Global census claims we have three trillion trees - but they are falling fast

[Credit: Ditte Mcneil/EyeEm/Getty Images

The good news there are about 422 trees for every person on Earth - eight times more than previously estimated. The bad news is that the number is falling by 15 billion trees every year.

Since human civilisation began. In that time, tree cover of the planet has nearly halved, scientists estimate.

A multi-national team of researchers led by Yale University has estimated there are about three trillion trees on Earth. They arrived at the number by both physically counting trees as well as supercomputer analysis of satellite imagery.

The research was reported in Nature.

"I don't know what I would have guessed, but I was certainly surprised to find that we were talking about trillions," the study's lead author Thomas Crowther of the Yale School of Forestry and Environmental Studies in Connecticut, told ABC news.

"The highest densities of trees were found in the boreal forests in the sub-arctic regions of Russia, Scandinavia and North America," the researchers say. "But the largest forest areas, by far, are in the tropics, which are home to about 43% of the world's trees."

What the stars can tell us about Mars' past

Yesterday we reported on NASA's new analysis of the rocks of Mars to test the theory that carbon sequestration accounted for the loss of much of the planet's atmosphere (it appears that it didn't).

Today, we look at the space agency's mission at the other end of the scale – the MAVEN spacecraft which is orbiting high above the thin Martian skies to determine how Mars lost its early atmosphere, and with it, its water.

MAVEN is looking for subtle changes in their colour of the stars for clues, as the NASA video above explains.

Previous reports on MAVEN's mission can be found here.

Hubble's clues to star births in neighbouring galaxy

This Hubble mosaic of 414 photographs of the M31, or the Andromeda galaxy. On the bottom left is an enlargement of the boxed field (top) reveals myriad stars and numerous open star clusters as bright blue knots,spanning 4,400 light-years across. On the bottom right are six bright blue clusters extracted from the field. Each cluster square is 150 light-years across.
[Credits: NASA/ESA, J. Dalcanton, B.F. Williams, L.C. Johnson (Univ. of Washington), PHAT team, and R. Gendler]

Astronomers have discovered that our neighbour, Andromeda galaxy, also known as M31, has a similar percentage of newborn stars to our own Milky Way galaxy.

NASA’s Hubble Space Telescope surveyed images of 2,753 young, blue star clusters in M31. It has helped scientists determine the percentage of stars with a particular mass within a cluster, known as the Initial Mass Function (IMF).

That helps scientists better interpret the light from distant galaxies and understand the formation history of stars.

The intensive survey, assembled from 414 Hubble mosaic photographs of M31, was a unique collaboration between astronomers and “citizen scientists,” volunteers who provided invaluable help in analyzing the mountain of data from Hubble.

“Given the sheer volume of Hubble images, our study of the IMF would not have been possible without the help of citizen scientists,” said Daniel Weisz of the University of Washington in Seattle, and lead author of a paper published in The Astrophysical Journal.

Stars are born when a giant cloud of molecular hydrogen, dust and trace elements collapses. The cloud fragments into small knots of material that each precipitate hundreds of stars. The stars are not all created equally: their masses can range from 1/12th to a couple hundred times the mass of our sun.

Before this survey, astronomers only had IMF measurements from within our own galaxy.

Magnetic fields provide a new wireless communication technique

A prototype of the magnetic field human body communication, developed in Mercier's Energy-Efficient Microsystems Lab at UC San Diego, consists of magnetic-field-generating coils wrapped around three parts of the body, including the head, arm and leg. [Credit: Jacobs School of Engineering, UC San Diego]

A prototype of the magnetic field human body communication, developed in Mercier's Energy-Efficient Microsystems Lab at UC San Diego, consists of magnetic-field-generating coils wrapped around three parts of the body, including the head, arm and leg. [Credit: Jacobs School of Engineering, UC San Diego]

Electrical engineers at the University of California, San Diego, have demonstrated a new wireless communication technique that works by sending magnetic signals through the human body.

They say the new technology could offer a lower power and more secure way to send information between wearable electronic devices.

They presented their findings late last month at the 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society in Milan, Italy.

Patrick Mercier, a professor in the Department of Electrical and Computer Engineering at UC San Diego who led the study, said his team was looking to save energy when personal electronics such as smart watches, fitness trackers and health monitors communicate.

"All of these devices will need to communicate information with each other. Currently, these devices transmit information using Bluetooth radios, which use a lot of power to communicate," he said. 

"We're trying to find new ways to communicate information around the human body that use much less power."

He said that Bluetooth technology uses electromagnetic radiation to transmit data, however these radio signals do not easily pass through the human body and therefore require a power boost to help overcome this signal obstruction, or "path loss."

While the team's work was still a proof-of-concept demonstration, the technique, called magnetic field human body communication, uses the body as a vehicle to deliver magnetic energy between electronic devices.

