2016: the year in space and astronomy

Alan Duffy, Swinburne University of Technology and Rebecca Allen, Swinburne University of Technology

The achievements of astrophysicists this year were as groundbreaking as they were varied. From reuniting a lander with a mothership on a comet, to seeing the most extreme cosmic events with gravitational waves, 2016 was truly out of this world for science.

Here are some of the highlights of the year that was.

1. Gravitational Waves

The spectacular announcement that ripples in the very fabric of spacetime itself had been found (and from surprisingly massive black holes colliding) sent similarly massive ripples through the scientific community. The discovery was made using the Laser Interferometer Gravitational-Wave Observatory (LIGO) and represents a fundamentally new sense with which to see the universe.

Animation showing how colliding black holes cause a ripple in spacetime that moves outwards into the universe as a gravitational wave.

The gravitational waves cause one arm of the LIGO detector to stretch relative to the other by less than a thousandth of the width of a proton in the centre of the atom. Relatively speaking, that’s like measuring a hair’s-width change in the distance to the nearest star.

This discovery was the end of a century-long quest to prove Einstein’s final prediction that these gravitational waves are real. It also allows us to directly “see” that famously and fundamentally invisible entity: the black hole (as well as definitively proving its existence). The fact that the two black holes collided 1.3 billion years ago and the waves swept through Earth just days after turning the detector on only add to the incredible story of this discovery.

The ‘sound’ of the black holes colliding where the measured signal from LIGO is converted to audio, the rising chirp sound towards the end is the two black holes spiralling together ever more quickly. A surprisingly wimpy sound for the most extreme collision ever detected.

2. SpaceX lands (and crashes) a rocket

The year started so well for SpaceX with the incredible achievement of sending a satellite into orbit, which is no mean feat itself at such low cost, before then landing that launch rocket on a barge in the ocean. A seemingly unstoppable sequence of launches and landings made it appear that a new era of vastly cheaper access to space through rockets that could be refuelled and reused was at hand.

A Falcon 9 first-stage automatically returns to the barge/droneship ‘Of Course I Still Love You’ in the middle of the Atlantic ocean.

Unfortunately, with the explosion of a Falcon 9 on the launchpad, the company was grounded, but apparently hopes for a resumed launch in early January.

SpaceX outlines a vision for travel to Mars with planned Interplanetary Transport System.

Add to that the visionary plans to settle Mars outlined by Elon Musk, albeit not without some audacious challenges, and it’s been a year of highs and lows for SpaceX.

3. Closest star may harbour Earth-like world

Proxima Centauri is our Sun’s nearest neighbour at just over four light years away, and it appears that its solar system may contain an Earth-like world. Until this year, astronomers weren’t even sure that any planets orbited the star, let alone ones that might harbour the best extrasolar candidate for life that spacecraft could visit within our lifetime.

What a trip to the Sun’s closet neighbour would look like.

The planet, creatively named “Proxima b”, was discovered by a team of astronomers at Queen Mary University in London. Using the light of Proxima Centauri, the astronomers were able to detect subtle shifts in the star’s orbit (seen as a “wobble”), which is the telltale sign that another massive object is nearby.

An artist’s impression of Proxima b’s landscape. ESO/M. Kornmesser

While Proxima Centauri is barely 10% the size of our Sun, Proxima b’s orbit is only 11 days long, meaning it is very close to the star and lies just within the so-called habitable zone. However, follow-up with either Hubble or the upcoming James Webb Space telescope is necessary to determine if the exoplanet is as well suited for life as Earth.

4. Breakthrough Listen listening and Starshot star-ted

With a potential Earth twin identified in Proxima b, now the challenge is to reach it within a human lifetime. With the breakthrough initiative starshot, which has been funded by Russian billionaire Yuri Milner and endorsed by none other than Stephen Hawking, lightweight nanosails can be propelled by light beams to reach speeds up to millions of kilometres an hour.

Such speeds would allow a spacecraft to arrive at Proxima b in about 20 years, thus enabling humans to send information to another known planet for the first time.

However, there are many challenges ahead, such as the fact that the technology doesn’t exist yet, and that high-speed collisions with gas and dust between stars may destroy it before it can reach its target.

But humans have proven to be resourceful, and key technology is advancing at an exponential rate. Incredibly the idea of sailing to another world is no longer science fiction, but rather an outrageously ambitious science project.

One of the founders of the Breakthrough initiatives, Yuri Milner, discusses the technology needed for breakthrough starshot.

