Contrary to what many think (and even Terri herself thought in the scene), even if the tether was long enough to reach Woody, she still had barely enough fuel to get back to REMO herself, not to mention that if he caught the tether, much of his inertia would've been transferred to her (he's heavier), meaning that she would've needed enough fuel to brake their combined mass and then accelerate it back in the other direction. Odds on, they both would've done a cannonball onto Mars.
Potentially doubles as Lethally Stupid from the Martians, who are questionably "benevolent" precursors that have built a security system that brutally kills you with a sentient-looking sand tornado if you send the wrong answer (and it even attacks you by ASSUMING you're trying to enter, like the radar signal Luke's team sent to scan the mountain). Could you imagine if another highly advanced alien race, say, General Zod's kryptonian scouts from Man of Steel came along, got attacked by the tornado, and then Zod got mad and decided to retaliate by using the World Engine to obliterate the whole structure?
The ending frames it as something beautiful, but think about it: it's been millions of years. Is there even a culture left at the place this spaceship is taking Jim to?
