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Mars Science Laboratory

Cruise Configuration

Cruise stage with flight system
The Mars Science Laboratory flight system consists of four major elements in three distinct phases (from left): the cruise stage, the aeroshell (heatshield and backshell), the descent stage, and the rover.

The cruise stage carries a spacecraft through the void of space and delivers it to Mars.

Similar in design to cruise stages on the Mars Pathfinder and Mars Exploration Rover missions, the cruise stage for Mars Science Laboratory weighed about 880 pounds (400 kilograms). During launch, it communicated with the rocket system that blasted it into space. In approaching the atmosphere of Mars, the cruise stage communicated with the entry vehicle that carried the rover to the planet's surface.

Along the way to Mars, the cruise stage performed four trajectory corrections to adjust the spacecraft's path toward its final, precise final landing site on Mars. Meanwhile, the flight computer on board the rover continually checked the health of the spacecraft and relayed the information to the cruise stage, which then sent the information to mission controllers via two antennas that communicate in the X-band.

A key task of the cruise stage was to control the temperature of all spacecraft systems. In some cases, fluids circulated through pumps and radiators in the Heat Rejection System and then dissipated the heat generated by power sources, such as solar cells and motors, into space. In other cases, insulating blankets kept sensitive science instruments warmer than the near-absolute zero temperature of space. Thermostats monitored temperatures and switched heating and cooling systems on or off as needed.

Mars Science Laboratory used the stars to navigate. An onboard star scanner kept the cruise stage on track by constantly monitoring its position relative to stars in our Milky Way galaxy.

Cruise primary structure
The cruise stage has support ribs, solar arrays, a radiator, and an adapter for connecting the vehicle to the rockets that launch it from Earth.

Cruise Mechanical Structure

The cruise stage had a central aluminum machined structure, with support ribs, solar arrays, a radiator, and an adapter for connecting the vehicle to the rockets that launched it from Earth. The structure fit inside a broad, circular fairing about 13 feet (4 meters) in diameter. Upon reaching Mars, a cable cutter separated the cruise stage at precisely the right moment from the aeroshell that shielded Mars Science Laboratory from frictional heat during its descent through the martian atmosphere.

The cruise stage had its own miniature propulsion system, consisting of eight thrusters fired on command using hydrazine fuel in two titanium tanks. It also had its own power system, consisting of a solar array and battery for providing continuous power. The vehicle maintained forward momentum by spinning about its central axis at two revolutions per minute.