Does twice the efficiency translate into twice the thrust force or twice the duration that the engine runs?

This concept might work well as a "cycler" with two of them remaining in space and orbiting between Mars and Earth every 26 months delivering payloads from LEO to LMO and back.

There's nothing to do on Mars and nowhere to go except back home.
I think it would be a 1-way trip to dullsville followed by some stupid, ghastly demise.

Is it safe enough not to scatter lethal radiation if it re-enters and crashes? Because my impression was that is the current standard. If you could guarantee that a running reactor would never land, that might be safe enough.

Perhaps we can use a version of it in a lead box to generate some electricity for us in remote areas.

We need Warp drives !!

The problem with space-based reactors has always been shielding human passengers from the reactor. There typically needs to be a massive radiation shield and astronauts have to be located long distances away from a reactor, often on a giant, awkward boom. The article says nothing about that critical issue, though the picture makes it look like the reactor and nozzel are quite close together and perhaps some kind of crew area is right on top of that. I doubt that would be safe. Putting a reactor in space has never been the main problem. Having it not kill human passengers has been.

@Heckler -- none of the above in this case. The article mentions this engine has double the specific impulse compared to chemical engines. Specific impulse is the change in momentum that a particular combination of propellant and engine provides. One way to get a higher specific impulse is to toss the same stuff out the back faster. Another is to toss a larger amount of something else at the same speed. For efficiency improvements in rockets, it's usually about tossing stuff out faster. Given that the nuclear fuel isn't going to be gone in a relatively short period of time, I'm assuming that this engine operates for an extended period, tossing a relatively small amount of working material at much higher speeds than chemical engines do. Double the specific impulse is really good, but I believe they'll need to get to 4-10x to challenge well known chemical rocket technology.

I cannot believe how stupid and pointless this idea is, except within a strange sub-community that fails to reflect on the stupidity and pointlessness of space exploration at this critical point in human evolution.

Why not use Liquid Thorium?1000 times the power. One tenth the weight. MUCH more safe. Smaller rocket. Lower cost. More power. Why do they keep going back to outdated uranium?