Tag Archives: Space

New evidence that volcanic eruptions triggered the dawn of the dinosaurs

Tamsin Mather, University of Oxford and Lawrence Percival, University of Oxford

The dinosaurs may have volcanoes to thank for their domination of the planet, at least according to one theory. Most scientists think that a severe bout of volcanic activity 200m years ago may have led to the mass extinction that cleared the way for the dinosaurs’ rise. Now we – with a team of colleagues – have discovered new evidence that strengthens this idea: a global geological “fingerprint” indicating volcanic gases were affecting the whole world at the time of the extinction.

Geologists have previously discovered that the Earth’s crust hosts massive amounts of volcanic rock from the end of the Triassic period, 200m years ago. We know from the fossil record that, at about the same time, a very large proportion of Earth’s species died out, which made space for the remaining dinosaurs (and other species) to flourish. As volcanoes can produce large amounts of carbon dioxide (CO2), it’s possible that the volcanic activity that left these massive lava flows behind also provoked global climate change that led to this mass extinction.

What was missing was evidence that the volcanic activity really had such a worldwide impact. By examining geological records from all over the world, we discovered that large amounts of mercury were released into the atmosphere at around the same time as the extinction. As mercury is also released by volcanoes, this suggests the volcanic eruptions really were severe enough to affect the whole world and potentially cause the mass extinction.

The Central Atlantic Magmatic Province (CAMP).
Williamborg/Wikimedia, CC BY-SA

The volcanic rocks cover a huge area, across four present-day continents. They are the remains of a huge episode of heightened volcanic activity that lasted about a million years known as the Central Atlantic Magmatic Province (CAMP).

Previous studies have shown that this volcanism might have occurred in pulses. But we didn’t know how the timing and frequency of these emissions compared to the timing of the extinction event and the subsequent recovery of life. Or whether the volcanoes had a worldwide effect. So we decided to look for a “fingerprint” of the eruptions in the same kind of sediments that record the mass extinction.

Mercury marker

Modern volcanoes emit a large number of gases, most famously sulphur dioxide and CO2, but also trace quantities of the metal mercury. This mercury can stay in the atmosphere for between six months and two years and that means it can be distributed around the world before eventually being deposited in sediments at the bottom of lakes, rivers, and seas.

These same sediments record evidence of bouts of climate change and mass extinction. So, if a sediment layer that records a mass extinction also features unusually high mercury concentrations, we can deduce that volcanic activity likely coincided with (and maybe caused) that extinction.

Working with colleagues from the universities of Exeter and Southampton, we investigated six sedimentary records of the end-Triassic extinction for mercury concentrations. These records were from the UK, Austria, Argentina, Greenland, Canada and Morocco. This spread over four continents and both hemispheres gave us global insight into the impact of volcanic gas emissions during the end-Triassic mass extinction.

Emissions culprit.
Shutterstock

Volcanic link

We found that five of the six records showed a large increase in mercury content beginning at the end of the Triassic period, with a distinct spike in mercury at the layer corresponding to the extinction itself. The extinction layer in the Morocco sample also overlaps with the volcanic rocks from the CAMP. This meant we could tie this large emission of mercury into the global atmosphere to a specific volcanic event, even though the eruption was around 200m years ago.

What’s more, this evidence reinforces the conclusion that mercury spikes found elsewhere in the geological record were caused by volcanic activity. We found other mercury peaks between the extinction layer and the layer that marked the start of the Jurassic period, which occurred approximately 100,000 to 200,000 years later. This suggests that multiple episodes of tremendous volcanic activity took place during and immediately after the end-Triassic extinction.

More importantly, we were able to show the elevated mercury emissions matched previously established increases in the amount of CO2 in the atmosphere. This strongly supports the theory that the CO2 emissions thought to cause the end-Triassic extinction came from volcanoes.

The ConversationThis link between increased atmospheric mercury and CO2 at the same time as the end-Triassic extinction offers fundamental insights into some of the factors governing the evolution of life on our planet. And, from a geological point of view, it highlights the potential of mercury to help explain other extinction events in Earth’s history.

Tamsin Mather, Professor of Earth Sciences, University of Oxford and Lawrence Percival, PhD Candidate, Department of Earth Sciences, University of Oxford

This article was originally published on The Conversation. Read the original article.

Elon Musk releases details of plan to colonise Mars – here’s what a planetary expert thinks

Andrew Coates, UCL

Elon Musk, the founder of SpaceX and Tesla, has released new details of his vision to colonise parts of the solar system, including Mars, Jupiter’s moon Europa and Saturn’s moon Enceladus. His gung ho plans – designed to make humans a multi-planetary species in case civilisation collapses – include launching flights to Mars as early as 2023.

The details, just published in the journal New Space, are certainly ambitious. But are they realistic? As someone who works on solar system exploration, and the European Space Agency’s new Mars rover in particular, I find them incredible in several ways.

