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Cubesat 10x10x10cm 1kg Payload, Lets here it then...
Bob Shaw
post Sep 16 2005, 03:49 PM
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QUOTE (paxdan @ Sep 16 2005, 04:38 PM)
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....
*


The absolute minimum of deployment is probably the way to go - movement of parts=risk to both the CubeSat and the host vehicle, and leads to weight gains, spiralling cost etc. KISS is the motto - it's not Rocket Science, after all, just building... ...er... ...maybe it is.


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Bob Shaw
post Sep 16 2005, 03:54 PM
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Did I mention that an old friend of mine is selling places on Dnepr launchers, and that if persuaded he might be the very man to find a launch slot? All we need is a spacecraft...


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ljk4-1
post Sep 16 2005, 04:41 PM
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DIY satellites reinvent the space race

New York Times September 14, 2005

CubeSat is giving students and
companies the opportunity to build
and launch functional satellites
into low Earth orbit at low cost....

http://www.kurzweilai.net/email/newsRedire...sID=4840&m=7610


As for doing astronomy with very small satellites, WIRE is using its 2-inch star tracker for just that purpose:

http://arXiv.org/abs/astro-ph/0509444


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paxdan
post Sep 16 2005, 05:03 PM
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QUOTE (Bob Shaw @ Sep 16 2005, 04:54 PM)
Did I mention that an old friend of mine is selling places on Dnepr launchers, and that if persuaded he might be the very man to find a launch slot? All we need is a spacecraft...
*

Well lets do it then. seriously. You can buy a lot of the kit you need for the cubesats off the shelf, as someone else pointed out 75% of the volume of a 10x10x10 cube is taken up by standard stuff, CPU, battery, radio, gyro/mag-torque, etc... What we need to focus on is what you would do with a 10x10x2.5 (or eqivalent) 250g payload.

The thing that got me thinking is that most telescopes are empty volume. instead of launching that empty volume, why not launch the volume filled with the support stuff, pack all the brains into that empty space for launch then clear the tube once on orbit.

Now the clever bit is to design it so that the mirrors and camera remain permenentaly fixed relative to each other. i.e., none of the deploy would be about moving the mirrors accurately, just clearing the tube. I have a design in mind that is essentailly a reflecting telescope with a single sprung hinge which rotates out the brains of the scope from the light path leaving behind a clear tube, you wouldn't even need fine control over the movement, it's a dead cert gross movement deploy. You turn a 10x10x10x satalite in a 10x10x20 telescope on orbit with a single hinge. and bingo there is you amateur telescope in space.

the thing is it's such a simple way of doing it, i know it must have been done before, are there any orbiting telescope that have used a similar deploy mechanism on orbit?.
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Bob Shaw
post Sep 16 2005, 10:26 PM
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QUOTE (paxdan @ Sep 16 2005, 06:03 PM)
Well lets do it then. seriously. You can buy a lot of the kit you need for the cubesats off the shelf, as someone else pointed out 75% of the volume of a 10x10x10 cube is taken up by standard stuff, CPU, battery, radio, gyro/mag-torque, etc... What we need to focus on is what you would do with a 10x10x2.5 (or eqivalent) 250g payload.

The thing that got me thinking is that most telescopes are empty volume. instead of launching that empty volume, why not launch the volume filled with the support stuff, pack all the brains into that empty space for launch then clear the tube once on orbit.

Now the clever bit is to design it so that the mirrors and camera remain permenentaly fixed relative to each other. i.e., none of the deploy would be about moving the mirrors accurately, just clearing the tube. I have a design in mind that is essentailly a reflecting telescope with a single sprung hinge which rotates out the brains of the scope from the light path leaving behind a clear tube, you wouldn't even need fine control over the movement, it's a dead cert gross movement deploy. You turn a 10x10x10x satalite in a 10x10x20 telescope on orbit with a single hinge. and bingo there is you amateur telescope in space.

the thing is it's such a simple way of doing it, i know it must have been done before, are there any orbiting telescope that have used a similar deploy mechanism on orbit?.
*


Paxdan:

I've never, ever, heard of an astronomical spacecraft which was built without that big hole in the middle (other than the James Webb chappie). I think mass/structure issues have tended to be the limiting factors, but with nanosats you may as well throw the rulebook away. For example, structural integrity in a 10cm cube, is, well, a given - so move on! If there's serious interest in actually building something - and between us, why not? - then let's build something! I'll make some discreet enquiries regarding a launch...

