Like a scientific commando lowered from a rocket powered hovercraft into a dangerous landing zone 154 million mi. from Earth, the NASA rover Curiosity– heavily armed with science instruments– will first do a comprehensive imaging reconnaissance of its Martian surroundings before starting to climb its primary objective, an 18,000 ft. mountain in search of clues to life on Mars.
“I think we all feel this incredible sense of pressure on MSL to do something grand and profound” said John Grotzinger MSL project scientist.
“I think its going to be thrilling. Personally I can just not imagine being disappointed scientifically,” he said.
The landing of the Mars Science Laboratory (MSL) rover in a narrow moat between the crater wall and mountain will occur Aug. 5 at 10:51 p.m. PDT ( Aug. 6 at 1:31 a.m. EDT) Earth receive time.
All of the landing events, be they successful or a failure, are to be relayed to Earth by the Mars Odyssey orbiter 13.5 min. of light travel time after they actually occur on Mars. Factors beyond NASA’s control could, however, delay landing confirmation for 2 hr. to a day or more.
The $2.5 billion science mission will be conducted much like an Earthly military campaign.
MSL mission controllers at the Jet Propulsion Laboratory (JPL) Pasadena, Calif. will use the initial surface images to develop both tactical near term plans and strategic longer term objectives.
The rover’s early images will be used as reconnaissance to begin planning where to rove, and where not to rover, and what to sample versus what to bypass. The initial plan for public release of specific imagery includes:
–Low resolution black and white images: Landing day and Days 2 and 3.
–Color images: Days 3 and 4.
–Movie scenes from the descent imager: Thumbnail stills starting from the ground up, are to be released on Day 2 with an increasing rate of release during August until the full movie is done about 3 weeks after landing.
As Curiosity undergoes about a month of checkouts, the team will likely identify early tactical objectives that will be in reach of the rover where it lands. These may include rocks close enough for its mast mounted U. S./French laser blaster to fire hundreds of pulses to vaporize spots on rocks for remote sensing of their composition.
Several weeks after touchdown, the rover will begin to rover, to nearby tactical science objectives as it drives toward the base of the mountain. At about six months into the mission, Curiosity will begin a two year climb through the foothills then the slopes of Mount Sharp, the 18,000 ft. mountain in the center of 96 mi. wide Gale Crater .
Gale Crater is named after a 19th century Australian astronomer, but the mountain has informally been named Mount Sharp by the MSL Science Team in tribute to the late geologist Robert P. Sharp, a highly respected planetary scientist who died in 2004 at age 93.
The mountain is composed of at least 5 separate zones, going back perhaps 4.2 billion years into Martian history. Curiosity’s mission is to read the many layers in these zones like the pages of a book to reveal ancient clues about the terrain and environment that could have supported Martian life. Debate still rages over 1976 findings that the Viking landers actually did find life
A key ingredient for life that has yet to be discovered by any lander on Mars is organic carbon that would be destroyed atop the soil by cosmic rays. It may, however, survive intact inches under the surface or within the layers of Gale Crater. Curiosity’s instruments are fine tuned to discover organic carbon and assay its molecular structure.
The large meteorite that gouged out Gale Crater 3.5 to 4.2 billion years ago created a location with an extraordinary depositional record for Curiosity to study. Imagery from the NASA Mars Reconnaissance Orbiter, the Odyssey orbiter and from the European Mars Express orbiter all show Gale Crater had previous eras with extensive water and was once likely a lake.
“Within this ancient impact crater, wind erosion over the eons, coupled with recent impacts, has exposed once buried materials, ancient river deposits that provide records of flowing surface water, and mineral-rich fractured terrains analogous to those on Earth, that lie above groundwater aquifers,” Grotzinger said in the July issue of Scientific American. “Our team has built the Mars Science Laboratory, on the hypothesis that Mars was once a habitable planet,” Grotzinger said.
Now Curiosity most go prove that hypothesis.
Some of the strata on Mt. Sharp will also reveal a history of environmental conditions on Mars that have been totally erased on Earth.
