Space/Science — HabitableZone

Space/Science » in reply to Re: Luna or Mars ?

It isn't a question of NEOs
Larry J — (archived)

My point is that you don't need to build an observatory on the moon to search for NEOs. There's absolutely no need to spend that kind of money required to build such a facility. It most definitely would not be the low cost or near-term option, either.

An option that provides a better near-term and reasonably priced solution would be to put a series of mid-sized telescopes either in LEO or at a LaGrange point. You could put a series of telescopes of perhaps 20-40" diameter up in space far sooner and at a much lower cost than any moon-based facility.

Furthermore, putting it there would be counterproductive when it comes to running a full-sky search. If you put it on lunar nearside, then a significant portion of the sky is blocked by the Earth itself. From the moon, the Earth appears as a disk 2 degrees across, compared to 0.5 degrees that the moon appears from the Earth's surface. You can't aim a sensitive telescope too close to a bright object without saturating the sensors, so you'd have to keep your lunar telescopes from pointing within a few degrees of the Earth. That creates a blind spot.

If you try to base your telescopes on lunar farside, then you need some means like communications satellites to relay your observations back to the Earth. That isn't cheap, either.

The sky is big, Ed. You don't necessarily need large telescopes for a whole-sky search because they have too narrow a field of view. Small to mid-sized telescopes give you a good compromise between field of view and light gathering ability. By the same token, radar is poorly suited for whole-sky searches.

I've worked space surveillance, Ed. You have not. You don't know what you're talking about.

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