Mika Mckinnon, Author at ��è��Ƶ

Cheer the first women-only spacewalk, but equality is still far away

Mika Mckinnon — Tue, 19 Mar 2019 12:30:00 +0000

The first women-only spacewalk is a cause for celebration, but we are still a long way from achieving equality in our space programmes

Spacecraft to study marsquakes lands on Mars after 7 minutes of terror

Mika Mckinnon — Mon, 26 Nov 2018 20:08:57 +0000

Mars, as seen by NASA’s InSight lander

Nasa/JPL-Caltech

The newest robotic resident of Mars defied the odds and landed safely on the surface, despite the thin atmosphere and strong gravity. On 26 November, Mars InSight faced six and a half minutes of terror, charring its heat shield, flinging its parachute out at supersonic speeds, and finally burning thrusters to set down gently at the end of its six-month journey from Earth. Unlike every other spacecraft that has visited Mars, InSight won’t explore the surface – this time it’s a mission to explore what’s inside Mars.

“Mars has so many missions that have been able to explore the exterior by orbiting or by roving around on the surface,” says Elizabeth Barrett, science system engineer with the mission. “InSight is going to be that first mission that will look further into the interior.”

For this landing, Mars InSight is recycling the method that worked for the Phoenix polar lander in 2008. Despite an entirely new payload of instruments and destination, InSight shares the Phoenix spacecraft’s body shape and characteristics. But this time, we had a real-time stream of data relayed by a pair of cubesats – lunchbox-sized satellites collectively known as Mars Cube One (MarCO) – that have accompanied InSight since its launch in May 2018.

The MarCO satellites were designed for a special trick: a bent pipe configuration lets them immediately shoot data back to Earth. While other orbiters like Mars Odyssey stand in silent sentinel during landing, only able to report back on their following orbit, MarCO A and B can observe and report at the same time. This means that for the first time, we received real-time reports of a Mars landing limited only by the speed of light.

Not only did the cubesats ease nerves stressed thin in anticipation, they also delivered the first photograph taken by InSight from the surface of Mars. But without fuel and engines to burn to enter orbit, the pair are hurtling past Mars and will be out of range before confirming the final critical stage of InSight’s solar array deployment.

The first image taken by NASA’s InSight lander on the surface of Mars

NASA/JPL-Caltech

Pins and needles

Like any landing, this one was full of nerves and excitement. At mission control in NASA’s Jet Propulsion Laboratory in California, the room was full of delighted relief, a celebratory feeling with a hint of shock that it all happened so quickly. With each new report of incoming data and beeps, cheers and clapping spread again. It’s perfect so far, an ideal landing to start InSight’s new adventure on Mars.

But that doesn’t mean the nervous anticipation is over. The wait isn’t done until the NASA control room in California gets confirmation that Mars InSight successfully deployed its solar panels. “Seeing those solar arrays open is what is going to guarantee that we can survive on the surface for an extended time,” says Barrett.

Now that touchdown is complete, NASA’s Entry, Descent, and Landing team can finally celebrate after years of dreaming up nightmare scenarios and putting fixes in place to avoid them. Next, it’s time for the rest of the team to assess the spacecraft’s health, ensure all the instruments are functional and figure out where exactly Mars InSight landed in Elysium Planitia.

This was selected as a landing site in the hopes it would be a big, flat, barren plain of sand. The team wants the landing site to have as few rocks as possible, because Mars InSight will use its robotic arm to gently pluck instruments from the spacecraft to nestle them onto the surface.

Diving deep

Mars InSight is equipped with an array of geophysics tools: a seismometer to detect vibrations as small as the diameter of an atom, a heat flow probe that will burrow like a mole into the depths, a weather station, and a radio experiment that will unmask even the tiniest slosh within the molten Martian core.

