NASA's Proposed Plasma Rocket Could Get Us to Mars in 2 Months?

[GenesisNemesis]

NASA's Proposed Plasma Rocket Would Get Us to Mars in 2 Months

The space agency is investing in the development of a propulsion system that uses nuclear power to create plasma bursts.

gizmodo.com

The future of space travel depends on our ability to reach celestial pit stops faster and more efficiently. As such, NASA is working with a technology development company on a new propulsion system that could drop off humans on Mars in a relatively speedy two months’ time rather than the current nine month journey required to reach the Red Planet.

NASA’s Innovative Advanced Concepts (NIAC) program recently selected six promising projects for additional funding and development, allowing them to graduate to the second stage of development. The new “science fiction-like concepts,” as described by John Nelson, NIAC program executive at NASA, include a lunar railway system and fluid-based telescopes, as well as a pulsed plasma rocket.

The potentially groundbreaking propulsion system is being developed by Arizona-based Howe Industries. To reach high velocities within a shorter period of time, the pulsed plasma rocket would use nuclear fission—the release of energy from atoms splitting apart—to generate packets of plasma for thrust.

Yeah, Gizmodo, blah blah blah, and I barely know stuff about rockets. But from what I do know... it sounds plausible? It's NASA, so it must be plausible, right?

 

[pood]

Yeah, Gizmodo, blah blah blah, and I barely know stuff about rockets. But from what I do know... it sounds plausible? It's NASA, so it must be plausible, right?

Just like the space shuttle.

 

[GenesisNemesis]

Yeah, Gizmodo, blah blah blah, and I barely know stuff about rockets. But from what I do know... it sounds plausible? It's NASA, so it must be plausible, right?

Just like the space shuttle.

Well it doesn't always explode.

 

[pood]

Yeah, Gizmodo, blah blah blah, and I barely know stuff about rockets. But from what I do know... it sounds plausible? It's NASA, so it must be plausible, right?

Just like the space shuttle.

Well it doesn't always explode.

Two explosions were more than enough, coupled with the fact that the shuttle did not accomplish any of the goals it was supposed to — safe, reliable, regular, relatively cheap space travel. The whole thing was a titanic waste of money.

I’m not buying anything NASA is peddling about human flight including this or the Artemis program. They do a good job with unmanned space exploration.

 

[Loren Pechtel]

Two explosions were more than enough, coupled with the fact that the shuttle did not accomplish any of the goals it was supposed to — safe, reliable, regular, relatively cheap space travel. The whole thing was a titanic waste of money.

Only one blew up. I do agree with the rest of it.

I’m not buying anything NASA is peddling about human flight including this or the Artemis program. They do a good job with unmanned space exploration.

I'm not so impressed with their unmanned stuff, either. We see the spectacular successes, we don't see how much of that was pork vs science.

 

[bilby]

Only one blew up.

Columbia fragmented at high speed due to the unintended presence of high pressure plasma inside the vessel.

To suggest that it didn't "blow up" is IMO incorrect. It didn't explode, but it certainly blew up.

 

[lpetrich]

This is the closest that I could come to a primary source: Pulsed Plasma Rocket (PPR): Shielded, Fast Transits for Humans to Mars - NASA

It's a modification of Pulsed Fission-Fusion (PuFF) Propulsion Concept - NASA

It's hard to tell how it's supposed to work. It seems to work like magnetic-confinement fusion, but with fission instead.

 Critical mass - has a table of masses and sizes for spheres of various fissile materials. That size is where a neutron escaping is improbable, meaning that most neutrons go into making new fissions.

Increasing its density will make it harder for its neutrons to escape, eventually causing a runaway fission reaction, like what a nuclear bomb has.

(mean free path F) = 1 / ( (number density of targets n) * (reaction cross section s) )

F = 1 / (n*s)

Le n = N / L³ for total number N and length scale L. Then

F = L³ / (N*s)

and
F/L = L² / (N*s)

One wants F/L less than about 1 for the reaction to proceed. That means making L as small as possible.

So it's like Project Orion, with its nuclear bombs, but using magnetic-confinement-fusion technology as its igniter.

 

[lpetrich]

There is a big problem with this magnetic-confinement compression scheme. It's hard to go much beyond ordinary-conditions density for uranium or plutonium unless one strips off a lot of electrons, and that will leave ions with lots of charge.

