Red Planet Roundup: February 2017

by Timothy Oleson
Wednesday, January 25, 2017

With two rovers patrolling the surface of Mars, six spacecraft orbiting above it, and scientists here on Earth studying the Red Planet from afar, new findings are announced often. Here are a few of the latest updates.

• NASA released new global images of Mars bathed in ultraviolet (UV) light obtained by the MAVEN orbiter, offering “some of the best high-resolution ultraviolet coverage of Mars ever obtained,” said MAVEN mission team member Nick Schneider of the University of Colorado Boulder (CU-Boulder), in a statement. UV light is generated by photochemical reactions in the atmosphere, allowing alternate views of planets from what is seen in visible light. The newly released images, which cast hues of yellow and green on the planet rather than its conventional red-orange coloration, display areas of ozone concentration and cloud formation, key components in Mars’ atmosphere.

The new images also provide the first views of nitric oxide-generated “nightglow” on Mars — a phenomenon hypothesized to occur there in which night skies glow slightly even without any external light — which should help scientists visualize wind patterns. Other recent observations by the orbiter, which on Oct. 3, 2016, marked one Mars year in orbit (one Mars year is a little over two Earth years), show that water loss from the planet’s atmosphere to space — measured as hydrogen escape — peaks when Mars is closest to the sun and ebbs when its orbit takes it farther away. The periodic difference in loss rate varies by a factor of 10. “Now that we know such large changes occur, we think of hydrogen escape from Mars less as a slow and steady leak and more as an episodic flow — rising and falling with season and perhaps punctuated by strong bursts,” said Michael Chaffin of CU-Boulder in a statement.

• The origins of some sites on Mars’ surface, like the volcano Olympus Mons, are relatively well known. But the geologic stories behind most of the Red Planet’s features are still shrouded in mystery. In a new study in the Journal of Geophysical Research: Planets, researchers have filled in details about one such little-known area, dubbed Greater Thaumasia, which sits just south of the massive Valles Marineris canyon. Although many rocks in Greater Thaumasia were known to be volcanic in origin, how adjacent parts of the region took on unique geochemical signatures and how its varied topography was shaped have been less clear.

Don Hood, a graduate student at Louisiana State University, and colleagues used geochemical data collected over Thaumasia by Mars Odyssey’s Gamma Ray Spectrometer along with geologic and mineralogic observations of the area to piece together an outline of the area’s evolution through Mars’ geologic history. Based in part on trends in elemental composition across the region — decreased abundances of potassium and thorium and increased silica from east to west, for example — “this environment was most likely shaped by a series of volcanic events that continually erupted from a changing mantle composition,” Hood said in a statement. The team found no evidence, however, of widespread salt deposits in Thaumasia, challenging a previous hypothesis that much of the region had been shaped by an enormous salt-lubricated landslide.

• After a seven-month trip from Earth, the spacecraft involved in the first half of the joint European Space Agency (ESA)-Roscosmos ExoMars mission — the Trace Gas Orbiter (TGO) and the Schiaparelli lander — arrived at Mars on Oct. 19, 2016. The TGO entered orbit successfully, joining the five spacecraft already there, and began prepping for its mission to study methane and other gases in the planet’s atmosphere. The Schiaparelli lander, meanwhile, after separating from TGO and descending through the Martian atmosphere, crashed to the planet’s surface while traveling more than 300 kilometers per hour. Schiaparelli’s fate was initially uncertain after contact with it was lost during the descent, but photographs taken by NASA’s Mars Reconnaissance Orbiter of the crashed lander, and its detached parachute and heatshield, on the surface confirmed the outcome. What caused the failed landing is still under investigation, with a full report expected in early 2017, although preliminary indications suggested that a navigational glitch led the spacecraft to deploy its parachute too early and to fire its braking thrusters for too short a time. Schiaparelli was intended primarily to test landing technology in advance of the arrival of the second half of the ExoMars mission, which is scheduled to launch in 2020 and will include a rover and surface platform.