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#1 2004-02-09 16:25:32

RobS
Member
From: South Bend, IN
Registered: 2002-01-15
Posts: 1,701
Website

Re: Ion Propulsion

This description of the JIMO (Jupiter Icy Moons Orbiter) is encouraging:

The mighty spacecraft NASA envisions would be powered by a nuclear fission reactor capable of pumping out 100 kilowatts of power. The reactor would power JIMO's propulsion system and provide more electricity than any spacecraft has ever had for instruments, computers and communications.

Mills said the spacecraft could easily be 50 meters long when fully deployed -- about half the size of the international space station. Boeing, at least, is concentrating on designing a spacecraft light enough to launch in one piece aboard a heavy lift version of either the Delta 4 or Atlas 5 rockets.

This is from http://www.space.com/spacenews/business … 0209.html, an article about Prometheus

I see two encouraging pieces of information:

1. A 100 kw reactor is what we need on the Martian surface, and probably on the moon as well if there's polar ice to refine.

2. The size of the vehicle means the ion engine will be about the size of the ion tug I've been writing about as something to move EELV cargos from LEO to Lagrange.

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#2 2004-02-12 13:37:13

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Ion Propulsion

A lovely presensation about all things nuclear... imparticularly, short and medium term reactor concepts: www.spacetransportation.com/ast/ presentations/7b_vandy.pdf

A neat timeline blurb on page 10... simple nuclear propulsion for Cislunar and limited Mars travel by 2020 (Nerva NTR, >1MWe NEP), and then cool stuff like VASIMR and GCNR by 2030 perhaps, in the time frame for Bush's proposed first Mars flights. Page 19 has a little rubric about near-future power plant concepts, from 100kWe to 400kWe up to 4MWe reactors! That would really move an ion powerd ship.


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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#3 2004-02-14 05:35:48

chat
Member
From: Ontario Canada
Registered: 2003-10-23
Posts: 371

Re: Ion Propulsion

Glad to see the nuke ideas are returning to what was done in the 60s with nuclear rocket tests.
To bad they were not developed more from what was done 40 years ago in Los Alamos.
You could only imagine what kind of power would be possible with 40 years of development.

I think without nuclear power no moon base or mars travel will happen.

Getting to mars is going to be a big venture, and if it's going to be done it better be done fast, with a reserve for a disaster.
To many nasty things can and do happen on the way to and from mars, let alone the radiation on mars and the occasional nasty weather on mars.

With a nuclear powered ion or acceleration drive with a few MW it's realistic to get people to and from mars and limit the exposure on route.

But a better plan i think is to get to the moon, create a small base that is self sufficient, learn all the nasty things that can go wrong on the moon.

Then once we have done that, send humans to mars to stay.
No return ticket included, but lots of frequent flyer points to be redeemed at a later point smile.


The universe isn't being pushed apart faster.
It is being pulled faster towards the clumpy edge.

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#4 2004-02-24 21:41:18

infocat13
Member
Registered: 2003-10-28
Posts: 21

Re: Ion Propulsion

nasa will spend $300 million to build a robotic reboost/deboost rocket for the HST. this could be the ion tug powered at first by solar panels move the HST to a orbit close to the ISS for refurbishment or boost to a high storage orbit.this protype should be refuelable and be human tended after its HST mission and stored at the ISS.

then ramp up this prototype tug with the promeathes reactor.

several weeks before nasa watchs editoral on this issue I had emailed this idea to them smile

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#5 2004-02-25 08:09:53

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Ion Propulsion

Although I like the idea of sending up an ion tug to push HST into a storage orbit, Hubble is a very heavy object... I have doubts that it could be pulled off with a small ion drive since it has to deal with LEO air resistance too.

Also, designing a nuclear/electric vehicle is so radicly different than making a solar/electric one, that it doesn't make much sense to base one off the other.