 Ionization energies of the elements (data page) and  Saha ionization equation for equilibrium of ionization level with surroundings.

 

[lpetrich]

When I saw that article, I thought of  Variable Specific Impulse Magnetoplasma Rocket (VASIMR)

VASIMR is a type of electrothermal plasma thruster/electrothermal magnetoplasma thruster. In these engines, a neutral, inert propellant is ionized and heated using radio waves. The resulting plasma is then accelerated with magnetic fields to generate thrust.

...
Based on data from VX-100 testing,[11] it was expected that, if room temperature superconductors are ever discovered, the VX-200 engine would have a system efficiency of 60–65% and a potential thrust level of 5 N. Optimal specific impulse appeared to be around 5,000 s using low cost argon propellant.

 Specific impulse
(Effective exhaust velocity) = (specific impulse) * (acceleration of Earth's gravity, using 9.80665 m/s^2)

So this is 500 km/s. Let's see how it compares to other existing ones. The EEV and the thrust are both the largest values, even if not for the same engine. All quantities are for vacuum unless specified otherwise.

• Solid engine (Shuttle, GEM): 2.4 km/s, 15 MN (sea level)
• Kerosene-LOX engine (Soyuz, Saturn V F1, SpaceX Merlin): 3.2 km/s, 7.770 MN
• LH2-LOX engine (Saturn V J2, Shuttle RS25, Centaur RL10): 4.6 km/s, 2.279 MN
• Electrostatic ion engine (Dawn NSTAR): 30 km/s, 90 mN
• Electrostatic ion engine (BepiColombo Kaufman): 42 km/s, 145 mN

LOX = liquid oxygen, not salmon

 

[lpetrich]

 Spacecraft propulsion has a big table of existing and proposed propulsion technologies. They are assessed by  Technology readiness level

The levels:

1. Basic principles formulated
2. Technology concept formulated
3. Experimental proof of concept
4. Component validated in lab
5. Component validated in vacuum
6. Prototype demonstrated on ground, model demonstrated in space
7. System demonstrated in space
8. Flight qualified
9. Flight proven

Chemical and ion engines are at 9, VASIMR is at 5, and this new system is at 2.

 

[Loren Pechtel]

Only one blew up.

Columbia fragmented at high speed due to the unintended presence of high pressure plasma inside the vessel.

To suggest that it didn't "blow up" is IMO incorrect. It didn't explode, but it certainly blew up.

I do not consider torn apart by the wind to be blown up even if it happened quickly.

 

[bilby]

Only one blew up.

Columbia fragmented at high speed due to the unintended presence of high pressure plasma inside the vessel.

To suggest that it didn't "blow up" is IMO incorrect. It didn't explode, but it certainly blew up.

I do not consider torn apart by the wind to be blown up even if it happened quickly.

The compression plasma that surrounds a reentering spacecraft isn't mere "wind". The wind doesn't burn itself an entry point and then blow up the structures it destroys.

As an aside, the heat of reentry is primarily an adiabatic phenomenon, and not a frictional phenomenon as is commonly believed.

 

[Jimmy Higgins]

Mars is an interesting nut because even if we shortened the trip to Mars, it is arguable we've made the problem of the trip even harder. Unless I'm mistaken, the soonest we can leave Mars is about one year after leaving Earth (and that is assuming a certain velocity, if we are traveling quicker, presumably we have to wait longer on/in/around Mars). Arriving at Mars quicker doesn't actually gain us anything unless we can live on (in?) Mars. And living on (in?) Mars is way way way down the road.

This isn't Pikmin, where we have infinite power to ascend back up to the mothership every day, and there are no fruit for us to harvest.

 

[Elixir]

The heat of reentry is primarily an adiabatic phenomenon

How does THAT work? The compression of the air/gas in front of the vehicle causes it to heat that much?
Why doesn't the hot air "slide" off the vehicle to be replaced with "fresh" air every millisecond?

 

[lpetrich]

The heat of reentry is primarily an adiabatic phenomenon

How does THAT work? The compression of the air/gas in front of the vehicle causes it to heat that much?
Why doesn't the hot air "slide" off the vehicle to be replaced with "fresh" air every millisecond?

