PEAR corner: Mars Rovers: Curiosity

The Mars Science Laboratory, also known as MSL, is the more recent mission that has been sent to explore Mars. Like Pathfinder and MERS missions, the MSL consist in place a rover with a scientific load on the Mars surface aiming to find more information about the past and present environmental conditions, and based on this information try to understand if Mars were capable of supporting life in the past, and also, if there is any chance to be inhabited. Curiosity is expected to arrive in August 2012 and It's been planned that the mission last one Mars year (23 Earth months).

Curiosity is 3.05m (10ft) long, 2.74m (9ft) wide, and 2.13m (7ft) tall and weighs 900 kg (2,000 pounds), being much bigger than previous rovers sent to the red planet. This fact makes possible to send most advance science instruments. In addition, unlike past missions, Curiosity will be powered by a radioisotope system that generates electricity from the heat of plutonium's radioactive decay.

Mars Rover family. From left to right MER, Sojourner and Curiosty

The rover has six wheels, each with its own individual motor. The two front and two rear wheels also have individual steering motors (1 each). This steering capability allows the vehicle to turn in place, a full 360 degrees. The 4-wheel steering also allows the rover to swerve and curve, making arching turns. The design of the suspension system for the wheels is based on the "rocker-bogie" system developed for Pathfinder and Mars Exploration Rover missions. The rover is designed to withstand a tilt of 45 degrees in any direction without overturning. However, the rover is programmed through its "fault protection limits" in its hazard avoidance software to avoid exceeding tilts of 30 degrees during its traverses. The rover rocker-bogie design allows the rover to go over obstacles or through holes that are more than a wheel diameter (50cm or about 20in) in size. Each wheel also has cleats, providing grip for climbing in soft sand and scrambling over rocks. Moreover, the rover carries an Inertial Measurement Unit (IMU) that provides 3-axis information on its position, which enables the rover to make precise vertical, horizontal, and side-to-side movements. The device is used in rover navigation to support safe traverses and to estimate the degree of tilt the rover is experiencing on the surface of Mars.

All the electronics are placed inside the Warm Electronics Box or WEB, the same name was used in previous rovers, which protect them against the rough environmental conditions. On-board memory includes 256MB of DRAM and 2 GB of Flash Memory both with error detection and correction and 256kB of EEPROM. This onboard memory is roughly 8 times as capable as the one onboard the Mars Exploration Rovers.

To communicate, Mars Science Laboratory has both a low-gain and high-gain antenna . They will be located on the rover equipment deck. The low-gain antenna is omni-directional sending and receiving information in every direction. The antenna transmits radio waves at a low rate to the Deep Space Network (DSN) antennas on Earth. The high-gain antenna can send a beam of information in a specific direction and it is steerable, so the antenna can move to point itself directly to any antenna on Earth. The benefit of having a steerable antenna is that the entire rover doesn't necessarily have to change positions to talk to Earth. Activities such as taking pictures, driving, and operating the instruments will be performed under commands transmitted in a command sequence to the rover from the flight team. The rover will generate constant engineering, housekeeping and analysis telemetry and periodic event reports that are stored for eventual transmission once the flight team requests the information from the rover.

In addition, Curiosity has a robotic arm which has flexibility through three joints: the rover's shoulder, elbow, and wrist. The arm enables a tool belt of scientists' instruments to extend, bend, and angle precisely against a rock to work as a human geologist would: grinding away layers, taking microscopic images, and analyzing the elemental composition of the rocks and soil.

To support science investigation, Curiosity will carry the following instruments:

Cameras
- Two Mast Camera or Mastcam will take color images and color video footage of the Martian terrain, and this data will be used to study the Martian landscape, and support the driving and sampling operations of the rover. Mastcams are moounted on a mast that extends upward from the rover body.
Curiosity MastCams
- Four Hazard Avoidance Cameras or Hazcams, which are mounted on the lower portion of the front and rear of the rover, these black-and-white cameras will use visible light to capture three-dimensional imagery. This imagery safeguards against the rover getting lost or inadvertently crashing into unexpected obstacles, and works with software that allows the rover make its own safety choices and to think on its own.
- Two Navcams are mounted on the mast (the rover "neck and head").The navigation camera unit is a stereo pair of cameras, each with a 45-degree field of view that will support ground navigation planning by scientists and engineers. They will work in cooperation with the hazard avoidance cameras by providing a complementary view of the terrain.
- The Mars Hand Lends or MAHLI will be used to get color close-up views of minerals, textures and structures in martian rocks and the surface of Mars. This devices is equivalent of the geologist's hand lens.
- And, the Mars Descent Imager or MARDI that will take 5 frames-per-second and colorful video during rover's descent towards the surface. This will help engineers and scientist to improve the techniques for landing.
Curiosity Mars Descent Imager
Spectrometers:
- The Alpha Particle X-Ray Spectrometer will measure the abundance of chemical elements in rocks and soils. The APXS will take measurements both day and night.
- ChemCam is a device that will fire a laser and analyze the elemental composition of vaporized materials from areas smaller than 1 millimeter on the surface of Martian rocks and soils. Using an on-board spectrograph, it will provide unprecedented detail about minerals and microstructures in rocks by measuring the composition of the resulting plasma.
Curiosity ChemCam Artist Concept
- The Chemistry and Mineralogy instrument or CheMin will identify and measure the abundances of various minerals on Mars. Minerals are indicative of environmental conditions that existed when they formed. To prepare rock samples for analysis, the rover will be able to drill into rocks, collect the resulting fine powder, sieve it, and deliver it to a sample holder. It will use a scoop for collecting soil. CheMin will then direct a beam of X-rays as fine as a human hair through the powdered material.
- The Sample Analysis at Mars instrument or SAM is a mass spectrometer that will separate elements and compounds by mass for identification and measurement. The gas chromatograph will heat soil and rock samples until they vaporize, and will then separate the resulting gases into various components for analysis.

Radiation detectors
- The Radiation Assessment Detector (RAD) will be one of the first instruments sent to Mars specifically to prepare for future human exploration. RAD will measure and identify all high-energy radiation on the Martian surface, such as protons, energetic ions of various elements, neutrons, and gamma rays. To prepare for future human exploration, RAD will collect data that will allow scientists to calculate the equivalent dose (a measure of the effect radiation has on humans) to which people would be exposed on the surface of Mars. A stack of paper-thin, silicon detectors and a small block of cesium iodide measure high-energy charged particles coming through the Martian atmosphere.
RAD instrument and Artist Concept
- The Dynamic Albedo of Neutrons will be used to look for water on Mars. The instrument will focus a beam of neutrons on the Martian surface, if liquid or frozen water is present, hydrogen atoms will slow the neutrons down. And, some of the neutrons escaping into space will have less energy and move more slowly. These slower particles will be measured with a neutron detector.
How DAN Works
Environmental sensor

The Rover Environmental Monitoring Station (REM) will measure and provide daily and seasonal reports on atmospheric pressure, humidity, ultraviolet radiation at the Martian surface, wind speed and direction, air temperature, and ground temperature around the rover.

And, atmospheric sensors

MSL Entry Descent and Landing instrument, also known as MEDLI, will collect engineering data during the spacecraft's high-speed, extremely hot entry into the Martian atmosphere. MEDLI data will be invaluable to engineers when they design future Mars missions. The data will help them design systems for entry into the Martian atmosphere that are safer, more reliable, and lighter weight.