Heat from friction could power hydrothermal activity on Saturn's moon Enceladus for billions of years if the moon has a highly porous core, according to a new modeling study by European and U.S. researchers working on NASA's Cassini mission.The study, published today in the journal Nature Astronomy, helps resolve a question scientist have grappled with for a decade:  Where does the energy to power the extraordinary geologic activity on Enceladus come from?

As global temperatures continue to rise, droughts are expected to become more frequent and severe in many regions during this century. A new study with NASA participation finds that land ecosystems took progressively longer to recover from droughts in the 20th century, and incomplete drought recovery may become the new normal in some areas, possibly leading to tree death and increased emissions of greenhouse gases.In results published Aug. 10 in the journal Nature, a research team led by Christopher Schwalm of Woods Hole Research Center, Falmouth, Massachusetts, and including a scientist from NASA's Jet Propulsion Laboratory, Pasadena, California, measured recovery time following droughts in various regions of the world. They used projections from climate models verified by observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Terra satellite and ground measurements. The researchers found that drought recovery was taking longer in all land areas. In two particularly vulnerable regions — the tropics and northern high latitudes — recovery took ever longer than in other regions.

Asteroid 2003 SD220 will safely fly past Earth on Dec. 24 at a distance of 6.8 million miles (11 million kilometers). Scientists at NASA's Jet Propulsion Laboratory in Pasadena, California, have generated the highest-resolution images to date of this asteroid using the Deep Space Network's 230-foot (70-meter) antenna at Goldstone, California. The radar images were acquired between Dec. 17 and Dec. 22, when the distance to this near-Earth object (NEO) was narrowing from 7.3 million miles (12 million kilometers) to almost the flyby distance.

NASA scientists are tracking the upcoming Halloween flyby of asteroid 2015 TB145 with several optical observatories and the radar capabilities of the agency's Deep Space Network at Goldstone, California. The asteroid will fly past Earth at a safe distance slightly farther than the moon's orbit on Oct. 31 at 10:05 a.m. PDT (1:05 p.m. EDT). Scientists are treating the flyby of the estimated 1,300-foot-wide (400-meter) asteroid as a science target of opportunity, allowing instruments on "spacecraft Earth" to scan it during the close pass.Asteroid 2015 TB145 was discovered on Oct. 10, 2015, by the University of Hawaii's Pan-STARRS-1 (Panoramic Survey Telescope and Rapid Response System) on Haleakala, Maui, part of the NASA-funded Near-Earth Object Observation (NEOO) Program. According to the catalog of near-Earth objects (NEOs) kept by the Minor Planet Center, this is the closest currently known approach by an object this large until asteroid 1999 AN10, at about 2,600 feet (800 meters) in size, approaches at about 1 lunar distance (238,000 miles from Earth) in August 2027.

A new NASA-led analysis of a moderate magnitude 5.1 earthquake that shook Greater Los Angeles in 2014 finds that the earthquake deformed Earth's crust across a broad region encompassing the northern Los Angeles Basin and northern Orange County. The shallow ground movements observed from this earthquake likely reflect strain accumulated on deeper faults, which remain locked and may be capable of producing future earthquakes.A team of NASA and university researchers led by geophysicist Andrea Donnellan of NASA's Jet Propulsion Laboratory, Pasadena, California, used GPS and NASA airborne radar data to measure surface deformation in Earth's crust caused by the March 28, 2014, earthquake, which was centered in La Habra, California. The earthquake was felt widely in Orange, Los Angeles, Ventura, Riverside, San Bernardino, Kern and San Diego counties. While the earthquake was relatively moderate in size, the earthquake's depth (3.6 miles, or 5.85 kilometers) and location within a highly populated region resulted in more than $12 million in damage. Most of the damage occurred within a 3.7-mile (6-kilometer) radius of the epicenter, with a substantial amount of damage south of the main rupture.

Levels of "background ozone" — ozone pollution present in a region but not originating from local, human-produced sources — are high enough in Northern California and Nevada that they leave little room for local ozone production under proposed stricter U.S. ground-level ozone standards, finds a new NASA-led study.

New findings from NASA's Mars Reconnaissance Orbiter (MRO) provide the strongest evidence yet that liquid water flows intermittently on present-day Mars.Using an imaging spectrometer on MRO, researchers detected signatures of hydrated minerals on slopes where mysterious streaks are seen on the Red Planet. 

When you fill a sink, the water rises at the same rate to the same height in every corner. That's not the way it works with our rising seas.According to the 23-year record of satellite data from NASA and its partners, the sea level is rising a few millimeters a year — a fraction of an inch. If you live on the U.S. East Coast, though, your sea level is rising two or three times faster than average. If you live in Scandinavia, it's falling. Residents of China's Yellow River delta are swamped by sea level rise of more than nine inches (25 centimeters) a year.These regional differences in sea level change will become even more apparent in the future, as ice sheets melt. For instance, when the Amundsen Sea sector of the West Antarctic Ice Sheet is totally gone, the average global sea level will rise four feet. But the East Coast of the United States will see an additional 14 to 15 inches above that average.

About one third of Earth's largest groundwater basins are being rapidly depleted by human consumption, despite having little accurate data about how much water remains in them, according to two new studies led by the University of California, Irvine (UCI), using data from NASA's Gravity Recovery and Climate Experiment (GRACE) satellites. This means that significant segments of Earth's population are consuming groundwater quickly without knowing when it might run out, the researchers conclude. The findings are published today in Water Resources Research.

NASA's Mars Curiosity rover has measured a tenfold spike in methane, an organic chemical, in the atmosphere around it and detected other organic molecules in a rock-powder sample collected by the robotic laboratory's drill. "This temporary increase in methane — sharply up and then back down — tells us there must be some relatively localized source," said Sushil Atreya of the University of Michigan, Ann Arbor, a member of the Curiosity rover science team. "There are many possible sources, biological or non-biological, such as interaction of water and rock."