“In ascending Mt. Sharp we are going to go through the major eras in the environmental history of Mars [and the solar system] that give us the basis for comparison to our own planet,” Grotzinger said.
“Even if life was never present on Mars I still see it as an extraordinary opportunity to get a bearing on our own existence on Earth,” he said.
As spectacular as the rover and landing systems are, the real marvels of MSL are its suite of instruments. MSL carries 10 instruments with a total mass of 165 lb. That compares with the Spirit and Opportunity geology rovers that carried only 5 instruments with a total mass of just 20 lb.
“The MSL rover has an incredible set of instruments to figure out if Mars could have ever supported microbial life,” said Ashwin Vasavada, MSL deputy project scientist.
“We are not actually looking for life and we have no way of detecting life if it is there. What we are looking for are the ingredients of life,” says Grotzinger.
“You can think of Spirit and Opportunity, which landed eight years ago, as robotic geologists. MSL goes one step further. Its not only a geologist but also a geochemist, so we needed a bigger rover because we have 10 science instruments and two of them fit inside the belly of the rover,” said Vasavada.
“We are bringing a state of the art laboratory to the surface of another planet to do a very detailed geochemical analysis of its rocks, soils and atmosphere,” he said. “This is the hardest NASA robotic mission ever attempted,” said former astronaut John Grunsfeld, NASA associate administrator for space science.
The MSL instruments and related systems include:
– Sample Analysis at Mars (SAMS): The $80 million instrument designed at the Goddard Space Flight Center, Greenbelt Md. is mounted internally and is the largest most complex science system on the rover. It combines two spectrometers and a French built gas chromatograph and an internal sample holding mechanisms. A team of 150 scientists from around the world are involved with the device.
“SAMS is a groundbreaking experiment to understand, if there are any organics possibly related to life that could have been preserved in ancient materials and if so, what do these signatures look like,” said Paul Mahaffy, principal investigator for SAMS. Early on in the mission SAMS will be used to sniff the air to see if any methane gas from possible living organisms is present at or near the landing site.
–Chemistry and Mineralogy Instrument (CheMin): Also mounted internally, the NASA Ames Research Center CheMin instrument will identify and measure the abundances of various minerals by bombarding samples with focused X-rays. Minerals are indicative of environmental and hydrological conditions that existed when they formed. To prepare CheMin samples for analysis, the rover’s 7.5 ft. arm will drill into rocks, collect the resulting fine powder, sieve it, and deliver it to a sample holder for X-ray analysis.
–ChemCam: The combined laser blaster and super imager at the top of Curiosity’s 7 ft. mast is a huge advancement over what the Spirit and Opportunity rovers could do on Mars They could take two to three days to determine the composition of a rock. But ChemCam’s laser removes the need to even touch the rock. It allows ChemCam to instantly determine a rock’s composition from a distance of 25-30 ft. On average, the ChemCam team expects to take approximately one dozen compositional measurements of rocks per day involving thousands of laser pulses.
Curiosity’s nuclear power source enables each laser pulse to focus the energy equivalent of one million light bulbs onto a tiny spot only slightly larger than a pinhole. The laser light can not be seen by the human eye and is generated by Neodymium doped Potassium-Gadolinium Tungstate crystals.
The system was developed by the Los Alamos National Laboratory in New Mexico, the Paris based French Space Agency (CNES), the French Research Institute in Astrophysics and Planetology (IRAP) in Toulouse, the Lunar and Planetary Institute (LPI), in Houston, Delaware State University in Dover and Mount Holyoke College in South Hadley Mass.
ChemCam fires its laser in a series of pulses to first remove the outer layer of dust on Martian rocks. Once the dust is removed, the laser is fired again in a series of pulses at the exposed rock surface. These laser pulses vaporize, the outer surface of the rock. Electrons within the atoms hit by the laser become “excited” and emit light in different colors visible to the rover.
