NASA's latest Mars rover Curiosity is just over 19 days away from reaching its destination.
Launched in November 2011, Curiosity is currently traveling at over 48,500 mph and has covered nearly 300 million miles with another 50 million to go. After years of work preparing the car-sized rover, the teams are anxious but optimistic as their creation nears its destination.
"It's arguably the most important event in the history of planetary exploration," Doug McCuistion, director of the Mars Exploration Program, said at a press conference Tuesday at NASA Headquarters in Washington D.C.
Curiosity and the other components of the Mars Science Laboratory (MSL) mission were fabricated and assembled in the Spacecraft Assembly Facility, a massive cleanroom at the Jet Propulsion Laboratory in Pasadena, Calif. That cleanroom keeps delicate instruments on the spacecraft clean as well as ensure any discoveries on Mars didn't come from Earth. In addition to the 1,982-pound Curiosity rover itself, the 1,188-pound cruise stage and backshell and 5,293-pound descent stage came together in the facility as well.
The cruise stage provides power and course correction on the way to Mars. The descent stage provides a never before attempted method of lowering the huge rover on cables. The heat shield and backshell enclose the rover and decent stage like an Easter egg providing protection during the journey and initial minutes in the Martian atmosphere.
Throughout the build process, onlookers watched progress via the "Curiosity cam" on JPL's Mars website.
Curiosity differs in many ways from her older and small sisters currently on Mars. The rover is loaded with 15 times the scientific payload (165 pounds vs 11 pounds), an robotic arm with nearly three times the reach and over seven times the primary mission length (a single Mars year vs. 13 weeks). This will require a lot of power. The solar panels which power earlier rovers aren't sufficient.
Curiosity will be powered by a multi-mission radioisotope thermoelectric generator (MMRTG) using the heat of radioactive decay of 10.6 pounds of plutonium-238. RTGs have been used for years to power deep space missions to cardiac pacemakers here on Earth. This design will not only power the rover far beyond the primary (Martian) year long mission, it will eliminate the challenge of operating solar panels in the dusty Mars environment.
The team at JPL has put the big rover through her paces long before she was packed up and sent to the Kennedy Space Center. Cameras, electrical systems and other instruments were tested and retested. The environment Curiosity must endure was simulated in a vacuum chamber and the "shake table." Those tests, informally known as "shake and bake," replicate the hot and cold conditions of space and operating on Mars as well as the vibrations endured during launch.
The parachute which will slow the spacecraft as it enters the thin atmosphere was thorougly tested as well. The largest parachute used on a spacecraft to date requires the world's largest wind tunnel for testing. That 80x120 foot wind tunnel, located at the NASA Ames Research Center near San Jose, Calif, has tested full-sized aircraft up to a Boeing 737. Such a large parachute is needed to slow the massive rover as it descends in the thin Mars atmosphere, just 1 percent as dense as Earth's. When that 52-foot parachute opens about seven miles above the surface, it will still generate a neck snapping 10-11 g of force and complete the job of slowing the spacecraft by 800 mph.
The rover is tucked up for its journey. One of the last things it will do before touching down is extend its six wheels. This was tested as well with a full-scale drop test at JPL. A southern California based helicopter normally used for filming movies was used in the desert for additional drop tests of radars used during the landing process.
As the big day approaches, teams are getting some time off but preparations continue. The Mars Yard, a big sandbox on the JPL campus which replicates the landscape challenges facing rovers, has been busy. Curiosity's twin – outfitted to replicate Mars gravity here on Earth – is being used by the team of rover drivers to hone their skills and complete verification of the software they will use to plan and execute daily operations.
Here in the Triangle, two local events are planned for Aug. 5-6 for the landing. The Morehead Planetarium and Science Center in Chapel Hill is hosting a series of 30-minute talks from NASA/JPL representatives beginning at 1:30 p.m. Aug. 5. Hands-on activities for children are also planned and the 3:30 p.m. planetarium show will have a Mars focus. That night, the North Carolina Museum of Natural Sciences will offer rare chance to spend a night at the museum. Beginning at midnight Sunday night, NASA/JPL talks continue on the rover, the mission and Mars leading up to the landing at 1:31 a.m with a live video feed from mission control at JPL.
Check back next week for more about the instruments on board Curiosity and how they give the mission its science laboratory name.
- 07/03: Mars exploration, past, present and future
- 07/09: Mars rover making trip through time, space
- July 24 Curiosity, an Astrobiologist on six wheels
- July 31 Seven minutes of terror, landing on Mars
Tony Rice is a volunteer in the NASA/JPL Solar System Ambassador program and software engineer at Cisco Systems. You can follow him on twitter @rtphokie.