Each is geared to explore the Mars’s structure. Some will help determine the thicknesses and materials of the crust, mantle, and core, and others will tell us how much heat the planet has now, allowing scientists to detangle its history of eruptions. By studying the inside of Mars, scientists will have a better understanding of how rocky planets form, and the differences and similarities in how Earth and Mars first formed.

This isn’t the first seismometer to go to Mars. Both the Viking missions in 1975 carried seismometers, although only one of them was functional after landing. But the Viking seismometer was mounted on the spacecraft’s deck.

“Unfortunately, the deck of the spacecraft is cushioned by springs that are dampening the landing, and it’s rocked by the wind as it blows past,” explains Barrett. “The seismometer was very good at measuring the wind rather than any actual seismicity of Mars!” She explained that one of the scientists saw his duty to InSight as ensuring they put the seismometer another three feet further down on the ground.

Today was a major celebration for Mars InSight, but Barrett says it’s hopefully just the first of many to come. She’s looking forward to the first pictures beamed back of Elysium Planitia. But most of all, she’s excited for those big milestones like hammering the heat flow probe into the ground, or recording the first marsquake on the seismometer.

NASA sent a robot to the Red Planet to listen for marsquakes

Mika Mckinnon — Sat, 05 May 2018 14:51:15 +0000

Under a blanket of fog, NASA’s InSight lander and a pair of cubesats roared into space and set out on a mission to explore deep beneath the surface of Mars

Sound waves may be able to trigger earlier tsunami warnings

Mika Mckinnon — Wed, 31 Jan 2018 19:54:52 +0000

Can sound waves improve tsunami warning systems?

ERNESTO BENAVIDES/AFP/Getty Images

When a tsunami is barreling towards a coastline, the only way to stay safe is to flee to higher ground. But even when people are far enough away from the start of the tsunami to have hours of warning, no one really knows how big a tsunami will be or the damage it will inflict until it comes ashore. Now, at the Massachusetts Institute of Technology and at Cardiff University hope to give people more warning time by detecting acoustic waves for earthquake-triggered tsunamis. Sound travels substantially quicker than the pressure wave of the tsunami currently used for warnings. Mei and Kadri calculate that high frequency sound waves can be detected far enough in advance to extend tsunami warnings, but at Northwestern University in Evanston, Illinois, cautions that their theoretical approach has limitations. “What I fear in a study like this is that you are measuring the wrong frequency,” says Okal. Both sound and tsunami are pressure waves. Mei and Kadri use the magnitude of high-frequency sound waves made by earthquakes to predict the distribution of resulting low-frequency tsunami waves. But it’s not a straightforward conversion because earthquakes aren’t so simple. How a fault moves during an earthquake and in turn trigger a tsunami can be complicated. The fault may move faster in some places, have more displacement, or even unzip from one end to another. All of this could impact the high frequency sound waves produced, confusing Mei and Kadri’s model.

Good for small quakes

This is going to be valid only for reasonably small earthquakes,” says Okal. “When you get to ones that generate tsunami, the higher frequency of big earthquakes are going to be controlled by the [tsunami] source not being homogenous.” The new model also doesn’t help with the other major limitation in current tsunami early warning: predicting wave height before it comes on shore. This, too, has its roots in the difficulty of quickly analyzing how a fault’s movement is displacing water to create a tsunami. We often have a difficult time determining if a tsunami will be a devastating series of waves several metres tall, or a meagre few centimetres like the event that swept down the coast of western North America after an earthquake in Alaska last week. For now, the best response for coastal communities is to head to higher ground immediately if the ground starts shaking. In the future, this model could be tested by modifying equipment already in place. The current network of early tsunami detection buoys – called Deep-ocean Assessment and Reporting of Tsunami, or DART buoys — could be used to detect any acoustic waves. Hydrophones, extremely sensitive underwater directional microphones used to monitor for violations of the nuclear test ban treaty, could also be put to use.

