Category Archives: Celestial Bodies

Ethiopia’s inhospitable Danakil Depression gives us clues about life on Mars


Barbara Cavalazzi, University of Bologna

The Danakil Depression, including the Dallol volcanic area is one of the most remote, inhospitable and poorly studied areas in the world. The Conversation

They are both found in the Afar Region of Ethiopia and are part of the East African Rift System – an active tectonic plate boundary that’s splitting apart plates at a rate of 7 mm per year. The combination of this area’s geology and environment make it a uniquely extreme place to do research. In collaboration with the Europlanet research team, I am investigating the geological and biological aspects of the Danakil Depression.

Our aim is to study microbes, specifically extremophiles – organisms that thrive in extreme environments. They can live in hot springs, acidic fields, salty lakes and polar ice caps – conditions that would kill humans, animals, and plants. Their existence suggests that life can develop mechanisms to withstand physical and chemical conditions like those on the planet Mars.

There’s no other natural environment like it. What we have found at the site is a combination of extreme physico-chemical parameters. Toxic gases saturate the air, the pH is extremely acidic and saline and metal concentrations are very high.

In these extreme ecosystems we expect to find microbial life in the form of extremophiles, polyextremophiles and potentially new forms of polyextremophiles – these are extremophilic organisms that can tolerate, or adapt, to a combination of physico-chemical parameters.

Harsh environment

This harsh environment was created by the splitting apart of the old African Plate into two plates – the Somali and Nubian Plates. In millions of years, these two plates will be definitively separated and a new ocean basin will form.

Much of the 40km by 10 km Danakil Depression lies between 150-100m below sea level. It’s therefore one of the lowest land areas on Earth. The Dallol volcano, in the northern part of the Danakil Depression, was formed in 1926 by a phreatic eruption. This is when groundwater is heated by magma – essentially, a steam eruption without the lava ejection. Dallol has an elevation of approximately 50m below sea level.

Barbara Cavalazzi collects samples at Dallol.

The Depression is known as the hottest place on Earth. It’s classified as a hyperarid climatic zone and is consistently hot throughout the year. In the Dallol, because of the area’s geothermal activity, the average daily temperature is 45°C. I have registered a temperature there of 55°C – when I had to stop working! The region’s precipitation ranges is very low with an average annual rainfall of only 100-200 mm. In the dry areas of South Africa there would be an average annual rainfall of at least 464mm.

Geothermally heated groundwater rises from the Earth’s crust to the surface, accumulating in the Dallol crater. This creates spectacular and colourful hot springs that are extremely acidic and salty. The area is also characterised by toxic sulphur and chlorine vapours as a result of natural degassing volcanic processes.

What can survive

Living organisms tend to be sensitive to drastic changes in their environments. The cells that make them up can be seriously compromised in extreme physical (relating to temperature, desiccation, radiation, and pressure) and (geo)chemical (such as salinity, pH or heavy metals) conditions.

So what could survive in the Danakil’s harsh environment?

After a detailed study of the area, we have determined that there’s DNA evidence of microbial life. Life that, because of the similar extreme salty environment with volcanic origin, could be what’s surviving on Mars.

The microorganisms able to survive such extreme conditions must be a group of prokaryotes. All living things consist of two cell types: prokaryotes and eukaryotes. Organisms whose cells lack a nucleus and have DNA floating loosely in the liquid centre of the cell are prokaryotes. These are the most common and most ancient forms of life on earth.

What these microorganisms need is liquid water, metabolically suitable carbon, energy, and nutrient sources.

Barbara Cavalazzi, Professor in Geobiology and Astrobiology at the Biological, Geological, and Environmental Sciences-BiGeA of the University of Bologna, Italy, and visiting lecturer at University of Johannesburg, South Africa., University of Bologna

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

Planet or dwarf planet: all worlds are worth investigating


Tanya Hill, Museum Victoria

Pluto’s status as a “dwarf planet” is once again stirring debate. This comes as some planetary scientists are trying to have Pluto reclassified as a planet – a wish that’s not likely to come true. The Conversation

Pluto has been known as a dwarf planet for more than a decade. Back in August 2006 astronomers voted to shake up the Solar System, and the number of planets dropped from nine to eight. Pluto was the one cast aside.

There was some outcry that Pluto had been destroyed in an instant and was no longer important, and the reverberations were most keenly felt across America.

After all, Pluto was “their planet”, discovered in 1930 through the meticulous observations of American astronomer Clyde Tombaugh at the Lowell Observatory in Arizona.

At the time of the vote, NASA’s New Horizons spacecraft was only seven months into its nine-year journey to Pluto. There was concern that when it finally arrived, would people even care about a dwarf planet?

For many astronomers, the demotion of Pluto was a defining moment. It wasn’t a gesture of destruction and it wasn’t aimed specifically at Pluto. What it signalled was a major leap forward.

In that moment the world’s astronomers acknowledged significant progress in our understanding of the Solar System, an achievement to be proud of – even if everyone was not entirely happy.

What’s in a name?

The first step to understanding a group of objects is to classify them. We group like with like to examine the aligned characteristics or any significant differences between groups. With this insight comes a deeper understanding of how things work, form or evolve.

The planets were originally grouped together because the ancient Greeks saw them as “the wanderers”, travelling across the sky. Five bright objects – Mercury, Venus, Mars, Jupiter and Saturn – may have looked like stars, but while stars stayed fixed within their constellations, these planets moved independently from them.

The cause of this planetary motion was eventually established by the Polish astronomer Nicolaus Copernicus in the 16th century, bringing with it a new revelation. Planets were more than wanderers, they were objects in orbit about the Sun and with this understanding Earth became a planet too.

Earth became a planet too, once the ‘wanderers’ were understood.
NASA/Reid Wiseman

Defining a planet in the 21st century

More than 400 years and many discoveries later, a new storm began brewing in our understanding of the Solar System.

