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Friday, March 2, 2018
Robert Zubrin: A Purpose-Driven Space Program
Thursday, March 1, 2018
Curiosity Tests a New Way to Drill on Mars
Curiosity Tests a New Way to Drill on Mars: NASA's Mars Curiosity rover has conducted the first test of a new drilling technique on the Red Planet since its drill stopped working reliably.
NASA InSight Mission to Mars Arrives at Launch Site
NASA InSight Mission to Mars Arrives at Launch Site: NASA's InSight spacecraft has arrived at Vandenberg Air Force Base in central California to begin final preparations for a launch this May.
Tuesday, February 27, 2018
Bacterial Bloom In World's Driest Desert Raises Hope For Life On Mars
Bacterial bloom in world's driest desert raises hopes for life on Mars
The discovery of bacterial colonies in the Atacama Desert suggests similar life could have survived on Mars
If the prospects of life on Mars were a pendulum, it's just swung back toward "favorable." An international team of researchers led by Washington State University planetary scientist Dirk Schulze-Makuch has found that the most Mars-like, apparently lifeless spot on the face of the Earth isn't so lifeless after all. Areas of the hyperarid Atacama Desert once thought lacking even microbes is showing blooms of specialized bacteria after rainfall, providing hope that similar dormant colonies may exist on the Red Planet.
The Atacama Desert is about as close to Mars as you can get on Earth. The Chilean desert has areas that are so inhospitable to life that not even bacteria can survive under normal circumstances. The nitrates falling from the sky that bacteria would normally gobble up remain uneaten and rainfall is measured in millimeters per decade. Though the 10 million-year-old desert is surprisingly cool with a Mediterranean climate, there isn't enough water to sustain life. Worse, the cooler temperatures means there's less energy available for growth and reproduction.
According to Schulze-Makuch, when the Washington study began in 2015, this reputation for utter lifelessness seemed intact. Though some microbes and traces of DNA have been found in the Atacama, these were always dying remnants that were unlucky enough to be blown in from the outside world.
That changed when the desert was subjected to its first rainfall in decades, activating long-dormant colonies buried under the surface that reproduced in that typically frantic manner of desert life making the most of the brief opportunity. When the team returned in 2016 and 2017, they found that the colonies had gradually gone dormant again as the soil dried out. However, by using sterilized spoons and special instruments, they were able to take uncontaminated samples and could identify several indigenous species of microbial life by genomic analysis.
"In the past researchers have found dying organisms near the surface and remnants of DNA but this is really the first time that anyone has been able to identify a persistent form of life living in the soil of the Atacama Desert," says Schulze-Makuch. "We believe these microbial communities can lay dormant for hundreds or even thousands of years in conditions very similar to what you would find on a planet like Mars and then come back to life when it rains."
Schulze-Makuch says that the implications for Mars are considerable. Though the Martian environment of today is so inhospitable that it makes the Atacama Desert look like Kew Garden on a spring afternoon, it was a very different place billions of years ago, with shallow seas, rivers, and lakes where very simple life could have evolved. It's possible that as the planet grew colder and drier, some lifeforms could have adapted by developing long-term dormancy.
"We know there is water frozen in the Martian soil and recent research strongly suggests nightly snowfalls and other increased moisture events near the surface," says Schulze-Makuch. "If life ever evolved on Mars, our research suggests it could have found a subsurface niche beneath today's severely hyper-arid surface."
The Washington team is scheduled to return to the Atacama Desert on March 15 for another fortnight's investigation, which will involve hunting for more microbes. In addition, the hope is to later study the Don Juan Pond in Antarctica, which is a very shallow lake so salty that it is liquid even at temperatures of -58° F (- 50° C).
"There are only a few places left on Earth to go looking for new lifeforms that survive in the kind of environments you would find on Mars," says Schulze-Makuch. "Our goal is to understand how they are able to do it so we will know what to look for on the Martian surface."
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Monday, February 26, 2018
European Mars Orbiter Completes 11 Month Aerobraking Maneuver
European Mars orbiter completes 11-month aerobraking maneuver
The TGO releasing the Schiaparelli lander prior to arriving in Mars orbit (Credit: ESA)
It has to be one of the slowest parking attempts ever made, but ESA's ExoMars Trace Gas Orbiter (TGO) has completed a daring maneuver that saw it surfing the outer layers of the Martian atmosphere for 11 months. The purpose of the exercise was to gradually lower the unmanned probe's trajectory to place it in a planet-hugging, near-circular orbit at an altitude of about 400 km (250 mi), allowing the spacecraft to begin its mission to study trace gases on Mars as well as act as a communications relay between Mars surface rovers and Earth.
Launched on March 14, 2016 atop a Proton-M rocket from the Baikonur Cosmodrome in Kazakhstan, the ExoMars Trace gas Orbiter arrived at Mars on October 19 of that year. However, the spacecraft was in a highly elliptical four-day orbit at an altitude ranging from 200 to 98,000 km (125 to 61,000 mi), which was completely unsuitable for its mission.
To alter this orbit in the most economical manner possible, in March 2017 mission control ordered the TGO to carry out a maneuver called aerobraking, which involves repeatedly hitting the very top layer of the Martian atmosphere to reduce its velocity and was first tried with ESA's Venus Express orbiter in 2014. Though to a human observer the atmosphere at about 103 km (64 mi) above Mars may seem like hard vacuum, there is enough air present to allow the solar panels on the TGO to act like the air brakes on an aircraft and slow it down.
According to ESA, this braking isn't much – only decelerating the spacecraft by 17 mm per second per second, which would bring a car traveling at 50 km/h (31 mph) to a stop over a distance of 6 km (3.7 mi). It's also a very tricky maneuver because with Mars at an average distance of 225 million km (140 million mi), it as to be carried out by the TGO under autonomous control. Worse, the Martian atmosphere expands greatly during the day and the summer months, so a single miscalculation could result in a probe burning up in an uncontrolled entry.
The braking took over 950 orbits of the TGO and was completed on February 20 at 17:20 GMT when the spacecraft fired its thrusters for 16 minutes, placing it an orbit ranging between 1,050 and 200 km (650 and 125 650 mi). This orbit will be fine tuned over the next month in a series of 10 thruster maneuvers to bring it into its final mission orbit in mid-April.
Once on station, the TGO will have completed a month of instrument tests and calibrations, after which it will begin its primary mission of making a detailed inventory of atmospheric trace gases that could provide key insights into geological activity and possible biological signatures. In addition, it will look for signs of subsurface ice as well as acting as a data-relay for surface lander missions beginning later this year.
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