By Leah Crane

Mercury is not a particularly pleasant place, with extreme temperatures ranging from -170°C during the night to 430°C in the daytime, and constant blasts of intense radiation. Nevertheless, that’s where the BepiColombo spacecraft is going — it’s a joint mission by the European Space Agency and the Japan Aerospace Exploration Agency. The spacecraft will launch towards the hellish planet closest to the sun on 20 October.

We have only sent two spacecraft to Mercury before: Mariner 10, which flew by three times in 1974 and 1975, and Messenger, which orbited the planet from 2011 to 2015. Those two missions taught us a great deal about the planet, but they also uncovered mysteries and left many more questions unanswered.

Mariner found that Mercury has a magnetic field, which was unexpected — Venus, Mars, and the moon don’t have them. BepiColombo will measure the structure of this strange field and hopefully help us figure out how it got there.

The planet’s surface is no less weird. Messenger spotted what seem to be pools of ice at the centres of craters near Mercury’s poles, which likely stay cool because sunlight never reaches the craters’ bottoms. But we don’t know how the ice got there in the first place. It also saw strange dips in the ground that don’t appear to be impact craters and do not appear on any other planets we know of.

“Mercury has a few unexpected results from previous missions which bring into question our planet formation models,” says BepiColombo project scientist Johannes Benkhoff. “If we can follow on with BepiColumbo and find a solution, that for me would be the most exciting thing that we could do with this mission.”

BepiColombo will carry with it two orbiters, one dedicated to studying the planet itself, from its iron core out to its tenuous atmosphere, and one to study its magnetosphere, the larger area of space within its magnetic field.

But before BepiColombo can work on solving any of these mysteries, it has to get to Mercury – and that is a challenge in and of itself. “You need almost the same amount of energy to bring a spacecraft to Mercury as you need to go to Pluto, although Pluto is 50,000 times farther away from Earth,” says Benkhoff.

To avoid flying right past Mercury and falling into the sun, the craft will take the scenic route, looping back around Earth once, Venus twice, and Mercury six times to get the energy it needs to get into orbit. If all goes well, BepiColombo will reach its final destination in December 2025.

The Hyperion supercluster. The blue cloud represents the likely position of the structure’s dark matterESO/L. Calçada & Olga Cucciati et al.   Home News Space  Daily news  17 October 2018

By Douglas Heaven

Giants have been around far longer than we thought. A survey of the early universe has revealed a gigantic structure that formed just two billion years after the big bang. Its existence could teach us more about how the universe developed and hints at how much dark matter was around at the time.

The half-formed supercluster of galaxies, nicknamed Hyperion after a Titan from Greek mythology, is the largest object ever seen from that epoch. Peering into deep space is effectively looking into the past, because of the time it takes for light to travel from distant corners of the cosmos.

Hyperion’s mass – calculated to be one million billion times that of the sun – puts it in the same league as the largest structures in the universe today, but those have had many more billions of years to grow as gravity pulled them together.

Pieces of the supercluster had been spotted before, but astronomers had not realised that they were looking at parts of a much larger whole. Very little light reaches us from the early universe, so most sky surveys focus only on small patches at a time.

Using the VIMOS instrument on the European Southern Observatory’s Very Large Telescope – a tool that lets astronomers take a more panoramic view of very distant regions of space – a team led by Olga Cucciati at the National Institute for Astrophysics in Bologna, Italy, were able to join the dots.

It makes sense that gigantic superclusters were around way back then, says Cucciati. “These things must be born somewhere, they don’t come out of the blue.” Yet they were still surprised when Hyperion emerged out of the mosaic of smaller objects. “It was great to discover it,” she says.

Finding such a massive supercluster so soon after the big bang will let us test our theories of how the universe evolved. Any explanation of how gravity pulled matter together into denser and denser objects will now need to account for how very large structures like Hyperion were able to form relatively early on.

And since gravity acts mainly on dark matter, which makes up 85 per cent of the matter in the universe, studying Hyperion should help reveal how much was around in the universe’s youth, says Cucciati. We are used to looking at galaxies and superclusters when they are fully formed, she says. “This lets us look at things while they are still happening.”

 

By Leah Crane of NewScientist for Science Daily

Gravitational waves, the ripples in space-time caused by the motions of massive objects, could act like sci-fi tractor beams.

We already know that a rotating beam of light can trap tiny particles and move them around – this year’s Nobel prize in physics was awarded for related research.

This works because particles essentially get stuck between peaks of the light wave as it propagates forward, like a surfer riding a swell. As the wave rotates, it acts like a sort of whirlpool of light, trapping the particle in place.