Since 1992, astronomers had begun to find objects orbiting the Sun out in the realm of Pluto. Were they planets too?

Conversely, Pluto was a bit of an oddball. It was smaller than several moons of other planets, and it had a highly inclined orbit that made it stand out from the others. Was it truly a planet or was it part of a much larger family of objects?

With the discovery of Eris (originally known by its designation 2003 UB313) in 2003, a decision could no longer be avoided. Eris was about the size of Pluto and certainly more massive. Was Eris a planet? And if not, where did that leave Pluto?

Astronomers have a forum for such deliberations via the International Astronomical Union (IAU). Representing astronomers worldwide, the IAU is the recognised authority responsible for naming and classifying planetary bodies and their satellites.

The IAU formed a Planet Definition Committee to consider the scientific, cultural and historical issues at hand. A draft proposal was put forward, and during the 2006 IAU General Assembly in Prague, with the world’s astronomers gathered together, the Committee’s proposal was vigorously debated.

A revised proposal was presented to the IAU membership on the final day of the General Assembly and was passed with a large majority.

Astronomers raise their yellow cards and Pluto becomes a dwarf planet.
Martin George

For the first time, a planet was formally recognised as being “a celestial body that”:

(a) is in orbit around the Sun

(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape

© has cleared the neighbourhood around its orbit.

Since Pluto had not “cleared the neighbourhood around its orbit”, it was not a planet but would be recognised as a “dwarf planet”.

A colleague of mine, Martin George, director of the Launceston Planetarium, was there when the vote was taken and captured the excitement and the nuance of the event.

There was quite a buzz in the room and we knew we were about to make history. Did everyone agree on the exact wording? Perhaps not. However, I think it would have been worse to see media headlines reading ‘Astronomers cannot decide what a planet is’.

Size matters and location too

The distinction of planet and dwarf planet brings a consistency to how objects are named across the universe. On the grand scale, there are galaxies and there are dwarf galaxies.

Within our Milky Way Galaxy, the Sun is a yellow dwarf star that in billions of years will evolve to become a red giant before ending its life as a white dwarf.

The Milky Way and its neighbouring dwarf galaxies, the Large and Small Magellanic Clouds seen in the lower left.
ESO/C. Malin

These distinctions among galaxies and stars helps astronomers interpret and understand them, tracing their evolution.

Planets and dwarf planets are distinct because of their size and their location in the solar system. It provides a way to examine how planets and dwarf planets may have originated and evolved differently.

Planetary resemblance

At present, the IAU has officially recognised five dwarf planets. They are Pluto, Eris, Makemake and Haumea, which orbit the Sun beyond Neptune, and Ceres, which is the only object in the asteroid belt massive enough to be spherical.

The dwarf planets compared to Earth.
NASA

Detractors and also supporters of the standing planet definition can point to problems with it. For instance, it only applies to objects orbiting the Sun. But what about exoplanets? And what is meant by “cleared its neighbourhood”? If Earth was located farther away from the Sun, would it be able to clear its orbit?

But, as astrophysicist Ethan Seigal explains, minor qualifications to the planet definition can bring it in line with exoplanets and allows the definition to work with renewed clarity.

Whereas the latest proposal to reinstate Pluto, advocates a geophysical definition of planet. Namely, that a planet should be large enough to be round, but not so big that it is a star. This broad definition casts the net wide, and not only Pluto, but also the Moon and more than 100 other Solar System objects would become planets.

There are many Solar System objects smaller than Earth.
primefac

Now wouldn’t that be a leap backwards in regards to structuring and understanding our Solar System? How much of it is driven by the notion that nothing but a planet is worth exploration?

There’s a plethora of “not-planets” in our Solar System that are worlds worthy of attention. This includes the fiery volcanoes of Io, the icy geysers of Enceladus, the reddish surface of Makemake, the crazy spin of Haumea and the mystery of hundreds of worlds unknown orbiting beyond Neptune.

So let the official word on planets and dwarf planets be as passed in 2006 and let our exploration of the Solar System continue to amaze us.

Tanya Hill, Honorary Fellow of the University of Melbourne and Senior Curator (Astronomy), Museum Victoria

Fly me to the Moon? Why the world should be wary of Elon Musk’s space race


Alan Marshall, Mahidol University

Want to fly to the moon? Well, now you won’t have to bother with all those years of rigorous astronaut training – all you need is a huge wad of cash. Elon Musk, technopreneur, has built a small spaceship called Dragon and if you slap down enough money – maybe a hundred million dollars or so – he’ll fly you to the Moon. The Conversation

The first flight is set for 2018, a target so ambitious it verges on the incredible.

Musk’s moonshot plan has been greeted enthusiastically by most space fans but some are a little doubtful. Other commentators remain totally uninspired, ridiculing the idea as a gigantic waste of money.

This ambivalence isn’t surprising really, since history shows that soon after the Apollo 11 moon landing in 1969, people switched their televisions to more down-to-earth events while wondering why NASA kept going back to the Moon again and again with Apollo 12, then Apollo 13, then Apollo 14 – all the way up to Apollo 17.

Natural process, or a social one?

Musk would tell you he’s not using taxpayer funds for his moonshot and that his SpaceX venture is a private commercial business. But SpaceX’s only significant customer so far has been NASA – a taxpayer-funded agency that pays it to deliver cargo to the International Space Station.

And even before SpaceX had delivered anything, NASA made a massive investment in the firm to get it up and running. Any claim that SpaceX is purely a commercial business, then, is also incredible.

Like many space fans, Musk will tell you that this moonshot is the first step in the “natural process” of human space expansion. The next steps involve the colonisation of the Moon and then Mars.

But space travel is not a natural process; it’s a social process involving domestic politics, international competition, the marketing of patriotic heroism, and the divvying up of state funds.