First of all, let’s not dismiss Musk as a Silicon Valley daydreamer. He has had tremendous success with rocket launches to space already. His paper proposes several interesting ways of trying to get to Mars and beyond – and he aims to build a “self-sustaining city” on the red planet.

Musk outlining initial plans in 2016.

The idea depends on getting cheaper access to space – the paper says the cost of trips to Mars must be lowered by “five million percent”. An important part of this will be reusable space technology. This is an excellent idea that Musk is already putting into practice with impressive landings of rocket stages back on Earth – undoubtedly a huge technological step.

Making fuel on Mars and stations beyond it is something he also proposes, to make the costs feasible. Experiments towards this are underway, demonstrating that choosing the right propellant is key. The MOXIE experiment on the NASA 2020 rover will investigate whether we can produce oxygen from atmospheric CO2 on Mars. This may be possible. But Musk would like to make methane as well – it would be cheaper and more reusable. This is a tricky reaction which requires a lot of energy.

Yet, so far, it’s all fairly doable. But the plans then get more and more incredible. Musk wants to launch enormous spaceships into orbit around Earth where they will be refuelled several times using boosters launched from the ground while waiting to head to Mars. Each will be designed to take 100 people and Musk wants to launch 1,000 such ships in the space of 40 to 100 years, enabling a million people to leave Earth.

There would also be interplanetary fuel-filling stations on bodies such as Enceladus, Europa and even Saturn’s moon Titan, where there may have been, or may still be, life. Fuel would be produced and stored on these moons. The aim of these would be to enable us to travel deeper into space to places such as the Kuiper belt and the Oort cloud.

The “Red Dragon” capsule is proposed as a potential lander on such missions, using propulsion in combination with other technology rather than parachutes as most Mars missions do. Musk plans to test such a landing on Mars in 2020 with an unmanned mission. But it’s unclear whether it’s doable and the fuel requirements are huge.

Pie in the sky?

There are three hugely important things that Musk misses or dismisses in the paper. Missions such as the ExoMars 2020 rover – and plans to return samples to Earth – will search for signs of life on Mars. And we must await the results before potentially contaminating Mars with humans and their waste. Planetary bodies are covered by “planetary protection” rules to avoid contamination and it’s important for science that all future missions follow them.

Musk inspecting a heat shield at the SpaceX factory.
Steve Jurvetson/Flickr, CC BY

Another problem is that Musk dismisses one of the main technical challenges of being on the Martian surface: the temperature. In just two sentences he concludes:

It is a little cold, but we can warm it up. It has a very helpful atmosphere, which, being primarily CO2 with some nitrogen and argon and a few other trace elements, means that we can grow plants on Mars just by compressing the atmosphere.

In reality, the temperature on Mars drops from about 0°C during the day to nearly -120°C at night. Operating in such low temperatures is already extremely difficult for small landers and rovers. In fact, it is an issue that has been solved with heaters in the design for the 300kg ExoMars 2020 rover – but the amount of power required would likely be a show-stopper for a “self-sustaining city”.

Musk doesn’t give any details for how to warm the planet up or compress the atmosphere – each of which are enormous engineering challenges. Previously, science fiction writers have suggested “terraforming” – possibly involving melting its icecaps. This is not only changing the environment forever but would also be challenging in that there is no magnetic field on Mars to help retain the new atmosphere that such manipulation would create. Mars has been losing its atmosphere gradually for 3.8 billion years – which means it would be hard to keep any such warmed-up atmosphere from escaping into space.

The final major problem is that there is no mention of radiation beyond Earth’s magnetic cocoon. The journey to and life on Mars would be vulnerable to potentially fatal cosmic rays from our galaxy and from solar flares. Forecasting for solar flares is in its infancy. With current shielding technology, just a round-trip manned mission to Mars would expose the astronauts to up to four times the advised career limits for astronauts of radiation. It could also harm unmanned spacecraft. Work is underway on predicting space weather and developing better shielding. This would mitigate some of the problems – but we are not there yet.

Europa.
NASA

For missions further afield, there are also questions about temperature and radiation in using Europa and Enceladus as filling stations – with no proper engineering studies assessing them. These moons are bathed in the strongest radiation belts in the solar system. What’s more, I’d question whether it is helpful to see these exciting scientific targets, arguably even more likely than Mars to host current life, as “propellant depots”.

The plans for going further to the Kuiper belt and Oort cloud with humans is firmly in the science fiction arena – it is simply too far and we have no infrastructure. In fact, if Musk really wants to create a new home for humans, the moon may be his best bet – it’s closer after all, which would make it much cheaper.

The ConversationThat said, aiming high usually means we will achieve something – and Musk’s latest plans may help pave the way for later exploration.

Andrew Coates, Professor of Physics, Deputy Director (Solar System) at the Mullard Space Science Laboratory, UCL

This article was originally published on The Conversation. Read the original article.

Could asteroids bombard the Earth to cause a mass extinction in 10 million years?

