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UWE-4 News: Successful first demonstration of orbit control on a 1U CubeSat

Posted: 22 Jul 2020 04:09 AM PDT https://amsat-uk.org/2020/07/22/uwe-4-news-successful-first-demonstration-of-orbit-control-on-a-1u-cubesat/

Altitude of UWE-4 since launch on December 27, 2018

The University Wuerzburg Experimental Satellite 4 (UWE-4) successfully used
its propulsion system in order to conduct orbit control. The 1U CubeSat, developed and built at the Chair for Robotics and Telematics, is equipped
with the electric propulsion system NanoFEEP which has been developed by TU Dresden.

Several manoeuvres have been performed within 11 days between June 23rd – July 3rd 2020 such that the altitude of the CubeSat was reduced by more
than 100 m, compared to an average of 21 m with natural decay. This marks
the first time in CubeSat history that a 1U CubeSat changed its orbit using
an on-board propulsion system.

As chance would have it, the team of UWE-4 received a conjunction data
message (CDM) in the morning of July 2nd 2020 from the United Air Force’s 18th Space Control Squadron. A conjunction of UWE-4 with a non-operational Iridium satellite (ID: 34147) in the morning of July 5th 2020 with a
minimum range of about 800 m was a threat to the safety of UWE-4. An
analysis has shown that the altitude of UWE-4 would already be below the Iridium satellite at the time of conjunction. Thus the on-going altitude lowering manoeuvre could only improve the situation and can be considered
as a collision avoidance manoeuvre. No further CDMs have been issued
regarding this possible conjunction. An analysis of the orbit of the two spacecraft after July 5th 2020 results in a closest approach of more than
6000 m.

Lowering the altitude of a spacecraft in low earth orbit (LEO) is
equivalent to a reduction of its lifetime, since satellites in LEO usually
burn up during re-entry due to the friction with the Earth’s atmosphere. Thus, this experiment is a concept demonstration of a de-orbiting manoeuvre shown at the smallest class of spacecraft in LEO. Today, there is no
commitment to carry a propulsion system for spacecraft. However, due to the vastly increasing number of satellites in mega constellations such
obligations are being discussed in the space agencies of several space
faring countries. The experiment of UWE-4 presents a de-orbiting solution
for the fraction of space debris of operational but unused satellites of
today and for the mega constellations of tomorrow.

Stay tuned for more updates on UWE-4 and the upcoming launch of NetSat – a formation flying nano-satellite mission from our partner institute Center
for Telematics which is expected to be launched September 2020!

Kind regards,

The UWE‑4 Team

UWE-4: First NanoFEEP thruster ignition

https://amsat-uk.org/2019/03/04/uwe-4-first-nanofeep-thruster-ignition/

UWE-4 435.600 MHz

http://www7.informatik.uni-wuerzburg.de/forschung/space-exploration/projects/uwe-4/

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