Journal of Fluid Mechanics

Planets near dangerous stars could shield alien life under smog

Mika Mckinnon — Mon, 04 Dec 2017 20:19:01 +0000

Red and white dwarfs make nasty neighbours due to spurts of deadly radiation, but alien life could still form on planets nearby if shielded by smog or oceans

Signs of running water on Mars dunes are probably just dry sand

Mika Mckinnon — Wed, 22 Nov 2017 17:02:45 +0000

The strange striped patterns that appear and fade away on Martian slopes were once thought to be evidence of flowing water – they’re actually made by dry sand

Black holes that shred stars burp out cosmic rays and neutrinos

Mika Mckinnon — Fri, 17 Nov 2017 21:27:40 +0000

Shredded to pieces

Chandra X-ray Observatory Center/NASA

White dwarf stars shredded by black holes could explain showers of high-energy cosmic rays and neutrinos we see on Earth.

Cosmic rays and neutrinos are part of the rain of subatomic particles from space that bombard Earth every day. But what produces these difficult-to-detect particles? A team led by at Deutsches Elektronen-Synchrotron in Germany suggest that tidal disruption events in white dwarfs could be responsible.

“A tidal disruption event is what happens when a star gets too close to a black hole and the strong gravity tears the star apart,” says at Arizona State University. “Part of the debris of the destroyed star falls into the black hole, and this causes the black hole to emit energy and accelerate particles.”

In theory, the extreme energy of black hole jets is enough to disintegrate atomic nuclei in a cascading reaction that produces both high-energy neutrinos and ultra high-energy cosmic rays. The researchers suggest a single process – the disintegration of nuclei torn from white dwarves and accelerated in the jets of black holes – could simultaneously produce both kinds of subatomic particles. at John Hopkins University agrees it’s a possibility.

Black hole jets

“We’re really not very good at understanding how cosmic rays are accelerated,” says Krolik. With an uncertain grasp of the mechanics behind how cosmic rays can reach such high velocities, it’s unclear if the extreme environment of black holes jets could be responsible.

Krolik explains that only a small portion of black holes produce relativistic jets, although scientists are uncertain why. Likewise, only a small portion of black holes have nearby white dwarf stars that can be torn apart to produce tidal disruption events. This means that it will take time and luck to successfully observe tidal disruption events on white dwarfs near black holes that are capable of producing jets.

Although tidal disruption events were theorised decades ago and researchers have spotted plenty of potential events, only a handful of observations are confirmed. “The rate of these events for a white dwarf is even more uncertain than the rate of events involving ordinary stars,” says Krolik.

An open question

This scant data means researchers don’t yet understand how tidal disruption events unfold, much less if they could be the mysterious source of the highest-energy cosmic rays and neutrinos.

Lunardini agrees and says this is a theoretical explanation that will only be confirmed if we see future simultaneous observations of X-rays indicative of a tidal disruption event and incoming neutrinos from the same patch of sky. Even then, other proceses may be at work that also produce these high-energy particles.

But as sky surveys get more comprehensive and particle detectors grow more sensitive, researchers will be better able to determine if tidal disruption events are responsible for the highest-energy particles. Even if they aren’t the only source, Lunardini thinks they could still contribute at least some of the particles.

“This is still a very open question,” agrees Lunardini. “It’s interesting to look for alternatives.”

ArXiv:

Tracking the first interstellar asteroid back to its home star

Mika Mckinnon — Thu, 09 Nov 2017 19:41:25 +0000

Where are you from?

NASA / ESA / D. Jewitt, University of California, Los Angeles

An apparent interstellar asteroid is flying out of our solar system after being first sighted in October. Now, astronomers are trying to trace exactly where it came from, and what this brief visitor might tell us about how planets form. The asteroid – now named 1I/ʻOumuamua, which means “to reach out from afar” in Hawaiian – sped through our solar system, steeply entering from above the plane on which planets orbit the sun. The gravitational pull of our sun adjusted its sharply curved path, flinging it back out of our solar system at a new angle, never to return again. Some scientists are turning space telescopes towards the asteroid to continue observing this ever-fainter object as it speeds away, while others are searching along the calculated trajectory to find out where it came from. A team led by at the University of Hawaii at Manoa calculated that ‘Oumuamua might have originally formed in loose star clusters in the Carina or Columba constellations, both found in the southern sky.

