Space

CubeSat to test harnessing Earth's magnetic field for propulsion

CubeSat to test harnessing Ear...
Artist's concept of MiTEE-1
Artist's concept of MiTEE-1
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MiTEE-1 undergoing acoustic testing
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MiTEE-1 undergoing acoustic testing
Artist's concept of MiTEE-1
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Artist's concept of MiTEE-1
Solar boards for MiTEE-1
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Solar boards for MiTEE-1
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A student-built CubeSat from the University of Michigan will investigate whether small satellites can be maintained in low Earth orbit without thrusters or propellant. Scheduled to launch from the Mojave Air and Space Port on Virgin Orbit’s Launch Demo 2 on January 10, 2020, the Miniature Tether Electrodynamics Experiment-1 (MiTEE-1) will test the concept of using the Earth's magnetic field to generate thrust.

About 60 percent of all satellites are in low Earth orbit. This is a bit of a problem because, though on a human scale it's a vacuum, there's actually a thin trace of atmosphere present – enough to generate drag, which causes the satellite's orbit to decay until it burns up on reentry.

The usual way to overcome this is to use thrusters to boost the satellite into a higher orbit, but for smaller spacecraft, and especially CubeSats, this isn't currently an option – although efforts like the ThermaSat design are looking to bring lightweight propulsion systems to CubeSats. The result is that many perfectly good pieces of hardware are destroyed prematurely, deorbiting in a matter of months or even days.

The MiTEE project will test the feasibility of using electromagnetism to provide propulsion by stringing a wire tether 33 to 100 feet (10 to 30 m) long between two CubeSats. The idea is that solar panels would provide electricity, which would run through the wire. As the satellite orbits the Earth, the ionosphere completes the circuit and, because a force is exerted on a wire when it conducts a current in a magnetic field, the tether generates thrust that can be used to boost the spacecraft into a higher orbit. As the force isn't very great, such an approach wouldn't be feasible for larger satellites, but the hope is it will be enough to allow small satellites to compensate for the drag of the atmosphere.

MiTEE-1 undergoing acoustic testing
MiTEE-1 undergoing acoustic testing

The result of two and half years of work, MiTEE-1 won't actually produce any thrust. Instead, it will consist of a satellite about the size of a loaf of breadbox and another about the size of a smartphone that deploys on a one-meter (33-in) rigid boom. This will measure how much current can be drawn from the ionosphere under various conditions.

The data from the mission will be used for planning and building the next MiTEE satellite, which will demonstrate the electric propulsion system concept in operation.

Source: University of Michigan

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8 comments
8 comments
Heckler
Sounds like "mighty." When crossing poles, will MiTEE-2 reverse its electric field, and/or will the CubeSats orbit each other at a specific rate?
wolf0579
Crappy luck on the timing for this endeavor.

As the earth's magnetic field switches polarity, it's strength is expected to drastically reduce, possibly to near zero for a time, until the new poles begin to form.
Philip Argy
The explanation of how it works is confusing to me, David. If solar-generated electricity travels down the tether wire between the large and the small box, what circuit is the ionosphere completing? And is what you refer to as "thrust" simply a magnetic repulsion force sufficient (hopefully) to counteract the consequences of air resistance on orbital declination?
Bricorn
This is basically an electric motor, with the Earth as one part and the CubeSats as the other. It'll be syphoning energy from the planet itself, a tiny, tiny amount NOW, but with millions of these over hundreds of years, will it add up to a significant amount?
My math isn't up to it, does anyone know? If it'll end up being "magnetic pollution" and detrimental to the planet as a whole, it would be best to stop it now.

Any opinions?
Kevin Ritchey
Utilizing a leveraged slingshot maneuver to boost a long or connected string of satellites by polarizing end segments seems almost too easy. They’ve probably been fighting such effects in the past because orientation is important to performance factors. Rather than fighting the behavior, using it to improve flight characteristics might be useful but once started, stopping it within positive parameters might take more effort outweighing the positive. Other, more reliable methods might still remain the best option over the lifespan of the devices.
Kpar
This has been mentioned in Sci-Fi novels in the not too distant past. As a matter of fact, I seem to recall that NASA had actually done an experiment of this sort, but there was a problem unwinding the tether.
IanL
Poor System Requirements and bad design. Utilising two satellites is fraught with risks, failures and other implementation & environmental risks. There is a much better 'single-Satellite' design mechanism utilising two inter-twined spiral wires that can be deployed in an 'umbrella-style' format for example. This maximises wire lengths with minimal spacial requirements as well as providing single failure (FMEA) support.
IanL
Bricon: The proposed system does not 'syphon' energy from the Earth. Rather it 'interacts' with the Earth's Magnetosphere to generate thrust. As for "magnetic pollution", the forces involved will be extremely localised to the connecting wire. The big issue is having two satellites, 10-30 metres apart, tethered with an electrical cable. This creates an unnecessarily larger 'Footprint' for the flight path of the "combined system". Plus failure of one satellite potentially affects ability to generate required thrust. As mentioned in another comment of mine (which may get removed - again!) - it is perfectly possible to create a singular satellite orientated mechanism with minimal spatial requirements.