Sanna Alwmark, Lund University and Matthias Meier, Swiss Federal Institute of Technology Zurich

Scientists have spent decades debating whether asteroids and comets hit the Earth at regular intervals. At the same time, a few studies have found evidence that the large extinction events on Earth – such as the one that wiped out the dinosaurs 66m years ago – repeat themselves every 26m to 30m years. Given that there’s good evidence that an asteroid triggered the dinosaur extinction, it makes sense to ask whether showers of asteroids could be to blame for regular extinction events.

The question is extremely important – if we could prove that this is the case, then we might be able to predict and even prevent asteroids causing mass extinctions in the future. We have tried to find out the answer.

Today, there are approximately 190 impact craters from asteroids and comets on Earth. They range in size from only a few meters to more than 100km across. And they formed anywhere between a few years ago and more than two billion years ago. Only a few, like the famous “Meteor crater” in Arizona, are visible to the untrained eye, but scientists have learned to recognise impact craters even if they are covered by lakes, the ocean or thick layers of sediment.

Meteor crater, Arizona.
Kevin Walsh/wikipedia, CC BY-SA

But have these craters formed as a result of regular asteroid collisions? And if so, why? There have been many suggestions, but most prominently, some scientists have suggested that the sun has a companion star (called “Nemesis”) on a very wide orbit, which approaches the solar system every 26m to 30m years and thereby triggers showers of comets.

Nemesis would be a red/brown dwarf star – a faint type of star – orbiting the sun at a distance of about 1.5 light years. This is not an impossible idea, since the majority of stars actually belong to systems with more than one star. However, despite searching for it for decades, astronomers have failed to observe it, and think they can now exclude its existence.

Difficult dating

Yet, the idea of periodic impacts persists. There are other suggestions. One idea is based on the observation that the sun moves up and down slightly as it orbits the galaxy, crossing the galactic disk every 30m years or so. Some have suggested that this could somehow trigger comet showers.

But is there any evidence that asteroid impacts occur at regular intervals? Most research so far has failed to show this. But that doesn’t mean it isn’t the case – it’s tricky getting the statistics right. There are a lot of variables involved: craters disappear as they age, and some are never found in the first place as they are on the ocean floor. Rocks from some periods are easier to find than from others. And determining the ages of the craters is difficult.

A recent study claimed to have found evidence of periodicity. However, the crater age data it used included many craters with poorly known, or even incorrect and outdated ages. The methods used to determine age – based on radioactive decay or looking at microscopic fossils with known ages – are continuously improved by scientists. Therefore, today, the age of an impact event can be improved significantly from an initial analysis made, say, ten or 20 years ago.

Another problem involves impacts that have near identical ages with exactly the same uncertainty in age: known as “clustered ages”. The age of an impact crater may be, for example, 65.5 ± 0.5m years while another is be 66.1 ± 0.5m years. In this case, both craters might have the same true age of 65.8m years. Such craters have in some instances been produced by impacts of asteroids accompanied by small moons, or by asteroids that broke up in the Earth’s atmosphere.

The Manicouagan crater in Canada seen from the International Space Station/
NASA/Chris Hadfield

The double impact craters they produce can make it look like they hit a time when there were lots of asteroid impacts, when actually the craters were formed in the same event. In some cases, clustered impact craters are spaced too far apart to be explained as double impacts. So how could we explain them? The occasional collision of asteroids in the asteroid belt between Mars and Jupiter might trigger short-lived “showers” of asteroids impacting the Earth. Only a few of these showers are necessary to lead to the false impression of periodicity.

Fresh approach

In contrast to previous studies, we restricted our statistical analysis to 22 impact craters with very well defined ages from the past 260m years. In fact, these all have age uncertainties of less than 0.8%. We also accounted for impacts with clustered ages.

Our article, recently published in Monthly Notices of the Royal Astronomical Society, shows that, to the best of our current knowledge, asteroid impacts do not happen at regular intervals – they seem to occur randomly.

Of course, we can’t be sure that there isn’t any periodicity. But the good news is that, as more impact craters are dated with robust ages, the statistical analysis we did can be repeated over and over again – if there is such a pattern, it should become visible at some point.

The ConversationThat means that there is presently no way to predict when a large asteroid collision may once again threaten life on Earth. But then when it comes to facing the apocalypse, maybe not knowing is not so bad after all …

Sanna Alwmark, Doctoral Candidate of Lithosphere and Biosphere Science, Lund University and Matthias Meier, Swiss National Science Foundation Ambzione Fellow in Geochemistry, Astrophysics, Swiss Federal Institute of Technology Zurich

This article was originally published on The Conversation. Read the original article.

How to backup life on Earth ahead of any doomsday event

Jonathan Roberts, Queensland University of Technology

There are ten asteroids that the space organisation NASA said this month have been classified as “potentially hazardous” based on their size and their orbits in our Solar system.

NASA has now identified 693 near-Earth objects thanks to the Wide-field Infrared Survey Explorer spacecraft that’s been looking for potential threats to Earth since 2013.

