Rover and lander specifications
Curiosity is 2.9 m (9 ft 6 in) long by 2.7 m (8 ft 10 in) wide by 2.2 m (7 ft 3 in) high, larger than Mars Exploration Rovers, which are 1.5 m (4 ft 11 in) long and have a mass of 174 kg (384 lb) including 6.8 kg (15 lb) of scientific instruments. In comparison to Pancam on the Mars Exploration Rovers, the MastCam-34 has 1.25× higher spatial resolution and the MastCam-100 has 3.67× higher spatial resolution.
Curiosity has an advanced payload of scientific equipment on Mars. It is the fourth NASA robotic rover sent to Mars since 1996. Previous successful Mars rovers are Sojourner from the Mars Pathfinder mission (1997), and Spirit (2004–2010) and Opportunity (2004–2018) rovers from the Mars Exploration Rover mission.
Curiosity comprised 23% of the mass of the 3,893 kg (8,583 lb) spacecraft at launch. The remaining mass was discarded in the process of transport and landing.
Dimensions: 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 ft 6 in) long by 2.7 m (8 ft 10 in) wide by 2.2 m (7 ft 3 in) in height.
The main box-like chassis forms the Warm Electronics Box (WEB).
Power source: Curiosity is powered by a radioisotope thermoelectric generator (RTG), like the successful Viking 1 and Viking 2 Mars landers in 1976.
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. Heat given off by the decay of this isotope generates electrical power using thermocouples, providing consistent power during all seasons and through the day and night. Waste heat is also used via pipes to warm systems, freeing electrical power for the operation of the vehicle and instruments. Curiosity's RTG is fueled by 4.8 kg (11 lb) of plutonium-238 dioxide supplied by the U.S. Department of Energy.
Curiosity's RTG is the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG), designed and built by Rocketdyne and Teledyne Energy Systems under contract to the U.S. Department of Energy, and fueled and tested by the Idaho National Laboratory. Based on legacy RTG technology, it represents a more flexible and compact development step, and is designed to produce 110 watts of electrical power and about 2,000 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 power source generates 9 MJ (2.5 kWh) of electrical energy each day, much more than the solar panels of the now retired Mars Exploration Rovers, which generated about 2.1 MJ (0.58 kWh) each day. The electrical output from the MMRTG charges two rechargeable lithium-ion batteries. This enables the power subsystem to meet peak power demands of rover activities when the demand temporarily exceeds the generator's steady output level. Each battery has a capacity of about 42 ampere hours.
Heat rejection system: The temperatures at the landing site vary seasonally and the thermal system warms the rover as needed. The thermal system does 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. The fluid loop serves the additional purpose of rejecting heat when the rover has become too warm, and it can also gather waste heat from the power source by pumping fluid through two heat exchangers that are mounted alongside the RTG. The HRS also has the ability to cool components if necessary.
Computers: The two identical on-board rover computers, called Rover Compute Element (RCE) 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 kilobytes (kB) of EEPROM, 256 megabytes (MB) of dynamic random-access memory (DRAM), and 2 gigabytes (GB) of flash memory. For comparison, the Mars Exploration Rovers used 3 MB of EEPROM, 128 MB of DRAM, and 256 MB of flash memory.
The RCE computers use the RAD750 Central processing unit (CPU), which is a successor to the RAD6000 CPU of the Mars Exploration Rovers. The IBM RAD750 CPU, a radiation-hardened version of the PowerPC 750, can execute up to 400 Million instructions per second (MIPS), while the RAD6000 CPU is capable of up to only 35 MIPS. Of the two on-board computers, one is configured as backup and will take over in the event of problems with the main computer. On February 28, 2013, NASA was forced to switch to the backup computer due to a problem with the active computer's flash memory, which resulted in the computer continuously rebooting in a loop. The backup computer was turned on in safe mode and subsequently returned to active status on March 4, 2013. The same problem happened in late March, resuming full operations on March 25, 2013.
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. The rover installed its full surface operations software after the landing because its computers did not have sufficient main memory available during flight. The new software essentially replaced the flight software.
The rover has four processors. One of them is a SPARC processor that runs the rover's thrusters and descent-stage motors as it descended through the Martian atmosphere. Two others are PowerPC processors: the main processor, which handles nearly all of the rover's ground functions, and that processor's backup. The fourth one, another SPARC processor, commands the rover's movement and is part of its motor controller box. All four processors are single core.
