Half of Earth’s satellites restrict use of climate data

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Dust storms in the Gulf of Alaska, captured by NASA’s Aqua satellite.
NASA

By Mariel Borowitz, Georgia Institute of Technology

Scientists and policymakers need satellite data to understand and address climate change. Yet data from more than half of unclassified Earth-observing satellites is restricted in some way, rather than shared openly.

When governments restrict who can access data, or limit how people can use or redistribute it, that slows the progress of science. Now, as U.S. climate funding is under threat, it’s more important than ever to ensure that researchers and others make the most of the collected data.

Why do some nations choose to restrict satellite data, while others make it openly available? My book, “Open Space,” uses a series of historical case studies, as well as a broad survey of national practices, to show how economic concerns and agency priorities shape the way nations treat their data.

The price of data

Satellites can collect comprehensive data over the oceans, arctic areas and other sparsely populated zones that are difficult for humans to monitor. They can collect data consistently over both space and time, which allows for a high level of accuracy in climate change research.

For example, scientists use data from the U.S.-German GRACE satellite mission to measure the mass of the land ice in both the Arctic and Antarctic. By collecting data on a regular basis over 15 years, GRACE demonstrated that land ice sheets in both Antarctica and Greenland have been losing mass since 2002. Both lost ice mass more rapidly since 2009.

Satellites collect valuable data, but they’re also expensive, typically ranging from US$100 million to nearly $1 billion per mission. They’re usually designed to operate for three to five years, but quite often continue well beyond their design life.

Many nations attempt to sell or commercialize data to recoup some of the costs. Even the U.S. National Oceanic and Atmospheric Administration and the European Space Agency – agencies that now make nearly all of their satellite data openly available – attempted data sales at an earlier stage in their programs. The U.S. Landsat program, originally developed by NASA in the early 1970s, was turned over to a private firm in the 1980s before later returning to government control. Under these systems, prices often ranged from hundreds to thousands of dollars per image.

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In other cases, agency priorities prevent any data access at all. As of 2016, more than 35 nations have been involved in the development or operation of an Earth observation satellite. In many cases, nations with small or emerging space programs, such as Egypt and Indonesia, have chosen to build relatively simple satellites to give their engineers hands-on experience.

Since these programs aim to build capacity and demonstrate new technology, rather than distribute or use data, data systems don’t receive significant funding. Agencies can’t afford to develop data portals and other systems that would facilitate broad data access. They also often mistakenly believe that demand for the data from these experimental satellites is low.

If scientists want to encourage nations to make more of their satellite data openly available, both of these issues need to be addressed.

Landsat 8, an American Earth observation satellite.
NASA, CC BY

Promoting access

Since providing data to one user doesn’t reduce the amount available for everyone else, distributing data widely will maximize the benefits to society. The more that open data is used, the more we all benefit from new research and products.

In my research, I’ve found that making data freely available is the best way to make sure the greatest number of people access and use it. In 2001, the U.S. Geological Survey sold 25,000 Landsat images, a record at the time. Then Landsat data was made openly available in 2008. In the year following, the agency distributed more than 1 million Landsat images.

For nations that believe demand for their data is low, or that lack resources to invest in data distribution systems, economic arguments alone are unlikely to spur action. Researchers and other user groups need to raise awareness of the potential uses of this data and make clear to governments their desire to access and use it.

Intergovernmental organizations like the Group on Earth Observations can help with these efforts by connecting research and user communities with relevant government decision-makers. International organizations can also encourage sharing by providing nations with global recognition of their data-sharing efforts. Technical and logistical assistance – helping to set up data portals or hosting foreign data in existing portals – can further reduce the resource investment required by smaller programs.

Promise for future

Satellite technology is improving rapidly. I believe that agencies must find ways to take advantage of these developments while continuing to make data as widely available as possible.

Satellites are collecting more data than ever before. Landsat 8 collected more data in its first two years of operation than Landsat 4 and 5 collected over their combined 32-year lifespan. The Landsat archive currently grows by a terabyte a day.

This avalanche of data opens promising new possibilities for big data and machine learning analyses – but that would require new data access systems. Agencies are embracing cloud technology as a way to address this challenge, but many still struggle with the costs. Should agencies pay commercial cloud providers to store their data, or develop their own systems? Who pays for the cloud resources needed to carry out the analysis: agencies or users?

