PpigScience: solar

Artist's impression of the asteroid ‘Oumuamua, also known as A/2017 U1(Credit: European Southern Observatory/M. Kornmesser)

You can't get much more mysterious than the interstellar asteroid 'Oumuamua, but is it mysterious enough to be an artificial probe designed by a spacefaring alien civilization? Researchers at the Breakthrough Listen initiative want to find out, and have begun observing the asteroid in an effort to determine if it's a naturally occurring object (unfortunately that's the far more likely scenario) or something else entirely.

When astronomers first discovered 'Oumuamua on October 19, the asteroid had already made its closest approach to the Sun, and was racing towards the outer reaches of the Solar System. Data collected on the asteroid allowed scientists to piece together its orbital trajectory to a high degree of accuracy.

The orbital data, in conjunction with the knowledge that 'Oumuamua was hurtling through the solar system at a top speed of around 196,000 mph (315,431 km/h) led scientists to conclude that the object was not gravitationally bound to our Sun, and was instead a transient visitor from interstellar space.

The fact that 'Oumuamua represents the first detection of an extrasolar object visiting our solar system is incredible enough in its own right, but the bizarre shape of the asteroid has some questioning whether it was more than it seemed.

According to this line of thinking, the 400 meter (1,312 ft)-long cigar-like shape of 'Oumuamua would make some sense in the context of an alien probe. Its streamlined profile would minimize the drag and damage caused by collisions with the clouds of gas and cosmic dust that populate the interstellar medium through which it may have been travelling for hundreds of millions of years prior to reaching our solar system.

Breakthrough Listen, which is engaged in an ambitious mission to search one million nearby stars, and 100 galaxies for evidence of technologically advanced alien species, has tasked the Robert C. Byrd Green Bank Telescope, located in West Virginia, with collecting data on the asteroid across four radio bands, from 1 – 12 GHz, over the course of an initial 10-hour period.

'Oumuamua, which is currently located about 186 million miles (300 million km) from Earth, has never been observed in these radio bands. Despite the vast gulf of space separating telescope from would-be-probe, Breakthrough Listen stated in a press release that the GBT would be able to detect a signal from an omnidirectional transmitter with the power of a cellphone less than a minute after it left its source. In other words, if E.T. is trying to radio us from 'Oumuamua, we stand a pretty decent chance of hearing them.

So, best-case scenario – we find out that we are not alone in the universe, finally answering a question that has occupied humanity since we first looked to the stars as more than remote islands of light in the firmament, and began to understand their true nature.

Of course, if this phenomenally unlikely scenario comes to pass, it could also end up being a worst-case scenario, depending on whether our new neighbors are in the market for a resource-rich blue marble.

Then there is the far more likely outcome, in which scientists are about to get their hands on a treasure trove of new data on an awesomely weird visitor to our solar system before it slips away into the cold expanse of interstellar space, never to be seen again.

Source: Breakthrough Initiatives, NewAtlas

The color-coded map (right) shows the gravity measurements of the dwarf planet Ceres, which reveals data about its internal structure(Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

Once thought to be a unique feature of Earth, evidence has been found to suggest that water does, or once did, exist on the Moon, Venus, Mars, Pluto, Enceladus, Titan, Charon and Ceres. Two new studies have focused on the lattermost of these, using data gathered by NASA's Dawn mission to determine that the dwarf planet's salty, icy crust could be the remains of an ancient global ocean – and there may still be some liquid water locked up deep beneath the surface.
Since Dawn entered Ceres' orbit in March 2015, the probe has spotted ice in dark craters at the poles, examined the mystery of its bright spots, and detected clear signs of organic molecules. Now two new studies of the dwarf planet's internal composition and structure suggest it was once covered in a global ocean. If that's the case, the missing water is locked in the planet's crust, which is made up of ice, salts and hydrated materials, while some traces may still exist in a liquid state deeper down.
"More and more, we are learning that Ceres is a complex, dynamic world that may have hosted a lot of liquid water in the past, and may still have some underground," says Julie Castillo-Rogez, co-author on both studies.
The first of the new studies aimed to determine the internal structure and composition of the dwarf planet, using shape and gravity data gathered by Dawn. The scientists compared models of Ceres' gravity with what Dawn observed, and found discrepancies over four major landmarks: three craters called Occator, Kerwan and Yalode, and a large mountain named Ahuna Mons. That suggests these landmarks are the result of gravity anomalies, and lends weight to the idea that Ceres is currently geologically active.
Studying Ceres's crust, the team discovered something strange: its density is close to that of ice, but it's far too strong for ice to be the main component. And that's where the second study comes in: that team modeled how the dwarf planet's surface would have changed over time, to determine what its crust is made of.
According to the model, the crust is most likely a mixture of ice, salts, rock and clathrate hydrates – a crystalline solid where water molecules surround and trap gas molecules. Altogether, this combination is about as dense as plain old ice but can be up to 1,000 times stronger, explaining both the crust's composition as well as the fate of the ancient ocean.
But that's not the whole story. The topographical model also revealed that Ceres' surface was once more mountainous, but these features have smoothed out over the last few billion years. For that to occur, the crust must be sitting on top of a slushy layer, which likely contains some liquid water.
The first study was published in the Journal of Geophysical Research, while the second appeared inEarth and Planetary Science Letters.