|from NASA news conference|
On Monday NASA announced that new findings from their Mars Reconnaissance Orbiter has shown that liquid salt water flows intermittently on present-day Mars. Using the imaging spectrometer on the Mars Reconnaissance Orbiter, scientists detected light absorption signatures of hydrated salts on slopes in four locations on Mars where mysterious streaks were observed on Mars. These darkish streaks appear to ebb and flow over time. They darken and appear to flow down steep slopes during warm seasons, and then fade in cooler seasons. The streaks have been observed to appear in four locations on Mars when temperatures are above minus 10 degrees Fahrenheit, and disappear at colder times.
Lujendra Ojha of the Georgia Institute of Technology is the lead author of a scientific paper just published by Nature Geoscience. There are eight co-authors of the paper, including Mary Beth Wilhelm at NASA's Ames Research Center in Moffett Field, California and Georgia Tech; and HiRISE Principal Investigator Alfred McEwen of the University of Arizona Lunar and Planetary Laboratory in Tucson, Arizona who participated in the new conference. The other authors include CRISM Principal Investigator Scott Murchie of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland and others at Georgia Tech, the Southwest Research Institute in Boulder, Colorado, and Laboratoire de Planétologie et Géodynamique in Nantes, France.
|from NASA news conference|
By comparing the light absorption patterns Lujendra Ojha and his co-authors interpreted the spectrometer readings to be of hydrated minerals called perchlorates. The hydrated salts most consistent with the spectral signatures are likely a mixture of magnesium perchlorate, magnesium chlorate and sodium perchlorate. Some perchlorates have been shown to keep liquids from freezing even when conditions are as cold as minus 94 degrees Fahrenheit. This is the first time chemical light absorption patterns have been identified from orbit. On Earth, naturally produced perchlorates are concentrated in deserts.
Lujendra Ojha first noticed the darkish streaks which are only about 16 feet wide as a University of Arizona undergraduate in 2010, using images from the Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (HiRISE). The Mars Reconnaissance Orbiter has been circling Mars with its six instruments since 2006, they have mapped only about 3-4% of the surface of the planet, but they have been able to document the continual reappearance of the dark downhill flows.
For years scientists watched as dark streaks, or downhill flows appears in the spring, grow during the Mars summer and disappear in the fall. These downhill flows, called by the scientists “recurring slope lineae” (RSL), had been described as possibly related to liquid water, but until these new findings of the appearance and disappearance of hydrated salts in conjunction with the RSL on the slopes confirmed the presence of water that was only speculation. The hydrated salts would lower the freezing point of a liquid brine and allow the water to flow in freezing temperatures. The scientists believe that there is likely a shallow subsurface flow, with enough water wicking to the surface to explain the darkening, though they do not know where the water comes from in the first place. What the scientists do know is that there is water flowing on Mars and that the planet has much more humidity in their remaining atmosphere than previously imagined.
Mars is the plant in our solar system most like earth. It is believed that once about 3 billion years ago it was much more like earth with an extensive atmosphere and ocean. Something happened to cause a major change in the planet’s climate that caused it to lose much of its water. Scientists have wondered if life started on Mars billions of years ago. The presence of water raises the question of whether life in some form exists on Mars today. We do not really know how to look for life on Mars, we only know what life on earth looks like. There is a lot more we need to learn before we can determine if there was or is life on Mars.
When NASA sent the Viking 1&2 orbiters and landers to Mars 1976 they found Mars to be a dessert planet assumed to be dead. At that time we knew less about microbes, and looked at only tiny bits of the planet. Atmospheric measurements from Viking confirmed that some meteorites found on Earth originated on Mars. This proved that some meteorites found on Earth were originally from Mars and advanced the theory that a giant meteor impact with Mars caused the catastrophic loss of atmosphere and ocean and sent pieces of the plant hurling towards earth. The more recent Mars missions have placed in orbit and on Mars itself a series of instruments including the Curiosity Rover that have allowed us to see a much more interesting and maybe viable planet.
During my adulthood, biologists have found that microbial life has amazing flexibility and can survive in extreme environments. Today we believe that the fundamental requirements for life are water, organic compounds (carbon compounds) and an energy source for synthesizing complex organic molecules. Even today we do not yet understand the environmental and chemical evolution that lead to the origin of life on earth or on other planets, but in recent decades scientists have realized that life can thrive in settings much different from the tropical soup rich in organic nutrients that was once the accepted science for the creation of life. Microbial life on our own planet has been found to an amazing flexibility for surviving in extreme environments, unimagined by earlier scientists. The challenge for the future is to understand where the water on Mars comes from and then look for life on Mars. Alfred McEwen the Mars Reconnaissance Orbiter HIRISE principal investigator stated in the new conference that there is the possibility of life in the interior of Mars, but we are a long way from being able to search for it.
While one of the area noted to have the RSL –water streaks within a couple of mile of the Curiosity Rover on Mount Sharp its mission cannot be used to investigate further. The distance, though sounding small, is an eternity for the slow moving Rover was not designed to climb slopes. In addition, the Curiosity Rover was not sterilized before it was sent to Mars and undoubtedly carried microbial life with it to Mars. The time the Rover has been exposed to extreme UV light may have sterilized the Rover, but maybe not. So Curiosity will avoid areas where there is water for planetary protection and to avoid detecting the microbial life we inadvertently sent to Mars.
On Earth where there is water there is life. The science of life needs to move forward to know how to search for life on Mars. Future missions to Mars will search for the source of the water. For now the working theory is deliquescence, pulling the moisture from the atmosphere. The discovery of flowing water and perchlorates on Mars make the possibility of a manned mission appear within reach this century. Water can be purified, it can be used to make breathable oxygen, and perchlorates can be used to make rocket fuel (aluminum perchlorates is rocket fuel)- all this could add up to an extended stay on Mars with a return trip. First, we need to turn our focus and investment to space.