The organisation doesn’t specify what kind of hazard these ten asteroids pose. But Earth has been hit by objects in the past, with devastating effects. Scientists largely agree that it was an asteroid or comet impact that started the chain of events that wiped out the dinosaurs around 60 million years ago.

This animation shows asteroids and comets observed by the Near-Earth Object Wide-field Survey Explorer (NEOWISE) mission.

Every year several previously unseen asteroids whizz past Earth, sometimes with only with a few days’ warning. This year two of these asteroids came very close to Earth, with one in May sailing past only 15,000km away. On cosmic scales, that was a very close shave.

But impacts from objects in space are just one of several ways that humanity and most of life on Earth could suddenly disappear.

We are already observing that extinctions are happening now at an unprecedented rate. In 2014 it was estimated that the extinction rate is now 1,000 times greater than before humans were on the Earth. The estimated number of extinctions ranges from 200 to 2,000 species per year.

From all of this very worrying data, it would not be a stretch to say that we are currently within a doomsday scenario. Of course, the “day” is longer than 24 hours but may be instead in the order of a century or two.

So what can we do about this potential prospect of impending doom? We can try to avoid some of the likely scenarios. We should act to tackle climate change and we can develop new asteroid-tracking systems and put in place a means to deflect an asteroid on a collision course with Earth.

But the threats we face are so unpredictable that we need to have a backup plan. We need to plan for the time after our doomsday and think about how a post-apocalyptic Earth may recover and humanity will flourish again.

A backup plan

Some efforts to backup life on our planet have already started. Since the 1970s scientists around the world began to store seeds of potentially endangered plants. There are now dozens of seed banks or vaults scattered around the world.

The most famous is the Svalbard Global Seed Vault, located on a remote Norwegian island about 1,300km from the North Pole. The location was deliberately chosen to afford the project safe and secure long-term storage in cold and dry rock vaults.

A risk of thawing at the Svalbard Global Seed Vault.
Flickr/Landbruks og matdepartementet, CC BY-ND

But there were reports earlier this year that the vault had suffered issues with water from the surrounding melting permafrost (caused by global warming) gaining entry to parts of the structure.

Less common are vaults for storing biological material from animals. There are a handful of so-called frozen zoos around the world. They store embryos, eggs, sperm and more recently DNA of endangered animals. So far, sperm, eggs and embryos that have been frozen for roughly 20 years have been shown to be viable.

All of the storage methods that involve freezing have the same problem that the material is at risk of thawing out if the freezing methods fail. Storing frozen biological material for centuries or even millennia on Earth is not realistic.

Humans can now sequence a whole genome of a living organism and the cost has reduced to the point where it costs less than US$1,000 to sequence the human genome. This process effectively turns the information from any organism’s cells into data.

If future scientists can create living DNA from the genome data and can then create living organisms from that DNA, then having the data alone may be sufficient to backup the Earth’s living organisms.

Where to store the backups?

But where should humanity store the backups? As French president Emmanuel Macron said recently, “there is no plan B because there is no planet B”, echoing 2014 comments from Ban Ki-moon when he was secretary general of the United Nations.

Backing up on Earth seems a high-risk strategy, equivalent to having a computer backup on an external hard drive that sits right next to your computer.

So given that the motivation for backing up Earth’s organisms is the likelihood of Earth itself suffering a catastrophe, it follows that our planet is not the best location for the backups. The partial flooding of the Svalbard Global Seed Vault illustrates that perfectly.

Perhaps the obvious place to locate the backups is in space.

Seeds have already been taken to space for short periods (six months) to test their viability back on Earth. These experiments so far have been motivated by the desire to eventually grow plants in space itself, on space stations, or on Mars.

Space is a harsh environment for biological material, where cells are exposed to potentially very high doses of radiation that will damage DNA. Storage of seeds in low Earth orbit is desirable as Earth’s magnetic field provides some protection from space radiation. Storage outside of this zone and in deep space would require other methods of radiation protection.

The other question is how you would get seeds and other biological material safely back to Earth after a global disaster. Now we get to the robotics that can help, as autonomous re-entry of biological material from orbit is totally feasible.

The tricky part is for our orbiting bio-backup to know when its cargo is required and where to send it to. Perhaps we need a global limited robot crew – such as David in the recent Alien films – that would wake up the orbiter when it is needed.

‘Hello, I’m David.’

Alternatively, it could be staffed by a rotating crew of wardens similar to the International Space Station. These people could carry out other important scientific work too.

Other locations in space for storage of biological material or data include the Moon, and the moons of our solar system’s gas planets asteroids or deep space itself on free flying spacecraft. Such projects have been proposed and groups around the world have begun planning such ventures.

The ConversationSo it seems that some people have already accepted the fate of humanity version 1.0 and that it will end sometime in the relative near term. The movement to create our backup ready for humanity version 2.0 has already begun.

Jonathan Roberts, Professor in Robotics, Queensland University of Technology

This article was originally published on The Conversation. Read the original article.

The new space race: why we need a human mission to Mars

Malcolm Walter, UNSW

If we want to know whether there is life beyond Earth then the quickest way to answer that question is to explore Mars. That exploration is currently being done by remote space probes sent from Earth.

