The device can make detections dozens of meters/yards underneath ground, such as for buried sand dunes or lava feature.[1]
RIMFAX takes its name from Hrímfaxi, the horse in Norse mythology that "faithfully brings the night."[2]
The radar operates at radio frequencies of 150–1200 MHz and uses a Bow-Tie Slot antenna.[3]
Overview
RIMFAX is a ground-penetrating radar, its antenna is located on the lower rear of the Perseverance rover. It is able to image different ground densities, structural layers, buried rocks, meteorites, and detect underground water ice and salty brine at 10 m (33 ft) depth.
Ground-penetrating radars (GPR) send radio frequency electromagnetic waves into the ground and then detect the reflected signals as a function of time to reveal subsurface structure as well as composition. RIMFAX is based on a number of GPR instruments developed at the Norwegian Defence Research Establishment (FFI).[4] RIMFAX was selected by NASA to be one of the instruments on the Mars 2020 rover in July 2014. RIMFAX provides the science team with the capability to assess the shallow layers and their stratigraphic relationship to nearby outcrops, and thus a window into the geological history and associated environmental history.[4]
RIMFAX employs a gated Frequency Modulated Continuous Wave (FMCW) waveform to probe the subsurface. Gated FMCW utilizes a single antenna for both transmission and reception, quickly switching the antenna between the transmitter and the receiver. RIMFAX is commanded to acquire radar soundings every 10–20 cm along the rover's path to create two-dimensional GPR images of subsurface structure.
An engineering model of RIMFAX was tested in several locations, primarily in Svalbard, and in the US Southwest. Modelling was carried out with gprMax, an open sourceelectromagnetic simulation tool, to assess the imaging potential at the landing site.[8][9] During development a detection range of about 10 yards/meters was targeted, and tests on glaciers were successful.[3]
^ abHamran, S. E.; Berger, T.; Brovoll, S.; Damsgård, L.; Helleren, Ø.; Øyan, M. J.; Amundsen, H. E.; Carter, L.; Ghent, R. (July 2015). "RIMFAX: A GPR for the Mars 2020 rover mission". 2015 8th International Workshop on Advanced Ground Penetrating Radar (IWAGPR). pp. 1–4. doi:10.1109/IWAGPR.2015.7292690. ISBN978-1-4799-6495-6. S2CID11358518.
^Paige, David (18 February 2021). "Q&A: David Paige on the Feb. 18 Mars Perseverance landing" (Interview). Interviewed by Stuart Wolpert. Since the rover will be working on Mars time, in which the days are 24.5 hours long, responsibility for the operation of RIMFAX will pingpong between Norway and UCLA every two weeks.