The UCL Antenna Group is involved with the design of the antennas for LaRa (Lander Radioscience) transponder. We appear as sub-contractor to Antwerp Space, who is leading the design of the LaRa transponder.

About LaRa Experiment

The LaRa experiment is part of the ESA-Roscosmos mission, the ExoMars program. The ExoMars program aims to deliver a European rover and a Russian surface platform to the Martian surface for a launch in 2020. The LaRa transponder will be located in the surface platform, and its purpose is to understand the deep interior of Mars by exploring remotely the geophysics of the planet.

The LaRa transponder directly receives an X-band signal from the Earth ground stations, and retransmits the signal back to Earth. A Doppler shift can then be observed because of the difference in the relative velocity of the two planets. The LaRa coherent transponder performs a down coherent conversion of the carrier signal arriving on the uplink from Earth, where the frequency stability is accurately maintained by the masers of the Earth’s ground stations. The downlink and the uplink carrier frequencies are related to the transponder ratio.

About LaRa Antennas

The LaRa transponder uses one antenna to receive the uplink signal from Earth at 7.174 GHz, and two antennas to transmit the downlink signal to Earth at 8.428 GHz. One of the transmit antennas is kept redundant in case of failure of the other one.

In order to improve the observation window of the Earth in the Martian sky, the LaRa antennas are designed to have a gain of at least 4 dB for an elevation of 30° to 55°.


The LaRa instrument is going through Phase C/D. The Critical Design Review (CDR) meeting was held from June 20-21, 2018 at ESTEC in Noordwijk, Netherlands.

The antennas are going through the qualification tests. Below you can see the video of the LaRa antennas subjected to vibration tests at ESTEC.

LaRa transmit and receive antennas before vibration tests