The StratosphericObservatory for Infrared Astronomy (SOFIA) hasdetected the presence of atomic oxygen in the upper atmosphere ofMars. The observation is the first of its kind for 40 years, and willallow planetary scientists to refine their models of the Martianatmosphere.
SOFIA is essentially aBoeing 747SP (the SP suffix standing for "special performance"owing to the increased range over the commercial variant) modified to house a 100 inch (254 cm) diametertelescope in the side of the aircraft. The instrumentation operated with the telescope is capable of being swapped out, allowing for flexibility.
"Atomic oxygen inthe Martian atmosphere is notoriously difficult to measure,"states Pamela Marcum, SOFIA project scientist. "To observe thefar-infrared wavelengths needed to detect atomic oxygen, researchersmust be above the majority of Earth's atmosphere and use highlysensitive instruments, in this case a spectrometer. SOFIA providesboth capabilities."
Atmospheric oxygen hadpreviously been detected by the Viking landers and the Marinerorbiters as they explored the Red Planet in the 1970s. During the Mariner 6, 7 and 9 flybys of Marsbetween 1969 and 1971, the spacecraft deduced the atomic oxygenlevels via an analysis of UV airglow. The Viking landers usedinstruments mounted in the air vents of their descent aeroshells known asneutral mass spectrometers to take detailed readings of the Martianatmosphere prior to touch down.
For the recentobservation SOFIA was fitted with advanced infrared equipment suitedto detecting and separating Mars' atmospheric atomic oxygen from itsEarth-bound counterpart. To further cut down on interference, theobservatory flew at an altitude of between 37,000 and 45,000 ft (11,278 – 13,716 m), high enough to cut out the majority of the disturbances created byEarth's atmosphere.
The levels of atomicoxygen detected in the Martian mesosphere wereonly around half of what was expected. The results of the study are significant, largely due to the fact that atomicoxygen plays an important role in, among other processes, the energyand mass flow throughout the Martian atmosphere, as well as the loss ofparticles to space through atmospheric erosion.
SOFIA will continue to take measurements of Mars' atomic oxygen levels going forward in an attempt to better understand the Red Planet's atmosphere.
Source: NASA
