1. Paper title: A first glimpse at the OLFAR satellites 2. Contact author:
Steven Engelen2, s.engelen@tudelft.nl 3. Co-authors
Alex Budianu1, Chris J.M. Verhoeven2, c.j.m.verhoeven@tudelft.nl, , David Smith2,
Kevin A. Quillien2, Mark.J. Bentum1,3, m.j.bentum@utwente.nl, J. Matthijs Klein2, R.
T. Rajan2,3, 4. Organizations 1 University of Twente
2 Technical University of Delft 3 ASTRON
5. Full contact details
Steven Engelen
Technical University of Delft
Faculty of Aerospace Engineering - Space System Engineering Kluyverweg 1, 2629 HS Delft, The Netherlands
Phone: +31 15-278 4959, Fax: +31 15-278 5322 Email: s.engelen@tudelft.nl
Chris J.M. Verhoeven Technical University of Delft
Faculty of Aerospace Engineering - Space System Engineering Kluyverweg 1, 2629 HS Delft, The Netherlands
Phone: +31 15-278 6482, Fax: +31 15-278 5322 Email: c.j.m.verhoeven@tudelft.nl
Mark J. Bentum University of Twente
Faculty of Electrical Engineering, Mathematics & Computer Science P.O. Box 217, 7500 AE Enschede, The Netherlands
Phone: +31 53 4892108, Fax: + 31 53 4895640 Email: m.j.bentum@utwente.nl
7. Abstract
Radio astronomical observations at low frequencies are affected by Earth’s ionosphere. This forces radio astronomers to place their antennas above the ionosphere, and given the significant radio frequency interference close to Earth, the antennas should be placed far away from Earth. OLFAR[1],[3], short
for Orbiting Low Frequency Antennas for Radio Astronomy, attempts to use a swarm of nano-satellites[2] to sample signals at frequencies between 0.3
and 30 MHz. The OLFAR swarm would initially be placed in lunar orbit, si!nce this orbit would be very beneficial for astronomy, with the RFI almost eliminated when the antennas are in the shadow of the Moon. Also, the complex gravitational field causes the satellites to drift naturally, allowing the telescope to sample many more points in space, resulting in a sharper image. Unfortunately, the high relative velocities force the swarm to decrease the snapshot integration time, resulting in an excessive increase in the amount of inter-satellite data communication, so alternative orbits are being sought.
The research performed in the project focused on four pillars: Accurate timing and clock-distribution across the network, design methodologies and performance metrics for the satellite swarm, design of the inter-satellite and swarm-to-Earth downlink, as well as calibration methods, and the design of the scientific antennas. Currently, effort is being put into the satellite design of the individual satellites, as well as the various antenna systems. Also the radio-astronomical imaging methods are being scrutinised.
This paper presents the current state of the satellite design; highlighting the achievements, as well as the hiatus in the design, which will be the focus of this year’s research. Particular focus is placed on the antenna deployment mechanism, as the payload of the satellites is deemed one of the critical components. We’ve proven 3 sets of 10m tip-tip dipoles are feasible given the current volume and mass constraints, whilst significantly reducing the cost-per-satellite for the mission.
8. References