Harkening back to the dark past

The “colonisation” theme of space expansion is also problematic since it signifies a potential re-emergence of the social injustices and environmental disasters wrought by past colonial ventures. Being a fan of “space colonisation”, then, can be likened to rejoicing in the displacement of native peoples and celebrating the destruction of wilderness.

Unfortunately, too often space expansion has utilised historic conquests to map out the future; witness Star Trek’s Space: the Final Frontier theme, or Musk’s own idea to colonise Mars.

Calling for a new “age of exploration” in space recalls past voyages of discovery ignores how Chritopher Columbus decimated native tribes with smallpox and how Spanish conquistadors ransacked Meso-America’s temples to loot gold.

Space fans might argue that there are no people in space to be colonised, that the Moon and Mars are uninhabited lands. But the plan to settle Mars, for example, and then to set about extracting valuable resources without working out if some alien species is living there – even if those life forms are microbial – seems reckless.

It also smacks of anthropocentrism since humans will doubtless carry to Mars the attitude that microbes are lower lifeforms and that it’s OK to stomp all over their planet spreading pollution and mucking up their environment.

Even if they are lifeless, we should consider that the Moon and Mars belong to all of us; they are the common heritage of humankind. And those who first to get to the Moon or to Mars shouldn’t be permitted to plunder these worlds just for the sake of their own adventure or profit.

An alliance of interests

One prominent fan of American space expansion is US President Donald Trump. “Space is terrific,” he said in Florida last year. Trump also called for more space exploration in his recent speech to Congress.

Many scientists are wary of Trump’s attitude to science but, in a surprising willingness to embrace both science and the wider universe beyond America, the president wants NASA to “explore the mysteries of deep space”.

In the process, Trump is also working out how to rid NASA of the those pesky climate scientists who, he claims, are peddling “politicised” science.

Trump met Elon Musk within days of assuming the presidency and, with their shared love of capitalism and penchant for self-promotion, they seem to be entering a working relationship, described by some as cronyism.

Trump seems willing to support Musk if the entrepreneur can help Make America Great Again by shooting Americans off to the Moon before China gets there. Musk may seem confident about his 2018 plans because he believes he has presidential blessing.

A note of caution

But perhaps it’s too soon to worry about Moon grabs or Martian colonialism.

First, both Trump and Musk are notorious “big talkers” and they may be playing with the macho spectacle of space travel. If their space plans gurgle into an economic sinkhole, they’ll probably quietly abandon them.

And the 2018 moonshot is not going to actually land on the Moon; it’s merely going to shoot around it and then head back to Earth. Nobody will get the chance to plant a flag.

Space tourism, moon bases and Martian colonies have all been predicted for decades and nothing has ever come of them. Wernher von Braun, the Apollo rocket hero (and ex-Nazi) showcased such prospective space endeavours on a television show with Walt Disney in the 1950s (using whizzing Disney graphics). But 70 years later, a space colony is nowhere to be found.

An outright Moon grab would also be illegal, since the 1967 UN Outer Space Treaty forbids such acts. The US has re-interpreted this treaty to suggest that it permits resource extraction from the Moon and the planets in the Solar System, but not all nations accept this view.

Not what we all want

If Musk does get his rich clients to circle the Moon next year, and then manages to set up bases and colonies on the lunar surface and then Mars, it won’t be because he’s made a business success out of space expansion. And it won’t be due to the scientific merit of moon bases.

Rather, it will be because he has managed to dupe the American taxpayer with expensive technological fantasies and because he’s broken the ideal of the common heritage of mankind enshrined in international law. Humanity and the Earth will be diminished in the process.

It’s possible the cosmos will be diminished and despoiled too with mining firms digging up the moonscape, rocket fuel spilled all over the Martian surface, and neon lights flashing in shiny space casinos.

Of course, some space fans believe the only way they’ll realise their space fantasies is to ride behind the glory of “visionaries” such as Musk – and the unknown mega-rich space passengers set to shoot off around the Moon next year.

But the Earth abounds with those willing to poke fun at such showy space adventures, which is good – Musk needs to know that not everybody is on board.

Alan Marshall, Lecturer in Environmental Social Sciences, Faculty of Social Sciences and Humanities, Mahidol University

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

It’s our Solar System in miniature, but could TRAPPIST-1 host another Earth?


Elizabeth Tasker, Japan Aerospace Exploration Agency (JAXA)

Scientists have discovered seven Earth-sized planets, so tightly packed around a dim star that a year there lasts less than two weeks. The number of planets and the radiation levels they receive from their star, TRAPPIST-1, make these worlds a miniature analogue of our own Solar System. The Conversation

The excitement surrounding TRAPPIST-1 was so great that the discovery was announced with an article in Nature accompanied by a NASA news conference. In the last two decades, nearly 3,500 planets have been found orbiting stars beyond our Sun, but most don’t make headlines.

How likely are we really to find a blue marble like our Earth among these new worlds?

Earth 2.0?

We still know little about these planets with certainty, but initial clues look enticing.

All seven worlds complete an orbit in between 1.5 and 13 days. So closely are they huddled that a person standing on one planet might see the neighbouring worlds in the sky even larger than our Moon. The short years place the planets closer to their star than any planet sits to the Sun. Happily, they avoid being baked by TRAPPIST-1 because it is incredibly dim.

TRAPPIST-1 is a small ultracool dwarf star with a luminosity roughly 1/1000th that of the Sun. Comparing the two at Wednesday’s news conference, lead author of the Nature paper, Michaël Gillon, said that if the Sun were scaled to the size of a basketball, TRAPPIST-1 would be a puny golf ball. The resulting paltry amount of heat means that three of the seven TRAPPIST-1 planets actually receive similar amounts of radiation as Venus, Earth and Mars.

This alternative Solar System does look like a compact version of our own, but does TRAPPIST-1 include an Earth 2.0?

