The bit you quoted sounds very strange. Any spacecraft, even a nuclear-powered one, is going to be expelling reaction mass. That’s how spaceships work - mass goes one way, spaceship goes the other way. You can use nuclear engines to expel the reaction mass, but you still need that mass.
The one exception would be something akin to a solar sail, which could use the radiation of a nearby star as a “wind” to propel the spacecraft - but you can’t maneuver in atmosphere with giant, flimsy solar sails.
As to how the government would respond to an alien landing - probably pretty sensibly, I think. So long as the aliens weren’t clearly hostile, the first priority would probably be to keep regular folks a safe distance from the spacecraft. (If they didn’t have a better idea, “safe distance” would likely be the blast radius of a sizable nuke, just in case that became necessary). After that, probably a bunch of drone overflights for recon, then you might send unmanned ground vehicles to try and get a closer look at the spacecraft. So long as no one came out, I expect “move very slowly, and try to signal exactly what we’re going to do before we do it” would be the order of the day.
Our government would deal with an alien landing with predictable panic followed by poor yet incredibly expensive decisions. Fox would accuse Democrats of (fill in paranoia here).
Well, yes, the sort of spaceships we can currently imagine with our current understanding of science. But it’s Clarke’s Third Law, isn’t it? There’s no reason to assume that a spaceship that landed here tomorrow would work by scientific principles that we understand today, or that we’d be able to understand it within the decade (or maybe century) without the aliens actually explaining it to us.
I don’t know about the aliens being able to protect themselves from anything we could throw at them.
How hard would it have been to damage the lunar lander? Not very.
They may be able to travel light years to get here but can they bring a tank? Maybe not.
If they could only come with a lunar lander equivalent, distance would be easy protection. They could observe us from a million miles away and we couldnt do squat, theyd see anything we tried coming from,well…
It’s pretty unlikely that two alien races will meet and have comparable levels of technology.
It’s common in sci-fi for alien races to just be like another population on earth, with maybe one species having a slight edge on another.
But given that planets have been around for billions of years, and technological development can make huge strides in mere decades (if we’re anything to go by), it’s much more likely that one species will appear almost godlike to the other.
And given that in this first contact scenario, one species has made the interstellar journey to our planet before we even knew they existed, it’s pretty clear who is going to be the godlike one in our relationship.
I doubt that they would see us attacking them as even a threat. But it’s certainly not something we’d want to test.