Charting the Milky Way From the Inside Out

NASA - Wide-field Infrared Survey Explorer (WISE) patch.

June 4, 2015

Image above: This artist's concept depicts the most up-to-date information about the shape of our own Milky Way galaxy. We live around a star, our sun, located about two-thirds of the way out from the center. Image credit: NASA/JPL-Caltech/R. Hurt (SSC/Caltech).

Imagine trying to create a map of your house while confined to only the living room. You might peek through the doors into other rooms or look for light spilling in through the windows. But, in the end, the walls and lack of visibility would largely prevent you from seeing the big picture.

The job of mapping our own Milky Way galaxy from planet Earth, situated about two-thirds of the way out from the galaxy's center, is similarly difficult. Clouds of dust permeate the Milky Way, blocking our view of the galaxy's stars. Today, researchers have a suitable map of our galaxy's spiral structure, but, like early explorers charting new territory, they continue to patiently and meticulously fill in the blanks.

Recently, researchers have turned to a new mapping method that takes advantage of data from NASA's Wide-field Infrared Survey Explorer, or WISE. Using WISE, the research team has discovered more than 400 dust-shrouded nurseries of stars, which trace the shape of our galaxy's spiral arms. Seven of these "embedded star clusters" are described in a new study published online May 20 in the Monthly Notices of the Royal Astronomical Society.

Image above: (Annotated) This artist's concept depicts the most up-to-date information about the shape of our own Milky Way galaxy. We live around a star, our sun, located about two-thirds of the way out from the center. Image credit: NASA/JPL-Caltech/R. Hurt (SSC/Caltech).

"The sun's location within the dust-obscured galactic disk is a complicating factor to observe the galactic structure," said Denilso Camargo, lead author of the paper from the Federal University of Rio Grande do Sul in Brazil.

The results support the four-arm model of our galaxy's spiral structure. For the last few years, various methods of charting the Milky Way have largely led to a picture of four spiral arms. The arms are where most stars in the galaxy are born. They are stuffed with gas and dust, the ingredients of stars. Two of the arms, called Perseus and Scutum-Centaurus, seem to be more prominent and jam-packed with stars, while the Sagittarius and Outer arms have as much gas as the other two arms but not as many stars.

The new WISE study finds embedded star clusters in the Perseus, Sagittarius, and Outer arms. Data from the Two Micron All Sky Survey (2MASS), a ground-based predecessor of WISE from NASA, the National Science Foundation and the University of Massachusetts, Amherst, helped narrow down the distances to the clusters and pinpoint their location.

Embedded star clusters are a powerful tool for visualizing the whereabouts of spiral arms because the clusters are young, and their stars haven't yet drifted away and out of the arms. Stars begin their lives in the dense, gas-rich neighborhoods of spiral arms, but they migrate away over time. These embedded star clusters complement other techniques for mapping our galaxy, such as those used by radio telescopes, which detect the dense gas clouds in spiral arms.

Image above: Astronomers using data from NASA's Wide-field Infrared Survey Explorer, or WISE, are helping to trace the shape of our Milky Way galaxy's spiral arms. Image credit: NASA/JPL-Caltech/Federal University of Rio Grande do Sul.

"Spiral arms are like traffic jams in that the gas and stars crowd together and move more slowly in the arms. As material passes through the dense spiral arms, it is compressed and this triggers more star formation," said Camargo.

WISE is ideal for finding the embedded star clusters because its infrared vision can cut through the dust that fills the galaxy and shrouds the clusters. What's more, WISE scanned the whole sky, so it was able to perform a thorough survey of the shape of our Milky Way. NASA's Spitzer Space Telescope also uses infrared images to map the Milky Way's territory. Spitzer looks along specific lines of sight and counts stars. The spiral arms will have the densest star populations.

NASA's Wide-field Infrared Survey Explorer, or WISE. Image Credit: NASA

NASA's Jet Propulsion Laboratory in Pasadena, California managed and operated WISE for NASA's Science Mission Directorate in Washington. The spacecraft was put into hibernation mode in 2011, after it scanned the entire sky twice, thereby completing its main objectives. In September 2013, WISE was reactivated, renamed NEOWISE and assigned a new mission to assist NASA's efforts to identify potentially hazardous near-Earth objects.

Other authors of the study are: Charles Bonatto and Eduardo Bica, also with the Federal University of Rio Grande do Sul.

