Digital Aurora

NASA's Interstellar Boundary Explorer (IBEX) to map the boundary between the solar system and interstellar space will be launched on a Pegasus XL rocket today. The two year mission, costing US$165 million, will study the region in space where the solar wind from the sun suddenly slows down as it reaches the thin, cold gas of interstellar space. This region, called the heliospheric boundary of the solar system, helps to deflect most of the potentially life-threatening forms of radiation coming from elsewhere in our galaxy.



IBEX will ride Pegasus to around 200 kilometres from earth, before boosting itself into its final earth orbit 322,000 kilometres away. The probe will capture energetic neutral atoms (ENAs), which are formed when positive ions in the solar wind hit neutral atoms of interstellar material and rip out electrons from them. IBEX-Lo and -Hi detectors will collect data on the ENAs to create a three-dimensional map of the heliosphere.

The heliospheric boundary was first probed by Voyager 1 in 2004 and later by Voyager 2 in 2007. The data from the two missions indicated several indentations on the heliospheric boundary. It is hoped that IBEX studies may reveal the cause of these indentations.

Recent observations indicate the solar wind pressure has weakened by 25 percent over the past decade and is presently at its weakest level in 50 years. Ibex studies could help confirm whether and why the heliosphere is shrinking. Scientists postulate that if the heliosphere continues to weaken, the amount of cosmic radiation reaching the inner parts of our solar system, including earth will increase. This could trigger growing levels of disruption to electrical equipment, damage satellites and possibly harm life on earth.

"Around 90 per cent of the galactic cosmic radiation is deflected by our heliosphere, so the boundary protects us from this harsh galactic environment," said Nathan Schwadron, co-investigator on the IBEX mission at Boston University. "IBEX gives us a chance to look at how our Solar System's bubble fits in as a tiny piece of the entire Galaxy," claimed David McComas of the Southwest Research Institute in San Antonio, Texas, and IBEX's principal investigator.

NASA's Innovative Partnerships Program has selected seven Small Business Innovation Research program, or SBIR, companies to participate in reduced-gravity test flights in early September. The companies will have the opportunity to test their newly developed hardware on an aircraft that simulates the weightless conditions of spaceflight. The fights will the first by NASA's Facilitated Access to the Space Environment for Technology Development and Training program, called FAST.



Testing new technologies in weightless conditions is an important step in making them available for applications in NASA space projects. An aircraft flying on a parabolic trajectory can create weightless conditions for up to 30 seconds at a time and simulate the reduced gravity conditions of the moon or Mars. This allows developers to test new technologies to ensure that they will work in space or, if they do not work during testing, understand why. It is difficult for emerging technology developers, especially small businesses, to gain access to parabolic aircraft flights. Through FAST, NASA will provide a flight demonstration opportunity while the developer provides the technology.

The selection for the first round of flights was limited to companies that already have SBIR contracts with NASA. The technologies being flown address needs in each of NASA's four core mission directorates. In the future, the competition will be extended to any companies and laboratories working in partnerships on technology of value to NASA's missions. Another important aspect of FAST is that the Zero-Gravity Corporation of Las Vegas will conduct the flights as a commercial service to NASA.

The Zero-Gravity Corporation contract is managed by NASA's Glenn Research Center in Cleveland and is part of an effort to expand the agency's use of commercial services. The reduced-gravity flights will be conducted from Ellington Field in Houston. NASA's Johnson Space Center in Houston and Glenn are providing technical support to the participating companies.

The September flights will include the following projects and companies:

• Vacuum-Compatible Multi-Axis Manipulator/Machining Center for Long-Duration Space Missions, Beck Engineering Inc., Port Orchard, Washington
• Investigation of Pneumatic Mining System under Lunar Gravity Conditions, Honeybee Robotics Spacecraft Mechanisms Corporation, New York
• Aircraft Sensor Logger, Metis Design Corporation, Cambridge, Mass.
• Microgravity Flight Testing of Passively Self-Deploying Shells, Mevicon Inc., Sunnyvale Calif.
• Virtual Sensor Test Instrumentation, Mobitrum Corporation, Silver Spring, Maryland
• Nanofluid Coolants, nanoComposix Inc., San Diego
• Constant-Force-Exercise Sled, Valeo Human Performance LLC, Houston.