Perhaps, aliens are already sending out their own information in the form of radio transmissions. In another breakthrough initiative called Listen, also championed by Hawking, astronomers will be searching the habitable zones around the million closest stars to try to detect incoming radio transmissions. Involving Australia’s very own Parkes telescope (as well as the Green Bank Telescope and Lick Observatory at visible wavelengths of light), observations have been running through 2016 and the search for alien signals will continue for the next decade.

5. Philae reunited with Rosetta

In 2014 the Philae lander became the first space probe to land on a comet, and even though its crash landing dictated that its science transmission would be a one-off, its recent rediscovery by Rosetta has allowed it to continue to contribute to analysis of comet 67P.

Philae’s crash location, as well as the orientation of the doomed probe, has allowed astronomers to accurately interpret data taken by Rosetta regarding the composition of the comet.

Where’s Philae? ESA

While Philae has literally been living under (crashed on) a rock for the past two years, Rosetta has been the busy bee, taking numerous images, spectroscopy and other data of the comet.

In fact, data taken from Rosetta’s spectrometer has been analysed and revealed that the amino acid, glycine, is present in the comet’s outgassing, which breaks away from the surface of the comet as it becomes unstable from solar heating. Glycine is one of the fundamental building blocks of life; necessary for proteins and DNA, and its confirmed extraterrestrial confirms that the ingredients for life are unique to Earth, and that we may have comets to thank for providing our microbial ancestors with those crucial ingredients.

Dust and gas emitted from comet 67P reveal an amino acid. ESA

Outlook for Down Under

The future for astrophysics in Australia in 2017 looks particularly bright, with two ARC Centres of Excellence: CAASTRO-3D studying the build of atoms over cosmic time; and OzGRav exploring the universe with gravitational waves; as well as SABRE, the world’s first dark matter detector in the Southern Hemisphere, installed by end of the year.

If you thought 2016 was a great year in space, then you’re in for a treat in 2017.

Alan Duffy, Research Fellow, Swinburne University of Technology and Rebecca Allen, PhD candidate researching galaxy formation and evolution, Swinburne University of Technology

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

Extinction alert: saving the world from a deadly asteroid impact

Michael Dello-Iacovo, UNSW Australia

Sixty-five million years ago, disaster struck the Earth. An asteroid or comet around 10km in diameter slammed into what is now the Yucatan Peninsula in Mexico.

While the idea was ridiculed at first, this event is now widely believed to be the reason the dinosaurs became extinct.

This realisation led to a rallying of scientists and engineers around the world to detect and monitor the asteroids in the heavens, and if need be, to be prepared to deflect one from hitting us.

Today, we have a Planetary Defense Coordination Office under NASA whose sole mission is to prepare us for this unlikely but devastating possibility.

It is believed that we have found all of the asteroids the size of that which killed the dinosaurs (at least those near Earth).

Recent impacts

But there are many smaller asteroids that can still do a lot of damage which are undetected. In 1908, the Tunguska event flattened about 2,000 square kilometres of forest in Siberia.

This asteroid was only about 50 metres across, but we have only found about 1% of the near Earth objects (NEOs) of this size.

Despite being so rare, if a large asteroid did hit Earth, it would cause extraordinary damage. In fact, you’re more likely to be killed by an asteroid than die in a shark attack.

We know about a number of recent asteroid impacts, but we’re still discovering more in the geological record. Currently it’s estimated that NEOs which can cause global ecological effects occur around once every 500,000 years.

Right now, despite being able to detect and track large asteroids (you can look at current known asteroid positions yourself using online databases), we know very little about their interior.

Much of what we do know is based on meteorite samples which have fallen to Earth. But it is difficult to extrapolate small samples to understanding what asteroids look like as a whole.

Asteroid types

Asteroids have several types based on mineral composition, but their internal structure can also potentially take several forms.

Some might be rubble piles, weakly held together by gravity and electrostatic forces, while others might be solid bodies of rock. Different structural types would require different methods of deflection.

For example, a rubble pile might break up if we hit it with an object, with each smaller piece still posing a threat. This might dictate a more finessed approach, such as hitting it with a smart cloud of smaller particles released by a space craft.

The use of explosive devices to move an asteroid is expected to be about 100 times less efficient on porous asteroids compared to more solid bodies.

Inside an asteroid

My research involves repurposing geophysical techniques used for more than a century on Earth to determine the strength and structure of asteroids. To test whether these techniques will work requires simulating asteroid conditions in a lab.