For more information on WISE, visit: http://www.nasa.gov/wise

Previous research from Camargo's team found two embedded clusters far outside the plane of our Milky Way, 16,000 light-years away. A feature story about that work is online at: http://www.jpl.nasa.gov/news/news.php?feature=4497

The new WISE study from the Monthly Notices of the Royal Astronomical Society is online at: http://mnras.oxfordjournals.org/content/450/4/4150.full?keytype=ref&ijkey=tjeJAezGAmgdXzc

Images (mentioned), Text, Credits: NASA/Felicia Chou/JPL/Whitney Clavin/Tony Greicius.

Best regards, Orbiter.ch

Historic handshake between space and Earth

ISS - International Space Station patch.

4 June 2015

ESA performed the first-ever demonstration of space-to-ground remote control with live video and force feedback today when NASA astronaut Terry Virts orbiting Earth on the International Space Station shook hands with ESA telerobotics specialist André Schiele in the Netherlands.

Terry was testing a joystick that allows astronauts in space to ‘feel’ objects from hundreds of kilometres away. The joystick is a twin of the one on Earth and moving either makes its copy move in the same way.

First handshake with space

The joystick provides feedback so both users can feel the force of the other pushing or pulling. Earlier this year, NASA astronaut Butch Wilmore was the first to test the joystick in space but without a connection.

Remote control

Landing astronauts on Mars and returning them home is a step too far for humanity at the moment, and operating rovers from Earth is difficult and tedious – it takes a command around 12 minutes to reach the planet. Instead, ESA envisages sending astronauts to orbit a planet and control robots on the surface from above.

Today’s test verified the communications network, the control technology and the software behind the connection. Each signal from Terry to André had to travel from the International Space Station to another satellite some 36 000 km above Earth, through Houston mission control in USA and across the Atlantic Ocean to ESA’s ESTEC technical centre in the Netherlands, taking up to 0.8 seconds in total both ways.

International Space Station

As the Space Station travels at 28 800 km/h, the time for each signal to reach its destination changes continuously, but the system automatically adjusts to varying time delays.

In addition to the joystick, Terry had an extra screen with realtime video from the ground and augmented reality added an arrow to indicate the direction and amount of force.

Behind today’s seemingly simple handshake is years of work for people to code the feedback, vision and communications software.

“The system worked even though the Space Station was flying over 5000 km away,” André commented. “It felt as though Terry was extending his arm down from space to shake my hand.”

André Schiele with Haptics-2 experiment

The next step is to do blind tests to distinguish between different objects made of foam to discover whether humans orbiting Earth can distinguish object stiffness remotely. This is important for more advanced remote robotic tasks in the future.

Space for ground

The system’s adaptability and robust design means it can be used over normal data cell-phone networks. This makes it well suited for remote areas that are difficult to access or when disasters have destroyed other communication networks.

Haptics-2 experiment

The direct and sensitive feedback coupled with safeguards against excessive forces would allow rovers and robots to carry out delicate operations in the extreme conditions found in offshore drilling and nuclear reactors, for example. It could even help to provide humanitarian aid after earthquakes or other natural disasters.

A follow-up experiment is planned for September to control a more advanced robot on the ground.

Related links:

Telerobotics and Haptics Laboratory: http://esa-telerobotics.net/

Telerobotics flight experiments: http://esa-telerobotics.net/meteron/flight-experiments

ESA Bulletin article on Meteron: http://www.esa.int/About_Us/ESA_Publications/ESA_Publications_Bulletin/ESA_i_Bulletin_i_147_August_2011

ESA Human Spaceflight: http://www.esa.int/spaceflight

Images, Text, Credits: ESA/J. Harrod/M. Aiple CC BY SA IGO 3.0/NASA.

Greetings, Orbiter.ch

Mars Missions to Pause Commanding in June, Due to Sun

NASA patch.

June 3, 2015

In June 2015, Mars will swing almost directly behind the sun from Earth's perspective, and this celestial geometry will lead to diminished communications with spacecraft at Mars.

The arrangement of the sun between Earth and Mars is called Mars solar conjunction. It occurs about every 26 months as the two planets travel in their sun-centered orbits. The sun disrupts radio communications between the planets during the conjunction period. To prevent spacecraft at Mars from receiving garbled commands that could be misinterpreted or even harmful, the operators of Mars orbiters and rovers temporarily stop sending any commands.