Artists impression of the seven TRAPPIST-1 worlds, compared to our solar system’s terrestrial planets.
NASA/JPL-Caltech

Here’s the good news first.

The seven siblings are all Earth-sized, with radii between three quarters and one times that of our home planet and masses that range from roughly 50% to 150% of Earth’s (the mass of the outermost world remains uncertain).

Because all are smaller than 1.6 times Earth’s radius, the seven TRAPPIST-1 planets are likely to be rocky worlds, not gaseous Neptunes. TRAPPIST-1d, e and f are within the star’s temperate region — aka the “Goldilocks zone” where it’s not too hot and not too cold — where an Earth-like planet could support liquid water on its surface.

The orbits of the six inner planets are nearly resonant, meaning that in the time it takes for the innermost planet to orbit the star eight times, its outer siblings make five, three and two orbits.

Such resonant chains are expected around stars where the planets have moved from where they originally formed. This migration occurs when the planets are still young and embedded in the star’s gaseous planet-forming disc. As the gravity of the young planet and the gas disc pull on one another, the planet’s orbit can change, usually moving towards the star.

If multiple planets are in the system, their gravity also pulls on one another. This nudges the planets into resonant orbits as they migrate through the gas disc. The result is a string of resonant planets close to the star, just like that seen encircling TRAPPIST-1.

Being born far from the star offers a couple of potential advantages. Dim stars like TRAPPIST-1 are irritable when young, emitting flares and high radiation that may sterilise the surface of nearby planets. If the TRAPPIST-1 system did indeed form further away and migrate inwards, its worlds may have avoided getting fried.

Originating where temperatures are colder would also mean the planets formed with a large fraction of ice. As the planets migrate inwards, this ice could melt into an ocean. This notion is supported by the estimated densities of the planets, which are low enough to suggest volatile-rich compositions, like water or a thick atmosphere.

Not an Earth?

Since our search for extraterrestrial life focuses on the presence of water, melted icy worlds seem ideal.

But this may actually bode ill for habitability. While 71% of the Earth’s surface is covered by seas, water makes up less than 0.1% of our planet’s mass. A planet with a high fraction of water may become a water world: all ocean and no exposed land.

Deep water could also mean there’s a thick layer of ice on the ocean floor. With the planet’s rocky core separated from both air and sea, no carbon-silicate cycle could form – a process that acts as a thermostat to adjust the level of warming carbon dioxide in the air on Earth.

If the TRAPPIST-1 planets can’t compensate for different levels of radiation from their star, the temperate zone for the planet shrinks to a thin strip. Any little variation, from small ellipicities in the planet’s orbit to variations in the stellar brightness, could turn the world into a snowball or baked desert.

Jupiter’s moon Io, is in resonance with moons Europa and Ganymede, and its tidal heating powers its volcanoes.
NASA/JPL/University of Arizona

Even if the oceans were sufficiently shallow to avoid this fate, an icy composition might produce a very strange atmosphere. On the early Earth, air was spewed out in volcanic plumes. If a TRAPPIST-1 planet’s interior is more akin to a giant comet than to a silicate-rich Earth, the air expelled risks being rich in the greenhouse gases of ammonia and methane. Both trap heat at the planet’s surface, meaning the best location for liquid water might actually be in a region cooler than the “Goldilocks zone”.

Finally, the TRAPPIST-1 system’s orbits are problematic. Situated so close to the star, the planets are likely in tidal lock – with one face permanently turned towards the star – resulting in perpetual day on one side and everlasting night on the other.

Not only would this be weird to experience, the associated extremes of temperatures could also evaporate all water and collapse the atmosphere if the planet’s winds are unable to redistribute heat.

Also, even a small ellipticity in the planets’ seemingly circular orbits could power a second kind of warmth, called tidal heating, making the planets into Venus-like hothouses. Slight elongations in the planet’s path around its star would cause the pull from the star’s gravity to strengthen and weaken during its year, flexing the planet like a stress ball and generating tidal heat.

This process occurs on three of Jupiter’s largest moons whose mildly elliptical paths are caused by resonant orbits similar to the TRAPPIST-1 worlds. In Europa and Ganymede, the flexing heat allows subsurface liquid oceans to exist. But Jupiter’s innermost moon, Io, is the most volcanic place in our Solar System.

If the TRAPPIST-1 planets’ orbits are similarly bent, they could turn out to be sweltering.

The view from here

So how will we ever know what the TRAPPIST-1 planets are really like? To investigate the possible scenarios, we need to take a look at the atmosphere of the TRAPPIST-1 siblings.

TRAPPIST-1 was named for the Belgian 60cm TRAnsiting Planets and Planetesimal Small Telescope in Chile that detected the star’s first three planets last year (it also happens to be the name of a type of Belgian beer). As the name suggests, both the original three worlds and four new planetary siblings were discovered using the transit technique; the tiny dip in starlight as the planets passed between the star and the Earth.

Transiting makes the planets excellent candidates for the next generation of telescopes with their ability to identify molecules in the planet’s air as starlight passes through the gas. The next five years may therefore give us the first real look at a rocky planet with a very different history to anything in our Solar System.

Thomas Zurbuchen, associate administer of the Science Mission Directorate at NASA, declared the discovery of TRAPPIST-1 as, “A leap forward to answering ‘are we alone?’”.

But the real treasure of TRAPPIST-1 is not the possibility that the planets may be just like the one we call home; it’s the exciting thought that we might be looking at something entirely new.

Elizabeth Tasker, Associate Professor, Japan Aerospace Exploration Agency (JAXA)

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

Tiny satellites poised to make big contributions to essential science


Tiny satellites, some smaller than a shoe box, are currently orbiting around 200 miles above Earth, collecting data about our planet and the universe. It’s not just their small stature but also their accompanying smaller cost that sets them apart from the bigger commercial satellites that beam phone calls and GPS signals around the world, for instance. These SmallSats are poised to change the way we do science from space. Their cheaper price tag means we can launch more of them, allowing for constellations of simultaneous measurements from different viewing locations multiple times a day – a bounty of data which would be cost-prohibitive with traditional, larger platforms.