This means we have to recreate the gravity, atmospheric and temperature conditions. We also have to find a material that matches the properties of an asteroid surface to test our equipment on.

NASA performs experiments in low gravity using a parabolic jet, which is temporarily in free fall. Atmospheric conditions can be modified in a vacuum chamber.

Researchers have developed simulant materials that are similar in chemical composition to various classes of asteroids. As well as being useful for testing mining equipment that might be used on asteroids, they can also be used to test geophysical equipment might be able to determine useful properties, such as structure.

Once this technology is proven, it can potentially be used to land on an asteroid and peer into its interior. By understanding its structure, porosity and strength, we can then start to plan deflection strategies for individual asteroids, and for asteroids in general.

Being prepared

The dinosaurs went extinct because they didn’t have a space program. Luckily, we are more prepared (although Australia is still one of just two OECD nations without a space program, the other is Iceland).

If we were to detect an inbound asteroid with warning of at least several years, we can send a mission to find out what it’s made of. Then we can plan the optimal strategy complete with backup plans.

In 1995, a workshop with ex-Cold War US and Russian weapons designers was held to propose a way of deflecting an asteroid if it was detected at the last minute. They came up with (though never built) a nuclear weapon capable of instantly vaporising a 1km asteroid.

It would also have the potential to move an extinction class asteroid out of our path given at least a few months notice, or a comet given two years notice. Given any less time, we may have to be content with evacuating as many people as possible from the predicted landing site.

Asteroid impacts aren’t the only event that might wipe us out. Nuclear warfare, biological terrorism and artificial intelligence all have the potential to destroy us. Some researchers have even suggested that the probability of humanity surviving until 2100 is just one in two.

Given this level of risk, one thing is certain: we can and should spend more time and resources trying to reduce these risks.

Michael Dello-Iacovo, PhD candidate (Mining Engineering), UNSW Australia

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

 

Why is Einstein’s general relativity such a popular target for cranks?

Michael J. I. Brown, Monash University

Scientists maybe celebrating the 100th anniversary of Albert Einstein’s general theory of relativity, but there was also a death in 1915. It was one of the many deaths of simple and intuitive physics that has happened over the past four centuries.

Today the concepts and mathematics of physics are often removed from everyday experience. Consequently, cutting edge physics is largely the domain of professional physicists, with years of university education.

But there are people who hanker for a simpler physics, toiling away on their own cosmologies. Rightly or wrongly, these people are often labelled cranks, but their endeavours tell us much misconceptions about science, its history and what it should be.

I regularly browse open access website arxiv.org to look for the latest astrophysics research. Real astrophysics, that is. But if I want to take a look at what pseudoscientists are up to, I can browse vixra.org. That’s right, “arxiv” backwards. The vixra.org website was founded by “scientists who find they are unable to submit their articles to arXiv.org” because that website’s owners filter material they “consider inappropriate”.

There are more than 1,800 articles on vixra.org discussing relativity and cosmology, and many don’t like relativity at all. Perhaps one reason why cranks particularly dislike relativity is because it is so unlike our everyday experiences.

Einstein predicted that the passage of time is not absolute, and can slow for speeding objects and near very massive bodies such as planets, stars and black holes. Over the past century, this bizarre predication has been measured with planes, satellites, and speeding muons.

But the varying passage of time is nothing like our everyday experience, which isn’t surprising as we don’t swing by black holes on our way to the shops. Everyday experience is often central to cranky ideas, with the most extreme example being flat earthers.

Thus many crank theories postulate that time is absolute, because that matches everyday experience. Of course, these crank theories are overlooking experimental data, or at least most of it.

History and linearity

One of the most curious aspects of pseudoscience is an oddly linear approach to science. To be fair, this can result from an overly literal approach to popular histories of science, which emphasise pioneering work over replication.

A pivotal moment in relativity’s history is Albert Michelson and Edward Morley’s demonstration that the speed of light didn’t depend on its direction of travel nor the motion of the Earth.

Of course, since 1887 the Michelson-Morley experiment has been confirmed many times. Modern measurements have a precision orders of magnitude better than the original 1887 Michelson-Morley experiment, but these don’t feature prominently in popular histories of science.

Interestingly many pseudoscientists are fixated on the original Michelson-Morley experiment, and how it could be in error. This fixation assumes science is so linear that the downfall a 19th century experiment will rewrite 21st century physics. This overlooks how key theories are tested (and retested) with a myriad of experiments with greater precision and different methodologies.