It can't move out of the way fast enough, so it gets very compressed, and it makes a discontinuity, a shock wave:

• Shock Waves | How Things Fly
•  Shock wave
• Shock Waves – The Physics Hypertextbook
• Shock waves, the sonic boom and the sound barrier - from Physclips waves and sound
• Sonic Boom > Air Force > Fact Sheet Display
• Schlieren Supersonic Shock Waves - NASA
•  Sonic boom

 

[lpetrich]

Mars is an interesting nut because even if we shortened the trip to Mars, it is arguable we've made the problem of the trip even harder. Unless I'm mistaken, the soonest we can leave Mars is about one year after leaving Earth (and that is assuming a certain velocity, if we are traveling quicker, presumably we have to wait longer on/in/around Mars). Arriving at Mars quicker doesn't actually gain us anything unless we can live on (in?) Mars. And living on (in?) Mars is way way way down the road.

•  Hohmann transfer orbit
• Hohmann Transfer — Orbital Mechanics & Astrodynamics
• Chapter 4: Trajectories - NASA Science

Discovered a century ago, it's a transfer orbit between two circular orbits that requires a minimum of velocity change (delta-v), and thus a minimum of rocket-fuel consumption. The orbit is elliptical, with the lowest distance at the inner orbit and the highest distance at the outer orbit.

The Earth and Mars have a relative or synodic period of 2 years 2 months, and that is how long one must wait between launch opportunities.

• Mars 44d ahead of the Earth, depart from the Earth
• From the Earth to Mars: 9 months
• Mars 75d behind the Earth, arrive at Mars
• At Mars: 1 year 3 months
• Mars 75d ahead of the Earth, depart from Mars
• From Mars to the Earth: 9 months
• Mars 44d behind the Earth, arrive at the Earth
• At the Earth: 1 year, 7 months

This trip takes two synodic periods.

 

[Jimmy Higgins]

So in order to go faster, you need to propel the rocket in such a manner to accelerate the ship while maintaining a vector to Mars, all the while, presumably you also need to slow down too. What type of g's would be involved to get to Mars in 2 months? It doesn't sound pleasant.

 

[bilby]

The heat of reentry is primarily an adiabatic phenomenon

How does THAT work?

Well:

The compression of the air/gas in front of the vehicle causes it to heat that much

Yes, that's right. The much slower compression of a far smaller amount of air is sufficient to raise diesel fuel to its ignition temperature in an internal combustion engine, so this shouldn't be difficult to envisage.

?
Why doesn't the hot air "slide" off the vehicle to be replaced with "fresh" air every millisecond?

It does. That's why it's possible to make a heat shield that can cope. If it didn't, any re-entering craft would be vapourised, heat shield and all.

 

[bilby]

So in order to go faster, you need to propel the rocket in such a manner to accelerate the ship while maintaining a vector to Mars, all the while, presumably you also need to slow down too. What type of g's would be involved to get to Mars in 2 months? It doesn't sound pleasant.

1g is a LOT of acceleration; If you had the fuel to do it, a constant 1g (flipping half way to avoid a very rapid fly-by) would be very quick indeed, and most astronauts would likely prefer 1g over microgravity.

According to the calculator at https://spacetravel.simhub.online/ a trip from Earth to Mars at 1g constant acceleration takes around 1.75 days, with a maximum speed of 0.00247c, or about 2.67 million km/h.

 

[steve_bank]

I thought that nuclear bombs was an old idea.

The Mouse on the Moon - Wikipedia

en.wikipedia.org

Financial disaster looms for Grand Fenwick when the current vintage of its only export, wine, starts exploding in would-be consumers' faces. Prime Minister Mountjoy (Ron Moody) decides to ask the United States for a loan, ostensibly to fund its entry in the race to the Moon, but actually to save the duchy (and install modern plumbing so he can have a hot bath). The devious politician knows that the Americans will not believe him, but will consider the half million dollars he is asking for to be cheap propaganda supporting their hollow call for international co-operation in space. He is delighted when they send him double the amount as an outright gift. The Soviets, not wishing to be one-upped by their Cold War rivals, deliver an obsolete rocket. Mountjoy asks resident scientist Professor Kokintz (David Kossoff) to arrange a small explosion during the "launch" of their lunar rocket to make it look like they have actually spent the money as intended.

It doesn't sound workable. Testing it in space to the point of reliability is no small task. It word have to be precise enough to maneuver into orbit, or have secondary propulsion. The complexity grows.

Then there is life support, and the psychology of a small group stuck in a small space for extended periods. No body knows what happens when humans are isolated in the space far from Earth. Human factors.


Maintenance in flight.