Called SmallSats, these devices can range from the size of large kitchen refrigerators down to the size of golf balls. Nanosatellites are on that smaller end of the spectrum, weighing between one and 10 kilograms and averaging the size of a loaf of bread.

Starting in 1999, professors from Stanford and California Polytechnic universities established a standard for nanosatellites. They devised a modular system, with nominal units (1U cubes) of 10x10x10 centimeters and 1kg weight. CubeSats grow in size by the agglomeration of these units – 1.5U, 2U, 3U, 6U and so on. Since CubeSats can be built with commercial off-the-shelf parts, their development made space exploration accessible to many people and organizations, especially students, colleges and universities. Increased access also allowed various countries – including Colombia, Poland, Estonia, Hungary, Romania and Pakistan – to launch CubeSats as their first satellites and pioneer their space exploration programs.

Initial CubeSats were designed as educational tools and technological proofs-of-concept, demonstrating their ability to fly and perform needed operations in the harsh space environment. Like all space explorers, they have to contend with vacuum conditions, cosmic radiation, wide temperature swings, high speed, atomic oxygen and more. With almost 500 launches to date, they’ve also raised concerns about the increasing amount of “space junk” orbiting Earth, especially as they come almost within reach for hobbyists. But as the capabilities of these nanosatellites increase and their possible contributions grow, they’ve earned their own place in space.

From proof of concept to science applications

When thinking about artificial satellites, we have to make a distinction between the spacecraft itself (often called the “satellite bus”) and the payload (usually a scientific instrument, cameras or active components with very specific functions). Typically, the size of a spacecraft determines how much it can carry and operate as a science payload. As technology improves, small spacecraft become more and more capable of supporting more and more sophisticated instruments.

These advanced nanosatellite payloads mean SmallSats have grown up and can now help increase our knowledge about Earth and the universe. This revolution is well underway; many governmental organizations, private companies and foundations are investing in the design of CubeSat buses and payloads that aim to answer specific science questions, covering a broad range of sciences including weather and climate on Earth, space weather and cosmic rays, planetary exploration and much more. They can also act as pathfinders for bigger and more expensive satellite missions that will address these questions.

I’m leading a team here at the University of Maryland, Baltimore County that’s collaborating on a science-focused CubeSat spacecraft. Our Hyper Angular Rainbow Polarimeter (HARP) payload is designed to observe interactions between clouds and aerosols – small particles such as pollution, dust, sea salt or pollen, suspended in Earth’s atmosphere. HARP is poised to be the first U.S. imaging polarimeter in space. It’s an example of the kind of advanced scientific instrument it wouldn’t have been possible to cram onto a tiny CubeSat in their early days.

HARP spacecraft and payload at different stages of development.
Spacecraft: SDL, Payload:UMBC, CC BY-ND

Funded by NASA’s Earth Science Technology Office, HARP will ride on the CubeSat spacecraft developed by Utah State University’s Space Dynamics Lab. Breaking the tradition of using consumer off-the-shelf parts for CubeSat payloads, the HARP team has taken a different approach. We’ve optimized our instrument with custom-designed and custom-fabricated parts specialized to perform the delicate multi-angle, multi-spectral polarization measurements required by HARP’s science objectives.

HARP is currently scheduled for launch in June 2017 to the International Space Station. Shortly thereafter it will be released and become a fully autonomous, data-collecting satellite.

SmallSats – big science

HARP is designed to see how aerosols interact with the water droplets and ice particles that make up clouds. Aerosols and clouds are deeply connected in Earth’s atmosphere – it’s aerosol particles that seed cloud droplets and allow them to grow into clouds that eventually drop their precipitation.

Pollution particles lead to precipitation changes.
Martins, UMBC, CC BY-ND

This interdependence implies that modifying the amount and type of particles in the atmosphere, via air pollution, will affect the type, size and lifetime of clouds, as well as when precipitation begins. These processes will affect Earth’s global water cycle, energy balance and climate.

When sunlight interacts with aerosol particles or cloud droplets in the atmosphere, it scatters in different directions depending on the size, shape and composition of what it encountered. HARP will measure the scattered light that can be seen from space. We’ll be able to make inferences about amounts of aerosols and sizes of droplets in the atmosphere, and compare clean clouds to polluted clouds.

In principle, the HARP instrument would have the ability to collect data daily, covering the whole globe; despite its mini size it would be gathering huge amounts of data for Earth observation. This type of capability is unprecedented in a tiny satellite and points to the future of cheaper, faster-to-deploy pathfinder precursors to bigger and more complex missions.

HARP is one of several programs currently underway that harness the advantages of CubeSats for science data collection. NASA, universities and other institutions are exploring new earth sciences technology, Earth’s radiative cycle, Earth’s microwave emission, ice clouds and many other science and engineering challenges. Most recently MIT has been funded to launch a constellation of 12 CubeSats called TROPICS to study precipitation and storm intensity in Earth’s atmosphere.

For now, size still matters

But the nature of CubeSats still restricts the science they can do. Limitations in power, storage and, most importantly, ability to transmit the information back to Earth impede our ability to continuously run our HARP instrument within a CubeSat platform.

So as another part of our effort, we’ll be observing how HARP does as it makes its scientific observations. Here at UMBC we’ve created the Center for Earth and Space Studies to study how well small satellites do at answering science questions regarding Earth systems and space. This is where HARP’s raw data will be converted and interpreted. Beyond answering questions about cloud/aerosol interactions, the next goal is to determine how to best use SmallSats and other technologies for Earth and space science applications. Seeing what works and what doesn’t will help inform larger space missions and future operations.