Another consequence of the pseudoscientific approach to history is that debunked results from decades past are often used by buttress pseudoscientific ideas. For example, many pseudoscientists claim Dayton Miller detected “aether drift” in the 1930s. But Miller probably underestimated his errors, as far more precise studies in subsequent decades did not confirm his findings.

Unfortunately this linear and selective approach to science isn’t limited to relativity. It turns up in cranky theories ranging from evolution to climate.

Climate scientist Michael E Mann is still dealing with cranky accusations about his seminal 1998 paper on the Earth’s temperature history, despite the fact it has been superseded by more recent studies that achieve comparable results. Indeed, it devoured so much of Mann’s time he has literally written a book about his experience.

What about the maths?

During the birth of physics, one could gain insights with relatively simple (and beautiful) mathematics. My favourite example is Johannes Kepler’s charting of the orbit of Mars via triangulation.

In the 17th century, Johannes Kepler used elegantly simple mathematics to chart the motion of Mars. Johannes Kepler / University of Sydney

Over subsequent centuries, the mathematics required for new physical insights has become more complex, as illustrated by Newton’s use of calculus and Einstein’s use of tensors. This level of mathematics is rarely in the domain of the enthusiastic but untrained amateur? So what do they do?

One option is to hark back to an earlier era. For example, trying to disprove general relativity by using the assumptions of special relativity or even Newtonian physics (again, despite the experiments to the contrary). Occasionally even numerology makes an appearance.

Another option is arguments by analogy. Analogies are useful when explaining science to a broad audience, but they aren’t the be-all and end-all of science.

In pseudoscience, the analogy is taken to the point of absurdity, with sprawling articles (or blog posts) weighed down with laboured analogies rather than meaningful analyses.

Desiring simplicity but getting complexity

Perhaps the most fascinating aspect of pseudoscientific theories is they hark for simplicity, but really just displace complexity.

A desire for naively simple science can produce bizarrely complex conclusions, like the moon landing hoax conspiracy theories. NASA/flickr

Ardents of the most simplistic pseudoscientific theories often project complexity onto the motives of professional scientists. How else can one explain scientists ignoring their brilliant theories? Claims of hoaxes and scams are commonplace. Although, to be honest, even I laughed out loud the first time I saw someone describe dark matter was a “modelling scam”.

Again, this isn’t limited to those who don’t believe in relativity. Simple misunderstandings about photography, lighting and perspective are the launch pad for moon landing conspiracy theories. Naively simple approaches to science can lead to complex conspiracy theories.

Changing intuition

Some have suggested that pseudoscience is becoming more popular and the internet certainly aids the transmission of nonsense. But when I look at history I wonder if pseudoscience will decay.

In the 19th century, Samuel Rowbotham promoted Flat Earthism to large audiences via lectures that combined wit and fierce debating skills. Perhaps in the 19th century a spherical world orbiting a sun millions of kilometres away didn’t seem intuitive.

But today we can fly around the globe, navigate with GPS and Skype friends in different timezones. Today, a spherical Earth is far more intuitive than it once was, and Flat Earthism is the exemplar of absurd beliefs.

Could history repeat with relativity? Already GPS utilises general relativity to achieve its amazing precision. A key plot device in the movie Interstellar was relativistic time dilation.

Perhaps with time, a greater exposure to general relativity will make it more intuitive. And if this happens, a key motivation of crank theories will be diminished.

Will general relativity become more widely understood via popular media, such as the movie Interstellar?

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Michael will be on hand for an Author Q&A between 4 and 5pm AEDT on Tuesday, November 24, 2015. Post your questions in the comments section below.

Michael J. I. Brown, Associate professor, Monash University

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

 

From Mercury to Pluto: the year ahead in planetary exploration

By Donna Burton, University of Southern Queensland

2015 is already shaping up to be a big year in astronomy and planetary exploration, with the best yet to come. Here are some highlights to keep your eye on throughout the year.

Opportunity

January 25 marked 11 years since the Opportunity Rover landed on Mars in 2004 just three weeks after its now inactive twin Spirit. This view is taken from the rim of the Endeavour Crater at a point known as Cape Tribulation.

Opportunity ’s view from Cape Tribulation on the rim of Endeavour Crater, January 22, 2015
NASA/JPL-Caltech/Cornell Univ./Arizona State Univ

This is the highest point that the rover Opportunity has reached since it left the Victoria Crater area back in 2008. It has taken three years for the 180kg solar powered robot to complete the journey down to the Endeavour Crater, which measures 22 kilometres in diameter.

