Cubesat 10x10x10cm 1kg Payload, Lets here it then... Options

[paxdan]

I'm sure many of you will be familar with the CubeSat project, in fact some of you may well have worked on one.

So lets hear it, what would you do with a 10x10x10cm 1kg payload in a CubeSat, beside the obvious like stick a camera in it and photograph your house.

Who knows, perhaps one day we may see the launch of the USF CubeSat

[tfisher]

I would like to have a cubesat whose goal is to return continuous brightness measurements for one of the known transiting extrasolar planet stars. There are I think 8 of these at current count, all of which have one known planet transiting at a period of a few days. The science return potential is good, giving a continuous data stream on something the pro telescopes only look at very occasionally. Maybe it would even catch something great, like small variations in the transit timing indicating more bodies in the system. And even if the cubesat dies within a week, still that gives a couple of transit curves so some good results.

So how to design such a thing? You need a ccd behind whatever telescope you can fit (a camera lens, probably). (TrES-1, for instance, has a magnitude 11 star, and the transit was discovered by a telescope with a 10cm primary...) You need enough computer to read the ccd, pick out the right star, and transmit the measured brightness. You need enough antenna to broadcast the result back to earth and to listen for a kill signal from the ground. You need some power source, maybe a small solar panel. And, perhaps most challenging, you need some way to get the thing pointed in the right direction and keep it there.

I'm picturing two ipods running linux, one at a side and one at the back of the box. Pointing would be accomplished by spinning up or spinning down the hard drives, with a goal of getting the satellite spinning with the spin axis pointed at the star. Automated pointing would be done by star tracking in the ccd image. Attach a tape-measure antenna and put solar cells on the sides.

Does that sound plausable?

[Bob Shaw]

I would like to have a cubesat whose goal is to return continuous brightness measurements for one of the known transiting extrasolar planet stars.  There are I think 8 of these at current count, all of which have one known planet transiting at a period of a few days.  The science return potential is good, giving a continuous data stream on something the pro telescopes only look at very occasionally.  Maybe it would even catch something great, like small variations in the transit timing indicating more bodies in the system.  And even if the cubesat dies within a week, still that gives a couple of transit curves so some good results.

So how to design such a thing?  You need a ccd behind whatever telescope you can fit (a camera lens, probably).  (TrES-1, for instance, has a magnitude 11 star, and the transit was discovered by a telescope with a 10cm primary...) You need enough computer to read the ccd, pick out the right star, and transmit the measured brightness.  You need enough antenna to broadcast the result back to earth and to listen for a kill signal from the ground.  You need some power source, maybe a small solar panel.  And, perhaps most challenging, you need some way to get the thing pointed in the right direction and keep it there.

I'm picturing two ipods running linux, one at a side and one at the back of the box.  Pointing would be accomplished by spinning up or spinning down the hard drives, with a goal of getting the satellite spinning with the spin axis pointed at the star.  Automated pointing would be done by star tracking in the ccd image.  Attach a tape-measure antenna and put solar cells on the sides. 

Does that sound plausable?

I think the attitude control via HDU technology is very interesting indeed - if you've ever tried to move a spinning HDU then you'll find quite surprising force is needed (depending on the way you want to turn it). Of course, you'd still need a way to dump the rotational energy (if I can put it that way) from time to time. Electromagnetic torque devices powered by solar panels, with stellar observations taking place only on night-side passes, perhaps?

[paxdan]

I had a look at the Damien Peach site, his work is stunning and represents just how far amateur ground based observation has come. now, i guess the thing to do would be to work out if it is possible to beat the resolution witha smaller scope in space. With a bit of ingineuty i'm sure you could design a extendible scope that would fit in a 10x10x10 cube which would produce results comparible to his work if not better.....

[Bob Shaw]

Here's a notional 'AstroCube2' dual cubesat astronomy satellite, using HDU-based gyro stabilisation, magnetic torque de-spin, and with an 8cm or thereabouts telescope. Note the absolute lack of extending or moving parts other than the HDUs. Some form of 'Reactolite' or similar coating on a window over the telescope aperture would protect the interior from direct sunshine, and the exterior surface would be covered in solar cells. Differential GPS might be a valuable add-on. I don't imagine you'd do any imaging with this class of equipment, but light-curves or spectra would be practical goals.

So, how are we gonna build it?

Bob Shaw

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