NASA wants space flights to be nuclear

TheStar.com ^ | 1/12/03 | GWYNETH SHAW

[Brett66]

NASA wants space flights to be nuclear Fission would be used to produce electricity Agency says safety top priority in 2-pronged project

GWYNETH SHAW
SPECIAL TO THE STAR

WASHINGTON—There's a fact that NASA chief administrator Sean O'Keefe has become fond of sharing during his first year in office: Today's spaceships travel at the same speed as the Friendship 7 when John Glenn rode it to fame with his 1962 orbit of the Earth.

O'Keefe's point: There have been few advances in space propulsion in the last 40 years.

If the chief has his way, however, that will change.

Last year, O'Keefe announced that the National Aeronautics and Space Administration will spend $1 billion (U.S.) during the next five years working to convert nuclear technology into electrical power, an advance that, if it works, would revolutionize the way robots and humans travel through space.

"It's a totally different system that opens up a whole new range of options for the scientific community," says Ray Taylor, a program executive in NASA's Office of Space Science.

"It would mean a real shift and expansion in the ability to do exploration of the solar system."

The proposed Nuclear Systems Initiative is a two-pronged approach. The first task is to develop a new generation of the radioisotope thermoelectric generators NASA has used for decades on robotic missions such as those undertaken by the Cassini and Galileo spacecraft.

The plutonium units, known as RTGs, use the heat from the natural decay of the radioactive materials to generate electricity. The units are self-contained, and there is no nuclear reaction.

In the second, more ambitious, phase of the program, NASA scientists will attempt to take a page from the U.S. Navy's nuclear-submarine fleet and explore using fission — a tightly controlled nuclear reaction — to provide electricity.

The more advanced technology not only could provide power for instruments on a spacecraft but also open the door for a faster way to propel the craft through space. That, in turn, would slash travel times for far-flung planets — exactly what NASA is hoping to do.

O'Keefe says the promise of nuclear technology will be useful across the board. But it's particularly important if NASA is ever going to send humans to Mars, a trip fraught with risk because of the dangerous ultraviolet radiation to which astronauts would be exposed.

"You can conquer that, partially, by getting there faster and getting back sooner," O'Keefe explains. "That's the reason why we're hell bent to leather on trying to pursue this."

NASA already has begun the competitive-bid process for research and development grants for both the advanced RTGs and the fission project, Taylor says. There is no set timetable for a finished product, although scientists are counting on the newer RTGs for a 2009 robotic mission to Mars.

If the technology can be developed, it would be a huge leap.

For example, Taylor says, an RTG such as the one aboard Galileo offered about 600 watts of electric power. A nuclear-electric propulsion system could have about 100,000 watts, which would be used to propel the spacecraft through its journey and then power cameras, sensors and other scientific instruments.

Says Taylor: "All these technologies are being developed so that mission planners will have more options to draw from in the future. Certainly, nuclear propulsion has tremendous benefits, not just for propulsion but because of the tremendous power it offers. That can be used to operate a whole new generation of instruments."

NASA is working closely with the U.S. Department of Energy on the program and O'Keefe and others throughout the agency have offered repeated assurances that nuclear power would be used only with safety as the absolute priority.

Prior flights that have used RTG units have drawn fire from nuclear critics, most recently before the 1997 launch of Cassini, the subject of heavy protests about the possibility of an accident on the launchpad.

"Safety is our Number 1 priority," says Taylor. "But all this is driven by the need to expand the ability to explore the solar system. That's why this is being done. It's not just a fun side activity."

Orlando Sentinel

[Centurion2000]

The postive benefit is that you could launch something the size of an aircraft carrier in a single stage launch from the floor.

The bad news: your launch site gets a little 'hot'

[Brett66]

Hey RA, do you know any specs for what the SP-100 was supposed to yield? Wattage, weight, dimensions. I couldn't find any hard numbers when I did a search. Though I found that Cassinis RTG's provided around 800+ watts.

[RadioAstronomer]

I have some old manuals on that program. Let me look tomorrow. :-) (remind me!) :-)

[Centurion2000]

Another image : Mars voyager concept craft

Image of Orion craft in Mars system

ORBITAL PROFILE

[Centurion2000]

Final images

The stars are the limit.

[roadcat]

"If you think the stink raised over the plutonium used on deep space probes was bad, if this ever gets off the drawing board, expect a lot of outrage."

