsion to drop the aphelion in from Jupiter distance to the edge of the asteroid belt. Then fly "backwards" down the asteroid belt, like a lunatic driving the wrong way down the highway, and have many, many asteroid flybys which are each very fast, because the relative velocity of the craft vs. the asteroids would be double the orbital speed at that distance.

Would a random orbit like that provide many close fly-bys? No. But if the goal were to maximize flybys, choosing whichever targets provided that goal, there could be an extraordinary number of fly-bys, as it would experience a conjunction with a known asteroid on average every two hours. Of course, most of these would be terribly distant flybys, but there would be a huge number of trajectories that would provide targeted flybys of 3 asteroids in a half orbit, and a few moderately close untargeted flybys. Then a propulsive maneuver could set up another set of targeted flybys, and I think you could get pretty good science on dozens of asteroids in one mission.

The Kuiper Belt doesn't make any of that math work out so nicely, but I suspect that a NH clone could achieve 3-5 flybys if we weren't picky about which targets it flew by. NH itself was "married" to one target. If a KB Explorer used a Neptune gravity assist to fly by two chosen targets, there'd almost certainly be a third bonus target reachable after that, so we'd get a look at the Neptune system plus 3 KBOs. Uranus could also drive something like that, and with two more probes, we'd get a flyby of Uranus and Neptune plus about 6 KBOs.

Posted by: SFJCody Jul 23 2015, 07:02 PM

One thing I'd like to see for a future New Horizons style mission is an attempt to draw out the flyby by giving the spacecraft a larger aperture telescope. Imagine how great it would be to have a mission with a HiRISE size instrument. Or even WFIRST!

Posted by: stevesliva Jul 23 2015, 07:13 PM

QUOTE (djellison @ Jul 11 2015, 02:52 PM) *
Unless you are actually building them at the same time, there is little to be saved by building any sort of copy.


2 is a good number. One J-U-TNO and one J-N-TNO. Same hardware, staggered so the same ops team handles every flyby. One "mission," two spacecraft, 4 giant planet flybys, then TNO science.

The problem is you get a smidge of science in a wide variety of buckets, so it's hard to write mission objectives for such a thing that sells it as advancing science in the way these things are justified.

Posted by: JRehling Jul 23 2015, 09:08 PM

I suppose one could group the Uranian and Neptunian satellites with TNOs as one, broad class of body that the mission(s) are exploring, just as Dawn had Vesta and Ceres as co-targets, not two unrelated goals. But Jupiter, jovian system (and Uranus/Neptune) observations would be quite unrelated: Nice to have, but not a rationale for the mission.

Posted by: stevesliva Oct 6 2015, 09:31 PM

QUOTE (JRehling @ Jul 23 2015, 05:08 PM) *
I suppose one could group the Uranian and Neptunian satellites with TNOs as one, broad class of body that the mission(s) are exploring, just as Dawn had Vesta and Ceres as co-targets, not two unrelated goals. But Jupiter, jovian system (and Uranus/Neptune) observations would be quite unrelated: Nice to have, but not a rationale for the mission.


Probably true. Looking at the new geology coming from the Pluto flyby, I'd think ice giant satellite flybys are not the un-novel already-been-done thing we tend to think of them as. The excellent may be the enemy of the good.

Posted by: JRehling Oct 7 2015, 05:28 PM

I took a quick glance at opportunities for Uranus/Neptune gravity assists to major KBOs. These bodies revolve so slowly that they may almost be regarded as stationary from the standpoint of planning over the next decade or two. It seems to me that Neptune seems well-placed for gravity assists to Eris or Sedna. Uranus might be well-placed for a gravity assist to Sedna if such a mission launched soon (which it won't). After another decade or two, Uranus will be positioned for gravity assists to Varuna; later, one to Orcus; still later, to Makemake and/or Haumea. Quaoar is odd-KBO out, with no opportunities for Uranus or Neptune gravity assists for a few decades.

So, a Neptune-Eris mission seems like a viable possibility in the decades to come, and a clone of that hardware might make a useful Uranus-Varuna mission. The latter mission would likely be complete before the Eris flyby from the former would take place due to the much longer cruise, which would require specialized hardware to suit the ultra-long distances.

Posted by: Ron Hobbs Nov 13 2015, 06:01 PM

Those would be great missions maybe for technology demonstration of the https://www.nasa.gov/content/heliopause-electrostatic-rapid-transit-system-herts/#.VkYjvPmrRhG

One can always dream! rolleyes.gif

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