Saturday, March 6, 2021

Want to see the GJ 876 planets?

Robert Zubrin cannot be accused of thinking small. With the hat-tip to Reynolds, now he has a telescope plan. This one would knock down the (kilo)grams needed to do space astronomy.

As for other factors, Teh Zoob seems to be competing against the Webb. This isn't a scanner; it's there to be pointed at a specific location, and to send data home. Probably not the Planet Nine solution.

Imagine, though: several Webb-like space telescopes that Rocket Lab (say) may send up into space for the same cost as the one, all working in tandem. That could be the Planet Nine scanner.

Thinking bigger (as Zubrin would) I don't know if he perused Stross but, yes, the Big Dumb Booster allows for that weight to be scaled right back up again, without risking astronauts' lives. This boils off some of the commenters' cold water on the lower-radius telescope options; raising the radius would correct the errors. So yes: I am recommending that SpaceX start here, rather than with human tourists.

A 'scope of this scale would be... impressive. Webb has only been rated for Gliese 832 b and for transits. For Zubrin's proposal, noted in the comments is Epsilon Eridani, whose planets are presently visible as... pixels. This telescope might even be able to see, say, the GJ 876 system being only 15 light years away as it is. Not to mention Alpha Centauri. Or such planets right here as we seem to be done sending probes at, namely Uranus and Neptune.

The 'scope does require a boost to pull the parabola back. That implies (to Zubrin) several sorts of mission: a 'scope spun on a tether, a propellant-limited mission, and a sail. (I'd add a statite high in Venus umbra.) For the propellant mission he'd have this thing out 3.1 AU from here: between Ceres and Hilda, more like 2530 Shipka. A mission with a sail means there is solar wind, which can interfere with the results; not, though, for results outside the Sun's electromagnetic range, as Zubrin notes for radio.

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