Month: February 2019

New NASA satellite will track ice melt on Earth

ICESat-2 will study seasonal changes using lasers to measure ice height worldwide.

NASA is launching a new laser satellite that will study Earth’s ice sheets and changes they undergo over the next three years.

Titled the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2), the satellite will measure and track changes in ice levels across the globe from one season to another. It will be capable of detecting thickness changes as small as one-fifth of an inch.

Two previous NASA probes, the original ICESat, launched in 2003 and Operation IceBridge, begun in 2009, previously monitored changes in ice thickness worldwide.

ICESat measured ice thickness by bouncing a single laser off the surface of ice in each area it studied. Operation IceBridge, which used an airplane rather than a satellite, focused on specific regions of ice deemed crucial and was largely a stopgap mission until the current satellite was ready for launch.

Unlike the previous missions, ICESat-2 will measure the world’s ice in 3D.

“The areas that we’re talking about are vast–think the size of the continental US or larger–and the changes that are occurring over them can be very small,” explained NASA scientist Tom Wagner at an August 22 press conference. “They benefit from an instrument that can make repeat measurements in a very precise way over a large area and that’s why satellites are an ideal way to study them.”

The first ICESat mission confirmed the planet’s sea ice is becoming thinner, Wagner said. “We’ve probably lost over two-thirds of the ice that used to be there back in the ’80s.”

Capable of monitoring ice levels on both land and sea, ICESat-2 will orbit 300 miles (500 km) above Earth’s surface. Its  Advanced Topographic Laser Altimeter System (ATLAS) will emit single laser beams of green light, each of which will be split into six separate beams, which will be bounced off ice surfaces in a grid-like pattern. The satellite will then measure the exact time it takes for these photons to bounce off the ice and return to ATLAS. Only a small number of the photons will return.

Mission scientists will use the amount of time the photons take to return to calculate the height of the surface from which the laser was bounced.

In order for ICESat-2 to observe the same locations during each season, “The orbit is designed so that after 91 days, which is 1,387 individual orbits of the Earth, it exactly repeats itself. This allows the mission to look at the same piece of Earth in each of the four seasons,” said ICESat-2 project manager Doug McLennan.

Launch of ICESat-2 from Vandenberg Air Force Base in California is scheduled for September 15.

 

Dark matter particles may come from decaying neutrons

Scientists measuring the lifetime of neutrons believe that the remaining particles could be dark matter.

Physicists studying decaying neutrons believe that the death of these particles may be a source of dark matter in the universe. By probing the lifetime of neutrons, researchers now suggest that about 1 percent of the time that neutrons decay—along with breaking down into a few known particles—also produce dark matter particles, writes Charles Q. Choi for Space.com.

There are two different ways to measure the lifetime of neutrons. In the experiment that some believe produces dark matter particles, researchers place ultracold neutrons in a bottle and see how many are left after a certain amount of time. “It would be truly amazing if the good old neutron turned out to be the particle enabling us to probe the dark matter sector of the universe,” says Bartosz Fornal, a theoretical physicist at the University of California. Fornal and Benjamin Grinstein conducted the bottle experiment and explored different scenarios of “dark decay” for neutrons, where neutrons break down into both dark matter particles and ordinary components such as gamma rays or electrons.

Grinstein explains that their proposed new particles are “dark in that, like dark matter, they interact feebly with normal matter.” Theoretical physicist Jessie Shelton, studying neutron decay in neutron stars, notes that if neutrons indeed decay into dark matter, they will not give rise to just one kind of particle, but at least two. However, as researchers continue to study exotic neutron dark decays, future experiments may prove that this anomaly has nothing to do with dark matter at all.

Jets of water vapor found streaming from newborn star

Various complex organic molecules also seen in star-forming region.

Astronomers who observed a turbulent star-forming region using the Atacama Large Millimeter/submillimeter Array’s (ALMA) highest frequency capabilities detected jets of water vapor streaming from a massive newborn star approximately 4,300 light years away.

ALMA uses an array of very precise antennas to study high-frequency radio light waves and was recently equipped with shortwave capabilities, enabling it to see a region in the electromagnetic spectrum at the boundary between infrared and radio wavelengths.

Located in the direction of the constellation Scorpius, the region observed, a section of the Cat’s Paw Nebula or NGC 63341, is an active stellar nursery. Previous ALMA observations of it at lower frequencies revealed it to be an active environment that harbors complex organic molecules.

On April 5, 2018, a team of scientists used ALMA to observe this region with the new, high-frequency technology. The Chilean observatory does this by assigning a series of “bands” designated one through 10, each of which studies a very small part of the spectrum. Band 10, the highest frequency, was used to look at the nebula’s star-forming region.

Two major discoveries were made from these observations–water vapor streaming away from a newborn star in jets and the fingerprints of a variety of molecules.

