Nasa’s proposed plasma rocket would get us to Mars in 2 months

*(Coincidentally, the first serious project was cancelled about 20 years before the present day [1]. That would have been an interesting alternate history...)

[0] https://www.howeindustries.net/ppr

[1] https://en.wikipedia.org/wiki/Jupiter_Icy_Moons_Orbiter

edit: To explain my reasoning a little: 10 gigawatts is gigantic amount of violently destructive energy—thermal energy, radiation energy, mechanical and vibrational [2] energy—you're trying to squeeze into a lightweight, complex, mass-optimized aerospace device that needs to run unattended and without maintenance for many years, without failing. That's probably very hard to get right. There have been many nuclear electric reactors in space already, but remarkably none of them, in operation, had any moving parts! They were all solid-state thermoelectric converters. I believe the bulk of that design choice boils down to "it's simple and conservative". Thermoelectrics aren't impressive by any other metric—just simplicity.

Even the first, smallest nuclear electric turbine in space will be a majorly impressive achievement, for whoever succeeds at it.

[2] Let's not forget: https://en.wikipedia.org/wiki/Galileo_project#High_gain_ante...

[1] https://www.youtube.com/watch?v=myYs4DCCZts

Of course once astronauts are on mars they will still be exposed to radiation, until some sort of shielding can be built.

Which would be an obscene undertaking, and involves moving lots of raw and refined materials to mars.

Which means hopefully the price of this rocket to get stuff off of earth is dirt cheap, because moving squishy humans to Mars, no matter the speed, is not the limiting factor! (Getting humans to Mars and keeping them alive there is!)

According to that show, we should have been on Mars for the last twenty years.

Both numbers are pulled out of thin air. The Hohmann transfer time between 2 planets is about half a year. Which year, you ask? The year of the inner planet, or of the outer planet. Well, it's the average of the 2 years. A Martian year is about 2 of our years, so the average is 1.5 years, divided by 2 it's 9 months.

But if you are willing to burn more fuel, you can cut down the travel time. The delta-v between Earth orbit and Mars is surprisingly low. From the Moon transfer orbit to the low Mars orbit it is 2.5 km/s. The rule of thumb is that a rocket can achieve twice the delta-v of its exhaust velocity. In the case of the SpaceX Starship, the exhaust velocity is 3.7 km/s, twice that is 7.4 km/s, about 3 times the delta-v needed for the Hohmann transfer. SpaceX states they will be able to get to Mars in 6 months [1]. Musk went further and claimed that the Starship could get to Mars in as little as 80 days, and this fantastic Stack Exchange post [2] explains that maybe 80 days is slightly too optimistic, but 90 days is doable.

Now this design here claims that the rocket can achieve an ISP of 5000 seconds, which means an exhaust velocity of 50 km/s. With such an exhaust velocity, basically they can pick any random number and claim they can get to Mars that fast. The shortest path between the two orbits, the radial one, is about 75 million km long. At 50 km/s, it takes 1.5 million seconds, or 17 days. Of course, this is for a one-way trip, but presumably in the far future we could preposition fuel in Mars orbit for the return trip.

Maybe they thought half a month will sound too wild, so they went for the 2 month number to make it sound more realistic. The problem is that compared to the 3 months doable by SpaceX, it's not all that impressive.

[1] https://www.spacex.com/humanspaceflight/mars/

[2] https://space.stackexchange.com/questions/57568/elon-musks-i...

But it's only a few days with a million ISP from fusion.. let's raise the bar ;)

So, do they mean 2 months at the minimum distance, or the maximum?