The race is on though to send human explorers to Mars and a number of Earth-bound projects are trying to learn what life would be like on the red planet.

But the notion of any one-way human mission to Mars is nonsensical, as is the thought that we should colonise Mars simply because we are making a mess of Earth.

The first suggestion is pointless and unethical – we would be sending astronauts to their certain death – while the second would be a licence for us to continue polluting our home planet.

I believe we should go to Mars because of what we can learn from the red planet, and from developing the technologies to get people there safely.

The SpaceX entrepreneur Elon Musk last September outlined his vision for a mission to send people to Mars by 2022. But first he is planning to send people around the Moon.

I think Musk will send two space tourists around the Moon and back to Earth, not in 2018 as he has predicted, but probably within a decade. He has not yet experimented with having passengers aboard a rocket.

Our journey into space

It’s worth looking at how we got to where we are now in terms of humans in space and space exploration.

More than a billion people watched Apollo 11’s Neil Armstrong take humankind’s first step on another world.
NASA

The first footprint on another world was made by US astronaut Neil Armstrong on July 20, 1969 (US time) when he left the Eagle lunar lander and stepped onto the Moon.

One small step…

The Moon is as far as humans have explored in space but we’ve sent probes to explore the other planets in our Solar system, including Mars.

Several failed attempts were made to send a probe to Mars but the US Mariner 4 was the first to successfully photograph another planet from space when it made a flyby of Mars in July 1965.

The red planet Mars.
NASA

The USSR’s Mars 2 orbited Mars for three months in 1971 but its lander module crashed onto the planet. The lander of the Mars 3 mission also failed.

NASA’s Viking 1 performed the first successful landing on Mars, on July 20, 1976, followed by Viking 2 on September 3, 1976.

The dunes of Mars as seen by Viking 1.
NASA/JPL

The Viking missions were the first to search for life on that planet, since when others such as the Spirit and Opportunity rovers, which landed days apart in January 2004, have looked to see if Mars could have had life in the past.

No evidence of life has been found so far, but the techniques available now are far more advanced and we know much more about the planet. We do have abundant evidence of water on Mars.

The benefits of space exploration

Apart from looking for life, why bother with a mission to send humans to Mars? Many aspects of our modern lives would not be possible if it were not for our interest in space.

We rely on satellites for communication, timing and positioning. Satellites help to keep us safe from severe weather, especially in Australia.

The Apollo and other NASA missions led to developments in micro-electronincs that later made it into household devices such as calculators and home computers.

NASA has detailed many of the spinoffs it says stem from its research for exploration of space, which even include the dustbuster.

The modern household dustbuster has its origins in the Apollo Moon missions.
Shutterstock/Sergey Mironov

Intangible, but critical nonetheless, is the inspiration we derive from space exploration. It can be very significant in attracting young people to science and engineering, something needed more and more as our economies continue to transition to an ever higher-tech future.

In the US there was a large spike in tertiary enrolments in science and engineering during the Apollo missions to the Moon.

A new space race

We are using more and more sophisticated craft to explore Mars. It is a broadly international venture involving NASA, the European Space Agency (22 member nations), the Russian Federal Space Agency, the Indian Space Research Organisation, the China National Space Administration, and the Japan Aerospace Exploration Agency.

We are witnessing not only collaboration but competition. Which nation (or company?) will first return to the Moon and then land astronauts on Mars? It is beginning to look like a new space race.

Why focus on Mars? We already know that early in its history, more than three billion years ago, Mars had a surface environment much like that of Earth at the same time, featuring volcanoes, lakes, hot springs, and perhaps even an ocean in the northern hemisphere.

This animation shows how the surface of Mars might have appeared billions of years ago.

Life on Earth then was microbial, the evidence for which is preserved in 3.5 billion year old rocks in the Pilbara region of Western Australia.

So we are searching for microbes on Mars. Despite being microscopic, bacteria and their cousins the Archaea are complex organisms. Methane already discovered in the atmosphere of Mars hints at the presence of such life but is not definitive.

If there ever was life on Mars it may still be there, underground where it will be protected from cosmic and ultraviolet radiation. From time to time it might emerge on the surface in some of the gullies that seem to result from the breaching of underground aquifers.

It might not seem exciting to discover former or living microbes, but if we can demonstrate that they represent an independent origin of life the consequences will be profound.

We will be able to predict confidently that there will be life all over the universe. Somewhere out there will be intelligent beings. What might happen then currently lies in the realm of science fiction.

The ConversationThe future lies in more missions to Mars. So far all missions have been one-way and robotic, but plans are underway for a mission to return samples from Mars, and sometime this century there will be astronauts on Mars, not in “colonies” but in research bases like those in Antarctica. It is inevitable.

Malcolm Walter, Professor of Astrobiology, UNSW

This article was originally published on The Conversation. Read the original article.