"This technique, to our knowledge, achieves the lowest path losses out of any wireless human body communication system that's been demonstrated so far. This technique will allow us to build much lower power wearable devices," said Mercier.

Where did Mars' atmosphere go? NASA rules out one theory

NASA's Mars Reconnaissance Orbiter provided this colour-coded map of a small portion of the Nili Fossae plains region of Mars' northern hemisphere. This site is part of the largest known carbonate-rich deposit on Mars. In the color coding used for this map, green indicates a carbonate-rich composition, brown indicates olivine-rich sands, and purple indicates basaltic composition. [Credits: NASA/JPL-Caltech/JHUAPL/Univ. of Arizona]

This view combines information from two instruments on NASA's Mars Reconnaissance Orbiter to map color-coded composition over the shape of the ground in a small portion of the Nili Fossae plains region of Mars' northern hemisphere.

This site is part of the largest known carbonate-rich deposit on Mars. In the color coding used for this map, green indicates a carbonate-rich composition, brown indicates olivine-rich sands, and purple indicates basaltic composition.

Carbon dioxide from the atmosphere on early Mars reacted with surface rocks to form carbonate, thinning the atmosphere by sequestering the carbon in the rocks.

An analysis of the amount of carbon contained in Nili Fossae plains estimated the total at no more than twice the amount of carbon in the modern atmosphere of Mars, which is mostly carbon dioxide. That is much more than in all other known carbonate on Mars, but far short of enough to explain how Mars could have had a thick enough atmosphere to keep surface water from freezing during a period when rivers were cutting extensive valley networks on the Red Planet. Other possible explanations for the change from an era with rivers to dry modern Mars are being investigated.

This image covers an area approximately 1.4 miles (2.3 kilometers) wide.  A scale bar indicates 500 meters (1,640 feet).  The full extent of the carbonate-containing deposit in the region is at least as large as Delaware and perhaps as large as Arizona.

The color coding is from data acquired by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), in observation FRT0000C968 made on Sept. 19, 2008.  The base map showing land shapes is from the High Resolution Imaging Science Experiment (HiRISE) camera. It is one product from HiRISE observation ESP_010351_2020, made July 20, 2013. Other products from that observation are online at http://www.uahirise.org/ESP_032728_2020. 

The Mars Reconnaissance Orbiter has been using CRISM, HiRISE and four other instruments to investigate Mars since 2006. The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, led the work to build the CRISM instrument and operates CRISM in coordination with an international team of researchers from universities, government and the private sector. HiRISE is operated by the University of Arizona, Tucson, and was built by Ball Aerospace & Technologies Corp., Boulder, Colorado.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the orbiter and collaborates with JPL to operate it.

Image credit: NASA/JPL-Caltech/JHUAPL/Univ. of Arizona

 

 

Carbon dioxide from the atmosphere on early Mars reacted with surface rocks to form carbonate, thinning the atmosphere by sequestering the carbon in the rocks, but nowhere near enough to account for total atmosphere loss, a new analysis suggests.

"The biggest carbonate deposit on Mars has, at most, twice as much carbon in it as the current Mars atmosphere," said Bethany Ehlmann of the California Institute of Technology and NASA Jet Propulsion Laboratory, both in Pasadena.

"Even if you combined all known carbon reservoirs together, it is still nowhere near enough to sequester the thick atmosphere that has been proposed for the time when there were rivers flowing on the Martian surface."

Carbon dioxide makes up most of the Martian atmosphere and until recently, scientists expected to find large deposits of carbonates holding much of the carbon from the planet's original atmosphere.

Instead, recent missions such as NASA's Mars Reconnaissance Orbiter have found low concentrations of carbonate distributed widely, and only a few concentrated deposits.

By far the largest known carbonate-rich deposit on Mars covers an area about the size of Arizona, in a region called Nili Fossae. Scientists estimate there would need to be 35 deposits this size to account for total sequestration of the atmosphere.

The latest discoveries have also caused some rethinking on the formation of the modern Martian landscape.

The current atmosphere is too tenuous for liquid water to persist on the surface, but a denser atmosphere on ancient Mars could have kept water from immediately evaporating and could have held in enough warmth to keep liquid water from freezing.

One possible explanation is that Mars did have a much denser atmosphere during its flowing-rivers period, and then lost most of it to outer space from the top of the atmosphere, rather than by sequestration in minerals.

"Maybe the atmosphere wasn't so thick by the time of valley network formation," says Christopher Edwards, a former Caltech researcher now with the U.S. Geological Survey.

"Instead of Mars that was wet and warm, maybe it was cold and wet with an atmosphere that had already thinned. How warm would it need to have been for the valleys to form? Not very. In most locations, you could have had snow and ice instead of rain. You just have to nudge above the freezing point to get water to thaw and flow occasionally, and that doesn't require very much atmosphere."

