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Posted by: Tom Womack Nov 25 2008, 01:41 PM

I presume that it is completely infeasible without a very powerful nuclear reactor and many years' production of ion engines to do anything remotely like Dawn in the Kuiper belt - the distances are just too long.

Is it in fact feasible with current technology even to get a probe into orbit around Haumea or Makemake? I'd suspect not, that the speed you need to get it out to the Kuiper belt in a lifetime is much too great to cancel down to orbital velocity.

Posted by: Fran Ontanaya Nov 25 2008, 02:29 PM

(warning: ignorant speculation) A "Huygens like" orbiter maybe? Send a robotic micro-orbiter on batteries without Direct-to-Earth communications hardware, orbit the KBO during several days, hibernate until the flyby probe passes by and upload the data to it so it's slowly retrieved through the DSN pipe.

Posted by: Rob Pinnegar Nov 26 2008, 01:29 AM

It's possible that it could be done with current technology. But it would be unbelievably expensive -- and yes, we'd be talking about decades before any science results came in.

I'm guessing that a Neptune flyby would pretty much be a prerequisite -- just to help get the thing into something resembling a desirable orbit. Unfortunately, it would also cut down the number of possible targets.

Posted by: xtruel Jan 14 2009, 04:43 PM

What seems far more realistic to me is a fly-by mission (similar to NH) which should greatly cut down costs, risks, technology challenges and travel time to such distant objects. Another reason is that I don’t see how it will be possible, from the scarce data collected by near-earth based observations of these objects, to define scientific goals which would be achievable by an orbiting mission but not by a fly-by mission and critical enough to justify the (big) drawbacks listed above. The exception being Pluto (a very interesting KBO indeed) if for some reason NH discoveries scheduled for 2015 raise some kind of interest for further investigation. I guess that any orbital mission to objects at typical KB distances would require at least 30 years to complete the trip, whatever the propulsion technology / gravitational assists strategy used.

About technology, Dawn’s solution (ion thrusters + solar panels) seems not feasible at KB where the distance to the sun is too great. I don’t believe in a solution of powering ITs by RTGs (too much power required ?). Given the fact that KBOs orbital velocity is rather low, it might be possible to design a rendez-vous trajectory (maybe with Neptune gravitational assist) where the delta-V required to enter orbit is small enough to be handled with standard chemical thrusters.

Posted by: abbath Feb 22 2010, 11:32 AM

it should be quite unfeasible to power the probe and the electric propulsion with RTG, since the power output decreases with time (power from a 238Pu source decays by about 10% per 10 years). Considering the cruise time needed to reach a KBO (with or without gravity assists), the spacecraft would reach its target with a small amount of power aveable to operate the instruments (and propulsion). IMHO, the best power source is a fission reactor.

Posted by: djellison Feb 22 2010, 11:36 AM

New Horizons is expected to reach, and be fully functional at, one or more KBO's after it's Pluto flyby.

Posted by: machi Feb 22 2010, 11:49 AM

At least Pluto orbiter is possible.
Some informations here:
http://www.esa.int/gsp/ACT/doc/MAD/pub/ACT-RPR-MAD-2006-(JSR)NonDedicatedOptionsToTestThePioneerAnomaly.pdf

Posted by: abbath Feb 22 2010, 01:03 PM

yes, i know, but the topic is about some Dawn-style mission, which involve ion propulsion, not just chemical. RTG of course is able to power a scientific platform, but is fat too unpowered to sustain some electric propulsion (a RTG unit can provide 300-400W, while a ion thruster needs several kW. Using multiple RTG units would result in a too heavy probe).

The real problem with nuclear reactors is that today they need a great R&D work. Just some prototipes have actually flown in space (i.e. USSR' topaz).

Posted by: abbath Feb 22 2010, 01:10 PM

Here's a publication I just found on a proposed fly-by mission to Neptune-Triton and KBOs

http://futureplanets.blogspot.com/2009/08/white-paper-argo-mission-to-neptune.html

Posted by: Greg Hullender Feb 23 2010, 04:59 AM

Yup. Here's the thread where we're talking about it.

http://www.unmannedspaceflight.com/index.php?showtopic=5413

It is a very appealing idea, isn't it?

--Greg

Posted by: Greg Hullender Feb 23 2010, 05:04 AM

This is a paper about the so-called Pioneer Anomaly. Did you post the wrong link?

--Greg

Posted by: machi Feb 23 2010, 09:00 AM

No. Some informations about this mission are in this paper and this is only paper which I found on net with some informations.
But I searched my personal archive and I have original paper about this mission (it's one of ESA ACT studies).
It was freely available on net, but now It's somewhere in ESA archives.
I don't know if I can send copy here, It's ESA copyrighted material.
But at least some informations about this study:

Pluto Orbiter Probe (POP):
Wet mass: 830 kg.
Dry mass: 510 kg.
Power: 4×GPHS-like RTG (MMRTG) (1.05 kW at Pluto).
Propulsion: 4×QinetiQ T5 ion engines with 270 kg of Xe.
Communication: X/Ka band. 380 bps to 35 meter ESA antenna (Ka band).
Instruments: Camera, near infrared spectrometer, X-ray spectrometer, radiation experiment, SAR, bolometer (20 kg).

Launch: XII.2016 (enhanced Ariane 5).
JGA: 2018.
Pluto orbit: VI.2034 (after 1 year spiral down phase).
Final orbit: Circular with a inclination 99°, altitude 1000 km, Charon visited on spiral-down phase.