The teams running NASA's three active Mars orbiters and two Mars rovers will refrain from sending commands to their spacecraft from about June 7 to June 21. During that period, the sun will be within two degrees of Mars in Earth's sky. (Don't try to look, though, because looking at the sun is dangerous to the eyes.) The operators also will put restrictions on commanding -- such as using only reduced data rates or communicating only in an emergency -- during the days before and after that period.

Image above: This diagram illustrates the positions of Mars, Earth and the sun during a period that occurs approximately every 26 months, when Mars passes almost directly behind the sun from Earth's perspective. This arrangement, and the period during which it occurs, is called Mars solar conjunction. Radio transmissions between the two planets during conjunction are at risk of being corrupted by the sun's interference, so NASA Mars missions have a moratorium on sending commands to spacecraft on the surface of Mars or in orbit around Mars. Image Credits: NASA/JPL-Caltech.

Spacecraft will continue making some science observations during the conjunction period, though rovers will not do any driving or arm movements.

"Our overall approach is based on what we did for the solar conjunction two years ago, which worked well," said Nagin Cox, a systems engineer at NASA's Jet Propulsion Laboratory, Pasadena, California, who is leading conjunction planning for NASA's Curiosity Mars rover. "It is really helpful to have been through this before."

NASA's MAVEN spacecraft, which arrived in Mars orbit last September, will be experiencing its first solar conjunction. Its team has prepared thoroughly. MAVEN -- short for Mars Atmosphere and Volatile Evolution -- will continue monitoring the solar wind reaching Mars and making other measurements. "The data will be stored and transmitted back to us after communications are reestablished at the end of the solar conjunction period," said James Morrissey, MAVEN deputy project manager at NASA's Goddard Space Flight Center, Greenbelt, Maryland.

Transmissions from NASA's two other Mars orbiters -- Mars Odyssey and Mars Reconnaissance Orbiter -- will continue through the conjunction period, but some of those transmissions are not expected to reach Earth. Science data transmitted during conjunction will also remain stored aboard the orbiters, for reliable retransmission in late June. The active Mars rovers -- Curiosity and Opportunity -- will send limited data to orbiters throughout conjunction for relay to Earth during and after conjunction.

Mars Odyssey, which reached Mars in 2001, will be in its seventh solar conjunction. For Opportunity and Mars Reconnaissance Orbiter, the 2015 solar conjunction is the sixth and fifth, respectively.

In preparation for conjunction, orbiter and Curiosity mission teams have been clearing some science data from spacecraft memories to optimize availability of memory for storing science data during the conjunction period. Data that Opportunity collects and sends daily to orbiters will be kept on the orbiters for replay after conjunction. No conjunction-period data from Opportunity will be kept on the rover. Opportunity will operate during conjunction in a mode avoiding use of non-volatile flash memory, the type of memory that can retain data when the rover powers down overnight.

A video showing Mars solar conjunction geometry is at:
http://mars.nasa.gov/allaboutmars/nightsky/solar-conjunction

NASA's five current missions at Mars are preparing the way for human-crewed missions there in the 2030s and later, in NASA's Journey to Mars strategy.

Editor Note:

Any space agencies are concerned by this solar occultation of Mars, the European Space Agency's with Mars Express and ISRO with its Mars Orbiter.

NASA's Goddard Space Flight Center manages the MAVEN project for the principal investigator at the University of Colorado, Boulder, and for the NASA Science Mission Directorate, Washington. JPL, a division of the California Institute of Technology in Pasadena, manages the Odyssey, Reconnaissance Orbiter, Opportunity and Curiosity projects, and NASA's Mars Exploration Program, for the Science Mission Directorate. Lockheed Martin Space Systems, Denver, built all three NASA Mars orbiters. For more about NASA's Mars Exploration Program, visit: http://mars.jpl.nasa.gov and http://www.nasa.gov/mars

Image (mentioned), Text, Credits: NASA/JPL/Guy Webster/Tony Greicius.

Greetings, Orbiter.ch

Hubble observes chaotic dance of Pluto’s moons

ESA - Hubble Space Telescope logo.

3 June 2015

The chaotic spin of Pluto’s moon Nix

In a new study, scientists have gathered all available NASA/ESA Hubble Space Telescope data on the four outer moons of Pluto to analyse the system in more depth than ever before. The observations show that at least two of Pluto’s moons are not neatly rotating on their axes but are in chaotic rotation while orbiting around Pluto and its companion Charon. The study also hints that one of the moons has a mysterious jet-black colouring. These surprising results appear in the 4 June issue of the journal Nature.