“High-frequency radio observations like these are normally not possible from the ground. They require the extreme precision and sensitivity of ALMA, along with some of the driest and most stable atmospheric conditions that can be found on Earth,” explained Brett McGuire of the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia.

ALMA detected the submillimeter wavelengths that are the fingerprints of light emitted by heavy water, a form of water in which some or all of the hydrogen molecules are replaced by the hydrogen isotope deuterium.

“Normally, we wouldn’t be able to directly see this particular signal at all from the ground. Earth’s atmosphere, even at remarkably arid places, still contains enough water vapor to completely overwhelm this signal from any cosmic source. During exceptionally pristine conditions in the high Atacama Desert, however, ALMA can in fact detect that signal. This is something no other telescope on Earth can achieve,” said Crystal Brogan, also of NRAO.

Most of the material in the protoplanetary disks surrounding baby stars falls onto them. However, a small amount of this material, including heavy water, gas, and other  molecules, is instead directed away from these stars in the form of jets traveling in opposite outward directions.

A paper on the findings has been published in Astrophysical Journal Letters.

Lunar meteorite suggests there could be water on the moon

A meteorite from the moon suggests that there is water on Earth’s natural satellite.

A lunar meteorite uncovered in Africa 13 years ago may hold a mineral that only forms in the presence of water, according to a new study published in the journal Science Advances.

The space rock — known as meteorite NWA2727 — is important because it is seemingly hard evidence that there is in fact water on or below the surface of the moon.

To make this discovery, scientists from Tohoku University analyzed the meteorite and found that it contained the substance moganite. As the mineral only forms in the presence of water, and as the meteorite landed in a desert, there must be some frozen liquid on the moon.

Moganite is commonly found within the cracks of rocks and appears through brecciation, where older rocks form a large mass. However, that process can only happen in the presence of water.

“For the first time, we can prove that there is water ice in the lunar material,” lead author Masahiro Kayama, a researcher at Tohoku University told Space.com. “In a moganite, there is less water, because moganite forms from the evaporation of water. That’s the case on the surface of the moon. But in the subsurface, much water remains as ice, because it’s protected from the sunlight.”

Though the team is not sure, they believe the water on the moon likely got there from asteroids and comets some three billion years ago. From there, they postulate the liquid became trapped in the surface and cooled. Then, another rock hit the moon and sent the water-filled rocks down to Earth.

The presence of moganite from a meteor that landed in a desert does suggest water on the moon, but it is not definitive evidence. Further missions need to collect samples from the lunar surface. It may also help to look back at older missions as well.

“It also highlights the need to study Apollo samples with modern analytical techniques,” said Noah Petro, a lunar geologist with NASA who was not involved in the research, according to Gizmodo.

In addition, scientists are not sure where water would sit on the moon or how much exists. Even if they do find water, nobody is sure how they would manage to extract or use it.

Moon may have been habitable twice in ancient past

Release of volatile gases and volcanic activity could have produced a lunar atmosphere and liquid water on the Moon’s surface.

The Moon may have been habitable for life during two separate periods in its ancient past, according to a study led by Dirk Schulze-Makuch of Washington State University (WSU).

Based on analyses of lunar rocks and data returned by various space missions, Schulze-Makuch’s research team believes the Moon may contain more water ice than scientists suspect, including possible water ice beneath its surface.

While the Moon is currently dusty and lifeless, it may have been habitable for two windows in the past, one four billion years ago, and the other 3.5 billion years ago, the researchers propose.

As it was forming four billion years ago, the Moon released massive amounts of volatile gases, including water vapor. Three-and-a-half billion years ago, the Moon was volcanically active.

Under both of these conditions, the volatile gases could have created a thick atmosphere that endured for several million years as well as pools of liquid water on the lunar surface.

The researchers theorize the ancient Moon also had a magnetic field that would have shielded any life present from solar radiation.

“There could have actually been microbes thriving in water pools on the Moon until the surface became dry and dead,” Schulze-Makuch said.

Today, the Moon has a very weak magnetic field and a very thin atmosphere composed of gases such as sodium and potassium.

Earth’s earliest life, cyanobacteria began sometime between 3.5 and 3.8 billion years ago. The ingredients needed by these single-celled organisms, which generate oxygen through photosynthesis, as well water and the organisms themselves, could have been brought to the Moon, as they were brought to the Earth, by meteorites.

Meteorite impacts were common in the violent early years of the solar system. It is possible that cyanobacteria-containing meteorites thrown off Earth’s surface during impacts could have delivered these microbes to the Moon.

“If liquid water and a significant atmosphere were present on the early Moon for long periods of time, we think the lunar surface would have been at least transiently habitable,” Schulze-Makuch stated.

Future searches for signs of ancient microbial life on the Moon could focus on obtaining samples from the areas known to have had the most volcanic activity 3.5 billion years ago, with the aim of finding water and/or fossils.

A paper on the researchers’ findings has been published in the journal Astrobiology.