Outrage aside, it seems like the pollution wouldn't be too bad. Isn't there already a lot of radiation in open space? So nuclear blasts in space aren't really contaminating anything. So then you're saying we only have to worry about the danger of lofting radioactive materials into space from Earth (because of concerns of the craft breaking up in Earth's atmosphere and spreading radioactivity).

Then the solution is to mine the radioactive materials off-world. Question is, how difficult will that be?

[Pyro7480]

That's a good question. If the theory is correct that everything in the solar system formed from the same nebula, then there should be fissionable materials elsewhere in the solar system. The problem comes with the concentration. Earth is the largest of the solid inner planets, so it probably gathered the most radioactive materials, most of which are actually below the crust (the intense heat of the mantle and the core come from both pressure and from the decay of radioactive materials). Even in the Earth's crust, the concentration of fissionable radioactive metals isn't high. It takes a lot of tons of rock to get the amount of nuclear material needed for nuclear fission, even with uranium ores. Then you need to build a reactor to produce plutonium, since it doesn't occur naturally (except in very minute quanities). So, the short answer is that we can do it, but it will be VERY expensive.

[sit-rep]

Any other questions ?

Whole bunch of 'em, but I'll cut it down a tad... Are we talking a nuclear detonation the size of a bomb that we are familiar with, or are we talking very small detonations?

[sit-rep]

Thanks for the reply gents...

Very interesting indeed. As stated to C2000, these detonations would need to be quite small, given the scale of Brett's first pic. Wondering how many "bombs" would be need for a trip to mars and back...

SR

[Centurion2000]

tiny ones ..... but you could use bigger ones ... just not as often.

[copycat]

This exploding nuclear propulsion idea sounds a little like some of the early flying attempts using bicycle pedals and flapping wings to me. IOW, nutty.

Has anyone explored the possiblility of using power form a nuclear core to generate some sort of magnetic field propulsion?

The key to feasible space travel is a NOT CARRYING FUEL. The amount of conventional rocket fuel, and even the amount of nuclear detonations that would be required seems to be prohibitive.

It seems to me any future space proplusion must not be of the type you burn as you go, but must be a sustainable power source.

[The_Victor]

Thanks for the ping. They've been yacking about this for about a year now. When is NASA going to start awarding the contracts for hardware development?

[ChemistCat]

Thanks for the ping!

[Frank_Discussion]

It seems to me any future space proplusion must not be of the type you burn as you go, but must be a sustainable power source.

OR, in the case of what O'Keefe is talking about, plasma propulsion. This type of technology uses electrical power to accelerate a plasma to very high speeds to create thrust. The plasma comes from a bank of fuel, like hydrogen. It doesn't "burn" the fuel, per se, but adds momentum directly, which is much more efficient than chemical systems. Thrust/power is dependent almost exclusively on the amount of electrical energy you have available, not on the fuel itself.

This is different from ion drives that eject ions from a grid plate material, which erodes and also limits the amount of electrical energy can be introduced into the system.

Someday, we will not need fuel. Until then, however, plasma drives will be the next breakthrough, IMO.

[MeekOneGOP]

bttt

[RightWhale]

Prior flights that have used RTG units have drawn fire from nuclear critics

A mere handful of anti-war activists and a small army of lemmings, who equate nuclear power with nuclear weapons, have somehow influenced enough congressmen that funding for nuclear propulsion has been denied for decades.

It is obvious that nuclear propulsion will open the solar system to colonization; and so, stopping human space development has become a secondary goal of many of the same people.

[copycat]

Sounds neat.. Plasma propulsion. I imagine the plasma is spun inside a coil of some sort which turns the work into electrical energy.

I'm wondering about magnetic drives...ever hear of that being developed.

What if you could figure out a way to generate a strong magnetic field outside the vehicle such that a positive and negative "pole" could be ceated that would attract AND repel the vehicle based on the pole alignment?

Similar to the magnetic drive systems they use to power the super-colliders.

[Frank_Discussion]

I imagine the plasma is spun inside a coil of some sort which turns the work into electrical energy.

Actually, one creates the plasma, then basically microwave it to add the energy, then shoot it out the back. Essentially the same as all other rocket propulsion, except your thrust is only limited to the power of your microwave, not to the chemical reactivity of your fuel, which is self-limiting. In terms of magnetic drives, plasma rockets do use such technology to encase the plasma in a magnetic field.

[Centurion2000]

It is obvious that nuclear propulsion will open the solar system to colonization; and so, stopping human space development has become a secondary goal of many of the same people.

Seems to me that a group of 'elites' per se don't seem to want anyone getting off the planet.