Author Topic: Time for Voyager 3?  (Read 5358 times)

Online Alpha_Centauri

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Re: Time for Voyager 3?
« Reply #20 on: 08/29/2010 07:57 PM »
It would be  cheaper two just use Atlas V or Delta IV
Atlas 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?

What is there to stop the use of 2 launches, one with the vehicle and the other with an EDS? It would still be at least an order of magnitude cheaper than developing and launching a new heavy lift rocket.

I still don't see why such a mission needs to be so large anyway, part of the reason for the size of even the Voyagers was because they were conducting planetary science all along the way.

Offline hop

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Re: Time for Voyager 3?
« Reply #21 on: 08/29/2010 08:11 PM »
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.
Look at http://www2.jpl.nasa.gov/basics/bsf4-1.php

Notice how little of voyagers final velocity came from the EDS. Their initial trajectory would have taken them only about to Jupiter's orbit.

Now compare to New Horizons, which was launched on an escape trajectory, picked up another 4kms from Jupiter, and is still slower than the Voyagers (but it spent less time getting to Jupiter...)

You really hit diminishing returns when you try to go that fast with chemical stages, you'd probably be better off spending the mass on radiation shielding so you could go real close to Jupiter. Nuclear electric (or possibly solar electric or solar electric/sail hybrid) also have the potential to do much better. AFAIK Dawn has 10kms of dV in it's propulsion system. That's about the same as you spend getting from earth to LEO, so to get the same capability in chemical propulsion, you'd need to launch something the size of a Falcon 1e (35 tons) instead of 1.2 tons.

If your destination is "leave the solar system" then Jupiter is available quite frequently, and it's by far the biggest bang for your buck.

Offline gospacex

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Re: Time for Voyager 3?
« Reply #22 on: 08/30/2010 12:14 AM »
Some wild ideas for science payloads for HLV:

* _Big_ telescopes (8m monolithic, 20m segmented). Hubble was only a beginning.
* Mars rovers + MSR technology demonstrator(s) + supporting comm orbiters - all in one launch.
* MSR

These should be built not in "minimal mass, maximum budget and schedule slip" mode, but cheaper, and several copies of each. One J-246 can throw how many MROs to Mars in one go?

Offline Proponent

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Re: Time for Voyager 3?
« Reply #23 on: 08/30/2010 12:19 AM »
Some wild ideas for science payloads for HLV:

* _Big_ telescopes (8m monolithic, 20m segmented). Hubble was only a beginning.
* Mars rovers + MSR technology demonstrator(s) + supporting comm orbiters - all in one launch.
* MSR

These things keep coming up, but they're just not plausible, because the NASA space-science budget cannot afford and HLV-sized program.

Offline RocketEconomist327

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Re: Time for Voyager 3?
« Reply #24 on: 08/30/2010 01:52 AM »
Some wild ideas for science payloads for HLV:

* _Big_ telescopes (8m monolithic, 20m segmented). Hubble was only a beginning.
* Mars rovers + MSR technology demonstrator(s) + supporting comm orbiters - all in one launch.
* MSR

These things keep coming up, but they're just not plausible, because the NASA space-science budget cannot afford and HLV-sized program.
Of course it can.  You just have to want to do the science and not become a jobs program.  NASA right now is a political jobs PR fiasco.

SpaceX and to some extent ULA are the models of the future.  We do not need mega centers anymore.  The days of Apollo are gone.  NASA will either "right size" or become completely inept; which would be sad.

VR
RE327
You can talk about all the great things you can do, or want to do, in space; but unless the rocket scientists get a sound understanding of economics (and quickly), the US space program will never achieve the greatness it should.

Putting my money where my mouth is.

Offline Robotbeat

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Re: Time for Voyager 3?
« Reply #25 on: 09/01/2010 05:57 AM »
A hybrid solar sail and very large solar array deposited on a thin-film membrane, like IKAROS did, could provide hybrid solar-electric propulsion for a long time. If more delta-v is needed after sunlight becomes too tenuous, the solar-electric "stage" could be shed at, say, Jupiter, and a radioisotope electric propulsion system could take over. I imagine you could get at least 50km/s (and perhaps more) extra from such a system, in addition to whatever your chemical stage gave you.

The next step would be something like the fission-fragment rocket (could be spontaneous fission, like a radioisotope, not necessarily a nuclear chain reaction), and although that is kind of getting a little outrageous, exhaust velocities of 1000-10000km/s are possible with that method... though, let me emphasize fission-fragment rockets are only an idea right now, an "advanced concept".
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

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