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abbath
Posted on: Mar 22 2010, 09:51 AM


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Falcon 9 (as falcon 9h) has a fairing diameter of 5.2m, and an iternal diameter of 4.6 (http://www.spacex.com/Falcon9UsersGuide_2009.pdf pag.30), even less than a standard Atlas 5.4m fairing.
I don't know if Falcon 9 is able to support a custom-made payload fairing.
  Forum: Past and Future · Post Preview: #157460 · Replies: 37 · Views: 21340

abbath
Posted on: Mar 12 2010, 09:00 AM


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looking at the sheet http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/37654/1/05-2760.pdf, JUNO seems to pass closer to the north pole than the south one on every orbit. Will this difference in altitude (hence in resolution) affect the results of the mission?

IMHO the southward moving apsides will make us miss some (maybe) important small-scale features in south pole.
  Forum: Juno · Post Preview: #156921 · Replies: 593 · Views: 290762

abbath
Posted on: Feb 22 2010, 03:31 PM


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Here is a great paper explaining some of the theories about the formation of Vastitas Borealis
http://arjournals.annualreviews.org/doi/pdf/10.1146/annurev.earth.35.031306.140220
  Forum: Mars · Post Preview: #155909 · Replies: 3 · Views: 5922

abbath
Posted on: Feb 22 2010, 03:23 PM


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I belive that Mars actually have never had active tectonism, able to create (and break apart) supercontinents. One proof of this may be the height of Tharsis volcanoes, created by hot-spot plumes (like Hawaii here on Earth), but with a fixed crust, magma kept on erupting (for milions of years?) always in the same place, creating these gigantic volcanoes. if there were some tectonism, there would be a chain of volcanoes istead.
(of course tharsis volcanism can be hundreds of milions of year younger than the last plate motion......if ever been one)
  Forum: Mars · Post Preview: #155907 · Replies: 3 · Views: 5922

abbath
Posted on: Feb 22 2010, 02:49 PM


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QUOTE (James Sorenson @ Feb 22 2010, 07:15 AM) *
Here is the IDD work volume pan taken between sol's 2163-2176 with L257. Lots of color variations in the soil smile.gif
[attachment=20798:MERA_tro...257_UMSF.jpg]


The fine lamination of the rock in the center of the pic is quite interesting. seems like a clay deposit (deep water???). I hope there'll be some future detailed analysis of that.
  Forum: Spirit · Post Preview: #155906 · Replies: 311 · Views: 147498

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


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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
  Forum: Pluto / KBO · Post Preview: #155900 · Replies: 11 · Views: 15493

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


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QUOTE (djellison @ Feb 22 2010, 12:36 PM) *
New Horizons is expected to reach, and be fully functional at, one or more KBO's after it's Pluto flyby.


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).
  Forum: Pluto / KBO · Post Preview: #155899 · Replies: 11 · Views: 15493

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


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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.
  Forum: Pluto / KBO · Post Preview: #155896 · Replies: 11 · Views: 15493


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