The seven most extreme planets ever discovered

Christian Schroeder, University of Stirling

Scientists recently discovered the hottest planet ever found – with a surface temperature greater than some stars. As the hunt for planets outside our own solar system continues, we have discovered many other worlds with extreme features. And the ongoing exploration of our own solar system has revealed some pretty weird contenders, too. Here are seven of the most extreme.

The hottest

How hot a planet gets depends primarily on how close it is to its host star – and on how hot that star burns. In our own solar system, Mercury is the closest planet to the sun at a mean distance of 57,910,000km. Temperatures on its dayside reach about 430°C, while the sun itself has a surface temperature of 5,500°C.

But stars more massive than the sun burn hotter. The star HD 195689 – also known as KELT-9 – is 2.5 times more massive than the sun and has a surface temperature of almost 10,000°C. Its planet, KELT-9b, is much closer to its host star than Mercury is to the sun.

Though we cannot measure the exact distance from afar, it circles its host star every 1.5 days (Mercury’s orbit takes 88 days). This results in a whopping 4300°C – which is hotter than many of the stars with a lower mass than our sun. The rocky planet Mercury would be a molten droplet of lava at this temperature. KELT-9b, however, is a Jupiter-type gas giant. It is shrivelling away as the molecules in its atmosphere are breaking down to their constituent atoms – and burning off.

The coldest

At a temperature of just 50 degrees above absolute zero – -223°C – OGLE-2005-BLG-390Lb snatches the title of the coldest planet. At about 5.5 times the Earth’s mass it is likely to be a rocky planet too. Though not too distant from its host star at an orbit that would put it somewhere between Mars and Jupiter in our solar system, its host star is a low mass, cool star known as a red dwarf.

Freezing but Earth-like: ESO OGLE BLG Lb.
ESO, CC BY-SA

The planet is popularly referred to as Hoth in reference to an icy planet in the Star Wars franchise. Contrary to its fictional counterpart, however, it won’t be able to sustain much of an atmosphere (nor life, for that matter). This because most of its gases will be frozen solid – adding to the snow on the surface.

The biggest

If a planet can be as hot as a star, what then makes the difference between stars and planets? Stars are so much more massive than planets that they are ignited by fusion processes as a result of the huge gravitational forces in their cores. Common stars like our sun burn by fusing hydrogen into helium. But there is a form of star called a brown dwarf, which are big enough to start some fusion processes but not large enough to sustain them. Planet DENIS-P J082303.1-491201 b with the equally unpronounceable alias 2MASS J08230313-4912012 b has 28.5 times the mass of Jupiter – making it the most massive planet listed in NASA’s exoplanet archive. It is so massive that it is debated whether it still is a planet (it would be a Jupiter-class gas giant) or whether it should actually be classified as a brown dwarf star. Ironically, its host star is a confirmed brown dwarf itself.

The smallest

Just slightly larger than our moon and smaller than Mercury, Kepler-37b is the smallest exoplanet yet discovered. A rocky world, it is closer to its host star than Mercury is to the sun. That means the planet is too hot to support liquid water and hence life on its surface.

The oldest

PSR B1620-26 b, at 12.7 billion years, is the oldest known planet. A gas giant 2.5 times the mass of Jupiter it has been seemingly around forever. Our universe at 13.8 billion years is only a billion years older.

Artist’s impression of the biggest planet known.
NASA and G. Bacon (STScI)

PSR B1620-26 b has two host stars rotating around each other – and it has outseen the lives of both. These are a neutron star and a white dwarf, which are what is left when a star has burned all its fuel and exploded in a supernova. However, as it formed so early in the universe’s history, it probably doesn’t have enough of the heavy elements such as carbon and oxygen (which formed later) needed for life to evolve.

The youngest

The planetary system V830 Tauri is only 2m years old. The host star has the same mass as our sun but twice the radius, which means it has not fully contracted into its final shape yet. The planet – a gas giant with three quarters the mass of Jupiter – is likewise probably still growing. That means it is acquiring more mass by frequently colliding with other planetary bodies like asteroids in its path – making it an unsafe place to be.

The worst weather

Because exoplanets are too far away for us to be able to observe any weather patterns we have to turn our eyes back to our solar system. If you have seen the giant swirling hurricanes photographed by the Juno spacecraft flying over Jupiter’s poles, the largest planet in our solar system is certainly a good contender. However, the title goes to Venus. A planet the same size of Earth, it is shrouded in clouds of sulfuric acid.

The ConversationThe atmosphere moves around the planet much faster than the planet rotates, with winds reaching hurricane speeds of 360km/h. Double-eyed cyclones are sustained above each pole. Its atmosphere is almost 100 times denser than Earth’s and made up of over 95% carbon dioxide. The resulting greenhouse effect creates hellish temperatures of at least 462°C on the surface, which is actually hotter than Mercury. Though bone-dry and hostile to life, the heat may explain why Venus has fewer volcanoes than Earth.

Christian Schroeder, Lecturer in Environmental Science and Planetary Exploration, University of Stirling

This article was originally published on The Conversation. Read the original article.