Bob Shaw


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um3k
post Sep 16 2005, 10:50 PM
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My idea is of a 9cm apochromatic objective, 36cm* focal length, which is extended linearly outward using something along the lines of spring tension. I have no idea whether it could work or not, and I have not really thought about anything other than the optical setup.

Here is a sample image of M13 using the above setup with a KAF-3200E(ME) CCD. (NOTE: this is not a real image. It is a simulated image created from DSS images.)
Attached Image


EDIT: Ignore this until I think about it more.
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djellison
post Sep 17 2005, 10:27 AM
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Within the 'scope' as it were of a cubesat, you dont have THAT tight a control on orientation, even with electro magnetic or gravity gradient stability control. It might be worth checking out previously actively stabalised sats to see how much pointing accuracy they could muster.

I think a sensible, modest Cubesat is a sensible precursor to anything more bold.

Every few days I get an email from Cutesat...

Hello! This is XI MAIL.

* Message from us
This picture was taken over Japan.

* Status of XI-IV
Remaining Battery Level : 49.8%
Charging Current : 0.0mA
Electricity Generated : 0.6W
Temperature(+X Panel) : 24.7deg
Temperature(-X Panel) : 24.7deg
Temperature(+Y Panel) : 24.7deg
Temperature(-Y Panel) : 21.2deg
Temperature(+Z Panel) : 23.3deg
Temperature(-Z Panel) : 18.4deg
Temperature(Battery) : 21.9deg
Temperature(Transmitter) : 21.9deg

and the attached image was todays image smile.gif

A 1024 x 1024 CCD camera - which could be commanded to take images as close to a given Lat/Long as possible would make an excellent resource and a superb outreach project - and as a second string, perhaps fly on one of the 6 sides - some prorotype solar cells as an engineering project.

iirc - baisc cube-sat kits are around $10k ish.
http://www.cubesatkit.com
http://cubesat.arizona.edu/rincon_sat/structures/cad.cgi
http://littonlab.atl.calpoly.edu/
http://www-ee.eng.hawaii.edu/~cubesat/

smile.gif

I'll tell you what genuine contribution I can make....pretty 3d pictures of a cubesat in 3ds max wink.gif

doug
Attached image(s)
Attached Image
 
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paxdan
post Sep 17 2005, 11:18 AM
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QUOTE (djellison @ Sep 17 2005, 11:27 AM)
I think a sensible, modest Cubesat is a sensible precursor to anything more bold. 

A 1024 x 1024 CCD camera - which could be commanded to take images as close to a given Lat/Long as possible would make an excellent resource and a superb outreach project - and as a second string, perhaps fly on one of the 6 sides - some prorotype solar cells as an engineering project.

doug
*

You are of course correct, keep it very simple. With a simple camera (or two: one narrow, one wide angle, one mounted pointing down the other horizontally) on a gravity gradient stablised craft there are several things that could be done.

Daylight photography of given lat and long as suggested by Doug,
I/R bolometer to measure fireballs entereing earths atmosphere as outlined by Bob Shaw.
You could use the CCD as a cosmic ray detector to measure the flux.

And the one that interests me would be night-time imaging of large storms to hunt for sprites and all the other as yet not fully understood upper atmosphere phenomenon associated with lightning.

The use of high sensitivity CCDs and optical enhancement routines during the night pass would enable this, and given their recent discovery and the paucity of imaging of these phenomenon returned from space, i think it would make a valid objective for a cube sat.

i would love to hear as many suggestions as possible for worthwhile imaging projects that could be pulled of with a pair of cheap CCDs in orbit.



I have edited this post for spelling.

This post has been edited by paxdan: Sep 17 2005, 11:35 AM
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Bob Shaw
post Sep 17 2005, 12:24 PM
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I've just had a flash of inspiration. It doesn't refer *exactly* to the CubeSat discussion, but *does* grow from it!

Here it is:

Use HDU technology to build a redundant array of inexpensive gyroscopes. Not RAID, but RAIG. You bolt together a goodly number of HDUs with bespoke controller cards and run 50% of them (with full SMART-style HD diagnostics running). As the running drives fail, you simply turn them off and fire up a spare. MTBF is verrrry high on HDUs now, measured in the hundreds of thousands of hours. The running HDUs keep the spares warm; the spares act as heat-sink for the running ones. And the cost? Tens of thousands of Dollars, Pounds, ECUs, whatever - ie, CHEAP!

Now, is that a good one, or what? (He purred).

Bob Shaw


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Bob Shaw
post Sep 17 2005, 01:05 PM
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QUOTE (paxdan @ Sep 17 2005, 12:18 PM)
You are of course correct, keep it very simple. With a simple camera (or two: one narrow, one wide angle, one mounted pointing down the other horizontally) on a gravity gradient stablised craft there are several things that could be done.

