'Avatar' Director James Cameron Stars in NASA Videos

Filmmaker James Cameron, known for out-of-this-world science fiction movies like "Avatar" and "Aliens," gives a thumbs-up to NASA's earth science programs in a series of new videos.

The three videos mix scenes from Cameron's 2009 film "Avatar" — which returns to select theaters this weekend — with photos and data from NASA satellites to describe how NASA's Earth-science program has helped boost environmental awareness and exploration on our home planet.

"Avatar" is a largely computer-animated science fiction film about the tall, blue-skinned inhabitants of the lush moon Pandora, which orbits a gas giant planet light-years from Earth. With the help of a former U.S. Marine, the aliens fend of human explorers who are mining their world for a precious mineral.

"In 'Avatar,' we showed you a planet in peril," Cameron says in one of the spots, which began airing this week. "Here on Earth, our species is learning how to care for our home. NASA's eyes in space enable unparalleled insights into our planet's health."

"When NASA ventures into space, it remembers to keep a steady eye on home," Cameron explains in another video, each of which is about 75 seconds long. "Its fleet of Earth-orbiting satellites constantly reveals our whole planet: its remotest places, its mysteries and the powerful influence of humans."

The team-up of NASA and Cameron has deep roots that began long before "Avatar," despite its themes of environmental awareness, space exploration and alien life.

The filmmaker has served on the NASA Advisory Council, and met with NASA Administrator Charles Bolden in January to discuss how to improve science education in the United States and engage the public in scientific exploration.

Cameron has also spearheaded an effort to add a 3-D camera for Mars to NASA's next rover — the Mars Science Laboratory Curiosity — before it launches toward the Red Planet in 2011.

Wanted: A Solar Space Robot That Roves By Night

NASA is getting serious about its latest challenge to space-minded engineers: Design a solar-powered night rover for exploring other worlds.

Unlike the solar-powered exploration vehicles being deployed on Mars, which have to bed down once the sun sets, the new rovers must function at a high level during the night as well as the day, NASA says.

The contest comes with a prize of $1.5 million and is open to private companies, student teams and independent inventors. It is one of three additions to NASA's Centennial Challenges competitions to spur innovation and interest in space technology and exploration.

"To do otherwise would require much larger batteries to operate during the nighttime hours. And that would have made the rovers heavier and ... the launch costs more expensive," said Mars Exploration Rover researcher Matthew Keuneke at NASA's Jet Propulsion Laboratory in Pasadena, Calif.Until now, rovers on the moon or Mars have operated almost exclusively during the day, reserving energy-draining nighttime tasks for once or twice a month. 

Even a small increase in the mass of exploration vehicles would makes their spaceship liftoffs more expensive by "tens of millions of dollars," Keuneke said.

Benefits of night rovers

A rover better capable of storing solar energy for nighttime activities would immediately free up more energy for daytime uses such as photographic imaging, Keuneke said.

Better energy storage could also allow rovers to conduct spectroscopic analysis (an effort that looks for chemical fingerprints of minerals) of rocks and samples every night, rather than once or twice a month.

"Right now we pick or choose what objects to use with a spectrometer. If we were able to use it more frequently and with less impact, we may discover something that truly surprises us," Keuneke said. "The thing we frequently discover is that the things we don't think are important are actually the important things."

As an example, he mentioned the Martian rover Spirit's 2007 discovery of silica channels indicative of past liquid water on Mars. Buried about 2 to 2.3 inches (5 to 6 cm) beneath the surface of ordinary terrain, the white trails were discovered only because a wheel of the rover broke and began churning up soil.   

The crippling cold

Barring the use of another fuel source, any innovation in the ability of rovers to operate in darkness will "almost certainly" be in its batteries, Keuneke said. The heart of the vehicle's solar energy system, batteries both store collected energy and regulate its usage into the steady stream appropriate for electronics. Without such mediating effects, a solar-powered rover would run into voltage faults and shut down whenever sunlight petered off beyond a critical point.   