The SmallSat revolution, boosted by popular access to space via CubeSats, is now rushing toward the next revolution. The next generation of nanosatellite payloads will advance the frontiers of science. They may never supersede the need for bigger and more powerful satellites, but NanoSats will continue to expand their own role in the ongoing race to explore Earth and the universe.

The Conversation

J. Vanderlei Martins, Professor of Physics, University of Maryland, Baltimore County

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

Is our Milky Way galaxy a zombie, already dead and we don’t know it?


Like a zombie, the Milky Way galaxy may already be dead but it still keeps going. Our galactic neighbor Andromeda almost certainly expired a few billion years ago, but only recently started showing outward signs of its demise.

Galaxies seem to be able to “perish” – that is, stop turning gas into new stars – via two very different pathways, driven by very different processes. Galaxies like the Milky Way and Andromeda do so very, very slowly over billions of years.

How and why galaxies “quench” their star formation and change their morphology, or shape, is one of the big questions in extragalactic astrophysics. We may now be on the brink of being able to piece together how it happens. And part of the thanks goes to citizen scientists who combed through millions of galactic images to classify what’s out there.

Galaxies grow by making new stars

Galaxies are dynamic systems that continually accrete gas and convert some of it into stars.

Like people, galaxies need food. In the case of galaxies, that “food” is a supply of fresh hydrogen gas from the cosmic web, the filaments and halos of dark matter that make up the largest structures in the universe. As this gas cools and falls into dark matter halos, it turns into a disk that then can cool even further and eventually fragment into stars.

As stars age and die, they can return some of that gas back into the galaxy either via winds from stars or by going supernova. As massive stars die in such explosions, they heat the gas around them and prevent it from cooling down quite so fast. They provide what astronomers call “feedback”: star formation in galaxies is thus a self-regulated process. The heat from dying stars means cosmic gas doesn’t cool into new stars as readily, which ultimately puts a brake on how many new stars can form.

Most of these star-forming galaxies are disk- or spiral-shaped, like our Milky Way.

Left: a spiral galaxy ablaze in the blue light of young stars from ongoing star formation; right: an elliptical galaxy bathed in the red light of old stars.
Sloan Digital Sky Survey, CC BY-NC

But there’s another kind of galaxy that has a very different shape, or morphology, in astronomer-parlance. These massive elliptical galaxies tend to look spheroidal or football-shaped. They’re not nearly so active – they’ve lost their supply of gas and therefore have ceased forming new stars. Their stars move on far more unordered orbits, giving them their bulkier, rounder shape.

These elliptical galaxies differ in two major ways: they no longer form stars and they have a different shape. Something pretty dramatic must have happened to them to produce such profound changes. What?

Blue=young and red=old?

The basic division of galaxies into star-forming spiral galaxies blazing in the blue light of massive, young and short-lived stars, on the one hand, and quiescent ellipticals bathed in the warm glow of ancient low-mass stars, on the other, goes back to early galaxy surveys of the 20th century.

But, once modern surveys like the Sloan Digital Sky Survey (SDSS) began to record hundreds of thousands of galaxies, objects started emerging that didn’t quite fit into those two broad categories.

A significant number of red, quiescent galaxies aren’t elliptical in shape at all, but retain roughly a disk shape. Somehow, these galaxies stopped forming stars without dramatically changing their structure.

At the same time, blue elliptical galaxies started to surface. Their structure is similar to that of “red and dead” ellipticals, but they shine in the bright blue light of young stars, indicating that star formation is still ongoing in them.

How do these two oddballs – the red spirals and the blue ellipticals – fit into our picture of galaxy evolution?

Galaxy Zoo allows citizen scientists to classify galaxies.
Screenshot by Kevin Schawinski, CC BY-ND

Send in the citizen scientists

As a graduate student in Oxford, I was looking for some of these oddball galaxies. I was particularly interested in the blue ellipticals and any clues they contained about the formation of elliptical galaxies in general.

At one point, I spent a whole week going through almost 50,000 galaxies from SDSS by eye, as none of the available algorithms for classifying galaxy shape was as good as I needed it to be. I found quite a few blue ellipticals, but the value of classifying all of the roughly one million galaxies in SDSS with human eyes quickly became apparent. Of course, going through a million galaxies by myself wasn’t possible.

A short time later, a group of collaborators and I launched galaxyzoo.org and invited members of the public – citizen scientists – to participate in astrophysics research. When you logged on to Galaxy Zoo, you’d be shown an image of a galaxy and a set of buttons corresponding to possible classifications, and a tutorial to help you recognize the different classes.

By the time we stopped recording classifications from a quarter-million people, each of the one million galaxies on Galaxy Zoo had been classified over 70 times, giving me reliable, human classifications of galaxy shape, including a measure of uncertainty. Did 65 out of 70 citizen scientists agree that this galaxy is an elliptical? Good! If there’s no agreement at all, that’s information too.

Tapping into the “wisdom of the crowd” effect coupled with the unparalleled human ability for pattern recognition helped sort through a million galaxies and unearthed many of the less common blue ellipticals and red spirals for us to study.

The galaxy color-mass diagram. Blue, star-forming galaxies are at the bottom, in the blue cloud. Red, quiescent galaxies are at the top, in the red sequence. The ‘green valley’ is the transition zone in between.
Schawinski+14, CC BY-ND

Unwittingly living in the green valley?

The crossroads of galaxy evolution is a place called the “green valley.” This may sound scenic, but refers to the population between the blue star-forming galaxies (the “blue cloud”) and the red, passively evolving galaxies (the “red sequence”). Galaxies with “green” or intermediate colors should be those galaxies in which star formation is in the process of turning off, but which still have some ongoing star formation – indicating the process only shut down a short while ago, perhaps a few hundred million years.