Daylight photography of given lat and long as suggested by Doug,
I/R bolometer to measure fireballs entereing earths atmosphere as outlined by Bob Shaw.
You could use the CCD as a cosmic ray detector to measure the flux.

And the one that interests me  would be night-time imaging of large storms to hunt for sprites and all the other as yet not fully understood upper atmosphere phenomenon associated with lightning.

The use of high sensitivity CCDs and optical enhancement routines during the night pass would enable this, and given their recent discovery and the paucity of imaging of these phenomenon returned from space, i think it would make a valid objective for a cube sat.

i would love to hear as many suggestions as possible for worthwhile imaging projects that could be pulled of with a pair of cheap CCDs in orbit.
I have edited this post for spelling.
*


Paxdan:

I like the sprites idea - and have thought of a way to reduce data transmission requirements fairly drastically.

As you probably know, many current digital cameras offer a 'time-machine' facility, where they constantly stare at a scene and record images to a temporary buffer. When you press the shutter, the last ten or so images are written to long-term storage. So, you see the splash as the swimmer dives into the water, and get the picture you really wanted a quarter of a second beforehand.

So, to record sprites, you have camera which 'stares' and records to temporary storage. You download thumbnails (a la MER) and volunteers check them (a la SOHO comets), or you use software if that's too slow. Only then do you actually download the full-sized images. Most sprites will be found between Latitudes X and Y (name a figure!) leaving many northern hemisphere passes free for downloads.

So, the initially high burden of recording images is made much more acceptable.

Imaging will always be costly, though, and anything that would reduce the number of images seems like a good idea. So, my next thought: Don't look down, but instead look sideways - with a slightly wobbly CubeSat, you can scan the horizon, and perhaps see many more events with much less real estate covered (plus, by using the 'time machine' technique, you could hope to get 3D imagery, and all the rest).

Phew!

Too much inspiration for one day!

Bob Shaw


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um3k
post Sep 17 2005, 05:17 PM
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How about a solar telescope? If a little car that drives itself towards a light source can be made as a science fair project, then surely a cubesat that points itself at the sun can be created, right?
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djellison
post Sep 17 2005, 06:21 PM
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Having it intelligent enough to know which way to point is easy

GETTING it to point in that direction is hard. micro-gyros are expensive, electromagnetic stabilisation is slow.

Doug
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um3k
post Sep 17 2005, 07:05 PM
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QUOTE (djellison @ Sep 17 2005, 02:21 PM)
Having it intelligent enough to know which way to point is easy

GETTING it to point in that direction is hard. micro-gyros are expensive, electromagnetic stabilisation is slow.

Doug
*

For the sun, all it needs is a sun-sensor and some way to spin to the right orientation, possibly mini reaction wheels. I don't think it would really need gyros.

How about this: 5 very low precision sun position sensors (just a light-sensitive chip), one for every side but the front; 1 low precision sun position sensor (a fisheye lens and a ccd); 1 medium precision sun position sensor (a medium focal length lens and a ccd); and the final positioning will be done with the telescope itself. And yes, I have loads of faith in modern miracles of miniaturization. tongue.gif
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Bob Shaw
post Sep 17 2005, 08:48 PM
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QUOTE (um3k @ Sep 17 2005, 08:05 PM)
For the sun, all it needs is a sun-sensor and some way to spin to the right orientation, possibly mini reaction wheels. I don't think it would really need gyros.

How about this: 5 very low precision sun position sensors (just a light-sensitive chip), one for every side but the front; 1 low precision sun position sensor (a fisheye lens and a ccd); 1 medium precision sun position sensor (a medium focal length lens and a ccd); and the final positioning will be done with the telescope itself. And yes, I have loads of faith in modern miracles of miniaturization. tongue.gif
*



As a technology demonstrator, something that can seek the Sun is probably about as easy as you can get - and I'd think in terms of light-sensitive diodes, not even chips! You're talking about an analog control system, or possibly something which might be considered as a neural network, with 'learning' to account for biased inputs. The HDU gyro idea seems like an ideal reaction control method, too - but you'll still need to de-spin at some point. Perhaps a gravity gradient default attitude would do the job, but that might require a boom - and I don't much like moving parts (spinning, that's fine!). If the system works, apply it to the next satellite...


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hendric
post Sep 18 2005, 07:27 AM
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Don't hard drives require air to levititate the heads off the platters? What happens in space? Did those previous experiments seal the HD's in their own atmo?


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