Mars Curiosity Rover or otherwise known as The Mars Science Laboratory (MSL) is a National Aeronautics and Space Administration (NASA) mission with the aim to land and operate a rover named Curiosity on the surface of Mars. The MSL was launched November 26, 2011 at 10:02 EST and is scheduled to land on Mars at Gale Crater between August 6 and August 20, 2012. The rover Curiosity, after a more precise landing than attempted previously, will help assess Mars' habitability. Its primary mission objective is to determine whether Mars is or was an environment able to support life but it will not look for any life itself. It will also analyze samples scooped up from the soil and drilled from rocks.
Curiosity is five times as large, and carries more than ten times the mass of scientific instruments as the Mars Exploration Rovers Spirit or Opportunity. The MSL rover Curiosity was launched by an Atlas V 541 rocket and is expected to operate for at least one Martian year (668 Martian sols/686 Earth days) as it explores with greater range than any previous Mars rover.
Mars Science Laboratory mission is part of NASA's Mars Exploration Program, a long-term effort of robotic exploration of Mars, and is a project managed by the Jet Propulsion Laboratory of California Institute of Technology for NASA. The total cost of the MSL project is about US$2.5 billion.
The MSL mission has four goals: To determine if life could have ever arisen on Mars, to characterize the climate of Mars, to characterize the geology of Mars, and to prepare for human exploration. To contribute to the four science goals, Mars Science Laboratory has eight scientific objectives:
In April 2008, it was reported that the project was $235 million, or 24%, over budget, and that the money to compensate this overrun may have to come from other NASA Mars missions. By October 2008 MSL was getting closer to a 30% cost overrun. As of November 2008, development was essentially finished, much of the MSL hardware and software complete and testing ongoing. On December 3, 2008, NASA announced that the MSL launch would be delayed until the fall of 2011 because of inadequate test time. The technical and budgetary reasons behind the delay were explained to the Planetary Science Community in a January 2009 meeting at NASA Headquarters.
From March 23–29, 2009, the general public had an opportunity to rank nine finalist names through a public poll on the NASA website as additional input for judges to consider the MSL rover name. On May 27, 2009 the winning name, Curiosity was selected, which was submitted by a sixth-grader, Clara Ma, from Kansas in an essay contest.
In late June 2010, engineers completed the installation of the suspension and wheel assemblies on the rover body. The six-wheeled rocker-bogie suspension is similar to the design found on Mars Exploration Rovers and Mars Pathfinder rover. Engineers began testing the integrated suspension system which will also serve as landing gear for the vehicle, unlike its smaller predecessors.
The rover Curiosity is 10 ft (3.0 m) in length, and weighs 1,984 lb (900 kg) including 176 lb (80 kg) of scientific instruments. It is approximately the size of a Mini Cooper automobile. This compares to the Mars Exploration Rovers which have a length of 5 ft (1.5 m) and weigh 384 lb (174 kg) including 15 lb (6.8 kg) of scientific instruments.
Once on the surface, Curiosity will be able to roll over obstacles approaching 75 cm (30 in) high. Maximum terrain-traverse speed is estimated to be 90 m (300 ft) per hour via automatic navigation, however, average traverse speeds will likely be about 30 m (98 ft) per hour, based on variables including power levels, difficulty of the terrain, slippage, and visibility. MSL is expected to traverse a minimum of 12 mi (19 km) in its two-year mission.
Curiosity will be powered by radioisotope thermoelectric generators (RTGs), as used by the successful Mars landers Viking 1 and Viking 2 in 1976. Radioisotope power systems (RPSs) are generators that produce electricity from the natural decay of plutonium-238, which is a non-fissile isotope of plutonium. Heat given off by the natural decay of this isotope is converted into electricity, providing constant power during all seasons and through the 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.