Inside the ice line

“For many millions of years after their birth, objects will actually preserve a velocity imprint of a birthmark of their origin,” Gaidos says. “This object has the same motion in space as these clusters.” They theorise that ‘Oumuamua formed within the ice line of its star, close enough to be mostly rock and not volatile ices. It could have been ejected by a collision during planet formation, sent hurtling free of the star’s gravitational grasp approximately 40 million years ago. “If this comes from another planetary system and it was somehow ejected when it was young and traveled all the way to see us, we have essentially witnessed or had a brief glance at a sample of that early planetary system,” says Giados. “This thing has been traveling between the stars in gentle bath of cosmic rays for a very long time,” says at Queen’s University Belfast, who observed ‘Oumuamua. When we look at the asteroid, we learn about its its original system and also about the environment between the stars. ‘Oumuamua shares a red-tinted light profile akin to distant Kuiper Belt Objects in our own solar system, which may be a hint about how prolonged exposure to deep space alters the composition of space rocks.

Cosmic clues

If Gaidos and his team are right, further collisions could have knocked free additional objects on similar trajectories, which means we may see more of this asteroid’s cousins. The team theorises we’ll find more interstellar debris entering our solar system along the the same steep path, akin to how comets leave behind a trail that results in meteor showers when Earth passes through it. But this, like everything else to do with ‘Oumuamua, is still a preliminary theory where more data will be needed. “Maybe this isn’t its first star system flyby. Who knows?” Bannister says. Given how dramatically our sun redirected ‘Oumuamua’s trajectory, such an encounter could have redirected it enough that we’re looking in entirely the wrong direction. “We just have some tantalising clues,” Gaidos says.

arXiv

Cosmic rays have revealed a new chamber in Egypt’s Great Pyramid

Mika Mckinnon — Thu, 02 Nov 2017 12:00:03 +0000

What’s hiding inside?

ScanPyramids

Cosmic rays may have just unveiled a hidden chamber within Egypt’s most famous pyramid.

An international team led by at Nagoya University in Japan used muons, the high-energy particles generated when cosmic rays collide with our atmosphere, to explore inside Egypt’s Great Pyramid without moving a stone.

Muons can penetrate deep into rock, and get absorbed at different rates depending on the density of the rock they encounter. By placing muon detectors within and around the pyramid, the team could see how much material the particles passed through.

“If there is more mass, fewer muons get to that detector,” says at Los Alamos National Laboratory, who uses similar techniques to image the internal structure of nuclear reactors. “When there is less mass, more muons get to the detector.”

By looking at the number of muons that arrived at different locations within the pyramid and the angle at which they were travelling, Morishima and his team mapped out cavities within the ancient structure.

This type of exploration – muon radiography – is perfect for sensitive historical sites as it uses naturally occurring radiation and causes no damage to the structure.

Mysterious cavern

The team mapped the pyramid’s three known chambers – the subterranean chamber, the Queen’s chamber, and the King’s chamber – along with connecting corridors. They also detected a new large void above the Grand Gallery that connects the King and Queen’s chamber. This new void is approximately the same volume as the Grand Gallery. The team believes it’s another oversized tunnel similar in dimensions to the Grand Gallery that is at least 30 metres long.

The team used three different muon detectors, starting with nuclear emulsion film within the Queen’s chamber. Like photographic film is exposed to light to make a photo, the emulsion reacts to muons and makes a record of their paths.

Once their initial findings indicated a potential cavity, they confirmed it by placing an instrument that emits a flash of light when struck by muons within the pyramid. Outside the pyramid, they also used detectors that record muons indirectly when the high-energy particles ionise the gas inside. After several months in position to record muons, all three methods confirmed a void in the same location.

