Mars Science Laboratory
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Template:Future Image:PIA04892.jpg Image:Mars Science Laboratory drawing.jpg The Mars Science Laboratory (or MSL for short) is a NASA rover scheduled to launch in December 2009 and perform a precision landing on Mars in October 2010. This rover will be three times as heavy and twice the width of the Mars Exploration Rovers (MERs) that landed in 2004. It will carry more advanced scientific instruments than any other mission to Mars. The international community will provide most of these instruments. The MSL rover will be launched by an Atlas V or Delta IV medium class booster. Once on the ground, MSL will analyze dozens of samples scooped up from the soil and cores from rocks. MSL will be expected to operate for at least 1 martian year (~2 Earth years) as it explores with greater range than any previous Mars rover. It will investigate the past or present ability of Mars to support life.
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Mission News
There is some discussion at NASA of delaying the launch to 2011 and sending two or three identical rovers [1] [2]. Since part of the MSL's mission is to locate a suitable landing spot for a future sample return mission, proponents of this option say it makes sense to cover multiple sites with the mission, therefore requiring multiple rovers. While the estimated cost of one rover is a billion USD, an additional rover would likely cost only $400 million, since most mission costs are incurred during the planning phase. As of June of 2005, Andy Dantzler, director of NASA's Solar System Division, has stated that MSL is on track for 2009 and he will expend considerable effort to make sure that date is not changed.[3] Several JPL engineers working on MSL have informally stated that the MSL design will likely be used on future rovers after the first MSL is launched in 2009. Image:H msl configuration 02.jpg
MSL Specifications
MSL is expected to weigh over 600 kg (1,320 lb) including 65 kg (143 lb) of scientific instruments, compared to the MERs which weigh 185 kg (408 lb) including 5 kg (11 lb) of scientific instruments. At present, MSL's mass is estimated at 775 kg (1,710 lb). MSL will be able to roll over obstacles approaching 75 cm (30 in) in height. Maximum terrain traverse speeds per hour for MSL is estimated at 90 m per hour via automatic navigation, or nearly a football field (<100 m, <300 ft), however, average traverse speeds will likely be 30 m (100 ft) per hour, based on variables including power levels, difficulty of the terrain, slippage, and visibility. MSL is expected to traverse a minimum of 6 km in its 2 year mission, perhaps further with extended mission time.
Proposed scientific payload
At present 10 instruments have been selected for development or production for MSL:
Mars Science Laboratory Cameras
All cameras are being developed by Malin Space Science Systems; all share common design components such as on-board electronic imaging processing boxes and 1600x1200 color CCDs.
- MastCam: This system will provide multiple spectra and true color imaging with two-camera stereoscopic (three-dimensional) vision. True-color are at 1200x1200 pixels and up to 10 frames per second hardware-compressed, high-definition video at 1280x720. For comparison the MER panoramic camera can only produce 1024x1024 black&white images. The same filter wheel design for multiple spectra images from MER will be used on MastCam. Both cameras will have mechanical zoom and can image objects as far away as one km at a resolution of 10 cm per pixel.
- Mars Hand Lens Imager (MAHLI): This system will consist of a camera mounted to a robotic arm on the rover. It will be used to acquire microscopic images of rock and soil, like the microscopic imager (MI) on MER. Unlike the MI, MAHLI will take true color images at 1600x1200 pixels with a resolution as high as 12.5 micrometers per pixel. MAHLI will have both white and UV LED illumination for imaging in darkness or imaging fluorescence. MAHLI will also have mechanical focusing in a range from infinite to mm distances.
- MSL Mars Descent Imager (MARDI): During the descent to the Martian surface MARDI will take approximately 500 color images at 1600x1200 pixels starting at distances of about 3.7 km to near 5 meters from the ground. MARDI imaging will allow the mapping of surrounding terrain and location of landing.
ChemCam
ChemCam is a remote LIBS system that can target a rock from up to 13 meters away, vaporizing a small amount of the underlying mineral and then collecting a spectrum of the light emitted by the vaporized rock by using a micro-imaging camera with a field of view of 80 microradians. It is being developed by the Los Alamos National Laboratory and the French CESR laboratory (in charge of the laser). [4]
Alpha-particle X-ray spectrometer (APXS)
This device will irradiate samples with alpha particles and map the spectra of X-rays that are reemitted. It is being developed by the Max Planck Institute for determining the elemental composition of samples.
CheMin
Chemin stands for "Chemistry & Mineralogy X-Ray Diffraction/X-Ray Fluorescence Instrument". Chemin is a X-ray diffraction/X-ray fluorescence instrument that will quantify minerals and mineral structure of samples. It is being developed by the NASA Ames Research Center.
Sample Analysis at Mars Instrument Suite (SAM)
Consisting of a gas chromatograph mass spectrometer and laser spectrometer, it will analyze organics and gases from both atmospheric and solid samples. It is being developed by the NASA Goddard Space Flight Center.