Almost every moon in the Solar System, including our Moon, rotates on its axis at the same speed as it orbits its parent body. It is for this reason that we always see the same side of the Moon facing us on Earth. On Pluto, however, astronomers have now discovered that there are no hidden sides to its moons.

In a surprising new study, it has been found that two of Pluto’s moons, Nix and Hydra, are in a chaotic rotation. This means that an observer on Pluto would not see the same face of the moons from one night to the next. For visitors on the moons themselves, things would get even more confusing, as every day would be a different length to the one that preceded it.

The other two moons studied, Kerberos and Styx, will likely be found to be chaotic too, pending further study.

“Prior to the Hubble observations, nobody appreciated the intricate dynamics of the Pluto system,” explains Mark Showalter of the Search for Extraterrestrial Intelligence (SETI) Institute in California, USA, main author of the study.

Pluto’s moons

The chaotic motion of the moons is caused by the system’s two central bodies, Pluto and Charon [1]. “These two bodies whirl around each other rapidly, causing the gravitational forces that they exert on the small nearby moons to change constantly,” explains Doug Hamilton, co-author of the study. “Being subject to such varying gravitational forces makes the rotation of Pluto’s moons very unpredictable. The chaos in their rotation is further accentuated by the fact that these moons are not neat and round, but are actually shaped like rugby balls!”

The movement of the moons in the Pluto–Charon system offers valuable insights into how planets orbiting a double star might behave. “We are learning that chaos may be a common trait of binary systems,” Hamilton continues. “It might even have consequences for life on planets orbiting binary stars.”

Clues to the Pluto system chaos first came when astronomers measured variations in the light reflected off of the two small moons. Looking at images taken by Hubble between 2005 and 2012, the brightness was found to change unpredictably — instead of following a regular cycle — in a way that could only be explained by chaotic movement.

These images also showed that the moon Kerberos is charcoal-black in colour, a stark contrast to the bright white of the other moons. It was predicted that pollution from dust blasted off the satellites by meteorite impacts would coat the moons, giving their surfaces a homogenous look, but why Kerberos is black is a mystery.

Animation of the chaotic spin of Pluto’s moon Nix

The chaotic rotation of the moons was not the only surprise that arose from the study; Hubble’s monitoring also revealed a connection between the orbits of the three moons Nix, Styx, and Hydra.

“Their motion is tied together in a way similar to that of three of Jupiter’s large moons,” noted Doug Hamilton of the University of Maryland, co-author of the study. “If you were sitting on Nix, you would see Styx go around Pluto twice every time Hydra goes around three times.”

The chaotic movements found in this fascinating system do not necessarily mean that it is on the brink of flying apart. More studies are needed to determine the long-term fate of the Pluto system.

The researchers agree that a combination of monitoring data from Hubble, a close-up look from NASA’s New Horizons space probe, which flies by the system in July 2015 [2], and, eventually, observations with the NASA/ESA/CSA James Webb Space Telescope will help to settle some of the many mysteries of the Pluto–Charon system.

“Pluto will continue to surprise us when New Horizons flies past it in July,” Showalter said. “Our work with Hubble just gives us a foretaste of what’s in store.”

Hubble in orbit

Notes:

[1] Due to Charon’s large size, Pluto and Charon orbit about a common centre of gravity that is located in the space between the bodies. Our moon has one eightieth of Earth’s mass, whereas Charon has one eighth of Pluto’s mass.

[2] NASA’s New Horizons space probe was launched in 2006 to study Pluto, its moons, and other Kuiper belt objects. It will fly past the Pluto-Charon system on 14 July 2015 and will produce detailed surface maps of Pluto and all of its moons.

Notes for editors:

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

The team of astronomers in this study consists of Mark R. Showalter (SETI Institute, USA) and Doug Hamilton (University of Maryland, USA)

Pluto’s moons are hypothesised to have formed by a collision between the dwarf planet and another similar-sized body early in the history of the solar system. The smashup flung material that coalesced into the family of satellites observed around Pluto today. Pluto’s large binary companion, Charon, was discovered in 1978. The object is almost half the size of Pluto. Hubble discovered Nix and Hydra in 2005, Kerberos in 2011, and Styx in 2012. These little moons, measuring just tens of miles across, were found as part of several Hubble searches for moons and rings to characterize the system in preparation for the New Horizons spacecraft flyby.