One of its key mission accomplishments has been the characterisation of soft rocks and soil to provide evidence of past water on the Mars. Asteroid 39392 Opportunity was named after this hardworking rover.

Dawn probe

This animation of the dwarf planet Ceres was made by combining images taken by NASA’s Dawn spacecraft on January 25, 2015.
NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Later this year in March, the NASA probe Dawn will arrive at the dwarf planet Ceres. Ceres is one of the largest known bodies in the asteroid belt. It is thought that favourable conditions for life may have once existed there, and the presence of water has recently been announced.

NASA also recently released amazing results from the Dawn mission about the asteroid Vesta. This asteroid was believed to be dry, since it was believed that asteroids are incapable of retaining water.

Yet the recent results provide evidence that Vesta may have had short-lived flows of water-mobilised material on its surface. These results make the asteroid very interesting as these characteristics were thought only to be present on planets. Who knows what interesting discoveries will be made with the upcoming rendezvous with Ceres?

MESSENGER to Mercury

Alver crater graces this image of Mercury’s limb. Secondary crater chains that scour the surface and lead toward the top right of the scene appear to be from the Rembrandt basin to the north.
NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

The MESSENGER ((Mercury Surface, Space Environment, Geochemistry, and Ranging Mission) to Mercury was due to end in March 2015. Launched on August 3, 2004, it entered orbit around Mercury on March 17, 2011, for a one-year discovery mission, and has provided unprecedented views of the innermost planet.

A manoeuvre on January 21 increased the altitude of its orbit, prolonging the mission for possibly another month. Sometime in late April, the probe will descend and crash into the surface of Mercury.

Happy 25th Hubble

The Hubble Space Telescope in a picture snapped by a Servicing Mission 4 crewmember just after the Space Shuttle Atlantis captured Hubble with its robotic arm on May 13, 2009.
NASA

The Hubble Space Telescope turns 25 on April 25, 2015.

Launched into space on the Shuttle Discovery in 1990, and in spite of early problems and repairs over the years, it is still going strong. It is expected to continue through to 2018 when the James Webb Telescope is launched.

New Horizons

Artist’s concept of the New Horizons spacecraft as it approaches Pluto and its three moons in summer 2015.
Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI)

My favourite event will occur on July 14 when NASA’s New Horizons spacecraft flies by Pluto and Charon.

The probe left Earth in 2006, just after Pluto was demoted to being a dwarf planet. It will provide us with the first up close and personal images of this outer solar system object. Initial observations started in January, but the best views will occur as it flies by the dwarf planet on July 14 before heading off to visit other objects far out in the Kuiper Belt.

Rosetta

Mosaic of four images taken by Rosetta’s navigation camera on 22 January 2015 at 28.0 km from the centre of comet 67P/Churyumov-Gerasimenko.
ESA/Rosetta/NAVCAM, CC BY-SA

Rosetta successfully launched the Philae lander onto the surface of Comet 67P/Churyumov-Gerasimenko on November 2014 and continues to orbit the comet as it makes closest approach to the sun on 13 August 2015.

Rosetta’s mission is to monitor how the comet changes as it approaches the sun. It is hoped that the Philae lander, currently in hibernation, will wake up in the early months of the year as it gets more sunlight on its solar panels and again gather data.

Cassini meets Enceladus

This view looks across the region of Enceladus’ geyser basin and down on the ends of the Baghdad and Damascus fractures that face Saturn.
NASA/JPL-Caltech/Space Science Institute

In October NASA’s Cassini mission is scheduled to undertake a close flyby of Saturn’s moon Enceladus.

The flyby will allow the spacecraft to get close enough to fly through the geysers of water that have been discovered emanating from this very interesting icy moon and hopefully reveal secrets of a possible subsurface ocean.

Goodbye Voyager 2

Artist’s impression of Voyager departing our solar system and entering deep space.
NASA/JPL

2015 will also see Voyager 2 follow its younger sibling out past the edge of our solar system sometime during this year.

Both Voyager spacecraft were launched in 1977 and, with Pioneer 10, are now the most distant man-made objects in the solar system. While Pioneer 10, launched in 1972, has not been contactable since 2003, both Voyager probes continue to send information.

This is just a snapshot of some of the highlights of 2015, which is sure to be a momentous year in space exploration.

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.