Radiation Assessment Detector (RAD)
This instrument will characterize the broad spectrum of radiation found near the surface of Mars for purposes of determing the viability and shielding needs for human explorers. Funded by the Exploration Systems Mission Directorate at NASA Headquarters.
Dynamic of Albedo Neutrons (DAN)
A pulsed neutron source and detector for measuring hydrogen or ice and water at or near the martian surface, provided by the Russian Federal Space Agency.
Rover Environmental Monitoring Station (REMS)
Meteorological package and an ultraviolet sensor provided by the Spanish Ministry of Education and Science. It will be mounted on the camera mast and measure atmospheric pressure, humidity, wind currents and direction, air and ground temperature and ultraviolet radiation levels.
Power source
The rover will probably be powered by radioisotope thermoelectric generators (RTGs). Solar power is not an efficient power source for Mars surface operations and was only used on Mars Pathfinder and MER because of politically imposed flight restrictions on RTGs. Solar power systems cannot operate effectively at high Martian latitudes, in shaded areas, nor in dusty conditions. Furthermore, it cannot provide power at night, thus limiting the ability of the rover to keep its systems warm, reducing the life expectancy of electronics. RTGs can provide reliable, continuous power day and night, and waste heat can be used via pipes to warm systems, freeing electrical power for the operation of the vehicle and instruments. Even so as of 2006 it is stated on the MSL home page that solar power is still an option under consideration.
The first successful Mars landers, Viking 1 and Viking 2 in 1976, were RTG-powered—the Viking 1 lander worked for six years on the Martian surface (ultimately failing due to faulty command sent by ground control that resulted in loss of contact). The proposed power plant will use "next generation" RTGs, either Boeing’s Multi-mission Radioisotope Thermoelectric Generator, which is a more flexible and compact power system under development and based on conventional RTGs, or Lockheed Martin’s Stirling Radioisotope Generator, which is more efficient but untested for use in space. Evidence points to the MMRTG being selected at this point, likely because of reliability and underdevelopment issues with the SRG.
Landing system
MSL will be set down on the Martian surface using a new NASA high-precision entry, descent, and landing (EDL) system that will place it within ten kilometers of an intended target, in contrast to the 150-kilometer error of previous landing systems used on Mars. The rover is folded up within an aeroshell which protects it during the travel through space and during the entry at Mars. Much of the reduction of the landing precision error is accomplished by an atmospheric entry guidance algorithm, similar to that used by the astronauts returning to Earth in the Apollo space program. This guidance uses the lifting force experienced by the aeroshell to "fly out" any detected error in range and thereby arrive at the targeted landing site. In order for the aeroshell to have lift, its center of mass is offset from the axial centerline which results in an off-center trim angle in atmospheric flight, again similar to the Apollo Command Module.
After the entry phase is complete and the capsule has slowed to Mach 2 several kilometers over the ground, a supersonic parachute is deployed and the aeroshell is discarded. The parachute is similar in design to that used by the Viking landers, Mars Pathfinder, and the Mars Exploration Rovers.
When the capsule reaches Mach .9 the supersonic parachute and top of the capsule is discarded and a very large (30+ meters in diameter) subsonic parachute is deployed. This parachute will reduce the amount of fuel needed for the landing rockets and increases the payload mass by 100-150 kg. Many schematics of the landing system do not show this second parachute and it may not be used in the final landing system design.
Early landing system proposals for the rover featured a "pallet" design (similar to that used for Mars Pathfinder and the Mars Exploration Rovers) with a liquid-fueled rocket thruster system to land the rover in the final seconds of descent. The pallet would have used airbags or a "crushable" design to permit a safe landing.
The rover will likely feature a "smart" landing system that will have a radar altimeter and mapping system working in conjunction with visual, camera-based mapping to allow it to autonomously select its precise landing area in order to avoid hazards.
Current landing system proposals feature a "sky crane" system: a platform above the rover with variable thrust hydrazine rocket thrusters (based on upgraded Viking heritage landing rockets) on arms extending around the rover will stop the descent in midair several meters above the martian surface. The rover would then be lowered by a tether(s) and gently placed on the ground, and the platform would then fly off to a crash landing away from the rover.
Future of MSL
It is possible NASA will adopt a plan to use multiple post-2011 MSLs to chemically sample, select, and haul rock samples to sample return "Mars ascent vehicles," possibly cutting the price tag for a future program that already threatens to balloon to extreme costs. This will only occur, of course, if various technological problems with the MSLs are ironed out and the missions are demonstrated as feasible during the 2009 missions. Not only will this take advantage of the lower cost per rover, but also would not require newly designed and specially incorporated rovers for the Mars ascent vehicles.
See also
External links
- MSL Home Page
- Malin Space Science Systems
- JPL's Mars Technology Program site
- Mars Science Laboratory Acquisition Program
- Short description of EDL system (PDF)
- Next on Mars (Bruce Moomaw, Space Daily, March 9, 2005): An extensive overview of NASA's Mars exploration plans, with many details on the Mars Science Laboratory
- nuclearspace.com overview of MSLde:Mars Science Laboratory
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