Attack on Titan

NASA announced last week that it had selected the Dragonfly mission to explore the prebiotic organic chemistry and look for signs of life on Titan. At 3,200 miles (5,150 km) across, Titan is the largest moon orbiting Saturn and the second-largest natural satellite in the Solar System. Larger than both the Moon and the planet Mercury.

Image result for Titan

Because it is so far from the Sun, about 886 million miles (1.4 billion km), its surface temperature is minus 290 degrees Fahrenheit (minus 179 degrees Celsius). Its surface pressure is also 50% higher than Earth’s.

Titan has a dense, nitrogen-based atmosphere like Earth. Unlike Earth though, it has clouds and rain made of methane. The moon’s weather and surface processes have combined complex organics, energy, and water similar to those that may have sparked life on our planet. Other organics are formed in the atmosphere and fall like light snow.

The Mars rover-size, drone-like vehicle will have eight rotors and will fly to dozens of promising locations on Titan looking for prebiotic chemical processes common on both Titan and Earth.

Dragonfly will visit a world filled with a wide variety of organic compounds, which are the building blocks of life and could teach scientists about the origin of life itself. The rotorcraft will fly for miles across the organic sand dunes of Saturn’s largest moon, investigating the processes that shape Titan’s extraordinary environment.

It will take advantage of Titan’s dense atmosphere to become the first vehicle ever to fly its entire science payload to new places for repeatable and targeted access to surface materials.

During its 2.7-year baseline mission, Dragonfly will explore diverse environments from the organic dunes to the floor of an impact crater where liquid water and complex organic materials key to life once existed together for possibly tens of thousands of years.

Dragonfly is scheduled to launch in 2026 and reach Titan in 2034.

Well That’s Weird…

The South Pole-Aitken basin, the largest crater in the Solar System, is a gigantic impact structure on the far side of the Moon. Data from NASA’s lunar spacecraft points to the existence of a large excess of mass of about 2.18*1018 kg (about five times larger than the Big Island of Hawaii) in the lunar mantle underneath the basin. According to new research, this mass anomaly may contain metal from a massive asteroid that crashed into the Moon and formed the crater.

The South Pole-Aitken basin is oval-shaped, as 1,600 miles (2,500 km) wide and 8.1 miles (13 km) deep. Despite its size, it cannot be seen from Earth because, you know, it is on the far side of the Moon.

Researchers measured and analyzed small changes in the strength of gravity around the Moon, using data from NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission. When they combined that with lunar topography data from NASA’s Lunar Reconnaissance Orbiter, they discovered the unexpectedly large amount of mass hundreds of miles underneath the South Pole-Aitken basin.

The dense mass, whatever it is, wherever it came from, is weighing the basin floor downward by more than half a mile.

Computer simulations of large asteroid impacts suggest that, under the right conditions, an iron-nickel core of an asteroid may be dispersed into the lunar upper mantle during an impact.

The findings appear in the journal Geophysical Research Letters.

New Neighbors

Image result for star

Astronomers using NASA’s Transiting Exoplanets Survey Satellite (TESS) have discovered a compact three-planet system around the star HR 858. The newly-discovered planets orbit HR 858, a slightly-evolved F-type star, which is also a member of a visual binary system. The star lies in the constellation of Fornax, approximately 104.4 light-years from Earth. It has a radius 30% larger than the Sun, and a temperature of about 10,700 degrees Fahrenheit (5,928 degrees Celsius).

Named HR 858b, c and d, the new planets are all about twice the size of Earth and have periods of 3.6, 6 and 11.2 days, respectively. This compact and near-resonant architecture harkens back to the systems of tightly packed inner planets discovered by Kepler, but HR 858 is hundreds to thousands of times brighter than the hosts of those Kepler systems.

According to the team, HR 858 is one of the brightest stars known to host transiting exoplanets, trailing only HD 219134, pi Mensae, and 55 Cancri.

Pre-launch estimates of the TESS planet yield predicted a handful of planet discoveries around naked-eye stars, and so far only HR 858 and pi Mensae have fit this description. HR 858 will likely retain its privileged position as one of the brightest transit hosts in the sky and most favorable systems for detailed study.

paper detailing the discovery will be published in a journal of the American Astronomical Society (AAS).

Ice, Ice, Baby

 

Image result for Mars

Planetary researchers using data from the Shallow Radar (SHARAD) instrument on NASA’s Mars Reconnaissance Orbiter have discovered rich deposits of water ice and sand hundreds of million years old beneath the current ice cap in the north polar region of the Red Planet. Published journal Geophysical Research Letters, the findings are important because the layers of ice are a record of past Martian climate in much the same way that tree rings are a record of past climate on Earth.

Scientists found layers of sand and ice that were as much as 90% water in some places. If melted, the newly-discovered ice would be equivalent to a global layer of water around Mars at least 5 feet (1.5 m) deep, which could be one of the largest water reservoirs on the planet.

The scientists suspect the layers formed when ice accumulated at the poles during past ice ages on Mars. Each time the planet warmed, a remnant of the ice caps became covered by sand, which protected the ice from solar radiation and prevented it from dissipating into the atmosphere.

Until now, scientists thought the ancient ice caps were lost. The new findings show that in fact significant ice sheet remnants have survived under the planet’s surface, trapped in alternating bands of ice and sand, like layers on a cake.

The total volume of water locked up in the buried polar deposits is roughly the same as all the water ice known to exist in glaciers and buried ice layers at lower latitudes on Mars, and they are approximately the same age.

The team’s findings were corroborated by an independent study using gravity data instead of radar, led by Johns Hopkins University’s Dr. Lujendra Ojha and also published in the journal Geophysical Research Letters.

Moonquakes Too

In 2010, an analysis of images from NASA’s Lunar Reconnaissance Orbiter (LRO) found that the Moon shriveled like a raisin as its interior cooled, leaving behind thousands of cliffs called thrust faults on the lunar surface. A new analysis of archival data from seismometers deployed during the Apollo missions gives the first evidence that these thrust faults are still active and likely producing moonquakes today as the Moon continues to gradually cool and shrink.

Researchers found that a number of the quakes recorded in the Apollo data happened very close to the faults seen in the LRO imagery. The LRO images also show physical evidence of geologically recent fault movement, such as landslides and tumbled boulders.

Image result for moon

Astronauts placed five seismometers on the Moon’s surface during the Apollo 11, 12, 14, 15, and 16 missions. The Apollo 11 seismometer operated only for three weeks, but the four remaining instruments recorded 28 shallow moonquakes from 1969 to 1977. On Earth, the quakes would have ranged in magnitude from about 2 to 5.

Using the revised location estimates from their new algorithm, scientists found that the epicenters of eight of the 28 shallow quakes were within 19 miles of faults visible in the LRO images. This was close enough for the team to conclude that the faults likely caused the quakes.

The researchers also found that six of the eight quakes happened when the Moon was at or near its apogee, the point in the Moon’s orbit when it is farthest from Earth. This is where additional tidal stress from Earth’s gravity causes a peak in the total stress on the Moon’s crust, making slippage along the thrust faults more likely.

The LRO imaged more than 3,500 fault scarps on the Moon. Some of these images show landslides or boulders at the bottom of relatively bright patches on the slopes of fault scarps or nearby terrain. Brighter areas indicate regions that are freshly exposed by an event such as a moonquake.

Other LRO fault images show fresh tracks from boulder falls, suggesting that quakes sent these boulders rolling down their cliff slopes. Such tracks would be erased relatively quickly, in terms of geologic time, by the constant rain of micrometeoroid impacts on the Moon.

The study appears in the journal Nature Geoscience.