Curiosity's power source will use the latest RTG generation built by Boeing, called the "Multi-Mission Radioisotope Thermoelectric Generator" or MMRTG. Based on classical RTG technology, it represents a more flexible and compact development step, and is designed to produce 125 watts of electrical power from about 2000 watts of thermal power at the start of the mission. The MMRTG produces less power over time as its plutonium fuel decays: at its minimum lifetime of 14 years, electrical power output is down to 100 watts. The MSL will generate 2.5 kilowatt hours per day compared to the Mars Exploration Rovers which can generate about 0.6 kilowatt hours per day. The MMRTG aboard Curiosity is fueled by 32 pellets each about the size of a marshmallow.
The temperatures in the potential areas at which Curiosity may land can vary from +30 to -127 °C (+86 °F to -197 °F). Therefore, the Heat rejection system (HRS) uses fluid pumped through 60 m (200 ft) of tubing in the MSL body so that sensitive components are kept at optimal temperatures. Other methods of heating the internal components include using radiated heat generated from the components in the craft itself, as well as excess heat from the MMRTG unit. The HRS also has the ability to cool components if necessary.
The two identical on-board rover computers, called "Rover Compute Element" (RCE), contain radiation hardened memory to tolerate the extreme radiation environment from space and to safeguard against power-off cycles. Each computer's memory includes 256 kB of EEPROM, 256 MB of DRAM, and 2 GB of flash memory. This compares to 3 MB of EEPROM, 128 MB of DRAM, and 256 MB of flash memory used in the Mars Exploration Rovers.
The RCE computers use the RAD750 CPU which is a successor to the RAD6000 CPU used in the Mars Exploration Rovers. The RAD750 CPU is capable of up to 400 MIPS while the RAD6000 CPU is capable of up to 35 MIPS.
The rover has an Inertial Measurement Unit (IMU) that provides 3-axis information on its position which is used in rover navigation. The rover's computers are constantly self-monitoring to keep the rover operational, such as by regulating the rover's temperature. Activities such as taking pictures, driving, and operating the instruments are performed in a command sequence that is sent from the flight team to the rover. In the event of problems with the main computer, the backup computer will take over.
Curiosity has two means of communication – an X-band transmitter and receiver that can communicate directly with Earth, and a UHF Electra (radio)-lite software-defined radio for communicating with Mars orbiters. Communication with orbiters is expected to be the main contributor to data return to Earth, since the orbiters have both more power and larger antennas than the lander. At landing time, 13 minutes, 46 seconds will be required for signals to travel between Earth and Mars
Like previous rovers Curiosity is equipped with 6 wheels in a rocker-bogie system. Those wheels are significantly larger than those used on MER or Pathfinder missions. Each wheel has a pattern which helps it maintain traction but also leaves patterned tracks in the sandy surface of Mars. That pattern is used by on-board cameras to judge the distance travelled. The pattern itself is Morse code for "JPL"
Ten instruments have been selected for development or production for the MSL rover Curiosity :
The MastCam, MAHLI, and MARDI cameras were developed by Malin Space Science Systems and they all share common design components, such as on-board electronic imaging processing boxes, 1600x1200 CCDs, and a RGB Bayer pattern filter.
Filmaker and inventor of 3D camera technology James Cameron participated in early design work on the MastCam. That zoom capability was not included in the final design due to time required to test the new technology and the looming November 2011 launch date
ChemCam is a suite of remote sensing instruments, including the first laser-induced breakdown spectroscopy (LIBS) system to be used for planetary science and a remote micro-imager (RMI). The LIBS instrument can target a rock or soil sample from up to 7 meters away, vaporizing a small amount of it and then collecting a spectrum of the light emitted by the vaporized rock. An infrared laser with 1067 nm wavelength and a 5 nanosecond pulse will focus on a sub-millimeter spot with a power in excess of 10 megawatts, depositing 15mJ of energy. Detection of the ball of luminous plasma will be done in the visible and near-UV and near-IR range, between 240 nm and 800 nm. Using the same collection optics, the RMI provides context images of the LIBS analysis spots. The RMI resolves 1 mm objects at 10 m distance, and has a field of view covering 20 cm at that distance. The ChemCam instrument suite is being developed by the Los Alamos National Laboratory and the French CESR laboratory. NASA's cost for ChemCam is approximately $10M, including an overrun of about $1.5M, which is less than 1/200th of the total mission costs. The flight model of the Mast Unit was delivered from the French CNES to Los Alamos National Laboratory and was able to deliver the engineering model to JPL in February 2008.
