Student satellite demonstrates drag sail to de-orbit old hardware A tiny satellite with a drag chute built by a team of students has been held up as one small possible solution to the thorny issue of space junk caused by defunct hardware cluttering up Earth’s orbit. SBUDNIC, a “Sputnik-like CubeSat,” was built by students at Brown University, Rhode Island, from low-cost commercial off-the- …
https://space.skyrocket.de/doc_sdat/sbudnic.htm
The satellite has 30 x 10 x 10 cm, a photo camera and solar panels in addition to the Arduino electronics, the radio and the battery charger.
I don't know how much the system will weigh to maintain the internal temperature.
I guess 225 grams is just the weight of the mechanism to take it out of orbit.
It's actually 6kg - we've fixed that in the piece. The 225g was the drag sail, not the full sat. The other dimensions are fine. If you spot anything that looks weird, drop us a note please to corrections@theregister.com and we'll get right on it.
PS: if you want more info on how it works, check out the project's site. It has lots of details.
C.
You latched onto the wrong detail there!
Energiser Lithium AAs apparently weigh ~14g each, so the battery mass alone was roughly 1kg.
I do wonder what they spent the remaining 4.5kg mass budget on. I was building 150g combat robots in my university dorm, and technology has greatly improved since.
Now I might be wrong, but one of the main features of Sputnik is that it was a sphere. And one of the main features, you might even say the defining feature, of a cube sat is that it is in fa ct a cube.
So a Sputnik like Cube Sat would in other words be a spherical cube which would appear to be something of an Oxymoron, no?
Still good work those students! It's always nice to see projects like this which will really catch these and future students interests...
Sputnik had only two purposes... to show that something could stay in orbit, and transmit a signal to show it was alive and kicking. It succeeded in both, and as such, this cubesat (SBUDNIC) had just a singular purpose (similar to Sputnik, i.e. "Sputnik-like") that was to demonstrate that extending its little foil sail would significantly shorten the time it would remain in orbit. Also Sputnik weighed 86kg and was around 60 cm wide, so you could also refer to Sputnik's size as a comparator (i.e. small like Sputnik), because cubesats can get up to 12U in size (3x4x1 cubes of 10cm3, or 3x2x2, 2x6x1, or 12x1x1). That's tiny compared to the usual car/bus-sized monsters that now orbit the planet.
So, the description is apt. It's not an "exact replica of Sputnik" or it would've been described in terms describing its form, but rather... "similar to Sputnik in its purpose" (or 'like Sputnik').
:-)
The problem with the fire door approach is it is power intensive. Which is usually not OK for spacecraft. However it would not take much additional code to have the Ardrino deploy the sail at a certain date if it's not been commanded to do so before that date, as a backup plan for a communication failure.
It used a Arduino and it failed. What a surprise! Maybe the friction-fit pin headers weren't the best call for something that's experiences a lot of vibration and acceleration on launch.
When you spot an Arduino that's the surest sign that the person who made it hasn't the slightest clue about electronics or embedded development and they've probably just copied some libraries from SparkFun and joined them with some if statements.
I don’t see the need for the superciliousness.
I don't see the need for the downvotes. It didn't sound superciliousness to me: merely descriptive. We're used to thinking of a comms satellites as being "an electronic device", but something like a drag sail in a cube sat is more mechanical-engineering, and material-science. There is no reason to expect that students involved in the drag-sail part of the project have any particular skill or inclination towards electronics, and the Arduino is further evidence of that.
There’s no reason to expect or assume anything. No reason to assume the project used friction fit headers. No reason to assume the students that were involved in engineering the sail part of the project were also involved in the electronics. No reason to assume that anything more than an arduino was required. No evidence of anything apart from superciliousness. The supercilious rarely see themselves as such.
Quoting the article, "Also 3D printed is the drag sail, made from Kapton polyimide film"
I find this somewhat unlikely, Kapton is fairly temperature resistant, being used to tape together things at temperatures up to 400oC. Apart from use holding together multi-layer insulation on spacecraft, it also holds the thermistor to the heated bed of my 3D printer. It's not going to be an easy material to print.
The film might have been cut using an automated cutting table though....
Maybe my understanding of spaaaaaace (etc) is a bit primitive, but as far as I am aware we reserve that definition for a location *beyond* our atmosphere.
Without an atmosphere, would a sail not more behave as in the Commodores song (stress on "on") rather than provide drag?
The Earths atmosphere extends a LONG way above us, well into the "empty" space of LEO. It's very, very thin[*] up there though, but is there. Then there are solar winds too. Have you ever wondered by the ISS needs it's orbit boosting periodically? Or why satellites carry "station keeping" fuel? The drag degrades their orbits and they need pushing back "up" every now and then.
* so thin that this test sat with it's sail will likely derbit in about 6.5 years compared to about 25 years without it, as per the article, which mentions other sats put up at the same time in similar orbits.
And FWIW, I learned the above by reading the articles and comments on El Reg, as well as lots of SF stories over the years :-)
Even between the stars*.
*Good thing too. Otherwise there wouldn't have ever been anywhere else to have stuff.
It's a common misconception that the atmosphere just comes to an end at some point, like there's air here but not ..... here.
It just keeps on getting thinner the further you get from the planet. At the altitude occupied by low orbit satellites the almost no atmosphere, like the difference between dead and mostly dead. A such there is - as the article suggests - some drag on low orbit satellites so their orbits do degrade but very slowly. The big drag sail would increase that drag to degrade the orbit more quickly. We're not talking about the sail slowing the satellite at the same rate as the chutes on a drag racer, but maybe causing the orbit to degrade four times as quickly as it otherwise would.
There are solutions to de-orbit a satellite much more quickly - some sort of rocket would be a favourite - but they weigh a lot more than 225g. And one significant cost of getting a satellite into orbit is the satellite's total mass. So the lighter and smaller the satellite the better. This sail adds very little mass and very little volume.
Bunnies don't like space!
Seems likely that the electronics failed because it was using AAs. The tabs on PCB mount AAs are subject to metal fatigue, quite weak and the AA can is quite massive. The vibration of launch likely ripped a few of them off the board.
Seen this a few times in handheld portable kit.
Bare lithium cells are much lighter and are flexible, so are easier to package for survival under high vibration.
That said, I suspect they used the AAs for sponsorship reasons and always knew they were a weakness that didn't really matter for the mission.
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