Most activities performed by the two  Martian exploration rovers have used use power directly from solar rays, saving excess energy for darker times of day. 

As darkness falls, each rover is designed to shut down, saving its energy for the critical task of keeping itself at a stable temperature during the Martian night, which can cause a rover to become as cold as minus 76 degrees Fahrenheit, or minus 60 degrees Celsius. The batteries become less efficient in the cold, subjecting the system to a "double hit," Keuneke said.

Unless contest entrants simply make a tradeoff in mass to accommodate a larger battery, the successful design is likely to include a model for more efficient batteries, he said.

Air Force Devises Backup Plan to Salvage Ailing Satellite

WASHINGTON — A propulsion system glitch aboard the U.S. Air Force's first Advanced Extremely High Frequency secure communications satellite has forced the service to devise a new orbit-raising plan utilizing smaller thrusters that will delay the craft's arrival at its operating orbit by six months to seven months, according to a service official.

The satellite's operational service life is not expected to be reduced as a result of the revised plan, said Dave Madden, director of the Air Force's Military Satellite Communications Systems Wing.

After years of delay, the Air Force on Aug. 14 launched AEHF-1 aboard an Atlas 5 rocket, which placed the satellite into an elliptical orbit ranging in altitude from 230 kilometers at perigee to 36,000 kilometers at apogee as planned, Madden said during an Aug. 30 media briefing. [Photo of the Atlas 5 rocket launch.]

Ground controllers initiated the orbit-raising sequence Aug. 15, but the hydrazine engine automatically shut down when an anomaly was detected, Madden said. Operators tried the maneuver two days later with the same result, and the engine is now considered a failure, Madden said.The deployment mission profile called for the satellite to then use its hydrazine-fueled liquid apogee engine to climb to an altitude of 19,000 kilometers at perigee over a span of 30 days. Then the satellite's electronic thrusters were to fully circularize the orbit over another 90 days.

The Air Force Space and Missile Systems Center, Aerospace Corp., and AEHF prime contractor Lockheed Martin Space Systems developed a backup plan to use one of the satellite's other propulsion systems to get it to its proper orbit, albeit later than planned, Madden said. The satellite has another propulsion system that is fueled by the same tank as the liquid apogee engine but produces only one-twentieth of the thrust. Engineers believe this system can be used to boost the spacecraft to 19,000 kilometers at perigee in seven months to eight months, Madden said.

Operators began executing the plan Aug. 29, firing the smaller thrusters for 40 minutes and raising the satellite's perigee to 950 kilometers. It was essential to raise the satellite as quickly as possible because it was losing about 2.5 kilometers of altitude per day because of atmospheric drag and the spacecraft had already had to be maneuvered to dodge an oncoming piece of debris, Madden said.

AEHF-1's revised orbit-raising plan will not consume any more fuel than the original plan, meaning the satellite is still expected to operate for 14 years as designed. However, the Air Force could decide it needs to have AEHF-1 in service sooner than now scheduled, and accelerating the orbit-raising sequence would burn more fuel and reduce the satellite's useful life, Madden said.

The Air Force has not yet identified the cause of the engine failure and hopes to do so within a month, Madden said. This is a critical step because the second AEHF satellite is slated for launch in February and it may require new hardware or additional testing, Madden said. If the launch of AEHF-2 is delayed significantly, finding a new slot on the Air Force's manifest could be difficult, Madden said. The service plans to launch the first Space Based Infrared System missile warning satellite right after AEHF-2, and NASA has reserved more than three months on the range starting in August to launch the Juno mission to Jupiter and the $2.5 billion Mars Science Laboratory.

The Air Force plans to buy four AEHF satellites from Sunnyvale, Calif.-based Lockheed Martin Space Systems at a total cost of $9.9 billion. The company may incur some financial penalty as a result of the AEHF-1 problem, but Madden said he could not yet provide specifics.

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