Author Topic: Time for Voyager 3?  (Read 5348 times)

Offline Space Invaders

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Time for Voyager 3?
« on: 08/28/2010 11:24 PM »
Voyager 1 and 2 entered the heliosheath a few years ago and are still transmitting data, albeit at a relatively slow rate of aprox. 180 bits per second. Now that they are so far from the Sun, they could provide us with extremely interesting information on the very edge of the Solar System. The problem is that some of their instruments are no longer working and within no more than 15 years they will run out of power, being unable to send any more information whatsoever.

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:

*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.

I have thought of these main advantages but might have forgotten other ones, and I might also have overlooked technical problems. Nevertheless, I think this would be a great use of super-heavy lift for unmanned missions - just think of the scientific return of having a fully powered and equipped probe right in the heliosheath.

So, what are your thoughts and opinions on this? Should we give priority to such a mission, or is it better to spend money and resources on studying the solar system itself? Discuss.

Online Alpha_Centauri

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Re: Time for Voyager 3?
« Reply #1 on: 08/29/2010 12:33 AM »
The words "sledgehammer" and "nut" spring to mind.  There would be far more useful ways to use a mission of that scale, and it requires a whole new heavy lift rocket to launch.  You simply don't need a huge "battlestar"-like probe to study the Heliosheath.  There's only so many cosmic ray experiments you can do!

No, future probes to the Heliosheath are likely to be solar sails anyway.  Here is an ESA reference study on the Interstellar Heliopause Probe,

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=40927#  (PDF at the bottom)

It's not an actual mission, yet, but you get the idea of the thinking over the type and scale.  The added benefit is given that it'd be relatively low cost you could launch multiple probes in different directions to measure the Heliosphere in 3D.
« Last Edit: 08/29/2010 12:54 AM by Alpha_Centauri »

Offline Cinder

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Re: Time for Voyager 3?
« Reply #2 on: 08/29/2010 02:07 AM »
Also IBEX.
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Offline Proponent

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Re: Time for Voyager 3?
« Reply #3 on: 08/29/2010 03:00 AM »
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....

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 that

Quote from: NRC
Virtually all of the science mission concepts that could take advantage of Constellationís unique capabilities are likely to be prohibitively expensive.

Offline Sparky

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Re: Time for Voyager 3?
« Reply #4 on: 08/29/2010 04:35 AM »
Quote from: Space Invaders link=topic=22603.msg632309#msg632309

*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.

As is said by corporate yuppies everywhere, work smarter, not harder. Rather than just using a bigger rocket to haul more fuel, you'd be better off using something like VASIMR or perhaps even a light sail. For the latter, you could power it with a laser beam shone from a spacecraft in the inner solar system, and get not only propulsion, but electrical power as well, eliminating the need for RTGs.
« Last Edit: 08/29/2010 01:56 PM by Sparky »

Offline Space Invaders

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Re: Time for Voyager 3?
« Reply #5 on: 08/29/2010 09:13 AM »
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

Offline Nathan

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Re: Time for Voyager 3?
« Reply #6 on: 08/29/2010 09:17 AM »
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

Wouldn't it be better to just launch the probe directly? Small probe, fast trajectory.
I've never understood why vasimir is seen as a universal solvent when it hasn't even flown in space and would weight an extraordinary amount when it does.
Voyager 3 as an ultrafast heliosphere mission launched on HLV sounds good to me.
Given finite cash, if we want to go to Mars then we should go to Mars.

Offline madscientist197

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Re: Time for Voyager 3?
« Reply #7 on: 08/29/2010 10:22 AM »
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 that

Quote from: NRC
Virtually all of the science mission concepts that could take advantage of Constellationís unique capabilities are likely to be prohibitively expensive.

I'm going to reply with a quote:
Because of the current budgeting system, HLV missions have to be overblown in order to justify all the amortised HLV fixed costs.
from http://forum.nasaspaceflight.com/index.php?topic=22381.msg632378#msg632378

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.
« Last Edit: 08/29/2010 10:24 AM by madscientist197 »
John

Offline Proponent

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Re: Time for Voyager 3?
« Reply #8 on: 08/29/2010 11:33 AM »
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.

I agree that if HLV costs were not allocated to the space-science program then a Discovery-class science mission become possible and possibly interesting.  But a very sophisticated Voyager 3, as here, does not fit that bill.

