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Cubesat 10x10x10cm 1kg Payload, Lets here it then...
paxdan
post Sep 15 2005, 06:53 PM
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I'm sure many of you will be familar with the CubeSat project, in fact some of you may well have worked on one. wink.gif

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 tongue.gif
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Bob Shaw
post Sep 15 2005, 08:27 PM
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QUOTE (paxdan @ Sep 15 2005, 07:53 PM)
I'm sure many of you will be familar with the CubeSat project, in fact some of you may well have worked on one. wink.gif

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 tongue.gif
*


Back in the mid-1970s I actually tried to put together a coalition to build a small gravity-gradient stabilised satellite which would have specifically looked for fireballs in the Earth's atmosphere. Sadly, nothing came of the By your Own Bootstrap SATellite - BOBSAT - but I still have a number of drawings etc of it, including a hand-launch by an astronaut in the shuttle cargo bay! I'll try to dig them out and post them. This predated UOSAT, and was very much driven by the OSCAR amateur satellites - everything was to be off-the-shelf, and as simple as possible.


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djellison
post Sep 15 2005, 08:40 PM
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Oh I LOVE cubesats...I have dozens of PDF's and PPT's about them. Infact, I get email from the Japanese 'Cutesat' which has a tiny camera in it smile.gif

I'd go with quite a long deployed antenna which would then create a nice gravity gradient to keep the spacecraft orientated to earth - perhaps deployed on a reel. To be honest, I think a camera is going to be the #1 cool thing to have on board, but I'd TRY and do pushbroom - not single shot. Basically - schedule it image at the best time of each orbit based on minutes after the arrays get over a certain voltage. Then, do as much as the memory can handle, and then keep it onboard until the next downlink pass.

The real problem is downlink capacity though - it's quite slow.

Cubesat's are just - JUST - too small to be brilliant, but a double cube sat ( 20x10x10) probably gives you enough mass and volume to have the power to do good imaging with downlink.

Actually - I'm surprised the Planetary Society havnt put together a cubesat proposal - it's just hard to find a scientific goal for one - apart from taking cool picture.

Doug
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paxdan
post Sep 15 2005, 09:25 PM
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QUOTE (djellison @ Sep 15 2005, 09:40 PM)
Actually - I'm surprised the Planetary Society havnt put together a cubesat proposal - it's just hard to find a scientific goal for one - apart from taking cool picture.

Doug
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The cool pictures part is of course paramount. Heck slap a bunch of filters on it and you got your self some multispectral capability.

However instead of looking inward, why not look out. Why not turn it in to a dedicated multispectral planetary scope. Kind of the equivalent of a webcam + telescope beloved of amateurs but in space.

The science goals could be to image all the planets in 6 wavelengths. Pick at least one that can't be done from the ground due to the atmosphere and use that as your rational.

Regarding Jupiter storm observations, you metioned that there was interesting amateur work being done on storm rotation velocities from the ground using amateur kit, well do it from space instead.

OK so a mini observatory in space is going to be far more complicated, however, gyros for these CubeSats are an off the shelf component, you could even make sure that if all the pointing capacity failed you could still do earth observation, by having a default gradient stable postition for which the camera pointed at the earth.

Of course this is still pretty picture science but not beyond the realm of possibility
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Bob Shaw
post Sep 15 2005, 09:48 PM
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Here's an illustration of BOBSAT as promised.

The upper 'cube' of BOBSAT enclosed the battery pack and instrument deck at launch. On-orbit, it would be ejected by springs (or manually) from the host vehicle and the upper and lower segments would be forced apart by pre-sprung steel tapes. Power would be fed via a cable to the battery pack. The whole structure would be wobbly, with the expectation that after several orbits the dissimilar masses would be gravity-gradient stabilised, but wobbling in a predicatable fashion (as identified by the radio signals from the satellite). The upper cube would have solar cells on five sides, and the battery pack would have solar cells on the base, so that whatever the orientation with regard to the sun there would still be some cells generating electricity. Twin boom antennae would protrude from the battery pack.

The sole experiment would be a I/R bolometer, and it was intended to quantify the number of fireballs entering the Earth's atmosphere.
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djellison
post Sep 15 2005, 10:02 PM
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You'd struggle to justify putting a tiny tiny scope in orbit and show a benefit compared to a 1500 9" scope on the ground - the work of Damien Peach with a modest scope and good seing is utterly remarkable. Canada has a suitcase size sat that does excellent work for extrasolar planets, but thats an order of magnitude or two outside the scope (no pun intended) of a Cubesat.

Cubesats to date have been mainly an engineering exercise ( and a superb one ) - but I'm sure there's something they could really do...maybe fields and particles with a cluster of a few of them - who knows. They need a 'killer ap' - and suddenly, once you've got $200k, and a spare 10kg on a Falcon 1, you've got something amazing.

Doug
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tfisher
post Sep 15 2005, 10:19 PM
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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?
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Bob Shaw
post Sep 15 2005, 10:34 PM
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QUOTE (tfisher @ Sep 15 2005, 11:19 PM)
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?


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paxdan
post Sep 16 2005, 11:39 AM
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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.....
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Bob Shaw
post Sep 16 2005, 01:26 PM
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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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djellison
post Sep 16 2005, 01:29 PM
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Looking at a typical cubesat, that double cubesat hasnt set aside enough room for the basics, such as the radio, central control, power and modem hardware. It's takes about 75% of a full cubesat just to do the basics, let alone anything else.

Tell you what WOULD be cool....

interplanetary cubes smile.gif

Doug
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Bob Shaw
post Sep 16 2005, 01:33 PM
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QUOTE (djellison @ Sep 16 2005, 02:29 PM)
Looking at a typical cubesat, that double cubesat hasnt set aside enough room for the basics, such as the radio, central control, power and modem hardware. It's takes about 75% of a full cubesat just to do the basics, let alone anything else.

Tell you what WOULD be cool....

interplanetary cubes smile.gif

Doug
*


Doug:

If anyone can figure out how to build a tiny ion-engine, then there's loadsa spare mass capability to GTO, then just spiral out... (a la SMART-1).

Bob Shaw


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djellison
post Sep 16 2005, 01:54 PM
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Need a lot of power and a high pressure Xenon tank. Wonder if it could be doable in a tripple cube.

Doug
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paxdan
post Sep 16 2005, 03:38 PM
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QUOTE (djellison @ Sep 16 2005, 02:54 PM)
Need a lot of power and a high pressure Xenon tank. Wonder if it could be doable in a tripple cube.

Doug
*

the power could come from a set of extendable solar panels, who says that once deployed it has to remain constrained to a 10x10x10 cube. I jsut spent an hour in a boring meeting trying to figure out how to get a tiny telescope deployed from a 10x cube. with a single pivot point. We need to start thinking outside the box....
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djellison
post Sep 16 2005, 03:48 PM
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Oh - extandorama - I've seen designs that include that (infact, I think Cutesat, the japanese one does )
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