November 14, 2013
NASA Offers A Peek Into Ancient Mars
[ Watch The Video: The Evolution Of Mars ]
Lee Rannals for redOrbit.com - Your Universe Online
NASA released a new video showing how its Mars Atmosphere and Volatile Evolution (MAVEN) mission will be able to look back at the history of the Red Planet.
Mars is a cold and barren dessert with red soil and little atmosphere. However, scientists believe that billions of years ago this planet could have not only had a thick atmosphere, but was warm enough to support oceans of liquid water. Surface features help scientists understand a bit more about what an ancient Mars may have looked like.
"There are characteristic dendritic structured channels that, like on Earth, are consistent with surface erosion by water flows. The interiors of some impact craters have basins suggesting crater lakes, with many showing connecting channels consistent with water flows into and out of the crater,” explained Joseph Grebowsky of NASA's Goddard Space Flight Center in Greenbelt, Maryland.
“Small impact craters have been removed with time and larger craters show signs of erosion by water before 3.7 billion years ago. And sedimentary layering is seen on valley walls. Minerals are present on the surface that can only be produced in the presence of liquid water, e.g., hematite and clays.”
The new video shows how the surface of Mars could have looked billions of years ago. It starts off with a flyover of a Martian lake surrounded by rocky mountains. Rapidly moving clouds can be seen floating above, and as the camera drifts away from the scene, the climate goes from ancient Mars to present-day, featuring a barren, cold, desert planet.
[ Watch the Video: Mars May Have Looked A Lot Different Billions Of Years Ago ]
Although water can be an indicator of life on another planet, the video creators did not show any signs of life, including plant life.
"The only direct evidence for life early in the history of a planet's evolution is that on Earth," said Grebowsky. "The earliest evidence for terrestrial life is the organic chemical structure of a rock found on the surface in Greenland. The surface was thought to be from an ancient sea floor sediment. The age of the rock was estimated to be 3.8 billion years, 700 million years from the Earth's creation. No fossil evidence of life has yet been found from this period.”
He said the oldest microfossils found on Earth date to about 3.5 billion years ago, which is around the same time when the existence of life-nurturing conditions on Mars ended.
“A comparison between the two planet's life histories must be done with caution, due to the different chemical compositions of the surfaces (e.g., Mars' chemistry may have been more suitable early on than Earth's) and different volcanic and meteoroid impact histories,” Grebowksy said. “Also, the histories of life on either planet may not have been continuous. Catastrophic events could have killed off all life at one time only to have it start anew."
The video wraps up by showing both an exterior shot of the ancient Red Planet filled with lakes and rivers, and another shot of Mars as we know it today.
MAVEN, scheduled to launch in November and arrive at the Red Planet in September 2014, will be investigating how Mars lost its atmosphere. Scientists have several theories as to why Mars was stripped of its thick atmosphere, with the leading theory being solar wind.
"Hydrodynamic outflow and ejection from massive asteroid impacts during the later heavy bombardment period (ending 4.1 billion to 3.8 billion years ago) were early processes removing part of the atmosphere, but these were not prominent loss processes afterwards," said Grebowsky. "The leading theory is that Mars lost its intrinsic magnetic field that was protecting the atmosphere from direct erosion by the impact of the solar wind."
MAVEN will be measuring the escape rates of all the applicable processes and will be able to single out the most prominent of these. The spacecraft will be measuring current rate of loss to space and the controlling processes. These measurements will help scientists paint a picture of what Mars’ atmosphere looked like 4 billion years ago.