Offline Space Invaders

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Re: Time for Voyager 3?
« Reply #9 on: 08/29/2010 11:49 AM »
So what about a not-so sophisticated Voyager 3, where the only improvements would be a much greater fuel mass to ensure it's still transmitting when it exits the solar system; and a somewhat larger Earth Departure System to make it reach the boundaries of the Solar System in no more than 20 years (like New Horizons)?

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.

Offline Jim

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Re: Time for Voyager 3?
« Reply #10 on: 08/29/2010 12:01 PM »
It would be  cheaper two just use Atlas V or Delta IV

Online ugordan

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Re: Time for Voyager 3?
« Reply #11 on: 08/29/2010 12:20 PM »
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.

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.

Offline Space Invaders

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Re: Time for Voyager 3?
« Reply #12 on: 08/29/2010 01:21 PM »
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.

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.
No, not 500 kg. It would be much heavier, with new instruments dedicated specifically to the heliosheath/heliopause and interstellar space, a more powerful communications system with a greater bandwidth, redundant systems in case something breaks down, more fuel for the RTGs, a larger EDS which can impart a very high escape speed to the probe, etc.

The 60-tonne capacity of the J-130 would give us enough margin to implement almost any upgrade we can imagine to the Voyagers. At no time did I suggest using a HLV to launch just 500 kg, I just wanted to point out that we don't need an Ares V, 180-tonne beast to launch a Flagship heliopause mission, and that it can be launched with a smaller HLV. We really do need a dedicated mission to research interstellar space in situ, one which crosses the heliopause in good condition and not with power shortages.

A J-130 would give us the means to do this, while costing less than a Space Shuttle launch. The cost of the probe itself would be in the ballpark of Cassini-Huygens.
« Last Edit: 08/29/2010 01:23 PM by Space Invaders »

Offline khallow

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Re: Time for Voyager 3?
« Reply #13 on: 08/29/2010 01:44 PM »

one which crosses the heliopause in good condition and not with power shortages.

While it's a bit off-topic, I heard that the Voyager and Pioneer spacecraft would last considerably longer, if it weren't for radiation damage to the thermocouples which reduced the effective power output from the RTGs. The point is that we might be able to get more power for longer with some design that is less radiation sensitive (say replacing the thermocouples with some sort of stirling engine).
Karl Hallowell

Offline ChrisGebhardt

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Re: Time for Voyager 3?
« Reply #14 on: 08/29/2010 03:28 PM »
Also IBEX.

Also New Horizons.

Offline Space Invaders

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Re: Time for Voyager 3?
« Reply #15 on: 08/29/2010 03:42 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?

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?
« Last Edit: 08/29/2010 03:42 PM by Space Invaders »

Offline GoForTLI

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Re: Time for Voyager 3?
« Reply #16 on: 08/29/2010 06:42 PM »

A probe with six RTG (compared to three for the originals)...

I seem to recall there is a shortage of RTGs, or the fuel that is used to manufacture them.
There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another theory which states that this has already happened. -- Douglas Adams

Offline MP99

Re: Time for Voyager 3?
« Reply #17 on: 08/29/2010 06:45 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?

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?

I recently posted the capabilities of a fully-fuelled DIVH upper stage, and the payloads that it could push BEO. This was in the context of J-130, so is obviously more than DIVH could achieve when the US also needs to burn to achieve orbit.

Details (inc spreadsheet with numbers & caveats) at http://forum.nasaspaceflight.com/index.php?topic=22381.msg631077#msg631077.

cheers, Martin

Offline Bubbinski

Re: Time for Voyager 3?
« Reply #18 on: 08/29/2010 06:56 PM »
Are there any mission concepts to bodies like Sedna or Eris being discussed?  I know New Horizons is going to Pluto and maybe a couple other KBO's, then will leave the solar system....hopefully it'll be able to transmit data from when it goes into interstellar space, whenever that will be.
I'll even excitedly look forward to "flags and footprints" and suborbital missions. Just fly...somewhere.

Offline Cinder

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Re: Time for Voyager 3?
« Reply #19 on: 08/29/2010 07:48 PM »
Also IBEX.

Also New Horizons.
I wrote that in a hurry.. I meant that IBEX' science results would be help in designing instruments around what the expected science requirements would be for this Voyager 3.

NH Would help this way but only years from now.
« Last Edit: 08/29/2010 07:49 PM by Cinder »
The pork must flow.

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".
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