Comparison of embedded computer systems on board the Mars rovers

The embedded computer systems onboard Mars rovers are designed to withstand high radiation levels and large temperature changes in space. For this reason their computational resources are limited compared to systems commonly used on Earth.Max Bajracharya, Mark W. Maimone, Daniel Helmick (2008) (Jet Propulsion Laboratory and California Institute of Technology); Autonomy for Mars rovers: past, present, and future; published in: Computer, a journal of the IEEE Computer Society, December 2008, Volume 41, Number 12, page 45, {{ISSN|0018-9162}}.

In operation

Direct teleoperation of a Mars rover is impractical, as the round trip communication time between Earth and Mars ranges from 8 to 42 minutes and the Deep Space Network system is only available a few times during each Martian day (sol). Therefore, a rover command team plans, then sends, a sol of operational commands to the rover at one time.

A rover uses autonomy software to make decisions based on observations from its sensors. Each pair of stereo images for the Sojourner rover could generate 20 3D navigation points. The Mars Exploration Rovers can generate 15,000 (nominal) to 40,000 (survey mode) 3D points.

Performance comparisons

With the exception of Curiosity and Perseverance, each Mars rover has had only one on-board computer. Both Curiosity and Perseverance have two identical computers for redundancy. Curiosity is, as of February 2013, operating on its redundant computer, while its primary computer is being investigated for signs of failure.{{Cite web|url=https://www.nasa.gov/mission_pages/msl/news/msl20130228.html |title=Computer Swap on Curiosity Rover |date=February 28, 2013 |accessdate=2017-06-12 |publisher=NASA/JPL }}{{Update inline|date=November 2023}}

class="wikitable sortable" \|+Comparison of embedded computer systems on board the Mars rovers ! Landing year !! Rover (mission, organization) !! CPUs !! RAM !! Flash !! EEPROM !! Operating system !! CPU time available for the autonomy software
1997	Sojourner rover (Pathfinder, NASA){{Cite web \|url=http://mars.jpl.nasa.gov/MPF/rover/faqs_sojourner.html \|title=Mars Pathfinder Frequently Asked Questions: Sojourner Rover \|date=April 10, 1997 \|access-date=March 27, 2009 \|publisher=NASA/JPL}}{{Cite web\|url=http://mars.jpl.nasa.gov/MPF/rovercom/data/ROV_PAST.TXT \|title=Mars Rovers: Past, Present, & Future \|date=May 10, 1997 \|access-date=April 18, 2009 \|author=Donna L. Shirley and Jacob R. Matijevic \|publisher=NASA/JPL }}{{Cite web\|url=http://www.eetimes.com/news/98/994news/robots.html/ \|title=U.S. plays catch-up as robots crawl into new applications \|date=February 18, 1998 \|access-date=April 18, 2009 \|author=Larry Lange \|publisher=EETimes.com }}	2 MHz 8-bit Intel 80C85[http://mars.jpl.nasa.gov/MPF/rover/faqs_sojourner.html#cpu Mars Pathfinder Frequently Asked Questions]	0.5 MB	{{ Nowrap\|0.172 MB}}	{{No\|None}}	Custom cyclic executive	Not applicable to Cyclic Executives
1997	Pathfinder Lander (NASA) (Base station for Sojourner rover)	20 MHz MFC	128 MB	{{No\|None}}	6 MB	VxWorks (multitasking){{Cite web \|url=https://www.windriver.com/news/press/news-314 \|title=Wind River Powers Mars Exploration Rovers—Continues Legacy as Technology Provider for NASA's Space Exploration \|date=June 6, 2003 \|access-date=August 28, 2009 \|publisher=Wind River}}	less than 75%
2004	Spirit and Opportunity (Mars Exploration Rover (MER), NASA)	20 MHz 32-bit BAE RAD6000 (PowerPC)	128 MB	256 MB	3 MB	VxWorks (multitasking)	less than 75%
2012	Curiosity (Mars Science Laboratory (MSL), NASA){{Cite web\|url=http://marsprogram.jpl.nasa.gov/msl/mission/rover/brains/ \|title=Mars Science Laboratory: Mission: Rover: Brains \|access-date=March 27, 2009 \|publisher=NASA/JPL }}{{Cite web\|url=http://www.baesystems.com/Newsroom/NewsReleases/autoGen_108517143749.html \|title=BAE SYSTEMS COMPUTERS TO MANAGE DATA PROCESSING AND COMMAND FOR UPCOMING SATELLITE MISSIONS \|date=June 17, 2008 \|access-date=November 17, 2008 \|publisher=BAE Systems }}	200 MHz 32-bit BAE RAD750 (PowerPC)	256 MB	2048 MB	0.25 MB	VxWorks (multitasking)	less than 75%
2021	Perseverance (Mars 2020, NASA){{Cite web\|url=https://mars.nasa.gov/mars2020/mission/rover/brains/\|title=Brains - Mars 2020 Rover\|last=mars.nasa.gov\|website=mars.nasa.gov\|access-date=2017-11-29}}	200 MHz 32-bit BAE RAD750 (PowerPC)	256 MB	2048 MB	0.25 MB	VxWorks (multitasking){{Cite web\|url=https://ai.jpl.nasa.gov/public/documents/papers/rabideau_iwpss2017_prototyping.pdf \|title=Prototyping an Onboard Scheduler for the Mars 2020 Rover}}	{{dunno}}

Mars rovers

{{Gallery

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|File:MER vs. Sojourner PIA04827.jpg|Size comparison of the Mars Exploration Rover (rear) and the Sojourner rover

|File:Mars_Science_Laboratory_mockup_comparison.jpg|Mars Science Laboratory (R); Mars Exploration Rover (L) and Sojourner rover (centre)

|File:NASA Mars Rover.jpg|Mars Exploration Rover

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References

External links

[http://www.cpushack.com/space-craft-cpu.html The CPUs of Spacecraft Computers in Space]
[https://web.archive.org/web/20221017125626/https://www.baesystems.com/en-media/uploadFile/20211206201500/1434554723601.pdf Radiation‑hardened electronics product guide] - BAE Systems

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Category:Space technology

Category:Exploration of Mars

Category:Computing comparisons