Daily Archives: December 8, 2020

Japanese space capsule carrying pristine asteroid samples lands in Australia

For the second time ever, humanity has brought asteroid samples down to Earth. A small capsule bearing pristine pieces of the near-Earth asteroid Ryugu touched down early this afternoon (Dec. 5) within the remote and rugged Woomera Prohibited Area, about 310 miles (500 kilometers) northwest of the South Australian capital of Adelaide. The samples were snagged millions of miles from Earth by Japan’s Hayabusa2 mission, which studied the 3,000-foot-wide (900 meters) Ryugu up close from June 2018 to November 2019.

Hayabusa2’s predecessor was the first to haul space-rock samples home, delivering pieces of the stony asteroid Itokawa in 2010. But the original Hayabusa (Japanese for “peregrine falcon”) returned less than 1 milligram of material. Hayabusa2’s bounty is expected to exceed 100 mg (0.0035 ounces), and its samples come from a very different kind of asteroid — a primitive “C-type” space rock rich in water and carbon-containing organic compounds. “The materials that formed the Earth, its oceans and life were present in the primordial cloud from which our solar system formed. In the early solar system, these materials were in contact and able to chemically interact within the same parent objects,” Japan Aerospace Exploration Agency (JAXA) officials wrote in an overview of Hayabusa2. “These interactions are retained even today in primitive bodies (C-type asteroids), so returning samples from these bodies for analysis will elucidate the origins and evolution of the solar system and the building blocks of life,” they added.

On Mars, internal heat may have powered habitable hotspots long ago

If life emerged on ancient Mars, it may have had the planet’s internal heat to thank. The Martian underground may have been habitable billions of years ago even if the planet’s surface was a dry, frigid wasteland. Mars likely churned out enough geothermal heat in the ancient past to melt the bases of thick ice sheets, generating large amounts of potentially life-supporting groundwater, a new study suggests. The results could help scientists get a better handle on a decades-old mystery known as the faint young sun paradox. Four billion years ago, the sun was about 30% dimmer than it is today — too weak, seemingly, to support a continuously warm and wet Mars. Yet evidence of liquid water during that epoch abounds; NASA’s Mars rover Curiosity, for example, has spent the last eight years exploring an ancient lake-and-stream system. Hence the paradox.

“Even if greenhouse gases like carbon dioxide and water vapor are pumped into the early Martian atmosphere in computer simulations, climate models still struggle to support a long-term warm and wet Mars,” study lead author Lujendra Ojha, an assistant professor at Rutgers University-New Brunswick in New Jersey, said in a statement. “I and my co-authors propose that the faint young sun paradox may be reconciled, at least partly, if Mars had high geothermal heat in its past,” Ojha said. He and his colleagues investigated whether the required internal heat — generated by the radioactive decay of elements such as thorium, potassium and uranium — did indeed flow during Mars’ Noachian era, which lasted from about 4.1 billion to 3.7 billion years ago. The researchers focused their attention on the Martian southern highlands, a region that likely supported large ice sheets at the time.