Links:

Images of Hubble: http://www.spacetelescope.org/images/archive/category/spacecraft/

Link to hubblesite release: http://hubblesite.org/newscenter/archive/releases/2015/24

Link to science paper: http://www.spacetelescope.org/static/archives/releases/science_papers/heic1512a.pdf

Images, Video, Text, Credits: NASA, ESA, M. Showalter (SETI Inst.), G. Bacon/A. Field (STScI).

Best regards, Orbiter.ch

Cassini Sends Final Close Views of Odd Moon Hyperion

NASA - Cassini International logo.

June 2, 2015

Image above: NASA's Cassini imaging scientists processed this view of Saturn's moon Hyperion, taken during a close flyby on May 31, 2015. Image Credits: NASA/JPL-Caltech/Space Science Institute.

NASA's Cassini spacecraft has returned images from its final close approach to Saturn's oddball moon Hyperion, upholding the moon's reputation as one of the most bizarre objects in the solar system. The views show Hyperion's deeply impact-scarred surface, with many craters displaying dark material on their floors.

Raw, unprocessed images from the May 31 flyby are available via the Cassini mission website at:
http://saturn.jpl.nasa.gov/photos/raw

A selection of some of the images is also available from the Cassini imaging team's website at:
http://www.ciclops.org/view_event/208/HYPERION-REV-216-RAW-PREVIEW

During this flyby, Cassini passed Hyperion at a distance of about 21,000 miles (34,000 kilometers) at closest approach. Cassini's closest-ever Hyperion flyby took place on Sept. 26, 2005, at a distance of 314 miles (505 kilometers).

Hyperion is the largest of Saturn’s irregular, or potato-shaped, moons and may be the remnant of a violent collision that shattered a larger object into pieces. Cassini scientists attribute Hyperion's peculiar, sponge-like appearance to the fact that it has an unusually low density for such a large object -- about half that of water. Its low density indicates Hyperion is quite porous, with weak surface gravity. These characteristics mean impactors tend to compress the surface, rather than excavating it, and most material that is blown off the surface never returns.

Image above: NASA's Cassini imaging scientists processed this view of Saturn's moon Hyperion, taken during a close flyby on May 31, 2015. Image Credits: NASA/JPL-Caltech/Space Science Institute.

Cassini will make several more close flybys of Saturn's moons this year before departing the planet's equatorial plane to begin a year-long setup of the mission's daring final act. For its grand finale, set for 2017, Cassini will repeatedly dive through the space between Saturn and its rings.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory in Pasadena, California, manages the mission for the agency's Science Mission Directorate in Washington. The Cassini imaging operations center is based at the Space Science Institute in Boulder, Colorado. The California Institute of Technology in Pasadena manages JPL for NASA.

For more information about Cassini, visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov and http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

Images (mentioned), Text, Credits: NASA/JPL/Preston Dyches/Tony Greicius.

Cheers, Orbiter.ch

Ultraviolet study reveals surprises in comet coma

ESA - Rosetta Mission patch.

2 June 2015

Rosetta’s continued close study of Comet 67P/Churyumov–Gerasimenko has revealed an unexpected process at work, causing the rapid breakup of water and carbon dioxide molecules spewing from the comet’s surface.

ESA’s Rosetta mission arrived at the comet in August last year. Since then, it has been orbiting or flying past the comet at distances from as far as several hundred kilometres down to as little as 8 km. While doing so, it has been collecting data on every aspect of the comet’s environment with its suite of 11 science instruments.

Rosetta uncovers processes at work in comet’s coma

One instrument, the Alice spectrograph provided by NASA, has been examining the chemical composition of the comet’s atmosphere, or coma, at far-ultraviolet wavelengths.

At these wavelengths, Alice allows scientists to detect some of the most abundant elements in the Universe such as hydrogen, oxygen, carbon and nitrogen.  The spectrograph splits the comet’s light into its various colours – its spectrum – from which scientists can identify the chemical composition of the coma gases.

In a paper accepted for publication in the journal Astronomy and Astrophysics, scientists report the detections made by Alice from Rosetta’s first four months at the comet, when the spacecraft was between 10 km and 80 km from the centre of the comet nucleus.

For this study, the team focused on the nature of ‘plumes’ of water and carbon dioxide gas erupting from the comet’s surface, triggered by the warmth of the Sun. To do so, they looked at the emission from hydrogen and oxygen atoms resulting from broken water molecules, and similarly carbon atoms from carbon dioxide molecules, close to the comet nucleus.

They discovered that the molecules seem to be broken up in a two-step process.

