Friday, 16 November 2012
|Image credit: NASA/JPL-Caltech|
Observations of wind patterns and natural radiation patterns on Mars by NASA's Curiosity rover are helping scientists better understand the environment on the Red Planet's surface. Researchers have identified transient whirlwinds, mapped winds in relation to slopes, tracked daily and seasonal changes in air pressure, and linked rhythmic changes in radiation to daily atmospheric changes.
The knowledge being gained about these processes helps scientists interpret evidence about environmental changes on Mars might have led to conditions favorable for life. During the first 12 weeks after Curiosity landed in an area named Gale Crater, an international team of researchers analyzed data from more than 20 atmospheric events with at least one characteristic of a whirlwind recorded by the Rover Environmental Monitoring Station (REMS) instrument.
Those characteristics can include a brief dip in air pressure, a change in wind direction, a change in wind speed, a rise in air temperature or a dip in ultraviolet light reaching the rover. Two of the events included all five characteristics. In many regions of Mars, dust-devil tracks and shadows have been seen from orbit, but those visual clues have not been seen in Gale Crater.
One possibility is that vortex whirlwinds arise at Gale without lifting as much dust as they do elsewhere. "Dust in the atmosphere has a major role in shaping the climate on Mars," said Manuel de la Torre Juarez of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. He is the investigation scientist for REMS, which Spain provided for the mission. "The dust lifted by dust devils and dust storms warms the atmosphere."
Dominant wind direction identified by REMS has surprised some researchers who expected slope effects to produce north-south winds. The rover is just north of a mountain called Mount Sharp. If air movement up and down the mountain's slope governed wind direction, dominant winds generally would be north-south. However, east-west winds appear to predominate.
The rim of Gale Crater may be a factor. "With the crater rim slope to the north and Mount Sharp to the south, we may be seeing more of the wind blowing along the depression in between the two slopes, rather than up and down the slope of Mount Sharp," said Claire Newman, a REMS investigator at Ashima Research in Pasadena. "If we don't see a change in wind patterns as Curiosity heads up the slope of Mount Sharp -- that would be a surprise."
REMS monitoring of air pressure has tracked both a seasonal increase and a daily rhythm. Neither was unexpected, but the details improve understanding of atmospheric cycles on present-day Mars, which helps with estimating how the cycles may have operated in the past. The seasonal increase results from tons of carbon dioxide, which had been frozen into a southern winter ice cap, returning into the atmosphere as southern spring turns to summer.
The daily cycle of higher pressure in the morning and lower pressure in the evening results from daytime heating of the atmosphere by the sun. As morning works its way westward around the planet, so does a wave of heat-expanded atmosphere, known as a thermal tide. Effects of that atmospheric tide show up in data from Curiosity's Radiation Assessment Detector (RAD). This instrument monitors high-energy radiation considered to be a health risk to astronauts and a factor in whether microbes could survive on Mars' surface. "We see a definite pattern related to the daily thermal tides of the atmosphere," said RAD principal investigator Don Hassler of the Southwest Research Institute's Boulder, Colo., branch. "The atmosphere provides a level of shielding, and so charged-particle radiation is less when the atmosphere is thicker. Overall, Mars' atmosphere reduces the radiation dose compared to what we saw during the flight to Mars."
The overall goal of NASA's Mars Science Laboratory mission is to use 10 instruments on Curiosity to assess whether areas inside Gale Crater ever offered a habitable environment for microbes.
Friday, 2 November 2012
Image Credit NASA TV
On Friday, November the 2nd 2012 Space Shuttle Atlantis departed the Kennedy Vehicle Assembly Building (VAB) on her last ever trip - the ten mile journey to the visitor complex. Riding on a 76-wheel flatbed vehicle called the Orbiter Transportation System, Atlantis stopped along the route for a retirement ceremony at 10 a.m. EDT.
NASA engineers have been preparing Atlantis for public display as part of NASA's transition and retirement processing of the shuttle fleet. A grand opening of Atlantis' new home at the Kennedy Space Center Visitor Complex is planned for July 2013.
|Image Credit NASA TV|
|Image credit: NASA/JPL-Caltech|
This is an artist's impression of NASA's Mars Science Laboratory Curiosity rover, a mobile robot for investigating Mars' past or present ability to sustain microbial life. Curiosity landed near the Martian equator about 10:31 p.m., Aug. 5 PDT (1:31 a.m. Aug. 6 EDT).
In this picture, the rover examines a rock on Mars with a set of tools at the end of the rover's arm, which extends about 7 feet (2 meters). Two instruments on the arm can study rocks up close. A drill can collect sample material from inside of rocks and a scoop can pick up samples of soil. The arm can sieve the samples and deliver fine powder to instruments inside the rover for thorough analysis.
The mast, or rover's "head," rises to about 6.9 feet (2.1 meters) above ground level, about as tall as a basketball player. This mast supports two remote-sensing science instruments: the Mast Camera, or "eyes," for stereo color viewing of surrounding terrain and material collected by the arm; and, the Chemistry and Camera instrument, which uses a laser to vaporize a speck of material on rocks up to about 23 feet (7 meters) away and determines what elements the rocks are made of.
NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages the Mars Science Laboratory Project for the NASA Science Mission Directorate, Washington.