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

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.

The Figure shows the altitude of UWE-4 since launch on December 27th 2018 based on Two-Line Elements published online by the North American Aerospace Defence Command (NORAD).

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-3 is celebrating his 6th birthday

UWE-3 News: Today UWE-3 is celebrating his 6th birthday

On a drizzly day in November 2013 for the first time UWE-3 saw the lights of the stars. Since this 21st of November in 2013 six years passed by in which UWE-3 and the team had a lot of work and fun together.

Day by day many radio amateurs from around the world send us UWE-3 beacons to supply us with the health state of UWE-3, which is still excellent. For example the batteries are still in a good shape:

Since the very first day we received great support from the radio amateur community. Our database counts already 291.104 external beacons sent to us from you.

Thank you!

Hopefully, UWE-3 will keep its good shape and the great support from you!

Kind regards,

The team of UWE‑3

Posted in UWE

UWE-4 News

Last week our Team returned from the Vostochny Launch Site (Russia) where we performed the last check out tests of UWE-4 before launch. The satellite will be launched through the German integrator ECM Space on a Soyuz-2 mission using a Fregat upper stage on 27th December 2018 at 02:07:18 UTC. UWE-4 transportation to Far East of Russia was very smooth, so only a last software update and recharging of the batteries needed to be performed. By now, UWE-4 has been successfully integrated into the launch deployer followed by the integration with the upper stage, the fairing encapsulation will occur today.

In the meantime we updated our website to provide more detailed information about the orbit and the communication parameter including the beacon decoding information. You can find all these and some more details here: http://www7.informatik.uni-wuerzburg.de/forschung/space-exploration/projects/uwe-4/ As soon as we can provide the TLE, you will find them also on our website.

Kind regards, The UWE‑4 Team

Posted in UWE

UWE-3 celebrating 4 years of operation in space.

UWE-3 News: celebrating 4 years of operation in space.

UWE-3 in clean room shortly before launch 2013.

During these last four years we received an outstanding support from the Radio Amateur Community from all over the world, which is highly appreciated. We would like to express our special thanks to:

DK3WN, Rainer, PE0SAT, SP7THR, EU1XX, JA1GDE, JA6PL, G7GQW, ON4HF, LU4EOU, DL8MCO, JA5BLZ, CU2JX, R4UAB, VK5HI, JA0CAW, IW0HLG, JO1PTD, YC3BVG, DB1VQ, JA6DHC, ZL4JL, VK2FAK, JE9PEL, JH4XSY, JF1EUY, N2ACQ, PY4ZBZ, CX8AF, DG4YDF, LU7DRR, PD0OXW, PA2EON, IK8OZV, ES5EC, K4KDR, ZR1ADC, JE1CVL, EA7ADI, EA1JM, PY2SDR, VE7CEW, PA3GUO, ES5TO, SM0TGU, EA4SG, DL1MX, W6YRA.

THANK YOU ALL FOR YOUR EXTRAORDINARY SUPPORT!

Yours sincerely,

UWE-3 Team.

UWE-3 News

UWE-3 News: Status report

On 21st of May 2016 UWE-3 celebrated 2.5 years in space without any significant failures. Batteries, EPS, OBC and ADCS are fine, nevertheless we were confronted with a minor problem with one of the radios UWE-3 autonomously recovered from. Since then UWE-3 is in a very stable condition again.

Some weeks ago we have re-initiated operations with UWE-3 on an interim basis. The goal is to test new magnetic control algorithms in space. Therefore we operate the satellite on the 436.395200 MHz frequency and perform data downloads from time to time. In the figure below the satellite’s rotation rate w is shown for one of the experiments. The goal was to establish a rotation about the satellite’s X-axis (blue) at 10 deg/s while the Y/Z-axes should be at 0 deg/s. In general the desired rotation rate could be achieved but with major deviations from the setpoint. With the intention of optimizing the relevant control laws we will continue with these experiments within the next days and weeks.

UWE-3-news-23-05-2016

During our experiments we received an outstanding support from the radio community from all over the world we are very thankful for. The received packets were instantaneous injected into our algorithms and delivered an important contribution to our research work. We would like to express our special thanks to DK3WN, PE0SAT, DL8MCO, EU1XX, ON4HF, Rainer, JA5BLZ, JA6PL, CU2JX, LU4EOU, JA1GDE, SP7THR, G7GQW, YC3BVG, JF1EUY, JE9PEL, JE1CVL, JO1PTD, ZL4JL, EA7ADI, K4KDR, JA0CAW, JH4XSY, PA2EON, SM0TGU. THANK YOU!

Yours sincerely,

UWE-3 Team.

UWE-3 Mission Logo

UWE-3 update 03-07-2015

UWE-3 Status report

UWE-3 redundant UHF SubSystem

After the communication anomaly and the autonomous recovery of UWE-3 two weeks ago we uploaded an extended software to the OBC to analyze the event in detail. As we already have known the EPS, OBC and ADCS were not affected, so the secondary radio.

During the tests made possible by the new software we temporarily switched back to the primary radio to check its electrical characteristics and communication performance. As the values were promisingly normal we performed extensive communication tests without seeing any existing anomaly. Therefore we will continue normal operation.