Iwo Bialynicki-Birula at the Polish Academy of Sciences and Szymon Charzyński at the University of Warsaw calculated that the same thing could happen with a rotating beam of gravitational waves, and in much the same way. An object could get stuck in a swell of increased gravity and rotation of the wave would trap it there.

“When something gets trapped, it is like it is in the eye of the gravitational wave hurricane,” says Bialynicki-Birula.

This sort of gravity vortex is probably produced when a pair of black holes or other enormous objects orbit one another, he says. All of the gravitational waves that we have observed came from systems like this, where orbiting black holes or neutron stars spiralled inwards and smashed together.

There’s just one problem, says Lionel London at Cardiff University, UK: for a tractor beam to do anything, it needs something to grab hold of, but black holes tend to sweep away or suck in surrounding matter.

Neutron star systems may host more matter, he says, but then it’s not certain the gravitational waves would be powerful enough to trap anything.

That said, if a rock passed by a pair of black holes at exactly the right time, it might be able to get trapped in a beam of gravitational waves, leaving it stuck in an eddy in the fabric of space-time.

The site of the controversy. Abigail Allwood

By Michael Marshall of New Scientist

The oldest fossils in the world might not be anything of the kind. Instead they may simply be deformed rocks, reopening the question of when life began to leave its mark in the fossil record.

However, even if the fossils are not real, other evidence still suggests that life began early in Earth’s history.

Click here for the complete article:

By Leah Crane Of NewScientist Daily

Life finds a way – perhaps even across the stars. It may be possible for organisms to travel all over the galaxy by hitching a ride on a fast-moving rock in a phenomenon called galactic panspermia. In this way, just a few inhabited worlds could spread life throughout the Milky Way.

In October 2017, astronomers spotted the first interstellar object we have ever seen come through our solar system, called ‘Oumuamua. That was the first concrete proof that rocks can be tossed out of orbit from distant stellar systems and make it intact to our solar system.

Of course, it is not enough for a space rock to travel between the stars. In order to transfer life, it must also be captured by the sun’s gravity and eventually smash into a planet.

Now, Idan Ginsburg, Manasvi Lingam and Avi Loeb at Harvard University have calculated just how often these banished rocks might be captured into a new stellar system, and how likely any life stuck on such interstellar projectiles would be to survive.

“It’s like billiards,” says Ginsburg. “You hit the cue ball and it hits the other balls, and beside just transferring momentum it also spreads life, and then life spreads across the whole table, which is the galaxy.”

The researchers found that up to 100 million life-bearing objects with a radius of 200 kilometres – about half the size of Saturn’s moon Enceladus – could have been captured in stellar systems around the Milky Way. Even about 1000 Earth-sized objects could have been captured in this way, they say.

Smaller objects are much more likely to make the journey between stars, but the smaller they get, the harder it is for microbes to take shelter from the punishing space environment in the interior of the rock.

“It’s a very dangerous ride, but you can think of the microbes as tiny astronauts sitting in a natural spacecraft,” says Loeb. “I would actually be thrilled to be a microbe sitting in a rock that makes it across the Milky Way.”

Once one of these life-laden rocks is captured into orbit around a new star, it can smash into a planet, dropping off its passengers. The same process on a smaller scale could also spread life to other planets in the system.

Many Mars rocks have been blown off the planet by impacts and ended up on Earth, leading some researchers to speculate that life on our planet could have come from Mars. It is even possible, if unlikely, that life on Earth began with interstellar microbes, says Loeb.

However, Ed Turner at Princeton University says the researchers may have overestimated the likelihood that these captured objects carry life. And many of these objects would not be chipped from larger, habitable planetary bodies, so if they have life it must have evolved there on its own.

“Only a tiny fraction of the objects that would be captured would plausibly carry life,” he says. “If that somehow were not the case and a lot of them carried life, then life is very common and you probably don’t need panspermia anyway.”

Our space-faring descendants may even be able to test this idea. If life in different places around the galaxy is varied and diverse, that would be an indication that it arose independently on each world. However, if there are groups of stellar systems with similar life on their planets, says Loeb, this could mean that microbes really are travelling between the stars.

Reference: arxiv.‌org/abs/1810.04307v1

Such an object would have to be close enough to its host moon to remain gravitationally bound to the moon instead of the larger planet, but not so close that it would get ripped apart or pulled out of orbit by the moon.

Read more: First known exomoon could be a baffling monster the size of Neptune

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