As a curious aside, the origin of the term “green valley” may actually go back to a talk given at the University of Arizona on galaxy evolution where, when the speaker described the galaxy color-mass diagram, a member of the audience called out: “the green valley, where galaxies go to die!” Green Valley, Arizona, is a retirement community just outside of the university’s hometown, Tucson.

For our project, the really exciting moment came when we looked at the rate at which various galaxies were dying. We found the slowly dying ones are the spirals and the rapidly dying ones are the ellipticals. There must be two fundamentally different evolutionary pathways that lead to quenching in galaxies. When we explored these two scenarios – dying slowly, and dying quickly – it became obvious that these two pathways have to be tied to the gas supply that fuels star formation in the first place.

Imagine a spiral galaxy like our own Milky Way merrily converting gas to stars as new gas keeps flowing in. Then something happens that turns off that supply of fresh outside gas: perhaps the galaxy fell into a massive cluster of galaxies where the hot intra-cluster gas cuts off fresh gas from the outside, or perhaps the dark matter halo of the galaxy grew so much that gas falling into it gets shock heated to such a high temperature that it cannot cool down within the age of the universe. In any case, the spiral galaxy is now left with just the gas it has in its reservoir.

Since these reservoirs can be enormous, and the conversion of gas to stars is a very slow process, our spiral galaxy could go on for quite a while looking “alive” with new stars, while the actual rate of star formation declines over several billion years. The glacial slowness of using up the remaining gas reservoir means that by the time we realize that a galaxy is in terminal decline, the “trigger moment” occurred billions of years ago.

A Hubble image of part of the Andromeda galaxy, which like our Milky Way may be a galactic zombie.
NASA, ESA, J. Dalcanton, B.F. Williams and L.C. Johnson (University of Washington), the PHAT team, and R. Gendler, CC BY

The Andromeda galaxy, our nearest massive spiral galaxy, is in the green valley and likely began its decline eons ago: it is a zombie galaxy, according to our latest research. It’s dead, but keeps on moving, still producing stars, but at a diminished rate compared to what it should if it were still a normal star-forming galaxy. Working out whether the Milky Way is in the green valley – in the process of shutting down – is much more challenging, as we are in the Milky Way and cannot easily measure its integrated properties the way we can for distant galaxies.

Even with the more uncertain data, it looks like the Milky Way is just at the edge, ready to tumble into the green valley. It’s entirely possible that the Milky Way galaxy is a zombie, having died a billion years ago.

The Conversation

Kevin Schawinski, Assistant Professor of Galaxy & Black Hole Astrophysics, Swiss Federal Institute of Technology Zurich

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

Do no harm to life on Mars? Ethical limits of the ‘Prime Directive’


NASA’s chief scientist recently announced that “…we’re going to have strong indications of life beyond Earth within a decade, and I think we’re going to have definitive evidence within 20 to 30 years.” Such a discovery would clearly rank as one of the most important in human history and immediately open up a series of complex social and moral questions. One of the most profound concerns is about the moral status of extraterrestrial life forms. Since humanities scholars are only just now beginning to think critically about these kinds of post-contact questions, naïve positions are common.

Take Martian life: we don’t know if there is life on Mars, but if it exists, it’s almost certainly microbial and clinging to a precarious existence in subsurface aquifers. It may or may not represent an independent origin – life could have emerged first on Mars and been exported to Earth. But whatever its exact status, the prospect of life on Mars has tempted some scientists to venture out onto moral limbs. Of particular interest is a position I label “Mariomania.”

Should we quarantine Mars?

Mariomania can be traced back to Carl Sagan, who famously proclaimed

If there is life on Mars, I believe we should do nothing with Mars. Mars then belongs to the Martians, even if the Martians are only microbes.

Chris McKay, one of NASA’s foremost Mars experts, goes even further to argue that we have an obligation to actively assist Martian life, so that it does not only survives, but flourishes:

…Martian life has rights. It has the right to continue its existence even if its extinction would benefit the biota of Earth. Furthermore, its rights confer upon us the obligation to assist it in obtaining global diversity and stability.

To many people, this position seems noble because it calls for human sacrifice in the service of a moral ideal. But in reality, the Mariomaniac position is far too sweeping to be defensible on either practical or moral grounds.

Streaks down Martian mountains are evidence of liquid water running downhill – and hint at the possibility of life on the planet.
NASA/JPL/University of Arizona, CC BY

A moral hierarchy: Earthlings before Martians?

Suppose in the future we find that:

  1. There is (only) microbial life on Mars.
  2. We have long studied this life, answering our most pressing scientific questions.
  3. It has become feasible to intervene on Mars in some way (for instance, by terraforming or strip mining) that would significantly harm or even destroy the microbes, but would also be of major benefit to humanity.

Mariomaniacs would no doubt rally in opposition to any such intervention under their “Mars for the Martians” banners. From a purely practical point of view, this probably means that we should not explore Mars at all, since it is not possible to do so without a real risk of contamination.

Beyond practicality, a theoretical argument can be made that opposition to intervention might itself be immoral:

  • Humans beings have an especially high (if not necessarily unique) moral value and thus we have an unambiguous obligation to serve human interests.
  • It is unclear if Martian microbes have moral value at all (at least independent of their usefulness to people). Even if they do, it’s certainly much less than that of human beings.
  • Interventions on Mars could be of enormous benefit to humankind (for instance, creating a “second Earth”).
  • Therefore: we should of course seek compromise where possible, but to the extent that we are forced to choose whose interests to maximize, we are morally obliged to err on the side of humans.

Obviously, there are a great many subtleties I don’t consider here. For example, many ethicists question whether human beings always have higher moral value than other life forms. Animal rights activists argue that we should accord real moral value to other animals because, like human beings, they possess morally relevant characteristics (for instance, the ability to feel pleasure and pain). But very few thoughtful commentators would conclude that, if we are forced to choose between saving an animal and saving a human, we should flip a coin.