The ConversationSatellite data can contribute significantly to a wide range of areas – climate change, weather, natural disasters, agricultural development and more – but only if users can access the data.

Mariel Borowitz, Assistant Professor of International Affairs, Georgia Institute of Technology

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

A giant ‘singing’ cloud in space will help us to understand how star systems form

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The dark band is the Dark Doodad Nebula, a place where new stars and planets can form.
Flickr/cafuego, CC BY-SA

By Aris Tritsis, Australian National University

We know that the birthplaces of stars are large molecular clouds of gas and dust found in space.

But what exactly determines the number and kind of stars and planets that are formed in these clouds? How was our Solar system nursed and how did it emerge from such a cloud billions of year ago?

These are mysteries that have been puzzling astronomers for decades, but research published today in Science adds an extra dimension to our understanding.

A 3D approach

Knowledge of the 3-dimensional structure of these clouds would be an important leap in our understanding of how stars and planets are born.




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From pancakes to soccer balls, new study shows how galaxies change shape as they age


The physics responsible for the formation of stars is also responsible for shaping the clouds. But even with the most advanced telescopes in the world we can only see the two-dimensional projections of clouds on the plane of the sky.

Thankfully, there is a way around this problem. A recently discovered type of structure in molecular clouds, called striations, was found to form because of waves.

Here enters Musca, a molecular cloud that “sings”. Musca is an isolated cloud in the Southern sky, below the Southern Cross, that looks like a thin needle (see top image). It is hundreds of light years away and stretches about 27 light years across, with a depth of about 20 light years and width up to a fraction of a light year.

Musca is surrounded by ordered hair-like striations produced by trapped waves of gas and dust caused by the global vibrations of the cloud.

3D model of Musca molecular cloud.
Aris Tritsis, ANU, Author provided

Trapped waves act like a fingerprint – they are unique and can be used to identify the sizes of the boundaries that trapped them. Boundaries are naturally created at the edges of clouds where their physical properties change abruptly.

Just like a cello and a violin make very distinct sounds, clouds with different sizes and structures will vibrate in very different manners – they will “sing” different “songs”.

A ‘song’ in the cloud

By using this concept and calculating the frequencies seen in observations of Musca it was possible to measure for the first time the third dimension of the cloud, the one that extends along our line of sight.

The frequencies found in the observations were scaled to the frequency range of human hearing to produce the “song of Musca”.

A “singing” molecular cloud.

The results from this method were amazing. Despite the fact that Musca looks like a thin cylinder from Earth, the true size of its hidden dimension is not small at all. In fact, it is comparable to its largest visible dimension on the plane of the sky.

No longer a thin cylinder when the extra dimension is revealed (Aris Tritsis)

Musca is not actively forming stars. It will be millions of years before gravity can overcome all opposing forces that support the cloud.




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As a result, with its structure now determined, Musca can be used as a prototype laboratory against which we can compare our models and study the early stages of star formation.

The ConversationWe can use Musca to better constraint our numerical models and learn about our own Solar system. It could help solve many mysteries. For example, could the ices found in comets have formed in clouds rather than at a later time during the life of our solar system?

Aris Tritsis, Postdoctoral Fellow, Australian National University

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

How I discovered the origins of the cigar-shaped alien ‘asteroid’ ‘Oumuamua

 

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Artist’s illustration of planet formation.
Image credit: NASA / Lynette Cook

By Fabo Feng, University of Hertfordshire

One of the highlights of 2017 was the discovery of the first object in our solar system that definitely came from somewhere else. At first we thought it was a comet, then an asteroid, and now the International Astronomical Union has reclassified it as something new entirely, an interstellar object. The Hawaiian astronomers who discovered it aptly named it ‘Oumuamua, which means “a messenger from afar arriving first”, reflecting that this object is like a scout sent from the past to reach out to us.

Research has already helped us learn a lot about ‘Oumuamua’s rare cigar-like shape, what it’s made of (ice with a carbon-rich surface) and its highly unusual orbit, which will take it out of our solar system at a speed of around 26 km/s. The Breakthrough Listen research program has even investigated whether ‘Oumuamua is an alien space ship by scanning the object for life forms with the Green Bank Telescope. No intelligent signals have been identified so far, though further observations are planned.

Now my latest study gives us a glimpse of exactly where ‘Oumuamua may have come from. Reconstructing the object’s motion, my research suggests it probably came from the nearby “Pleiades moving group” of young stars, also known as the “Local Association”. It was likely ejected from its home solar system and sent out to travel interstellar space.