This device will irradiate samples with alpha particles and map the spectra of X-rays that are re-emitted for determining the elemental composition of samples. The APXS is a form of particle-induced X-ray emission (PIXE), which has previously been used by the Mars Pathfinder and the Mars Exploration Rovers. The APXS is being developed by the Canadian Space Agency. MacDonald Dettwiler (MDA), the Canadian aerospace company that build the Canadarm and RADARSAT, will be responsible for the engineering design and building of the APXS. The APXS science team includes members from the University of Guelph, the University of New Brunswick, the University of Western Ontario, NASA, the University of California, San Diego and Cornell University.
CheMin stands for "Chemistry and Mineralogy" and is a X-Ray diffraction instrument that will quantify minerals and mineral structure of samples. It is being developed by David Blake at NASA Ames Research Center and the NASA's Jet Propulsion Laboratory
The SAM instrument suite will analyze organics and gases from both atmospheric and solid samples. It is being developed by the NASA Goddard Space Flight Center, the Laboratoire Inter-Universitaire des Systèmes Atmosphériques (LISA) of France's CNRS and Honeybee Robotics, along with many additional external partners. The SAM suite consists of three instruments:
The SAM also has three subsystems: The chemical separation and processing laboratory (CSPL), for enrichment and derivatization of the organic molecules of the sample; the sample manipulation system (SMS) for transporting powder delivered from the MSL drill to a SAM inlet and into one of 74 sample cups. The SMS then moves the sample to the SAM oven to release gases by heating to up to 1000 oC; and the wide range pumps (WRP) subsystem to purge the QMS, TLS, and the CPSL.
This instrument will characterize the broad spectrum of radiation found near the surface of Mars for purposes of determining the viability and shielding needs for human explorers. Funded by the Exploration Systems Mission Directorate at NASA Headquarters and the German space agency, DLR, RAD was developed by Southwest Research Institute (SwRI) and the extraterrestrial physics group at Christian-Albrechts-Universität zu Kiel, Germany.
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.
Meteorological package and an ultraviolet sensor provided by the Spanish Ministry of Education and Science, with Finnish Meteorological Institute as a partner. 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. REMS has been designed to record six atmospheric parameters: wind speed/direction, pressure, relative humidity, air temperature, ground temperature, and ultraviolet radiation. All sensors are located around three elements: two booms attached to the rover Remote Sensing Mast (RSM), the Ultraviolet Sensor (UVS) assembly located on the rover top deck, and the Instrument Control Unit (ICU) inside the rover body. REMS will provide new clues about: Signature of the Martian general circulation, Microscale weather systems, Local hydrological cycle, Destructive potential of UV radiation and Subsurface habitability based on ground-atmosphere interaction.
The MEDLI project’s main objective is to measure aerothermal environments, sub-surface heat shield material response, vehicle orientation, and atmospheric density for the atmospheric entry through the sensible atmosphere down to heat shield separation of the Mars Science Laboratory entry vehicle. The MEDLI instrumentation suite will be installed in the heatshield of the MSL entry vehicle. The acquired data will support future Mars missions by providing measured atmospheric data to validate Mars atmosphere models and clarify the design margins on future Mars missions. MEDLI instrumentation consists of three main subsystems: MEDLI Integrated Sensor Plugs (MISP), Mars Entry Atmospheric Data System (MEADS) and the Sensor Support Electronics (SSE).
The MSL will use two pairs of black and white navigation cameras located on the front left and right and rear left and right of the rover. The Hazard Avoidance Cameras (also called Hazcams) are used for autonomous hazard avoidance during rover drives and for safe positioning of the robotic arm on rocks and soils. The cameras will use visible light to capture stereoscopic three-dimensional (3-D) imagery. The cameras have a 120 degree field of view and map the terrain at up to 10 feet (3 meters) in front of the rover. This imagery safeguards against the rover inadvertently crashing into unexpected obstacles, and works in tandem with software that allows the rover to make its own safety choices.