The energy of the light that is emitted depends on the atom. For example, excited electrons within an atom of carbon will emit light with a different energy than excited electrons within an atom of oxygen. The emitted light from all atoms present in the rock is received by a telescope within the ChemCam housing. From the telescope, the light enters a spectrometer where it is broken down and read by the onboard computer.
ChemCam’s spectrograph will provide unprecedented detail about minerals, their composition and microstructures. Its camera will acquire mineral details that are 5 to 10 times smaller than those visible with the cameras used by Spirit or Opportunity.
–Alpha Particle X-Ray Spectrometer (APXS): A Canadian Space Agency instrument, APXS will be on the arm to measure the abundance of chemical elements in rocks and soils. It is similar to the APXSs carried on the MER rovers.
–MastCams: There are four different imaging systems on Curiosity using a total of 17 cameras. The most powerful are the MastCams on the rover’s mast. Developed by Malin Space Science Systems in San Diego, Each camera has its own 8 gb storage chips to better manage data handling without losing images. These improved versions will be able to make fast turnaround digital images. The system will obtain color, multispectral color, stereo, and high definition video views of the terrain using a 34 mm fixed focal length camera head and a 100 mm fixed focal length camera. Smaller stereo Navcams sit nearby the MastCams to provide good resolution imagery to navigate the rover to its target The rover also carries two forward facing and two aft facing hazard cameras at wheel level.
-- Mars Hand Lens Imager (MAHLI): The microscopic image of rock and soil grains is very important to characterizing the Martian surface character. On Curiosity’s powerful arm will be the Malin built MAHLI that can magnify objects as small as 12.5 microns. It will return color images like typical digital cameras synthesizing the best in focus images and creating depth of field range maps. It will also provide controlled illumination of the rock and soil grains by using white light and ultraviolet LEDs.
–Mars Descent Imager (MARDI) : Also built by Malin the imager is on the side of the lander facing down. It will take HD resolution images for two minutes at nearly 5 frames per sec. starting with the separation of the heat shield through touchdown. A spectacular movie showing the terrain under the entire landing descent is expected to be completed 3-4 weeks after landing, says Pete Thesinger, JPL rover project manager.
—- Radiation Assessment Detector (RAD): A toaster sized instrument from the Southwest Research Institute in San Antonio, Texas will be one of the first instruments sent to Mars specifically to prepare for future human exploration by measuring radiation from the Sun and Mars and gases in the Martian atmosphere.
–Dynamic Albedo of Neutrons (DAN): This detector from the Russian Space Research Institute (IKI) in Moscow will sense whether water or water ice lies under the rover wherever it travels. It will do this by measuring neutrinos given off by water.
–Rover Environmental Monitoring Station (REMS): Developed by Spain this instrument is essentially a weather station with two masts to obtain environmental measurements around Curiosity.
–Sample Acquisition Processing and Handling (SA/SPaH) System: Although not a science instrument this Honeybee Robotics device mounted to the front of the rover can be used in connection with the manipulator arm to brush surfaces, place and hold surface contact instruments, acquire core samples up to 2 inches deep, acquire 70 rock or dirt samples by coring or using a scoop and process rocks, pebbles or regolith into powder for analysis.
–Curiosity’s arm will also be inherent to science operations.
The 7.5 ft. MSL arm is much beefier and stronger than the 3 ft. MER arm, says Matt Robinson, lead engineer for robotic arm systems . Just the turret on the MSL arm weighs more than the whole arm electronics and science on the smaller MER rovers, he said. On MSL the arm holds 66 lb. of tools to drill for samples and pulverize them into power which it sieves and sorts for rover instruments.
MSL also has far more diverse arm motions “because we use a lot more “gravity relevant” motions to move samples where we want them to fall inside the mechanisms,” says Chris Leger, robotic arm flight software developer and the surface software development lead for the MSL flight.
A lot of arm trajectory calculations will be specific to get samples in test chambers and to move them through the internal sample paths, he said.
