When sending satellites into space, the idea is to place them into as stable an orbit as possible in order to maximize both the time the satellite is useful and the economics of sending it there in the first place. This tends to become rather untenable as the amount of space junk continues to pile up for all but the lowest of orbits, but a team at Brown University recently tested a satellite that might help solve this problem, at least for future satellite deployments.
The main test of this satellite was its drag sail, which increases its atmospheric drag significantly and reduces its spaceflight time to around five years. This might make it seem like a problem from an economics standpoint, as it’s quite expensive to build satellites and launch them into space, but this satellite solves these problems by being both extremely small to minimize launch costs, and also by being built out of off-the-shelf components not typically rated for spaceflight. For example, it gets its power solely from AA batteries and uses an Arduino for its operation and other research.
The satellite is currently in orbit, and has already descended from an altitude of 520 km to 470 km. While it won’t help reduce the existing amount of debris in orbit, the research team hopes to demonstrate that small satellites can be affordable and economically feasible without further contributing to the growing problem of space junk. If you’re looking to launch your own CubeSat one day, take a look at this primer which goes over most of the basics.
18 thoughts on “One Method For Removing Future Space Junk”
Aw, I was hoping for detail about the release mechanism. Ideally it’d be something very simple, self-timed, like a pressurized bag that holds the mechanism locked while it leaks through a pore.
Or just through atomic diffusion, like helium leaking out of mylar. Clever
The standard way to deploy such devices is to have them spring loaded and held closed using nylon fishing line that is also wrapped around a resistor sized such that it heats up and melts the fishing line releasing the springs to deploy the antenna, solar panel or drag device. Just need a transistor, resistor and one GPIO, no moving parts (beyond springs).
And power. You also need power. And a functioning CPU to turn on the GPIO.
Fortunately, designers acknowledge that, and the backup is to rely on the plastic being degradable by the abundant UV and/or energetic oxygen in low earth orbit. Left long enough, the plastic line will fall apart anyway.
I didn’t know about the UV degradable plastic line, that is a good idea as it’s practically fool proof.
It is worth mentioning that the second student satelite in Poland also used a similar method back in 2018: https://www.pw.edu.pl/engpw/News/The-PW-Sat2-launch
Hm. Am I the only one who wonders why satellites aren’t made to last longer, so less rocket starts and space debris are being caused ? Quality/planning ahead vs. planned obsolescence?
Some of the older satellites like AO-7 still work in principle. Why can’t we build things to last anymore?
If the satellite has a programmable DSP/FPGA and an SDR, it could still be very flexible in the future.
This is an industry and you don’t wanna sell yourself out of a market for the next forty years. We aren’t even afraid of Venus syndrome, let alone Kessler syndrome
It depends on whether you can manage the risk of failure.
Though the harder limit is running out of propellant and wearing out the batteries by constant cycling every 30 minutes.
Don’t know about battery cycles, but lack of propulsion/positioning fuel is the biggest issue since you need enough left to deorbit or park and it aint cheap to put it up there. Dropping a used sat on other contries is considered bad politics
Its not that they don’t want them to last, but as simple as satellites seem they are are under severe stress, Low Earth Orbiting (LEO) satellites do an orbit every 90min, 45min exposed to the sun heating up and charging, 45min exposed to the cold of space with no incoming power. Batterys have only so many charge/discharge cycles and there are the thermal stresses on many part of the structure and functional parts of the satellite. They are generally designed to last at least 5 years by the manufactures (often pieces from multiple suppliers, all with differing tolerances) so they hope they last longer but are only designed to last for a given period. And then of course there is radiation causing SEU (Single Event Upsets) which can destroy control circuits or change one bit in memory that causes an infinite loop which may or not be recoverable.
Partly it’s because few people can be bothered to think farther ahead than the next quarter, and five years out is considered “long range” planning.
Partly it’s because electronics tech is changing so fast right now that a satellite designed today would be uselessly obsolete in 40 years. Imagine trying to work with a satellite built with the tech of 1983.
How old are the oldest television satellites in geosynchronous orbit? DBS digital satellite TV didn’t launch all new ones specially built for relaying digital signals. DBS was designed to run encrypted digital video via the same radio frequencies that were previously used for analog TV, and similar technology would later be used for digital terrestrial broadcast TV using the VHF and UHF bands.
“Imagine trying to work with a satellite built with the tech of 1983”
Hubble Space Telescope. Project was started in 1977:
It does beg the question, why not just send up a gigantic chunk of ballistics gel. Add a few thrusters to keep it from hitting anything important.
It’ll catch some and slow others, eventually it’ll de-orbit.
It’s the problem of weight. Weight is expensive to put in space. Plus ballistic gell is probably basically water, and so would boil off or freeze.
The best solution for reducing space junk would be to keep a certain nation that currently owns 70% of all satellites in an orbit around earth from launching even more. Especially “megaconstellations” that will easily triple or quadruple the number of objects in orbit just to provide internet connectivity.
Those megaconstellations are in a low enough orbit that aerodynamic drag will drop them in 5 years after propellant loss, give or take. They are self-removing space junk. They started low to increase signal strength on the ground for the size and power of the transmitter and to lower the time it takes for the signal to go up and come back down. Losing them after 5 years means they won’t compete with more advanced and more capable future satellites and, because of the drag, coming down is fail-safe. I think they can be commanded to de-orbit earlier, but if that fails it’s a nuisance, not a big problem. That life limit also cuts the time anyone has if they manage to break control encryption to act on it. Also, because they are low they orbit faster. If a satellite dies in the constellation and leave a hole, that hole might only become an outage for a few minutes.
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