The MSL will use a pair of black and white navigation cameras mounted on the mast to support ground navigation. The cameras will use visible light to capture stereoscopic 3-D imagery. The cameras have a 45 degree field of view
The MSL was launched from Cape Canaveral Air Force Station Space Launch Complex 41 on November 26, 2011 using the Atlas V 541 provided by United Launch Alliance. This two stage rocket includes a 3.8 m (12 ft) common core booster (CCB) powered by a single RD-180 engine, four solid rocket boosters (SRB), and one Centaur III with a 5.4 m (18 ft) diameter payload fairing. This vehicle is capable of launching up to 17,597 lb (7,982 kg) to geostationary transfer orbit. The Atlas V has also been used to launch the Mars Reconnaissance Orbiter and New Horizons.
The first and second stage along with the solid rocket motors were stacked on October 9, 2011 near the launch pad. The fairing containing MSL was transported to the launch pad on November 3, 2011
Landing a large mass on Mars is a difficult challenge. The atmosphere is thick enough to prevent rockets being used to provide significant deceleration, as flying into the plume at supersonic speed is notoriously unstable. Also, the atmosphere is too thin for parachutes and aerobraking alone to be effective. Although some previous missions have used airbags to cushion the shock of landing, the MSL is too large for this to be an option.
Curiosity will be set down on the Martian surface using a new high-precision entry, descent, and landing (EDL) system that will place it within a 20 km (12 mi) landing ellipse, in contrast to the 150 by 20 km (93 by 12 mi) landing ellipse of the landing systems used by the Mars Exploration Rovers.
For this, the MSL will employ a combination of several systems in a precise order, where the entry, descent and landing sequence will break down into four parts.
The rover is folded up within an aeroshell which protects it during the travel through space and during the atmospheric entry at Mars. Atmospheric entry is accomplished using a Phenolic Impregnated Carbon Ablator (PICA) heat shield. The 4.5 m (15 ft) diameter heat shield, which will be the largest heat shield ever flown in space, reduces the velocity of the spacecraft by ablation against the Martian atmosphere, from the interplanetary transit velocity of 5.3 to 6 km/s (3.3 to 3.7 mi/s) down to approximately Mach-2, where parachute deployment is possible. Much of the reduction of the landing precision error is accomplished by an 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. This is accomplished by a series of ejectable ballast masses. The lift vector is controlled by four sets of two Reaction Control System (RCS) thrusters that produce approximately 500 N of thrust per pair. This ability to change the pointing of the direction of lift allows the spacecraft to react to the ambient environment, and steer toward the landing zone. Prior to parachute deployment the entry vehicle must first eject the ballast mass such that the center of gravity offset is removed. Parachute will deploy at about 10 km (6.2 mi) altitude at about 470 m/s (1,500 ft/s).
When the entry phase is complete and the capsule has slowed to Mach 2 and at about 7 km altitude, the heat shield will separate and fall away. The Mars Science Laboratory will then deploy a supersonic parachute, as was done by previous landers such as Viking, Mars Pathfinder and the Mars Exploration Rovers.
In March and April 2009 the parachute for the MSL was tested in the world's largest wind tunnel and passed flight-qualification testing. The parachute has 80 suspension lines, is over 165 feet (50 meters) long, and is about 51 feet (16 meters) in diameter. The parachute is capable of being deployed at Mach 2.2 and can generate up to 289 kN (65,000 pounds) of drag force in the Martian atmosphere. A camera on the bottom of the rover will acquire 5 frames/min below 3.7 km.
Following the parachute braking, at about 1.8 km altitude, still travelling at about 100 m/s, the rover and descent stage drop out of the aeroshell. The descent stage is a platform above the rover with variable thrust mono propellant hydrazine rocket thrusters on arms extending around this platform to slow the descent. Each of the 8 rockets on this stage produce up to 3.1 kN (700 pounds) of thrust and were derived from those used on the Viking landers. Meanwhile, the rover will transform from its stowed flight configuration to a landing configuration while being lowered beneath the descent stage by the "sky crane" system.
