Will NASA Use Nuclear Propulsion For Faster Crewed Mission Transport?

Are nuclear rockets the future of space travel? Or will the anti-nuke crowd win
out?

"During an Oct. 9 Aviation Week webinar moderated by Space Editor Irene Klotz,
three former NASA administrators agreed that the U.S. needs to harness nuclear
technology to propel humans beyond low Earth orbit.

With the rapid development of the Chinese space program, the U.S. does not have
the luxury of waiting to develop new technology, said Dan Goldin, who led NASA
during three presidential administrations from 1992 to 2001. “We’ve been using
the same damn rocket technology since Apollo. It’s time to grow up and say the
magic term ‘nuclear.’ There I said it, ‘nuclear,’� Goldin said. “We’re going to
need nuclear power on planetary bodies. We’re going to need nuclear power for
propulsion. And if America intends to be a world leader, we’re going to have to
grow up and learn to live with nuclear.�

The U.S. has been exploring the technology for a long time, points out Sean
O’Keefe, NASA administrator during George W. Bush’s presidency in 2001-05. But
he says the nation needs to pick up the pace. Project Prometheus, an in-space
propulsion effort started in 2003 to develop radioisotope power systems and
nuclear power and propulsion systems. The program was designed to support a
space science mission to study the icy moons of Jupiter, but it was scrapped in
favor of higher priorities.

The technology in Prometheus “has been developed now to a much higher extent,
but nowhere near as quickly as we needed to see significant changes over the
last 15 years,� O’Keefe said. “We’re in a better place now in terms of
developing that technology that has been used on a limited basis in the past—to
seriously examining that as an in-space propulsion capacity. We just need to do
it a hell of a lot faster.�"

See:

https://aviationweek.com/defense-spa...sion-transport

On Sat, 24 Oct 2020, wrote:

Are nuclear rockets the future of space travel? Or will the anti-nuke crowd win
out?

To they thinkk that they can launch a nuclear rocket from Earth?

"During an Oct. 9 Aviation Week webinar moderated by Space Editor Irene Klotz,
three former NASA administrators agreed that the U.S. needs to harness nuclear
technology to propel humans beyond low Earth orbit.

With the rapid development of the Chinese space program, the U.S. does not have
the luxury of waiting to develop new technology, said Dan Goldin, who led NASA
during three presidential administrations from 1992 to 2001. “We’ve been using
the same damn rocket technology since Apollo. It’s time to grow up and say the
magic term ‘nuclear.’ There I said it, ‘nuclear,’� Goldin said. “We’re going to
need nuclear power on planetary bodies. We’re going to need nuclear power for
propulsion. And if America intends to be a world leader, we’re going to have to
grow up and learn to live with nuclear.�

The U.S. has been exploring the technology for a long time, points out Sean
O’Keefe, NASA administrator during George W. Bush’s presidency in 2001-05. But
he says the nation needs to pick up the pace. Project Prometheus, an in-space
propulsion effort started in 2003 to develop radioisotope power systems and
nuclear power and propulsion systems. The program was designed to support a
space science mission to study the icy moons of Jupiter, but it was scrapped in
favor of higher priorities.

The technology in Prometheus “has been developed now to a much higher extent,
but nowhere near as quickly as we needed to see significant changes over the
last 15 years,� O’Keefe said. “We’re in a better place now in terms of
developing that technology that has been used on a limited basis in the past—to
seriously examining that as an in-space propulsion capacity. We just need to do
it a hell of a lot faster.�"

See:

https://aviationweek.com/defense-spa...sion-transport

Will NASA use it?

No. But a private company might.

Dave

On Nov/5/2020 at 02:22, JF Mezei wrote :
On 2020-11-03 18:47, David Spain wrote:
Will NASA use it?

No. But a private company might.

If you're carrying humans (or Martians, apparently they have bee voting
illegally in USA :-), I have to assume that shielding requirements will
be very hefty. Does all that extra mass make this type of propulsion
worthwile?

You just put the reactor far from the crew and put a little shielding
near the reactor. You also have to put shielding around the crew, which
you would have to do even if your propulsion method was chemical. There
are all kinds of radiations in space, you need shielding.

And out of curiosity, how does nuclear propulsion work?

I am aware of nuclear batteries that generate electricity.
Am aware of nuclear reactors that heat water into steam and drive
turbines. But how is nuclear fission used as propulsion?

There are several different methods. But basically, if you heat a gas to
high temperature, whether you heat it by chemical reactions, nuclear
energy or some other method, the gas wants to expand. You just have to
make sure that the expansion happens in the opposite direction to where
you want the rocket to go.

