Tag: European Space Agency

Gaia Mission Releases Map Of More Than A Billion Stars – Here’s What It Can Teach Us

Most of us have looked up at the night sky and wondered how far away the stars are or in what direction they are moving.

The truth is, scientists don’t know the exact positions or velocities of the vast majority of the stars in the Milky Way.

But now a new tranche of data from the European Space Agency’s Gaia satellite, aiming to map stars in our galaxy in unprecedented detail, has come in to shed light on the issue.

The Gaia Archive opened on April 25, making public Gaia’s second data release to everyone.

To quote the character Dave Bowman in the sci-fi classic 2001: A Space Odyssey: “It’s full of stars”. In fact, it contains data on the distances to more than 1.3 billion stars.

The Gaia satellite was launched in 2013 and has been scanning the sky with its two telescopes continuously ever since, with the aim of deciphering how our Milky Way galaxy formed and evolved.




To do this, it is measuring something called parallax. If you hold a finger at arms length and look at it with one eye and then the other, your finger appears to shift position compared to the background.

The angular change is called parallax.

Being in space allows Gaia to see similar tiny shifts in star positions. Observations at different locations six months apart (half way of its orbit around the Earth) are akin to looking at your finger with one eye and then the other.

When you know the parallax as well as the distance from Gaia to the sun (or the distance from your nose to your eye), you can use simple trigonometry to work out the distance to each star (or your finger).

Gaia also sees stars move in the plane of the sky over time. These units of “angle per time” can be converted to a physical unit of speed (for example kilometres per second) if we know the distance to the stars.

However, to know how a star is moving in three dimensions in space requires that we also measure the speed perpendicular to the sky along the line-of-sight. This requires a galactic speed camera!

A normal radar speed camera uses the Doppler effect – the stretching or squashing of waves because of motion – by measuring the change in the radio frequency from signals bounced off cars to measure their speed.

Similarly, Gaia measures the change in frequency in the light from stars to check their speed. The star light is bluer if the star is moving towards us or redder if the star is moving away from us. This is called radial velocity.

Gaia’s first data release in 2016 published the distances of around two million stars but did not include any radial velocities.

However we already knew the radial velocity of less than 400,000 of these stars – measured from the ground by many different surveys.

Gaia’s second data release includes information on sky positions and brightness for nearly 1.7 billion stars and more than seven million radial velocities.

Not only does this make Gaia the largest radial velocity survey ever – it increases the number of stars with accurate 3D space velocities by a factor of 18.

A series of Gaia science demonstration papers have also been published alongside the star catalogue. I was involved in the research behind one of these papers, constructing the most detailed map ever of 3D space velocities to date.

The next data release by Gaia will be in 2020. This is expected to boost the numbers of stars with known radial velocities from seven million today to around 30m – keeping our team busy for several years yet.

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Pass it on: Popular Science

NASA’s Mars Reconnaissance Orbiter And ESA’s Venus Express Are Using Atmosphere To Get Closer To The Planet

Mars has historically been unfriendly to Earth’s attempts to visit it. More missions have been attempted to Mars than to any other place in the Solar System except the Moon, and about half of the attempts have failed.

Some of these failures occurred because Mars was the first planet Earth attempted to explore, and the early exploration attempts taught us many lessons that have made subsequent missions more successful.

But many failures have occurred relatively recently, proving again and again that space exploration is very, very difficult.

But since 1996, Mars exploration has undergone a Renaissance, with data from four orbiters and four landed missions developing a revolutionary new view of Mars as an Earth-like world with a complex geologic history.




ExoMars Trace Gas Orbiter

This first mission of ESA’s ExoMars program consists of a Trace Gas Orbiter plus an Entry, descent and landing Demonstrator Module, known as Schiaparelli (which transmitted data during its descent before crash landing on the martian surface).

The main objectives of this mission are to search for evidence of methane and other trace atmospheric gases that could be signatures of active biological or geological processes and to test key technologies in preparation for ESA’s contribution to subsequent missions to Mars.

