Curiosity ERD

CURIOSITY

Curiosity is a car-sized rover designed to explore Gale Crater on Mars as part of NASA's Mars Science Laboratory mission (MSL). Curiosity was launched from Cape Canaveral on November 26, 2011, at 15:02 UTC aboard the MSL spacecraft and landed in Gale Crater on Mars on August 6, 2012, 05:17 UTC. The Bradbury Landing site was less than 2.4 km (1.5 mi) from the centre of the rover's touchdown target after a 560 million km (350 million mi) journey.

The objectives of the mission of Curiosity are the following:

Biological
1.	Determine the nature and inventory of organic carbon compounds
2.	Investigate the chemical building blocks of life (carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulphur)
3.	Identify features that may represent the effects of biological processes (bio-signatures and biomolecules)

Geological and geochemical
4.	Investigate the chemical, isotopic, and mineralogical composition of the Martian surface and near-surface geological materials
5.	Interpret the processes that have formed and modified rocks and soils

Planetary process
6.	Assess long-timescale (i.e., 4-billion-year) Martian atmospheric evolution processes
7.	Determine present state, distribution, and cycling of water and carbon dioxide

Surface radiation
8.	Characterize the broad spectrum of surface radiation, including galactic and cosmic radiation, solar proton events and secondary neutrons. As part of its exploration, it also measured the radiation exposure in the interior of the spacecraft as it travelled to Mars, and it is continuing radiation measurements as it explores the surface of Mars. This data would be important for a future manned mission.

Curiosity has a mass of 899 kg (1,982 lb) including 80 kg (180 lb) of scientific instruments. The rover is 2.9 m (9.5 ft) long by 2.7 m (8.9 ft) wide by 2.2 m (7.2 ft) in height. Curiosity is powered by a radioisotope thermoelectric generator (RTG). Radioisotope power systems (RPSs) are generators that produce electricity from the decay of radioactive isotopes, such as plutonium-238, which is a non-fissile isotope of plutonium.

The temperatures at the landing site can vary from −127 to 40 °C; therefore, the thermal system of Curiosity will warm the rover for most of the Martian year. The thermal system will do so in several ways: passively, through the dissipation to internal components; by electrical heaters strategically placed on key components; and by using the rover heat rejection system (HRS). It uses fluid pumped through 60 m (200 ft) of tubing in the rover body so that sensitive components are kept at optimal temperatures.

Curiosity uses two identical on-board rover computers, called Rover Computer Element (RCE), that contain radiation-hardened memory to tolerate the extreme radiation from space and to safeguard against power-off cycles. The computers run the VxWorks real-time operating system (RTOS). Each computer's memory includes 256 kB of EEPROM, 256 MB of DRAM, and 2 GB of flash memory.

In order to communicate with Earth, Curiosity is equipped with several telecommunication means – an X-band Transmitter/Receiver that can communicate directly with Earth, and a UHF Electra-Lite software-defined radio for communicating with Mars orbiters.

Communication with the orbiters is expected to be the main path for data return to Earth, since the orbiters have both more power and larger antennas than Curiosity, thus allowing for faster transmission speeds. The rover has two UHF radios, the signals of which the 2001 Mars Odyssey orbiter is capable of relaying back to Earth. An average of 14 minutes, 6 seconds will be required for signals to travel between Earth and Mars. Curiosity can communicate with Earth directly at speeds up-to 32 kbit/s, but the bulk of the data transfer should be relayed through the Mars Reconnaissance Orbiter and Odyssey orbiter. Communication from and to Curiosity relies on internationally agreed space data communications protocols as defined by the Consultative Committee for Space Data Systems.

Curiosity is equipped with six 50 cm (20 in) diameter wheels in a rocker-bogie suspension. The suspension system also serves as landing gear for the vehicle, unlike its smaller predecessors. Each wheel has cleats and is independently actuated and geared, providing for climbing in soft sand and scrambling over rocks. Each front and rear wheel can be independently steered, allowing the vehicle to turn in place as well as execute arcing turns. Each wheel has a pattern that helps it maintain traction but also leaves patterned tracks in the sandy surface of Mars.

Curiosity has 17 cameras: HazCams (8), NavCams (4), MastCams (2), MAHLI (1), MARDI (1), and ChemCam (1). Each MastCam includes the Medium Angle Camera (MAC) which has a 34 mm (1.3 in) focal length, a 15° field of view, and can yield 22 cm/pixel (8.7 in/pixel) scale at 1 km (0.62 mi). The other camera in the MastCam is the Narrow Angle Camera (NAC), which has a 100 mm (3.9 in) focal length, a 5.1° field of view, and can yield 7.4 cm/pixel (2.9 in/pixel) scale at 1 km (0.62 mi). A pair of MastCams were developed which include zoom lenses, but these were not included in the rover because of the time required to test the new hardware and the looming November 2011 launch date. Each MastCam has eight gigabytes of flash memory, which is capable of storing over 5,500 raw images, and can apply real time lossless data compression.

ChemCam is actually two different instruments combined as one: a laser-induced breakdown spectroscopy (LIBS) and a Remote Micro Imager (RMI) telescope. The purpose of the LIBS instrument is to provide elemental compositions of rock and soil, while the RMI will give ChemCam scientists high-resolution images of the sampling areas of the rocks and soil that LIBS targets. ChemCam has the ability to record up to 6,144 different wavelengths of ultraviolet, visible, and infrared light.

MAHLI is a camera on the rover's robotic arm, and acquires microscopic images of rock and soil. MAHLI can take true-colour images at 1600×1200 pixels with a resolution as high as 14.5 micro-meters per pixel. MAHLI has an 18.3 to 21.3 mm (0.72 to 0.84 in) focal length and a 33.8–38.5° field of view. MAHLI has both white and ultraviolet LED illumination for imaging in darkness or fluorescence imaging. MAHLI also has mechanical focusing in a range from infinite to millimetre distances.

Curiosity stores the images generated by MastCams, the ChemCam and MAHLI in three different databases. Field-Programmable Gate Arrays (FPGAs) are used by Cusiosity in order to categorize these images based on their significance and store them in the respective database. The significance of an image is defined by image processing algorithms that identify specific features of each image (eg. density, contrast) and produce a decision about them. For example, if the image processing algorithms identify the significance of an image to be above 70%, then they store the image in Database A. If the significance of the image is between 45% to 69%, it is stored in Database B while for significance below 45%, then the image is stored in Database C. It is possible that an image is elevated to Database A from Database B or even from Database C depending on the conditions of the mission of Curiosity on the surface of Mars or inversely, an image can be downgraded to Database C from Database A. These elevations and/or downgrades can be done randomly depending on the change of each mission's conditions.

The most significant pictures are emitted by FPGAs through the UHF Electra-Lite software-defined radio to the Mars orbiters and then back to earth. All the images though are used for obstacle track identification on the Mars surface and coordinates definition for the rover. Specifically, a data clustering algorithm is used to extract the coordinates identified in each image and place them to a 3D coordinate system. Every day, the 3D coordinate system is updated and a copy of the updates is stored on the memory of RCE. These copies are then sent directly to Earth through Curiosity's X-band transmitter so that NASA knows exactly the route followed by the rover.