I personally hope that one of our many probes to the planets will turn up an anomaly that can’t be explained as a natural formation. The weird thing in Saturn’s rings, the white spot of Venus and rectangular craters on the Moon are pretty odd, but not overly compelling – the scale is too vast or our resolution is too poor. Yet the Monoliths of Mars (and Phobos) are kind of cool…
Buzz Aldrin discusses the Phobos Monolith
…I think Buzz is pretty sure the Phobos ‘object’ is just a boulder BUT that’s not the point. Doesn’t matter how good our resolution gets, we just won’t know what these things are until we can go look for ourselves… and that’s reason enough to get to the planets! Because we don’t know/can’t know what we’ll find in person.
And I think getting there is getting easier all the time. We don’t need nukes necessarily either. Ultra-light photovoltaic arrays are being developed which can supply in-space electrical power at 10 kWe/kg. RTGs struggle to get 10-20 W/kg and solid-core nuclear reactors struggle to get ~0.1-0.5 kWe/kg, so those space-rated ultra-light PVs are a step ahead. We just need a decent rocket to attach them too, and as I have discussed here a few posts ago VASIMR is the right rocket for the job.
But there’s another point in favour of such systems IMHO… they provide a LOT of power even when you’re not flying between the planets. Megawatts of power on Phobos can power space refuelling systems, extracting water from the rocks and electrolysing it for LH2/LOX propellant. Then a Mars lander can be fuelled AT Mars, so we don’t have to cart the stuff all the way from Earth (and watch 20% boil-off en route.) A Mars lander can then land on FULL rocket thrust after a bit of aerobraking and NOT stack like just about every other landing scenario yet studied.