Radar for Europa Assessment and Sounding: Ocean to Near-surface
{{short description|Ice-penetrating radar for Europa Clipper}}
{{Infobox spacecraft instrument
| Name =
| Image = Europa Clipper radar.jpg
| Caption = Artist's impression of the Europa Clipper{{'s}} REASON instrument in action, using dual-frequency radar to map Europa's ice layer
| Operator = NASA
| Manufacturer = Jackson School of Geosciences
and JPL
| Type = Ice penetrating radar
| Function = Characterize ice shell structure
| Mission_Duration = Cruise: 5.5 years
Science phase: 4 years
| Began =
| Ceased =
| Webpage =
| Mass = 32.2 kg
| Dimensions = Antenna: 16 m (52 ft)
| Number =
| Power_consumption = 55 W
| Resolution =
| Spectral_Band =
| Data_Rate = 5 - 80 Mbps
| Spacecraft = Europa Clipper
| SC_Operator = NASA
| Launch = {{Start date text|October 14, 2024, 16:06:00|timezone=yes}} UTC (12:06 p.m. EDT)
| Rocket = Falcon Heavy
| Launch_Site = Kennedy Space Center
| COSPAR =
}}
The Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) is a multi-frequency, multi-channel ice penetrating radar system that will be flown on board the Europa Clipper mission to Jupiter's moon Europa. REASON investigation will provide the first direct measurements of Europa's ice shell surface character and subsurface structure.[http://adsabs.harvard.edu/abs/2015AGUFM.P13E..05M REASON for Europa]. Moussessian, A.; Blankenship, D. D.; Plaut, J. J.; Patterson, G. W.; Gim, Y.; Schroeder, D. M.; Soderlund, K. M.; Grima, C.; Young, D. A.; Chapin, E. American Geophysical Union, Fall Meeting 2015, abstract #P13E-05. December 2015.
Overview
File:Europa Clipper REASON Deployment.webm
The REASON instrument makes innovative use of radar sounding, altimetry, reflectometry, plasma and particles analyses. These investigations will use a dual-frequency radar emitting HF (9 MHz) and VHF (60 MHz) with concurrent shallow and deep sounding.{{cite journal |title=Radar signal propagation through the ionosphere of Europa |journal=Planetary and Space Science |date=November 2015 |last=Grima |first=Cyril |last2=Blankenship |first2=Donald |last3=Schroeder |first3=Dustin M. |volume=117 |pages=421–428 |doi=10.1016/j.pss.2015.08.017 |bibcode=2015P&SS..117..421G }}{{cite journal |title=Bright prospects for radar detection of Europa's ocean |journal=Icarus |date=1 January 2017 |last=Aglyamov |first=Yury |last2=Schroeder |first2=Dustin M. |last3=Vance |first3=Steven D. |volume=281 |pages=334–337 |doi=10.1016/j.icarus.2016.08.014 |bibcode=2017Icar..281..334A }} Both VHF and HF radiating elements are mounted on a single boom, reducing antenna
mass. The mission plan also includes using REASON as a nadir altimeter capable of measuring tides to test ice shell and ocean hypotheses as well as characterizing roughness across the surface to identify potential landing sites for a future Europa Lander.
The REASON instrument will also be able to spot pockets of water within the ice shell that could serve as a passageway for chemicals on the moon's surface to the ocean below — an environment where life could potentially develop.
The instrument was developed by the Jackson School of Geosciences,{{cite news |last=Caputo |first=Anton |url=https://news.utexas.edu/2015/06/01/antarctica-radar-to-scour-europa-for-life-supporting-environ |title=Radar Techniques Used in Antarctica Will Scour Europa for Life-Supporting Environments |work=UT News |date=1 June 2015 |accessdate=2017-11-04 }} and its Principal Investigator is Donald Blankenship. REASON was fabricated by engineers from NASA's Jet Propulsion Laboratory and the University of Iowa.
Specifications table
| class="wikitable floatleft" | |
| REASON | Units/performance |
|---|---|
| Electronics mass | 17.5 kg |
| Antenna mass | 14.7 kg |
| Total mass | 32.2 kg |
| Operating power | 55 W |
| Antenna length | {{convert|16|m|ft|abbr=on}} |
| VHF (shallow sounding) | 300 m to 4.5 km |
| HF (deep sounding) | 1 km to 30 km |
| Pulse length | 30 - 100 μs |
| Operational altitude | 10 - 1000 km |
| Radar potential | HF: 63 dB VHF: 72 dB |
| Data rate | 5 - 80 Mbps |
| Data volume per flyby | 24 Gbits |
{{clear}}
Objectives
The scientific objectives of the REASON investigation are: [https://www.lpi.usra.edu/opag/meetings/aug2015/presentations/day-1/8_f_REASON.pdf Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON)] (PDF). D. Blankenship. 2015
- Characterize the distribution of any shallow subsurface water
- Search for an ice-ocean interface and characterize the ice shell's global structure
- Investigate the processes governing material exchange among the ocean, ice shell, surface, and atmosphere
- Constrain the amplitude and phase of gravitational tides
- Characterize scientifically compelling sites, and hazards, for a potential future Europa Lander mission
References
{{reflist}}
{{Europa Clipper}}
{{Astrobiology}}
{{Europa}}
{{Satellite and spacecraft instruments}}