Curiosity Comes to Mars

With the Mars Science Laboratory—a rover called Curiosity—safely installed in its spacecraft, the mission set out for the red planet on November 26, 2011, with a projected arrival at Mars on August 5, 2012 PDT. About the size of a small SUV, Curiosity is truly a sophisticated mobile laboratory with the most advanced instruments ever sent to Mars.

Curiosity’s Job on Mars
The main science goal of the mission is to evaluate whether Mars has or has ever had an environment that could support bacteria or other microbial life. To try to find out, Curiosity will study rocks and soil to find records of the geologic and climate history of Mars. It will also look for carbon and other chemical building blocks of life.

Rover Innovations
With each new Mars mission, NASA has reused technologies and design elements that have worked well in the past. Curiosity has six-wheels, for example, as did the earlier rovers, and a rocker-bogie suspension system that has proven to provide excellent stability and obstacle-climbing ability. But each mission has brought innovations as well. Here’s what’s new for Curiosity:

Landing   A change dictated partly by necessity is a new descent and landing procedure. Curiosity weighs in at almost 2,000 pounds (900 kg), which is far too heavy for the airbag-assisted landings used formerly, so an ingenious new plan was devised. Once the spacecraft has entered the martian atmosphere, it will fire rocket thrusters to guide its descent. Almost as if an astronaut were at the controls, the spacecraft will perform a series of maneuvers that will help it reach its designated landing site. It will deploy a large parachute to significantly reduce its speed (as did earlier rovers), and then jettison parts that are no longer needed, including the parachute. Retrorockets will cause further deceleration. When it’s close to the surface, the top part of the spacecraft will act as a sky crane, lowering the rover toward the ground on cables. (After the landing, the cables will be cut and the sky crane will move away from the rover, eventually to crash-land.) The rover will extend its wheels much as an airplane lowers its landing gear, and when it touches down, after a few self-checks, it will be ready to roll.

Sky Crane
This artist’s concept shows the sky crane lowering Curiosity to the martian surface.
Image courtesy of NASA/JPL-Caltech

One important advantage of this new landing procedure is that it's far more precise than the previous air-bag assisted method and gave scientists a much greater choice of landing areas. The final selection was the floor of Gale crater, where Curiosity will land within an elipse about 12 miles by 4 miles (20 km by 7 km) near the foot of Mount Sharp. Layers of this mountain contain minerals that form in water, according to data from Mars orbiters, making the mountain a prime destination for the rover. As with other martian exploration sites, this choice reflects the strategy of "follow the water" in the effort to find life.

Power   The power source for Curiosity is plutonium. Plutonium is a radioactive element, which means that its atomic nuclei spontaneously disintegrate, releasing radiation in a process called radioactivity or radioactive decay. Heat is a by-product of this process, and it’s the heat that will be converted into electricity by a device called a radioisotope thermoelectric generator. The power supply is designed to last a minimum of a martian year, which is 687 earth days.

With no worries about dust obscuring solar panels or having to practically hibernate during the martian winter when sunlight is weak (which happened to earlier rovers), Curiosity will be free to explore all year long and at a wide range of latitudes and altitudes.

Instruments   Curiosity sports a number of familiar tools such as a variety of cameras and a robotic arm. But it’s called a science laboratory because, unlike its predecessors, it can analyze the rock and soil samples it collects, as well as atmospheric samples, using onboard test instruments. For example, one instrument (which uses X-ray diffraction and fluorescence) will identify and quantify the minerals in the rock and soil samples. A suite of three instruments (a quadrupole mass spectrometer, a gas chromatograph, and a tunable laser spectrometer) can identify organic compounds including carbon and oxygen.

Scientific tools for this mission have been contributed by Canada, Russia, and Spain, as well as by institutions in the United States. For a detailed description of Curiosity’s science instruments, visit the MSL Science Corner on the Jet Propulsion Laboratory’s website.

Mobility   While not quite able to leap the martian equivalent of tall buildings, Curiosity’s designed to roll over objects a remarkable 29 inches (75 cm) high. And it can move rather quickly—up to almost 300 feet (90 m) an hour—although usually it will move more slowly.

The Mars Exploration Program
The Mars Science Laboratory mission is part of NASA’s long-term Mars Exploration Program, which is trying to understand if Mars is or has ever been a habitable planet. The program has four primary scientific goals:
•  to determine if there has ever been life on Mars
•  to understand the climate history of Mars
•  to understand the geology of Mars
•  to prepare for human exploration of Mars

In planning future missions, the Mars Exploration Program will focus on high-priority scientific objectives such as returning martian rock and soil samples to Earth for further study. It will also be developing technology to meet President Obama’s goal of sending astronauts to Mars orbit and safely back to Earth in the mid-2030s, with a landing on Mars to follow.

But now it’s time for Curiosity to do its part.

The Mars Science Laboratory project is managed for NASA by the California Institute of Technology’s Jet Propulsion Laboratory.