Simplistic claims of moral equality are another example of overgeneralizing a moral principle for rhetorical effect. Whatever one thinks about animal rights, the idea that the moral status of humans should trump that of microbes is about as close to a slam dunk as it gets in moral theory.

On the other hand, we need to be careful since my argument merely establishes that there can be excellent moral reasons for overriding the “interests” of Martian microbes in some circumstances. There will always be those who want to use this kind of reasoning to justify all manner of human-serving but immoral actions. The argument I outline does not establish that anyone should be allowed to do anything they want to Mars for any reason. At the very least, Martian microbes would be of immense value to human beings: for example, as an object of scientific study. Thus, we should enforce a strong precautionary principle in our initial dealings with Mars (as a recent debate over planetary protection policies illustrates).

For every complex question, there’s a simple, incorrect answer

Mariomania seems to be the latest example of the idea, common among undergraduates in their first ethics class, that morality is all about establishing highly general rules that admit no exception. But such naïve versions of moral ideals don’t long survive contact with the real world.

By way of example, take the “Prime Directive” from TV’s “Star Trek”:

…no Star Fleet personnel may interfere with the normal and healthy development of alien life and culture…Star Fleet personnel may not violate this Prime Directive, even to save their lives and/or their ship…This directive takes precedence over any and all other considerations, and carries with it the highest moral obligation.

Hollywood’s version of moral obligation can be a starting point for our real-world ethical discussion.

As every good trekkie knows, Federation crew members talk about the importance of obeying the prime directive almost as often as they violate it. Here, art reflects reality, since it’s simply not possible to make a one-size-fits-all rule that identifies the right course of action in every morally complex situation. As a result, Federation crews are constantly forced to choose between unpalatable options. On the one hand, they can obey the directive even when it leads to clearly immoral consequences, as when the Enterprise refuses to cure a plague devastating a planet. On the other hand, they can generate ad hoc reasons to ignore the rule, as when Captain Kirk decides that destroying a supercomputer running an alien society doesn’t violate the spirit of the directive.

Of course, we shouldn’t take Hollywood as a perfect guide to policy. The Prime Directive is merely a familiar example of the universal tension between highly general moral ideals and real-world applications. We will increasingly see the kinds of problems such tension creates in real life as technology opens up vistas beyond Earth for exploration and exploitation. If we insist on declaring unrealistic moral ideals in our guiding documents, we should not be surprised when decision makers are forced to find ways around them. For example, the U.S. Congress’ recent move to allow asteroid mining can be seen as flying in the face of the “collective good of mankind” ideals expressed in the Outer Space Treaty signed by all space-faring nations.

The solution is to do the hard work of formulating the right principles, at the right level of generality, before circumstances render moral debate irrelevant. This requires grappling with the complex trade-offs and hard choices in an intellectually honest fashion, while refusing the temptation to put forward soothing but impractical moral platitudes. We must therefore foster thoughtful exchanges among people with very different conceptions of the moral good in order to find common ground. It’s time for that conversation to begin in earnest.

The Conversation

Kelly C. Smith, Associate Professor of Philosophy & Biological Sciences, Clemson University

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

Kepler Confirms 1,284 Exoplanets Outside Solar System


A study published yesterday in the Astrophysical Journal by a group of researchers confirms an additional 1,284 exoplanets have been spotted by Kepler, NASA’s planet-hunting spacecraft. That brings the total number of verified exoplanets from Kepler to more than 2,000 — more than doubling the amount spotted by the spacecraft.

“We have more than doubled the number of known exoplanets smaller than the size of Neptune,” Tim Morton, an associate research scholar at Princeton University.

For the complete study, visit The Astrophysical Journal.

Astrobiologists Use Biosignature Gases To Search For Aliens


Professor Sara Seager of Massachusetts Institute of Technology says her team of scientists is looking for biosignatures from gases emitted by alien life forms on habitable extrasolar planets. Many of these gases could be detected remotely by telescopes, but could end up having quite different compositions from those in the atmosphere of our planet.

Prof. Seager and her colleagues explained,

“Thousands of exoplanets are known to orbit nearby stars. Plans for the next generation of space-based and ground-based telescopes are fueling the anticipation that a precious few habitable planets can be identified in the coming decade. Even more highly anticipated is the chance to find signs of life on these habitable planets by way of biosignature gases.”

Seager’s team proposes in their paper published online in the journal Astrobiology that all stable and potential volatile molecules should be considered as possible biosignature gases, laying the groundwork for identifying such gases by conducting a massive search for molecules with six or fewer non-hydrogen atoms in order to maximize their chances of recognizing biosignature gases. They say they promote the concept that “all stable and potentially volatile molecules should initially be considered as viable biosignature gases.”

The scientists created a list of about 14,000 molecules that contain up to 6 non-H atoms. About 2,500 of these are CNOPSH (C – carbon, N – nitrogen, O – oxygen, P – phosphorus, S – sulfur, and H – hydrogen) compounds.

This means that instead of the costly and controversial method of netting strange creatures from the bottom of the sea, these scientists have decided to search and find thousands of curious, potentially biogenic gas molecules.

Mars and Earth are getting closer together


On May 30, our cold, red sandy neighbor outside Earth’s orbit is getting very close to us, at least for a short duration of time.

Scientists say Mars will be closer to Earth than it’s been since the past eleven years. At about 46.8 million miles away, it’s still a rather distant journey away, but the planet can typically be about 250 million miles away.

According to NASA, from May 18th until June 3rd, the great red planet will be bigger, brighter and hopefully more visible, weather permitting.

Skywatchers should expect to see a reddish star in the mornings at dawn or slightly before, if you are in the UK. United States watchers should look for it around midnight.

For a better view, look up your local astronomy club where members are likely to have powerful telescopes. If you’re looking for a telescope yourself, check out the Celestron C9.25 and get ready for some mindblowing astronomy at home.