Extreme Meteorite Hunt Yields Cosmic Clues: Photos
A great hunt for meteorites in Antarctica is showing us more about the moon, Mars and other cosmic locations.
It takes a hardy person to willingly go to isolated Antarctica and work in the cold for a few weeks or months. Every year, however, meteorite-hunters descend on the continent because it is the perfect spot to find these space rocks.
. Here are some of the images from that post, along with detailed descriptions of what this means for our history of the solar system.
Every year, a group of researchers head down to Antarctica and catalog as many meteorites they can find. The annual Antarctic Search for Meteorites (ANSMET) has recovered roughly 20,000 space rocks there since 1976. There are three reasons that meteorites are so easy to find in Antarctica, according to a 2015 Discover Magazine article. The first is many meteorites are made of metallic iron, which would degrade quickly in a humid climate (whereas Antarctica is dry.) The second is meteorites show up very well on Antarctica's ice. The last is Antarctica's ice sheet, which is stalled from falling into the sea due to mountains; this lets evaporation wind down the layers until meteorites emerge on the surface.
The Smithsonian Institution, which is a member of ANSMET,
as an "inexpensive yet guaranteed way to recover meteorites from the Moon, Mars, and previously un-sampled asteroids." Many thousands of meteors hit the Earth every year, with a fraction of the larger ones surviving and hitting the surface.
Since previous impacts have blasted rocks off of the moon, Mars, Vesta and other locations, this allows us a way to see the interior of these locations without visiting. In the case of Mars, it also allows us to compare the present atmosphere with the past atmosphere that was trapped in meteorites.
Image: Meteorite-hunters use snow scooters to get around the harsh Antarctic climate.
, a team of four to eight scientists venture down to Antarctica for six weeks between November and January, when the continent is at its warmest. They try to collect meteorites systematically and without bias.
The researchers do their searches in two stages. They first do parallel transects by snowmobile on top of ice that has no snow on it, also known as "blue ice." If many meteorites are discovered, the scientists disembark and begin searches on foot. This allows them to pick up meteorites of even 1 cm in diameter. Many locations are so dense with meteorites that the researchers need to come back over several seasons.
Image: A scientist collects a meteorite sample during the 2015 ANSMET field season.
The next stage of preservation is to ship the meteorites to the Meteorite Curation Facility at the NASA Johnson Space Center. "They are dried, chipped, sawed, weighed, and photographed in controlled atmosphere cabinets formerly used to process lunar samples,"
. Scientists are invited to ask for samples if they are interested in looking at them, resulting in about 75 requests for an average 600 new samples found annually.
Some of the more prominent meteorites recovered include the first asteroid from the moon, the first asteroid from Mars, and an infamous Martian meteorite
. Roughly 10 years ago, this meteorite hit the news (so to speak) when one scientific team said it may contain evidence of Martian life, but that hypothesis is still greatly debated today.
Image: The meteorite samples are delivered to the Johnson Space Center in Houston.
One fun potential of meteorites will happen when a sample is returned from Mars today. Such a mission has been identified as a burning priority by scientists in the National Science Foundation Decadal Survey of 2013-2022. If we can compare a meteorite from older-day Mars to a sample from current-day Mars, this would give us more insights into how the planet came to be. Some of its enduring mysteries include what its interior was made of, and where all the atmosphere (the atmosphere that allowed water to flow on its surface) disappeared to.
A sample return mission, however, comes with its own set of headaches. Nothing has ever lifted off from Mars to return to Earth, so a spacecraft would need to be designed to make sure this could happen. There also is the small but pressing issue of contamination. Because there is a possibility of Martian life, there would need to be measures taken that the sample does not contaminate Earth -- and that Earth's environment does not contaminate the sample. While no sample return mission is yet funded, two new rovers from Europe and NASA are expected to start work on Mars in 2018 and 2020, respectively. This will help build more scientific evidence for when that mission comes to pass.