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#51 2003-02-16 11:15:18

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

Re: Do you support a Nuclear Space Initiative? - Poll Results.

I'm in favour of water-ice-use as much as possible in interplanetary spacecraft, to the extent of being actually surrounded by a "cake of ice," as the solution to many of the problems arising in connection with human transportion in space. I'm assuming, according to latest estimates, there'll be plenty of (admittedly dirty) cometary ice to be found for this purpose, orbiting inside or crossing Earth's orbit.

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#52 2003-02-16 11:48:15

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,924
Website

Re: Do you support a Nuclear Space Initiative? - Poll Results.

Water is H2O. Hydrogen has an atomic weight of 1.0079 and oxygen is 15.9994; so the molecular weight of oxygen is 18.0152. Thrust is generated from gas expansion, so breaking water into mono-atomic gasses would produce 3 atoms for every molecule of water. Hydrogen would produce 2 atoms from each molecule of LH2. LH2 masses 2.0158 grams per mole, vs water at 18.0152 grams per mole. There are 6.022*10^23 molecules per mole. This means water or ice would substantially increase the mass of propellant for a given thrust, and that dramatically reduces specific impulse (Isp). Would the reduced Isp really be worth the reduced tank size?

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#53 2003-02-16 23:02:16

Echus_Chasma
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From: Auckland, New Zealand
Registered: 2002-12-15
Posts: 190
Website

Re: Do you support a Nuclear Space Initiative? - Poll Results.

Would the reduced Isp really be worth the reduced tank size?

Depends, which would be more fuel efficient?
Personally, I would go for an increased Isp, cos, I suppose with more fuel efficiency, you don't need to carry as much fuel, so, therefore you don't need a biggish fuel tank.

Sorry, but I can't do any of that maths too work it out.


[url]http://kevan.org/brain.cgi?Echus[/url]

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#54 2003-02-23 20:19:32

soph
Member
Registered: 2002-11-24
Posts: 1,492

Re: Do you support a Nuclear Space Initiative? - Poll Results.

If you had a fusion drive, water would be worthwhile-because that would be your propellant, and you would need only 1%-10% propellant, depending on your mass.

If you were on an interplanetary mission-water is the way to go, crack for fuel, use for radiation protection, and crack for oxygen.  Especially on an interplanetary mission.  However, for a fission-based launch vehicle or SSTO, water isnt the way to go.

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#55 2003-02-26 17:29:38

Shaun Barrett
Member
From: Cairns, Queensland, Australia
Registered: 2001-12-28
Posts: 2,843

Re: Do you support a Nuclear Space Initiative? - Poll Results.

Timberwind or liquid core NTR, what are the chances of getting it past the screaming rent-a-crowd protesters?
    As has been pointed out elsewhere in New Mars, they practically had apoplexy about the Cassini RTG! Imagine the orchestrated insanity we'd see with NTR ground launches!

    I don't mean to be a party-pooper, but ...
                                   sad


The word 'aerobics' came about when the gym instructors got together and said: If we're going to charge $10 an hour, we can't call it Jumping Up and Down.   - Rita Rudner

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#56 2003-02-27 00:13:24

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,924
Website

Re: Do you support a Nuclear Space Initiative? - Poll Results.

Perhaps you're right. I was saying the same thing until the announcement about Prometheus. However, that initiative is focusing on nuclear electric propulsion for interplanetary spacecraft.

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#57 2003-02-27 12:33:43

TJohn
Banned
Registered: 2002-08-06
Posts: 149

Re: Do you support a Nuclear Space Initiative? - Poll Results.

RobertDyck,

How long do you think we will be able to use nuclear electric propulsion to transport humans to the moon, Mars, and other areas within the inner solar system?


One day...we will get to Mars and the rest of the galaxy!!  Hopefully it will be by Nuclear power!!!

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#58 2003-02-27 16:57:22

soph
Member
Registered: 2002-11-24
Posts: 1,492

Re: Do you support a Nuclear Space Initiative? - Poll Results.

TJohn:

I don't think NEP should ever be our primary propulsion method.  Fusion will be ready by the time we get any significant thrust out of NEP, so I think the best use for an NEP would be as a hybrid NTP/NEP, to maximize thrust and fuel efficiency.

However, NEP might be a good option for probes, where speed is not as much of an issue.

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#59 2003-02-28 07:27:23

TJohn
Banned
Registered: 2002-08-06
Posts: 149

Re: Do you support a Nuclear Space Initiative? - Poll Results.

Thanks, soph. 

You mentioned that NEP be used for probes.  Is the JIMO mission NEP?


One day...we will get to Mars and the rest of the galaxy!!  Hopefully it will be by Nuclear power!!!

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#60 2003-02-28 11:31:12

soph
Member
Registered: 2002-11-24
Posts: 1,492

Re: Do you support a Nuclear Space Initiative? - Poll Results.

I believe so.

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