Soyuz lifts off for the space station

Soyuz TMA-18M launches to the International Space Station on 2 September from the Baikonur Cosmodrome in Kazakhstan. [Credit: ESA/S. Corvaja]

Soyuz TMA-18M launches to the International Space Station on 2 September from the Baikonur Cosmodrome in Kazakhstan. [Credit: ESA/S. Corvaja]

The Soyuz TMA-18M launched from the Baikonur Cosmodrome in Kazakhstan to the International Space Station at 10:37am local time.

At launch, the station was flying 250 miles above south-central Kazakhstan, having passed over the Baikonur Cosmodrome less than a minute before lift-off.

It was the 500th launch of both manned and unmanned spacecraft from the launch pad used in 1961 by Yuri Gagarin, the first man in space, the commentator said.

On board the launch craft were Andreas Mogensen, the first Dane in space, veteran Russian cosmonaut Sergei Volkov and Kazakh Aidyn Aimbetov.

Volkov is following in the footsteps of his father, who 24 years ago launched into space with the first astronaut from Kazakhstan.

Sergey Volkov of Roscosmos, Andreas Mogensen of ESA (European Space Agency) and Aidyn Aimbetov of the Kazakh Space Agency are now are safely in orbit on a two-day course to dock to the station on Friday, 4 September.

With the arrival of Volkov, Mogensen and Aimbetov, nine people will be aboard the orbiting laboratory for the first time since 2013.

Gaia celebrates first year of main star survey mission

The outline of our Galaxy, the Milky Way, and of its neighbouring Magellanic Clouds, in an image based on housekeeping data from ESA’s Gaia satellite, indicating the total number of stars detected every second in each of the satellite's fields of view. [Credit: ESA/Gaia – CC BY-SA 3.0 IGO]

The outline of our Galaxy, the Milky Way, and of its neighbouring Magellanic Clouds, in an image based on housekeeping data from ESA’s Gaia satellite, indicating the total number of stars detected every second in each of the satellite's fields of view. [Credit: ESA/Gaia – CC BY-SA 3.0 IGO]

ESA’s billion-star surveyor, Gaia, has completed its first year of science observation in its main survey mode.

The first Sun-Earth Lagrange point, L1, is 1.5 million km from the Earth towards the Sun, and there have been many solar observatories located here, including DSCOVR. L2 is 1.5 million kilometres from Earth away from the Sun. This where Gaia is and the James Webb Telescope will be situated. [Credit: NASA]

The first Sun-Earth Lagrange point, L1, is 1.5 million km from the Earth towards the Sun, and there have been many solar observatories located here, including DSCOVR. L2 is 1.5 million kilometres from Earth away from the Sun. This where Gaia is and the James Webb Telescope will be situated. [Credit: NASA]

Located at the Lagrange point L2, 1.5 million kilometres from Earth, Gaia surveys stars and other astronomical objects as it spins. It repeatedly measures the positions of the stars with extraordinary accuracy, to calculate distances and motions through the Milky Way galaxy.

The satellite was launched in December 2013 followed by a six-month long in-orbit commissioning period. It began routine scientific operations on 25 July 2014 and for 28 days, operated in a special scanning mode that sampled great circles on the sky, but always including the ecliptic poles.

This meant that the satellite observed the stars in those regions many times, providing a database for Gaia’s initial calibration for its main survey operation which began on 21 August 2014.

The European Space Agency writes:

The Gaia team have spent a busy year processing and analysing these data, en route towards the development of Gaia’s main scientific products, consisting of enormous public catalogues of the positions, distances, motions and other properties of more than a billion stars. Because of the immense volumes of data and their complex nature, this requires a huge effort from expert scientists and software developers distributed across Europe, combined in Gaia’s Data Processing and Analysis Consortium (DPAC).

“The past twelve months have been very intense, but we are getting to grips with the data, and are looking forward to the next four years of nominal operations,” says Timo Prusti, Gaia project scientist at ESA.

“We are just a year away from Gaia's first scheduled data release, an intermediate catalogue planned for the summer of 2016. With the first year of data in our hands, we are now halfway to this milestone, and we’re able to present a few preliminary snapshots to show that the spacecraft is working well and that the data processing is on the right track.”

There is more about the mission on the ESA website.

Chameleons change colour to stand out, not hide

Chameleons don't change colour to match their environment – it's just the opposite. How do they do it? By manipulating tiny crystals in their skin, as we explained here

Now, UC Berkeley researchers are on a quest to create synthetic chameleon skin, mimicking the reptiles' ability.

KQED, the PBS station in San Francisco, recently produced a segment delving into chameleons color-changing ways for their 4K YouTube series Deep Look. Thanks to Twisted Sifter for pointing it out.