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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#6 2004-02-25 11:19:40

dicktice
Member
From: Nova Scotia, Canada
Registered: 2002-11-01
Posts: 1,764

Re: Ion Propulsion

infocat13: Where did you find out about that? We need to know, because up until now HST was to be simply deorbited by some means for reentry and dumping into the ocean. The self-docking and remote control , etc. (not to mention ion-drive) you envisage still has to be perfected by NASA, I submit. The Russians, if they were brought in, could surely do the deed using Progress freighter established procedures. The means of attaching to, and detaching from, the HST are already in hand, I assume? Let's have a little backup!

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#7 2004-02-25 12:21:16

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Ion Propulsion

Ah but the Progress vehicle only works well when the target is equipped with docking guideance hardware, I believe... Since HST isn't, the Russian system would be useless, same thing with the ESA ATV?


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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#8 2004-02-25 12:36:06

DanielCook
Member
From: Atlanta, GA
Registered: 2004-02-19
Posts: 90

Re: Ion Propulsion

I think infocat is referring to the fact that NASA would need to have a controlled descent for HST as it represents to high a risk for impacting populated areas. As HST does not have this capabilities in itself, hence they will have to design a "deorbit" module than can autonomously attach to HST and deorbit.

One of the arguments used against deorbiting the HST was because the servicing mission and this "deorbit" module would have cost about the same. (Total spent on the servicing mission to date is around 200+ million, about 500 budgeted.)

And since the HST was not designed to be docked with, there is the possibility that designing this module might be more expensive than doing the servicing mission.


-- memento mori

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#9 2004-02-25 19:07:31

infocat13
Member
Registered: 2003-10-28
Posts: 21

Re: Ion Propulsion

the argument is also being made that the deorbit module nasa wants could also orbit HST into a storage orbit that would last decades.
This same money could be used for a very large solar eletric tug.
It has also been suggested(for planetary missions and more) that prometheus a thermal nuclear rocket would also be a electricity generater(stirling ?)(rtg coupling?)this power could be used for ion power station keeping or orbit transfer
you would not be powering up a thermal nuclear rocket for every little bit of  isp you need.keeping a thermal nuclear fuel cool might be a chore.thermal nuclear may not end up being used for cargo only missions out there any how.this may be a mission for a very large nuclear eletric egine(ion)

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#10 2004-02-25 20:15:28

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Ion Propulsion

Making a nuclear ion tug in this short of a time frame would be a problem, but not impossible, my gut feeling is that this is still a job for chemical engines... anyone have any figures on how much more Delta-V it would take to put Hubble into a higher orbit than it would to deorbit?


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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#11 2004-02-25 21:34:45

infocat13
Member
Registered: 2003-10-28
Posts: 21

Re: Ion Propulsion

I was thinking a large solar electric for this mission but the solar panels would have yet more drag.of course the ion engine it self would need a boost into  orbit so...................................... cool

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#12 2004-02-26 10:11:08

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Ion Propulsion

Plus you have to keep in mind that an ion powerd vehicle would have lousy orbital maneuvering capability with its low-thrust engine, requiring the addition of a chemical system of some sort to get from the upper stage to dock with HST.


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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#13 2004-02-26 12:06:21

DanielCook
Member
From: Atlanta, GA
Registered: 2004-02-19
Posts: 90

Re: Ion Propulsion

Maybe directed compressed gas? I think the Shuttle uses something like that for orbital maneuvering.


-- memento mori

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#14 2004-02-26 15:02:20

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,453
Website

Re: Ion Propulsion

X-38 was going to use cold nitrogen gas to prevent damaging ISS. However, Shuttle uses Nitrogen tetroxide / Monomethylhydrazine (N2O4/MMH) for its OMS and RCS engines.

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#15 2004-02-26 15:33:11

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Ion Propulsion

Heh designing the escape vehicle so it won't damage the disintigrating space station?

Anyway, whatever system would be used needs to be fairly powerful in order to push a >1 ton ion drive system able to nudge the big HST, some sort of combustion engine would be nessesarry.


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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