The sky crane system will lower the rover to a soft landing–wheels down on the surface of Mars. This consists of 3 bridles lowering the rover and an umbilical cable carrying electrical signals between the descent stage and rover. At roughly 7.5 m (25 ft) below the descent stage the sky crane system slows to a halt and the rover touches down. After the rover touches down it waits 2 seconds to confirm that it is on solid ground and fires several pyros (small explosive devices) activating cable cutters on the bridle and umbilical cords to free itself from the descent stage. The descent stage promptly flies away to a crash landing, and the rover gets ready to roam Mars. The planned sky crane powered descent landing system has never been used in actual missions before.
Based on rankings of the proposed sites by investigators working on the project, the Gale Crater was selected by NASA administrators as the landing site. Within Gale Crater is a mountain of layered rocks, rising about 5 km (3.1 mi) above the crater floor, that Curiosity will investigate. The landing site (marked by the yellow ellipse in the image) is a smooth region inside the crater in front of the mountain. The landing site is elliptical, 20 by 25 km (12 by 16 mi). Gale Crater diameter is 154 km (96 mi).
The landing site contains material washed down from the wall of the crater, which will provide scientists with the opportunity to investigate the rocks that form the bedrock in this area. The landing ellipse also contains a rock type that is very dense and very bright colored; it is unlike any rock type previously investigated on Mars. It may be an ancient playa lake deposit, and it will likely be the mission's first target in checking for the presence of organic molecules.
However, the area of top scientific interest for Curiosity lies at the base of the mound, just at the edge of the landing ellipse and beyond a dark dune field. Here, orbiting instruments have detected signatures of both clay minerals and sulfate salts. Scientists studying Mars have several hypotheses about how these minerals reflect changes in the Martian environment, particularly changes in the amount of water on the surface of Mars. The rover will use its full instrument suite to study these minerals and how they formed. These rocks are also a prime target in checking for organic molecules, since these environments may have been able to support microbial life.
Two canyons were cut in the mound through the layers containing clay minerals and sulfate salts after deposition of the layers. These canyons expose layers of rock representing tens or hundreds of millions of years of environmental change. Curiosity may be able to investigate these layers in the canyon closest to the landing ellipse, gaining access to a long history of environmental change on the planet. The canyons also contain sediment that was transported by the water that cut the canyons. This sediment interacted with the water, and the environment at that time may have been habitable. Thus, the rocks deposited at the mouth of the canyon closest to the landing ellipse form the third target in the search for organic molecules.
The essential issue when selecting an optimum landing site is to identify a particular geologic environment, or set of environments, that would support microbial life. To mitigate the risk of disappointment and ensure the greatest chance for science success, interest is placed at the greatest number of possible science objectives at a chosen landing site. Thus, a landing site with morphologic and mineralogic evidence for past water, is better than a site with just one of these criteria. Furthermore, a site with spectra indicating multiple hydrated minerals is preferred; clay minerals and sulfate salts would constitute a rich site. Hematite, other iron oxides, sulfate minerals, silicate minerals, silica, and possibly chloride minerals have all been suggested as possible substrates for fossil preservation. Indeed, all are known to facilitate the preservation of fossil morphologies and molecules on Earth. Difficult terrain is the best candidate for finding evidence of livable conditions, and engineers must be sure the rover can safely reach the site and drive within it.
Current engineering constraints call for a landing site less than 45° from the Martian equator, and less than 1 km above the reference datum. At the first MSL Landing Site workshop, 33 potential landing sites were identified. By the second workshop in late 2007, the list had grown to include almost 50 sites, and by the end of the workshop, the list was reduced to six; in November 2008, project leaders at a third workshop reduced the list to these four landing sites
On August 20, 2009, NASA sent out a call for additional landing site proposals and issued another request for proposals on November 16, 2010. A fourth landing site workshop was held in late September 2010. A fifth and final workshop took place during May 16–18, 2011.
On July 22, 2011, it was announced that Gale Crater had been selected as the landing site of the Mars Science Laboratory mission