Nuclear has some important advantages over combustion. Low mass
molecules move faster at the same temperature than higher mass
molecules. So if you are heating hydrogen to 3000 °C, the molecules of
hydrogen will move faster than water at the same temperature. Therefore
heating hydrogen with a nuclear reaction can give more push than burning
it and exhausting water.


Alain Fournier

On 2020-11-05 14:36, Alain Fournier wrote:
On Nov/5/2020 at 02:22, JF Mezei wrote :
On 2020-11-03 18:47, David Spain wrote:
Will NASA use it?

No. But a private company might.

If you're carrying humans (or Martians, apparently they have bee voting
illegally in USA :-), I have to assume that shielding requirements will
be very hefty. Does all that extra mass make this type of propulsion
worthwile?

You just put the reactor far from the crew and put a little shielding
near the reactor. You also have to put shielding around the crew, which
you would have to do even if your propulsion method was chemical. There
are all kinds of radiations in space, you need shielding.

And out of curiosity, how does nuclear propulsion work?

I am aware of nuclear batteries that generate electricity.
Am aware of nuclear reactors that heat water into steam and drive
turbines.Â* But how is nuclear fission used as propulsion?

There are several different methods. But basically, if you heat a gas to
high temperature, whether you heat it by chemical reactions, nuclear
energy or some other method, the gas wants to expand. You just have to
make sure that the expansion happens in the opposite direction to where
you want the rocket to go.

There's also nuclear-electric propulsion, where you use nuclear energy
to generate electrical power for an ion drive. This is more efficient in
propellant, but I believe the problem here is to get rid of the waste
heat from the fission-to-electricity step -- large radiators may be needed.

Alain Fournier writes:

On Nov/5/2020 at 02:22, JF Mezei wrote :
On 2020-11-03 18:47, David Spain wrote:
Will NASA use it?

No. But a private company might.

If you're carrying humans (or Martians, apparently they have bee voting
illegally in USA :-), I have to assume that shielding requirements will
be very hefty. Does all that extra mass make this type of propulsion
worthwile?

You just put the reactor far from the crew and put a little shielding near the
reactor. You also have to put shielding around the crew, which you would have
to do even if your propulsion method was chemical. There are all kinds of
radiations in space, you need shielding.

Water makes for great shielding. So most designs I've seen put large
fuel tanks of just plain (pureified) water between the crew and the reactor(s).

And out of curiosity, how does nuclear propulsion work?

I am aware of nuclear batteries that generate electricity.
Am aware of nuclear reactors that heat water into steam and drive
turbines. But how is nuclear fission used as propulsion?

There are several different methods. But basically, if you heat a gas to high
temperature, whether you heat it by chemical reactions, nuclear energy or some
other method, the gas wants to expand. You just have to make sure that the
expansion happens in the opposite direction to where you want the rocket to
go.

Nuclear has some important advantages over combustion. Low mass molecules move
faster at the same temperature than higher mass molecules. So if you are
heating hydrogen to 3000 °C, the molecules of hydrogen will move faster than
water at the same temperature. Therefore heating hydrogen with a nuclear
reaction can give more push than burning it and exhausting water.

Yeah but hydrogen is a PITA to store. I suspect early Nuclear (fission)
Thermal Propulsion systems NTP in the parlance would just shoot
pureified water right through the moderator flash it over and out a
vacuum optimized nozzle.

Another optimization that I haven't seen discussed anywhere is the
possibility of a multi-stage NTP design. Where first water is pumped
into the reactor and allowed to dissocate thermally into its elemental
constituents of oxygen and hydrogen which is then heated further in a
main chamber before being exhausted. Could be a good way to get that higher
ISP w/o the storage headaches of cyrogenics.

Nuclear electric ion-drive was the proposed method of propulsion for
Discovery from 2001 A Space Odyssey. But they dispensed with the reactor
radiators in the movie version design because they thought that having a
space vehicle with what appeared to be wings would be a hard sell to the
near (almost) scientific literati according to what I read by A.C. Clark
in his book on the making of the movie.

Dave

New nuclear engine design:


The Thermal Nuclear Engine That Could Get Us to Mars in Just 3 Months:

"Ultra Safe Nuclear Corporation (USNC) has designed a new thermal nuclear engine
it says could carry astronauts to Mars in just three months—and back to Earth in
the same amount of time. By using ceramic microcapsules of high assay low
enriched uranium (HALEU) fuel, USNC's thermal nuclear engine could cut the trip
in half even from optimistic estimates."

See:

https://www.popularmechanics.com/sci...r-engine-mars/