I was thinking how useful it would be to send up a "Voyager 3" on a Jupiter-246 rocket and for the express purpose of studying the outer solar system. The J-246 mass to LEO, six times as much as that of the rocket which launched the Voyagers, would allow for fantastic upgrades....
Virtually all of the science mission concepts that could take advantage of Constellation’s unique capabilities are likely to be prohibitively expensive.
*A much more comprehensive instrument package, designed specifically for studying the outer heliosphere.*A much more generous amount of radioactive fuel for the RTGs, providing for a much longer mission duration and preempting the need for instrument power sharing.*A much bigger Earth departure stage, imparting the spacecraft with a higher velocity and thus allowing it to reach its destination quicker.
Wouldn't the mass of the whole VASIMR pack (including structure, solar arrays/nuclear reactor, fuel tank, avionics, propellant and cargo) be in the heavy-lift class as well?This paper says a complete VASIMR-based tug would weigh about 100 tonnes in LEO, and that's for a Moon mission.http://www.adastrarocket.com/Tim_IEPC07.pdf
The trouble using HLVs for science missions is that the cost would cripple the space-science budget.At the behest of the National Academy of Science, a few years ago the National Research Council studied the potential scientific uses of heavy-lift rockets, specifically Ares 5. A summary of the Council's report is attached. The Council concluded thatQuote from: NRCVirtually all of the science mission concepts that could take advantage of Constellation’s unique capabilities are likely to be prohibitively expensive.
Because of the current budgeting system, HLV missions have to be overblown in order to justify all the amortised HLV fixed costs.
If you don't charge the science mission any of the HLV fixed costs, then the science missions don't have to be overambitious in order to justify the costs. The increase in marginal costs over EELV is sufficiently small that it isn't implausible that Discovery missions could use HLV. There is no reason why a mission has to fully take advantage of the capabilities of the HLV if:* HLV is going to exist no matter what science does (e.g. Congress insists on one for HSF)* HLV wins out on a cost benefit analysis over EELV for the mission (when only charging marginal cost of an extra launch). This might include factors like the extra delta v available and less mass constraints.
A probe with six RTG (compared to three for the originals) and an extended Centaur upper stage with some more fuel could potentially be launched by a Jupiter-130 instead of a J-246, reducing cost while still keeping the most important upgrades. Adding new instruments wouldn't have a significant impact since we can just take out those which in the original Voyagers were used for the planetary part of the mission.
Quote from: Space Invaders on 08/29/2010 11:49 amA probe with six RTG (compared to three for the originals) and an extended Centaur upper stage with some more fuel could potentially be launched by a Jupiter-130 instead of a J-246, reducing cost while still keeping the most important upgrades. Adding new instruments wouldn't have a significant impact since we can just take out those which in the original Voyagers were used for the planetary part of the mission.So you're saying it's a dedicated Jupiter launch, but which the science team would not have to pay for (since it couldn't anyway, given the amount of science this mission would provide and the budget it would thus get) to launch nothing else but a crippled Voyager spacecraft? Basically a HLV to launch a 500 kg or so spacecraft.If that doesn't sound like a solution (HLV) in search of a problem, I don't know what does.
one which crosses the heliopause in good condition and not with power shortages.
Also IBEX.
It would be cheaper two just use Atlas V or Delta IV
A probe with six RTG (compared to three for the originals)...
Quote from: Jim on 08/29/2010 12:01 pmIt would be cheaper two just use Atlas V or Delta IVAtlas V Heavy would be able to lift an improved, heavier Voyager with extra fuel and instruments. But with only 10-15 tonnes to LEO payload advantage over the Titan III which launched the original Voyagers, would it be able to carry a big enough EDS to significantly reduce cruise time compared with the originals?If the answer is yes, then obviously an EELV is better, but maybe Jim can give us some information on how significant the escape velocity improvement would be compared with the Titan III.On another note, obviously the Grand Tour won't be available for a century or so, but is there any significant gravity assist opportunity in the next two decades?
Quote from: Cinder on 08/29/2010 02:07 amAlso IBEX.Also New Horizons.