On MSL (unlike the MERs) the team will not have to write a sequence of hundreds and hundreds of lines of software for daily operations, said Leger. Those are already are part of rover software he said.
The science team is intrigued by orbiter data that shows in the middle of the landing site there are materials that have an unusually high ability to retain heat. They have been color coded red on rover terrain and mineralogy maps.
“What its thermal inertia tells us is that its probably harder material and just may be water precipitated minerals,” said Grotzinger. “We are pretty optimistic it has to do with water.”
“So we see this red feature and its our first indicator of what is in the landing ellipse. Data from the orbiters say that we should look for hydrated minerals like sulfates and clay minerals. Those are the targets of our mission,” says Grotzinger.
“But what is really interesting about this feature that we are going to land on is that it does have a different look to it than what is around it. We do not know what it means, but relative to adjacent areas this place stays warmer later at night.
“So after about a month as we finish checkout we are going to approach one of these features, and the first thing we are going to do is sample the soil.
“We are then going to approach a rock outcrop and try to drill it. And when we drill it we will pass the material into the CheMin instrument and into SAMS that will tell us what is there.
“This is the really cool thing because from orbit we really do not know what is there, but with Curiosity we can make discoveries on what is actually present,” said Grotzinger.
After that we will hit the road and work our way toward the lower reaches of Mt. Sharp where we will begin to explore clay minerals and sulfate minerals and other features that suggest the presence of water,” he said.
“Then we will actually figure out the environment in which they formed and from that ask ourselves “is this the kind of environment that could have actually supported microbial life,” asked Grotzinger.
Science team members will also use the rover’s powerful cameras to specifically look for visible evidence of past life on Mars, like the 3.5 billion yr. old fossilized microbe colonies found on Earth called stromatolites.
“There are a number of people on the team interested in this question” of finding evidence for life with Curiosity, said Grotzinger “It tends to come up quite a bit” within the science team, Grotzinger said.
NASA Public Affairs and MSL managers have pressed the non life detection theme throughout the MSL development.
The project, however, has recently acknowledged the importance of serendipitous discovery in scientific breakthroughs and the importance true evidence of Martian life would have for science, religion, NASA’s future and public interest in space.
Grotzinger said that because the Gale Crater landing target was a water rich environment early in Martian history it is possible that multibillion groups of microorganisms, primarily cyanobacteria , solidified there into rocks with distinctive patterns called stromatolites. But that would raise the same question as arises on earth, whether the striking rock patterns are always indicative of past life, the MSl science manager says.
“If they are at this site we would expect to see those with our cameras and be challenged with the same questions we have about them on Earth, whether they constitute definitive evidence for the presence of past life,” said Grotzinger.
“I think that we would be thrilled enough to actually see something like that to warrant a Martian sample return mission, ” he said.
About the author
Senior writer Craig Covault has covered 17 U. S., Russian and European Mars orbiter and lander missions over the last 40 years, most of them with Aviation Week & Space Technology and now with AmericaSpace.
Favorites include his coverage at the NASA Langley Research Center of the development of the 1976 Viking 1 and 2 landers and the landings and surface coverage from the JPL of the Spirit and Opportunity rovers in 2004. Steve Squyres Mars Exploration Rover Principal Investigator allowed Covault exclusive JPL access to the science and surface operations teams after Spirit and Opportunity landed.
Covault also did extensive coverage of the Phoenix North Polar Lander development and its descent to the Martian arctic in 2008.
Covault began interviews and hardware familiarization with Mars Science Laboratory Rover and Sky Crane developments at JPL starting in 2004 and was able to see the Curiosity and the Sky Crane hardware take shape throughout the development including an initial look a Curiosity when it was just a block of aluminum with holes being milled into it.
AmericaSpace and The Mars Society have partnered to provide in-depth coverage of the arrival of the Mars Science Laboratory rover “Curiosity” to Mars. Stay tuned for regular updates as AmericaSpace correspondents Craig Covault and Frank O’Brien travel to NASA’s Jet Propulsion Laboratory in California for live coverage.