Difficulties of the Nuclear Powered Prometheus Project

brandido writes "Space.com is reporting on some of the technological difficulties facing the nuclear powered Prometheus Project. In particular, it is focusing on the fact that the Prometheus project promises to represent a paradigm shift in the capabilities of interplanetary probes. Such a large shift in capabilities entails the development of new technologies and designs, a process that is often full of mishaps and setbacks."

Comments

Not A Lot

[turgid]

Firstly, unused nuclear fuel is not very radioactive relatively speaking and is not very toxic.
Secondly, the fuel can (and is) built into very strong and resilliant "cans" and can be further protected to the point that even a fall from a great height such as earth-orbit will not result in any radioactive release.
Thirdly, any engineer woth their salt will design the darned thing such that it will not start its nuclear reactor (when the nasty fission products start to be produced) until the craft is either a significant distance away from earth already, or has achieved escape velocity and can not fall back to earth.
I am a qualified nuclear engineer with several years reactor physics experience at a nuclear power station.

Re:Just one problem...

[BigBir3d]

Just like last time...

1965

Re:This is why we need manned missions...

[barakn]

No, we don''t. If for the price of one manned mission we can build 10 unmanned missions and 50% of those fail, we're still ahead by 4 missions. And did the presence of humans help with Columbia or Challenger?

You mean "propellant?"

[Spamalamadingdong]

These craft typically use heat to make electricity, and then use the electricity to power a thruster of some kind; the thruster accelerates propellant. Ion thrusters have been made to use a great many different things as reaction mass (propellant), ranging from argon to bismuth to Buckyballs to xenon. The Deep Space One probe which was so phenomenally successful used xenon in its ion engine.

Re:fuel?

[jwdg]

See, for example: this ESA article: Solar-electric propulsion is ESA's new spacecraft engine. It does not burn fuel as chemical rockets do; instead the technique converts sunlight into electricity via solar panels and uses it to electrically charge heavy gas atoms, which accelerate from the spacecraft at high velocity. This drives the spacecraft forwards. In a chemical rocket, burning the fuel creates gas that is expelled relatively slowly compared to electric thrusters. However, in an ion engine, the gas is ejected at large velocities, which makes it generally much more efficient, so less fuel is required.

Because propulasion works by conservation of momentum, if you can fire the ions out the back fast enough you don't need too many of them. The problem with normal jet propulsion is that the jets aren't very high velocity.

Interesting topic...

[Unknown Kadath]

...and just in time for me to go home, too.

Here's a NASA page on Project Prometheus.

Have a good weekend, all.

-Carolyn

Re:Just one problem...

[spike hay]

Uh, first of all, the reactor would only contain uranium at launch. Uranium, with a half life of over a billion years, is barely radioactive at all. The main danger from uranium is actually not radiation, but heavy metal poisoning. Secondly, the fuel is contained in cans that are easily capable of withstanding rocket failures. Thirdly, there have been dozens of craft safely launched with radioisotope thermal generators for power. These typically use plutonium as a heat source. They have failed before, with the plutonium cans remaining intact.

The rocket in the article you linked to only would hit people with 5.7 millirad. That really isn't much anyway.