‘Oumuamua’s journey.

Based on ‘Oumuamua’s trajectory, I simulated how it has probably travelled through the galaxy and compared this to the motions of nearby stars. I found the object passed 109 stars within a distance of 16 light years. It went by five of these stars from in the Local Association (a group of young stars likely to have formed together), at a very slow speed relative to their movement.

It’s likely that when ‘Oumuamua was first ejected into space, it was travelling at just enough speed to break away from the gravity of its planet or star of origin, rather than at a much faster speed that would require even more energy. This means we’d expect the object to move relatively slowly at the start of its interstellar journey, and so its slow encounters with these five stars suggests it was ejected from one of the group.

When was it kicked out of its home?

Stars typically move with an average speed when they are formed and gradually change speed as they encounter very large objects, such as massive stars and molecular clouds and are affected by their gravity. Unlike most nearby stars, ‘Oumuamua moves very slowly compared to the average motion of the rest of the galaxy. This suggests it has only been travelling in interstellar space for a relatively short time and hasn’t had a chance to encounter many massive objects that would speed it up.

We also have evidence for ‘Oumuamua’s relatively young age from the colour of its surface. Outside of the protection of a star’s magnetic field, objects in space are bombarded with cosmic rays and interstellar dust and gas that gradually alter their surfaces and turn them very red in colour. But ‘Oumuamua has a more neutral colour, suggesting it has only been impacted by cosmic rays for, at most, hundreds of million years rather than for the billions of years that our solar system has existed.

How was it ejected?

‘Oumuamua is extremely elongated and has quite a different shape from other objects in our solar system. It was probably formed by a relatively high-energy process such as a collision, or ejected from a forming star. Most objects in the outer part of a planetary system are made more of ice and most objects in the inner regions are made more of rocks. Since ‘Oumuamua is a more even mix of ice and rocks, it’s likely it came from the middle part of a solar system, similar to the asteroid belt between Mars and Jupiter that features a mixture of icy and rocky asteroids.

Young visitor.
ESO/M. Kornmesser, CC BY-SA

Perhaps the most plausible scenario is that ‘Oumuamua was ejected from a closely separated binary star system made of two stars closely orbiting each other. Objects orbiting one of the stars in a binary system will be strongly affected by the gravity of the other and so can be more easily ejected from the system than if it had just one star.

‘Oumuamua is probably just the tip of the iceberg. My research suggests there are likely more than 46m similar interstellar objects crossing the solar system every year. Most of them will be too far away for us to see with our current telescopes. But new telescopes and surveys should soon be able to find these interstellar messengers, which may be sending us important information about how stars and planets formed. Studying more objects like ‘Oumuamua will enable us to work out how much debris is left over from star formation and how much this adds to the mass of our galaxy.

The ConversationAnother reason to study these interstellar objects is that they could one day threaten to collide with the Earth and cause catastrophic events such as mass extinctions. The more we know, the better prepared we’ll be if that day ever comes.

Fabo Feng, Postdoctoral fellow, University of Hertfordshire

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

Piercing the mystery of the cosmic origins of gold

Neutron Stars Rip Each Other Apart to Form Black Hole
“Neutron Stars Rip Each Other Apart to Form Black Hole”, NASA

Jérôme Margueron, University of Washington

Where does gold, the precious metal coveted by mortals through the ages, come from? How, where and when was it produced? Last August, a single astrophysical observation finally gave us the key to answer these questions. The results of this research were published on October 16, 2017.

Gold pre-exists the formation of Earth: this is what differentiates it from, for example, diamond. However valuable it may be, this precious stone is born out of mere carbon, whose atomic structure is modified by enormous pressure from the earth’s crust. Gold is totally different – the strongest forces in the earth’s mantle are unable to change the composition of its atomic nucleus. Too bad for the alchemists who dreamed of transforming lead into gold.

Yet there is gold on Earth, both in its deep core, where it has migrated together with heavy elements such as lead or silver, and in the planet’s crust, which is where we extract this precious metal. While the gold in the core was already there at the formation of our planet, that in the crust is mostly extraterrestrial and arrived after the formation of Earth. It was brought by a gigantic meteor shower that bombarded the Earth (and the Moon) about 3.8 billion years ago.

