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RIMFAX
	RIMFAX radar imager
Operator	NASA
Manufacturer	Norwegian Defence Research Establishment
Instrument type	Ground-penetrating radar
Function	Study subsurface structure
Properties
Mass	3 kg (6.6 lb)
Dimensions	19.6 × 12.0 × 0.66 cm
Power consumption	Max: 10 watts
Resolution	15 cm to 30 cm; (3" to 12")
Host spacecraft
Spacecraft	Perseverance
Operator	NASA
Launch date	30 July 2020, 11:50:00 UTC
Rocket	Atlas V
Launch site	Cape Canaveral, SLC-41
COSPAR ID	2020-052A

The Radar Imager for Mars' subsurface experiment (RIMFAX) is a ground-penetrating radar on NASA's Perseverance rover, part of the Mars 2020 mission. It uses radar waves to see geologic features under the surface.

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]

The RIMFAX instrument was developed and built by FFI, and it was delivered to NASA's Jet Propulsion Laboratory for integration with the rover in December 2018. Due to Mars's 24.5 hour long day, RIMFAX operations are shared between centers at University of California, Los Angeles (UCLA) and the University of Oslo (UiO), swapping every two weeks.^[5] The RIMFAX data is archived by NASA's Planetary Data System.^[6] The RIMFAX principal investigator is Svein-Erik Hamran of FFI, and his team includes scientists from Norway, Canada and the United States.^[7]

Specifications

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.

Specifications	Units/performance^[2]^[4]
Mass	3 kg (6.6 lb)
Power	5 to 10 watts
Dimensions	19.6 × 12.0 × 0.66 cm (7.0" × 4.7" × 2.4")
Data return	5 to 10 kbytes per sounding location
Frequency range	150 to 1200 MHz
Vertical resolution	15 cm to 30 cm (6" to 12")
Penetration depth	≤10 m (33 ft)
Measurement interval	Every 10 cm (3.9 in)

Development

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 source electromagnetic 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]

Contemporaries

Other Mars radar experiments include SHARAD, MARSIS, and WISDOM.^[10]

External links

Scholia has a profile for RIMFAX (Q42317746).

NASA project homepage
FFI project homepage
RIMFAX data on the Planetary Data System
gprMAX Electromagnetic simulation software

References

^ "Next Mars rover will use 'X-ray vision' to spot buried treasure". CBC News. Retrieved 24 January 2018.
^ ^a ^b "Mars 2020 Rover - RIMFAX". NASA. 2017. Retrieved 22 October 2017. This article incorporates text from this source, which is in the public domain.
^ ^a ^b Hamran, 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. ISBN 978-1-4799-6495-6. S2CID 11358518.
^ ^a ^b ^c "RIMFAX - ground penetrating radar". Norwegian Defence Research Establishment. 14 August 2015. Retrieved 17 December 2020.
^ 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.
^ "PDS Data Release Calendar 2021". Anticipated Release Date - 08/20/2021
"Mars 2020 Mission Perseverance Rover". The first release of PDS data will be on August 20, 2021.
^ "RIMFAX science team". Norwegian Defence Research Establishment. 19 September 2014. Archived from the original on 25 April 2019. Retrieved 28 March 2021.
^ Svein-Erik Hamran; David A. Paige; Hans E.F. Amundsen; et al. (3 November 2020). "Radar Imager for Mars' Subsurface Experiment—RIMFAX" (PDF). Space Science Reviews. 216 (8). 128. Bibcode:2020SSRv..216..128H. doi:10.1007/S11214-020-00740-4. ISSN 0038-6308. Wikidata Q105715907.
^ Craig Warren; Antonios Giannopoulos; Iraklis Giannakis (December 2016). "gprMax: Open source software to simulate electromagnetic wave propagation for Ground Penetrating Radar". Computer Physics Communications. 209: 163–170. doi:10.1016/J.CPC.2016.08.020. ISSN 0010-4655. Wikidata Q64455906.
^ Svein-Erik Hamran; Hans E.F. Amundsen; Lynn Carter; Rebecca Ghent; Jack Kohler; Michael Mellon; David Paige (2014). "THE GROUND PENETRATING RADAR RIMFAX ON THE MARS 2020 MISSION" (PDF). Proceedings of the International Workshop on Instrumentation for Planetary Missions. S2CID 4975188. Wikidata Q105725095. Archived from the original (PDF) on 28 March 2021.