Can a Bright Flash in Space Help Detect Dark Objects Beyond Pluto?

[chroot]

Memnoch,

It's indeed a cool idea! Just make sure you temper your ideas with reality. Building and flying such a flash into interplanetary space is a much bigger project that you seem to recognize; it costs hundreds of millions of dollars to launch a spacecraft as small as the Mars landers, and I have the feeing your flash would be much, much much heavier, since it would have to include an enormous energy source. All in all, it seems we'd be better off using our natural light source -- the sun -- and using arrays of cheap ground-based light-bucket telescopes to do our minor planet hunting.

Have you done the math to figure out how bright a flash would have to be to light up a planet by some amount? Say, take the energy received on Earth in sunlight reflected by a planet like Jupiter as one unit. How much energy would it take for your flash to light up Jupiter an extra unit, given that the flash is some given distance x away from Jupiter? I bet you'd be utterly staggered at how much energy it would take! I would be more than happy to work out the numbers with you.

- Warren

 

[Memnoch]

Oh and Chroot,
Here's some more info on that project for detecting more objects in space.
http://www.space.com/news/neo_hearing_040408.html

 

[Nereid]

Objectives, methods, etc

Doing something cool, just to see what happens, is what all kinds of folk have done, no doubt for thousands of years. If the 'something cool' costs a lot of €, then you have to convince someone who's got lots of € that it's worth their while to spend those € on your idea (unless you have lots of €, then the sales pitch is much more straight-forward ). Somewhere in any realistic sales pitch would be a statement of objectives - what is it that we might expect to get from the investment of lots of €. If the € needed is significant, the pitch would also need to include some stuff on why your method is better than the competition's.

If your objective has to do with learning more about objects in the solar system, it'd be best to break your proposal into two parts - detection and observation (finding objects not previously detected, and learning more about objects previously found).

For detection, there are essentially two questions - how comprehensive (e.g. all objects in the EKB with diameters > 40km), and where (e.g. all objects with orbits between Mercury and Mars). If your interest is 'anything' which orbits beyond ~Mars, then some kind of ground-based survey program would likely give the best bang for the € - e.g. telescopes near Keck and the VLT, or maybe just one telescope near the WHT in the Canaries. What about a Memnoch flash? Big no-no; as Janitor pointed out, it'd have to be brighter than the most powerful nuclear devices ever detonated on Earth, probably by a factor of >1,000,000,000; the inverse square law - applied twice - guarrantees that very few photons would get back to you (not to mention the need to watch the whole sky for tiny flashes).

If it's NEOs you want to catch, a survey program would still be best, but you'd need different telescopes (and detectors, and software, ...), and a lot more of them. A Memnoch flash? While you wouldn't need such a powerful nuclear device (perhaps as weak as 100,000 times as powerful as the biggest ever set off on Earth), you'd need to set one off every few months, if not weeks. Oh, and the all-sky tiny flashes problem would be the same. Same old friend inverse square, twice.

For observation, existing ground-based telescopes - plus instruments and software - will continue to give the best overall results. For some objectives, Hubble and Spitzer will do a better job, and if there's a spacecraft on its way (e.g. Casini-Huygens towards Saturn and its moons). A Memnoch flash? Kg for kg, a spacecraft with well-designed instruments would likely win with the evaluation committee.