A small motor in the robotic arm of NASA's Mars Exploration Rover Opportunity that began stalling occasionally more than two years ago has become more troublesome recently.

Rover engineers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., are diagnosing why the motor, one of five in the robotic arm, stalled on April 14 after much less motion that day than in the case of several earlier stalls. They are also examining whether the motor can be used and assessing the impact on Opportunity's work if the motor were no longer usable.

The motor controls sideways motion at the shoulder joint of the rover robotic arm. Other motors provide up-and-down motion at the shoulder and maneuverability at the elbow and wrist. A turret at the end of the arm has four tools that the arm places in contact with rocks and soils to study their composition and texture.

"Even under the worst-case scenario for this motor, Opportunity still has the capability to do some contact science with the arm," said JPL's John Callas, project manager for the twin rovers Opportunity and Spirit. "The vehicle has quite a bit of versatility to continue the high-priority investigations in Victoria Crater and back out on the Meridiani plains after exiting the crater."

The performance of the motor in the past week is consistent with increased resistance in the electrical circuit, such as from degrading of wire in the winding, rather than a mechanical jam. Additional tests are planned for checking whether the apparent resistance is localized or intermittent.

Opportunity and Spirit landed on Mars in January 2004 to begin missions originally planned for three months. They have continued operating for more than four years, though each with some signs of aging.

Opportunity's balky shoulder motor began stalling occasionally in November 2005. The motor could still be operated by applying increased voltage. Engineers assessed it has an increased likelihood of becoming unusable, however, so the team changed its standard procedures for stowing and unstowing the arm.

Until then, on days when the arm would not be used, the team kept it stowed, resting on a hook under the front of the rover deck. Motion of the stall-prone shoulder motor is necessary to unstow the arm, so if the motor were to become unusable with the arm in the stowed position, the arm could not be deployed again. With diminished confidence in the balky motor, the team began unstowing the arm at the end of each day's drive rather than leaving it stowed overnight. This keeps the arm available for use even if the motor then stops working.

This spring, Opportunity is crossing an inner slope of Victoria Crater to reach the base of a cliff portion of the crater rim, a promontory called "Cape Verde." On April 14, Opportunity was backing out of a sandy patch encountered on the path toward Cape Verde from the area where the rover descended into the crater. As usual, the commands included unstowing the arm at the end of the day's short drive. The shoulder motor barely got the arm unstowed before stalling.

"We'll hold off backing out of the sand until after we've completed the diagnostic tests on the motor," Callas said. "The rover is stable and safe in its current situation, and not under any urgency. So we will take the time to act cautiously."

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for the NASA Science Mission Directorate, Washington. Additional information about Spirit and Opportunity is available online at http://www.nasa.gov/rovers.

Being tiny has its advantages, and a newly discovered microbe in Greenland has exploited this fully. The bacterium survived more than 120,000 years beneath the ice where inhospitable conditions reach new lows. Most organisms constantly deal with trade-offs, such as some hot-desert residents that take advantage of sunshine yet must endure dehydration.



The new microbe makes dehydration seem like a walk in the park. Called Chryseobacterium greenlandensis, the tiny bacterium was found 2 miles (3.2 km) beneath a Greenland glacier. There, conditions are extreme, with temperatures below 16 degrees F (-9 degrees C), high pressure, very little oxygen and meager food.

The ultra-small size of the new species - about 10 to 100 times smaller than E. coli bacteria - could explain why it was able to gain a foothold in such harsh conditions and survive for so long, scientists say. Tiny microbes like this one likely can more efficiently absorb nutrients due to a larger surface-to-volume ratio. They also may be able to hide more easily from predators and take up residence in microenvironments, such as microscopic veins or cracks in the ice.

Link: Life Endures 120,000 Years Under Ice.