Formation of heavy elements

How gold is produced in the universe? The elements heavier than iron, including gold, are partially produced by the s process during the ultimate evolution phases of the stars. It is a slow process (s stands for slow) that operates in the core of what are referred to as AGB stars – those of low and intermediate mass (less than 10 solar masses) that can produce chemical elements up to polonium. The other half of the heavy elements is produced by the r process (r stands for rapid). But the site where this nucleo-synthesis process takes place has long remained a mystery.

To understand the discovery enabled by the August 17, 2017, observation, we need to understand the scientific status quo that existed beforehand. For about 50 years, the dominant assumption among the scientific community was that the r process took place during the final explosion of massive stars (specialists speak of a core collapse supernova). Indeed, the formation of light elements (those up to iron) implies nuclear reactions that ensure the stability of the stars by counteracting contraction induced by gravity. For heavier elements – those from iron and beyond – it is necessary to add energy or to take very specific paths, such as the s and r processes. Researchers believed that the r process could occur in ejected matter from the explosion of massive stars, capturing a part of the released energy and participating to the dissemination of material in the interstellar medium.

Despite the simplicity of this explanation, numerical modelling of supernovae has proved extremely complicated. After 50 years of efforts, researchers have just begun to understand its mechanism. Most of these simulations do unfortunately not provide the physical conditions for the r process.

These conditions are however quite simple: you need a lot of neutrons and a really warm environment.

Fusion of neutron stars

Two ounces of gold … from outer space.
Wikimedia, CC BY

In the last decade or so, some researchers have begun to seriously investigate an alternative scenario of the heavy-element production site. They focused their attention on neutron stars. As befits their name, they constitute a gigantic reservoir of neutrons, which are released occasionally. The strongest of these releases occurs during their merging, in a binary system, also called kilonova. There are several signatures of this phenomenon that luckily were seen on August 17: a gravitational-wave emission culminating a fraction of a second before the final fusion of the stars and a burst of highly energetic light (known as a gamma-ray burst) emitted by a jet of matter approaching the speed of light. Although these bursts have been observed regularly for several decades, it is only since 2015 that gravitational waves have been detectable on Earth thanks to the Virgo and LIGO interferometers.

August 17 will remain a major date for the scientific community. Indeed, it marks the first simultaneous detection of the arrival of gravitational waves – whose origin in the sky was fairly well identified – and a gamma-ray burst, whose origin was also fairly well localized and coincided with the first one. Gamma-ray burst emissions are focused in a narrow cone, and the astronomers’ lucky break was that this one was emitted in the Earth’s direction.

In the following days, telescopes continuously analysed the light from this kilonova and found confirmation of the production of elements heavier than iron. They were also able to estimate the frequency of the phenomenon and the amount of material ejected. These estimates are consistent with the average abundance of the elements observed in our galaxy.

In a single observation, the hypothesis that prevailed until now – of a r process occurring exclusively during supernovae – is now seriously under question and it is now certain that the r process also takes place in kilonovae. The respective contribution of supernovae and kilonovae for the heavy elements’ nucleo-synthesis remains to be determined, and it will be done with the accumulation of datum related to the next observations. The August 17 observation alone has already allowed a great scientific advance for the global understanding of the origin of heavy elements, including gold.

This NASA animation is an artist’s view and accelerated version of the first nine days of a kilonova (the merging of two neutron stars) similar to that observed on August 17, 2017 (GW170817). In the approach phase of the two stars, the gravitational waves emitted are coloured pale blue, then after the fusion a jet near the speed of light is emitted (in orange) generating itself a gamma burst (in magenta). The material ejected from the kilonova produces an initially ultraviolet light (violet), then white in the optics, and finally infra-red (red). The jet continues its expansion by emitting light in the X-ray range (blue)

A new window on the Universe

The ConversationA new window to the universe has just been opened, like the day that Galileo focused the first telescope on the sky. The Virgo and LIGO interferometers now make it possible to “hear” the most violent phenomena of the universe, and immense perspectives have opened up for astronomers, astrophysicists, particle physicists and nuclear physicists. This scientific achievement was only possible thanks to the fruitful collaboration between highly supportive nations, in particular the United States, Germany, France and Italy. As an example, there is only one laboratory in the world capable of reaching the required precision for the mirrors reflecting lasers, LMA in Lyon, France. New interferometers are under development in Japan and Indian, and this list will surely soon become longer given huge discoveries expected for the future.

Jérôme Margueron, Chercheur en astrophysique nucléaire, University of Washington

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