Mission to the sun will protect us from devastating solar storms and help us travel deeper into space

David Jess, Queen’s University Belfast

From prayer and sacrifice to sunbathing, humans have worshipped the sun since time immemorial. And it’s no wonder. At around 150m km away, it is close enough to provide the light, heat and energy to sustain the entire human race. But despite the fact that our parent star has been studied extensively with modern telescopes – both from home and in space – there’s a lot we don’t know about it.

This is why NASA has recently announced plans to launch a revolutionary probe, set to lift-off in 2018, that will literally touch it. Initially dubbed the Solar Probe Plus mission, the spacecraft has now been renamed the Parker Solar Probe. This is to honour physicist Eugene Parker who carried out important work on the solar wind – a stream of charged particles from the sun.

Helios 2 mission.
NASA

There have been many missions to investigate the sun. In 1976, the Helios 2 spacecraft came as close as 43m km from the sun’s atmosphere. But the $1.5 billion Parker probe will travel to just 6m km above the solar surface – some nine times closer than any spacecraft has ever gone before. This will open a new era of understanding as, for the first time, sensors will be able to detect and analyse phenomena as they occur in the sun.

While the cruising altitude of the mission may sound like a safe distance at millions of kilometres, the sun’s immense energy will relentlessly bombard the payload with heat. An 11.5cm thick carbon composite shroud, similar to what modern Formula 1 race cars employ in their high-performance braking systems, will shield the sensitive equipment. This will be crucial as temperatures will soar beyond 1,400°C.

At these extreme temperatures, the solar arrays that power the spacecraft will retract. This manoeuvre will allow the instruments and power sources to remain close to room temperature in the shadow of the carbon composite shield. Just as well, as the spacecraft will experience radiation 475 times more intense than Earth orbit.

Any errors in the planned spacecraft trajectories could result in the probe sinking deeper into the sun’s atmosphere, which is several million degrees hot. This could ultimately destroy the spacecraft.

Solar science

So what can we learn from this risky mission? The dynamic activity brought about by supercharged particles and radiation being released from the sun – encountering the Earth as they pass through the inner solar system – is called space weather. The consequences of space weather can be catastrophic, including the loss of satellite communications, changes to the orbits of spacecraft around Earth and damaging surges throughout global power grids. Most important is the risk to astronauts exposed to the powerful ionising radiation.

The devastating cost of such fierce electromagnetic storms has been estimated at $2 trillion, resulting in space weather being formally listed in the UK’s National Risk Registry.

Parker probe.
NASA

The new solar probe will revolutionise our understanding of what conditions are necessary in the sun’s atmosphere to generate severe bouts of space weather by making direct measurements of the magnetic fields, plasma densities and atmosphere temperatures for the first time. In a similar way to how an elastic band can snap following excessive stretching, it is believed that the continual twisting and churning of the magnetic field lines that permeate the solar atmosphere may give rise to particle acceleration and radiation bombardment. Once the magnetic fields break, we can experience severe space weather.

Unfortunately, we presently have no direct method of sampling the sun’s magnetic fields. Scientists are attempting to uncover new techniques that will allow the twists, strengths and directions of the sun’s powerful fields to be determined, but so far they can’t provide an accurate enough understanding. This is where the Parker probe will provide a new age of understanding, since it will be able to sample the sun’s powerful magnetic fields while there.

Round-the-clock observations and direct measurements of the atmospheric conditions responsible for increased levels of space weather are paramount in order to provide crucial warning of imminent solar threats. An instrument suite on-board the probe, the FIELDS suite, will provide such unprecedented information. Scientists can then feed this into intensive computer models, ultimately allowing space, aviation, power and telecommunication authorities to be alerted when potentially devastating space weather is imminent.

Of course, understanding the origins of space weather also has implications for other important areas of astrophysical research. It will allow space agencies to better protect astronauts during future manned missions to Mars, where the thinner Martian atmosphere offers little protection to incoming solar radiation.

The ConversationAlso, by being able to accurately model the effects of the streaming solar wind, future spacecraft will be able to effectively use solar sails to help them reach further into the depths of the solar system, perhaps eventually opening up the possibility of truly interstellar travel.

David Jess, Lecturer and STFC Ernest Rutherford Fellow, Queen’s University Belfast

This article was originally published on The Conversation. Read the original article.

The first results from the Juno mission are in – and they already challenge our understanding of Jupiter

Leigh Fletcher, University of Leicester

Ten months after its nerve-wracking arrival at Jupiter, NASA’s Juno mission has started to deliver – forcing scientists to reevaluate what they thought they knew about the giant planet. The first findings from Juno, published in Science, indicate that many aspects of Jupiter have defied expectation – including the strength of its magnetic field, the shape of its core, the distribution of ammonia gas and the weather at its poles. It certainly makes this an exciting time to be a Jupiter scientist. The Conversation

Juno arrived at Jupiter in July 2016, and began a long, looping first orbit that took it far out from the planet before zipping back in for its first scientific close-up (perijove) on August 27. It is this fleeting meeting that the new studies are based on. Today, despite initial problems with Juno’s engine and spacecraft software, the mission has settled into a regular pattern of close perijoves every 53.5 days – the sixth such flyby happened on May 19, the seventh will be on July 11.