“It’s marvelous,” Morris says, noting that the long exposure times increase the robustness of the results. “What they’ve seen is fairly definitive,” he says, although it will take drilling and cameras to determine if the cavity is a structural chamber, or a void created by a long-forgotten collapse.

A team led by Luis Alvarez first tried using muon radiography to map pyramids in 1970, but they were unable to detect new voids. If confirmed, this would be the first newly rediscovered chamber within the Great Pyramid in more than a century.

“I’d love to be there when they first stick a camera through a drill hole,” Morris admitted. “It’s not every day we discover a chamber in a pyramid.”

Nature

The mysterious bright spots on Ceres may have a common origin

Mika Mckinnon — Mon, 02 Oct 2017 15:33:14 +0000

Pockmarked body

NASA/JPL

The bright spots of Ceres, a dwarf planet in the main asteroid belt, have provoked curiosity and speculation ever since NASA’s Dawn spacecraft spotted them in 2015. Now it seems they might all have formed the same way, even though they are made of different materials. Ceres is speckled with hundreds of bright splotches. An international team led by Ernesto Palomba at the National Institute for Astrophysics in Rome is analysing the light reflected by them – as observed by Dawn, presently in orbit around Ceres – to identify any differences between them. “The bright spots are only bright relative to Ceres’ already-dark surface,” says , a collaborator at the California Institute of Technology. “If you saw those spots on Earth or even on [the asteroid] Vesta you would consider them to be dark spots.” While the biggest and brightest spots are in Occator crater, more exist elsewhere on the dwarf planet. “Almost all of them are associated with impact craters,” says Stein. The team found 90 per cent of the bright spots are in craters or are debris ejected from a crater. Researchers theorise that the spots are the result of the heat of an impact melting subsurface materials, which then well up to the surface to create the bright spots. “As of 20 years ago we would have said that Ceres was just a big, round rock that was the same the whole way through,” explains Andy Rivkin, a planetary astronomer at the Johns Hopkins University Applied Physics Laboratory in Maryland. The jagged mountains and craters led researchers to theorise that Ceres might have an icy core with a rock-ice mantle. But these spots are telling a story of a younger, more geologically active Ceres than researchers expected. That’s because we would expect material ejected by impacts to mix eventually and create a uniform surface. “Mixing hasn’t had time to occur yet, which means these spots must be young.”

Changing its spots

Over time, the bright spots could be darkening as exposure to the harsh conditions of space scours their surface, or because darker material is being tossed around by subsequent impacts. Most of the spots are made from the same basic material as the rest of Ceres’s surface: calcium or magnesium carbonates mixed with ammonia-rich clays. But a handful of the spots in the youngest craters – including the exceptionally bright spots in Occator crater – are made of sodium carbonates without nearly as much ammonium clay. These are small variations, but they are enough to point to new avenues of enquiry. “Does this mean that there are different formation mechanisms that account for the different compositions?” asks Stein, “or is it just that they’re end-members of the same process?” The compositions of the bright spots seem similar enough that they could be explained by the impact-melt and upwelling theory, just modified by local conditions on the surface. “Carbonates are interesting because they’re made via reactions between water and minerals with carbon in them,” says Rivkin. While researchers don’t expect to find life on Ceres, understanding the processes that created carbonates in the bright spots will help them think about the types of reactions necessary for life to occur in such a hostile environment. The next step is to build a computer model of Ceres based on everything scientists have learned about its composition, then start pelting it with simulated rocks to try to match the craters and bright spots we see there today. “We have all the information we need,” says Stein. Now researchers just need to figure out how to piece it together. And after that? “These bright spots are almost certainly where you would want to send the next mission,” says Rivkin, dreaming of future exploration with robotic landers or rovers on Ceres.

Icarus

Mika Mckinnon, Author at ��è����Ƶ