Mars Reconnaissance Orbiter

The Mars Reconnaissance Orbiter is searching for evidence of past water on Mars, using the most powerful camera and spectrometer ever sent to Mars.

Its cameras are also helping in the search for landing sites for future Mars rovers and landers, and to monitor martian weather on a day-to-day basis.

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Pass it on: Popular Science

This Is NASA’s Plan For Humanity’s Return To The Moon, And Beyond

There is still no official NASA mission to Mars, but after years of uncertainty, America’s space agency is giving us a glimpse of its grand strategy to extend human presence beyond low-Earth orbit with a plan to build a solid technological foundation for sending astronauts to other worlds.

The decades-long space exploration schedule, detailed in a press conference last week with NASA’s William Gerstenmaier, lists 10 upcoming missions involving NASA’s new-generation Orion spacecraft.

But unlike earlier disjointed proposals for loosely defined missions, this new plan is laid out more like an Ikea manual—a step-by-step guide on how to get to Mars.




NASA says the enterprise relies on a substantial but not outrageous budget, and that the plan has been drafted in close coordination with NASA’s key partners like the European Space Agency, Roscosmos, JAXA, and the Canadian Space Agency.

The main goal of the Orion program is to assemble a Moon-orbiting space station, which by the end of the 2020s could be beefed up to become a kind of interplanetary mothership.

Without additional money, the proposed spacecraft will not be able to put astronauts onto the surface of Mars, but it will be able to carry a crew into the vicinity of the Red Planet as early as 2033, says Gerstenmaier.

Visits to Martian moons Phobos and Deimos and expeditions to asteroids might also be possible.

In a nutshell, this is the closest humanity’s ever been to setting foot on Mars and many other destinations in the Solar System.

The program will certainly be the boldest, riskiest, and most ambitious undertaking for human spaceflight in nearly half a century—since the end of the Apollo program in 1972.

Now for a gut punch of reality. Due to budget constraints, the Mars program likely move at a snail’s pace, according to available flight manifests.

That means its unlikely astronauts will have a chance to leave new footprints on another world before well into the 2030s.

An even longer wait is a bitter pill to swallow, and that probably explains why NASA has been shy about publicizing its mega-plan right away.

It’s easy to draw parallels with the Apollo program’s 10-year plan for putting a man on the moon to the Orion project, which has been in planning and development since 2003 and is not even expected to carry its first crew until 2021.

The first manned flight of Orion, called Exploration Mission 2 or EM-2 was recently “de-ambitioned” from entering a lunar orbit to just running a quick loop behind the Moon and returning to Earth eight days after liftoff from Cape Canaveral.

In the meantime, NASA’s international partners will have an opportunity to dispatch robotic and, possibly, even human missions to the surface of the Moon.

With the nascent outpost growing in the vicinity of the Moon, the Orion crews could extend their stays in lunar orbit from a week to months or even a year.

Inhabitants of the outpost could also make outings to other locations near the Moon, such as a visit to a scientifically interesting Lagrangian points, where gravitational forces of the Moon and the Earth cancel each other out.

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Pass it on: New Scientist

Take A Virtual Tour Of The International Space Station

google_iss

Ever wondered what it’s like to be an astronaut aboard the International Space Station? Now, thanks to the French astronaut Thomas Pesquet and Google, you can find out.

Pesquet returned to Earth in June after six months as a European Space Agency astronaut on the ISS.

During his trip, he made an exhaustive photographic survery of the interior of the station and sent the images down to Google engineers on Earth.




They in turn stitched the photos together into 360-degree panoramas that can be navigated using the Google Street View interface.

So what’s it like? Words like “cramped”, “cluttered” and “claustrophobic” spring to mind for this armchair astronaut, though the explanatory notes are fascinating and the views out the window are truly superb.

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Pass it on: Popular Science