Mysteries in the deep

Jupiter seen by Juno.
Credits: NASA/JPL-Caltech/SwRI/MSSS/Gabriel Fiset

One of Juno’s key strengths is its ability to peer through the overlying shroud of clouds to study the gases below, such as the cloud-forming substance ammonia. Flows of ammonia help form Jupiter’s distinctive features. The gas was expected to be well mixed, or drenched, below the topmost clouds. That idea has been turned on its head – the ammonia concentration is much less than expected.

Intriguingly, much of the ammonia is concentrated into an equatorial plume, rising from the depths of Jupiter to the cloud-tops due to some powerful up-welling force. Scientists are likening this to Earth’s Hadley cell, with plumes dredging ammonia up from hundreds of kilometres below.

We’ve known that ammonia is enhanced at Jupiter’s equator for some time, but we never knew how deep this column went. However, it’s important to remember that this is only one location on Jupiter, and that Earth-based infrared observations suggest that the plume may not be this strong elsewhere around Jupiter’s equator, but could be patchy. Only with more perijove passes will we begin to understand the strange dynamics of Jupiter’s tropics.

We’ve never been able to see this deep before, so even the first observations from Juno’s microwave instrument provide a treasure trove of new insights. These show that the banded structure that we see at the surface is really just the tip of the iceberg – Jupiter exhibits banding all the way down to 350km. This is much deeper than what we’ve generally thought of as Jupiter’s “weather layer” in the upper few tens of kilometres. What’s more, that structure isn’t the same all the way down – it varies with depth, indicating a large, complex circulation pattern.

Gravity and magnetic fields

The surprises didn’t stop here. Juno can probe even deeper into the planet by monitoring small tweaks to the spacecraft’s orbit by the gravity field of Jupiter’s interior. Ultimately, these will be used to assess Jupiter’s core, although that cannot be done from a single perijove pass. Most scientists believe that the planet has a dense core made up of around ten Earth masses of heavy elements and occupying a small fraction of the radius. But the new measurements are inconsistent with any previous model – possibly hinting at a “fluffy” core dispersed out to half of Jupiter’s radius.

Indeed, Jupiter’s interior appears to be anything but uniform. We have to remember that scientists have spent years developing models of the interior of Jupiter based on sparse data taken from great distances – Juno is now testing these models to the extreme because it is flying so close.

Infrared image showing Jupiter’s aurora (blue) and internal glow (red).
Credit: NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM

Jupiter has the most intense planetary magnetic field in the solar system, causing a pile-up where the solar wind is slowed down (known as the bow shock). Juno first passed through this region and into the Jovian magnetosphere on June 24. At its closest approach, the strength of Jupiter’s magnetic field was twice as strong as any model had predicted and much more irregular.

That’s important, because it suggests that the magnetic field could be generated at shallower depths than expected, above the “metallic hydrogen” layer that is thought to exist at very high pressures. If proven, this has substantial implications for studies of magnetic fields at all of the giant planets. Perhaps the Cassini mission will be able to confirm whether this is the case as it makes its final measurements of Saturn’s magnetic field before it crashes into the planet in September.

Chaos at the poles

If you’ve ever been lucky enough to see Jupiter through a telescope, you’ll be familiar with the organised, striped structure of whiter zones and dark brown belts. These colourful bands are bordered by powerful jet streams whizzing east and west around the planet. On Saturn, this organised, banded structure persists all the way to the poles, with one jet showing a strange hexagonal wave pattern encircling a hurricane-like polar cyclone. But Jupiter’s poles are different. Gone is the organised structure of jets. There’s no evidence for hexagons or anything like it. And instead of one cyclone, we see multitudes, surrounded by a whole host of chaotic and turbulent features.

Jupiter’s poles.
J.E.P. Connerney et al., Science (2017)]

With the ability to see structures as small as 50km, Juno’s camera has revealed numerous bright cyclones of a variety of appearances – some appear sharp, some have clear spirals, some are fluffy and diffuse, and the largest is some 1400km across. That’s about the same distance between London and Majorca. These bright storms sit on top of dark clouds, giving the appearance of “floating” on a dark sea, and it will be some time before we understand the lifetimes and motions of these storms.

You might imagine that, faced with throwing out models that have taken careers to develop, scientists might be a little glum. But the exact opposite is true. A mission like Juno, accessing regions that no robotic spacecraft has ever probed before, is designed to test the models to the extreme. If they break, then the search to find the missing pieces of the puzzle will provide deeper insights into the physics of the Jovian system. All these surprises have come from just the first perijove encounter, and I’m sure there are plenty more revelations to come.

Leigh Fletcher, Royal Society Research Fellow, University of Leicester

This article was originally published on The Conversation. Read the original article.