First, an ultraviolet photon from the Sun hits a water molecule in the comet’s coma and ionises it, knocking out an energetic electron. This electron then hits another water molecule in the coma, breaking it apart into two hydrogen atoms and one oxygen, and energising them in the process. These atoms then emit ultraviolet light that is detected at characteristic wavelengths by Alice.

Rosetta’s continued close study of Comet 67P/Churyumov–Gerasimenko has revealed an unexpected process at work, causing the rapid breakup of water and carbon dioxide molecules spewing from the comet’s surface.

ESA’s Rosetta mission arrived at the comet in August last year. Since then, it has been orbiting or flying past the comet at distances from as far as several hundred kilometres down to as little as 8 km. While doing so, it has been collecting data on every aspect of the comet’s environment with its suite of 11 science instruments.

One instrument, the Alice spectrograph provided by NASA, has been examining the chemical composition of the comet’s atmosphere, or coma, at far-ultraviolet wavelengths.

At these wavelengths, Alice allows scientists to detect some of the most abundant elements in the Universe such as hydrogen, oxygen, carbon and nitrogen.  The spectrograph splits the comet’s light into its various colours – its spectrum – from which scientists can identify the chemical composition of the coma gases.

Rosetta’s imaging and spectroscopy instruments

Similarly, it is the impact of an electron with a carbon dioxide molecule that results in its break-up into atoms and the observed carbon emissions.

“Analysis of the relative intensities of observed atomic emissions allows us to determine that we are directly observing the ‘parent’ molecules that are being broken up by electrons in the immediate vicinity, about 1 km, of the comet’s nucleus where they are being produced,” says Paul Feldman, professor of physics and astronomy at the Johns Hopkins University in Baltimore, and lead author of the paper discussing the results.

By comparison, from Earth or from Earth-orbiting space observatories such as the Hubble Space Telescope, the atomic constituents of comets can only be seen after their parent molecules, such as water and carbon dioxide, have been broken up by sunlight, hundreds to thousands of kilometres away from the nucleus of the comet.

“The discovery we’re reporting is quite unexpected,” says Alice Principal Investigator Alan Stern, an associate vice president in the Space Science and Engineering Division of the Southwest Research Institute (SwRI).

“It shows us the value of going to comets to observe them up close, since this discovery simply could not have been made from Earth or Earth orbit with any existing or planned observatory. And, it is fundamentally transforming our knowledge of comets.”

“By looking at the emission from hydrogen and oxygen atoms broken from the water molecules, we also can actually trace the location and structure of water plumes from the surface of the comet,” adds co-author Joel Parker, an assistant director in SwRI’s Space Science and Engineering Division in Boulder, Colorado.

Comet on 20 May 2015 – NavCam

The team likens the break-up of the molecules to the process that has been proposed for the plumes on Jupiter’s icy moon Europa, except that the electrons at the comet are produced by solar photons, while the electrons at Europa come from Jupiter’s magnetosphere.

The results from Alice are supported by data obtained by other Rosetta instruments, in particular MIRO, ROSINA and VIRTIS, which are able to study the abundance of different coma constituents and their variation over time, and particle detecting instruments like RPC-IES.

“These early results from Alice demonstrate how important it is to study a comet at different wavelengths and with different techniques, in order to probe various aspects of the comet environment,” says ESA’s Rosetta project scientist Matt Taylor.

“We’re actively watching how the comet evolves as it moves closer to the Sun along its orbit towards perihelion in August, seeing how the plumes become more active due to solar heating, and studying the effects of the comet’s interaction with the solar wind.”

More information:

“Measurements of the near-nucleus coma of Comet 67P/Churyumov-Gerasimenko with the Alice far-ultraviolet spectrograph on Rosetta,” by P Feldman et al is accepted for publication in Astronomy and Astrophysics.
http://www.aanda.org/10.1051/0004-6361/201525925

About Rosetta:

Rosetta is an ESA mission with contributions from its Member States and NASA. Rosetta’s Philae lander was provided by a consortium led by DLR, MPS, CNES and ASI. Rosetta is the first mission in history to rendezvous with a comet. It is escorting the comet as they orbit the Sun together. Philae landed on the comet on 12 November 2014. Comets are time capsules containing primitive material left over from the epoch when the Sun and its planets formed. By studying the gas, dust and structure of the nucleus and organic materials associated with the comet, via both remote and in situ observations, the Rosetta mission should become the key to unlocking the history and evolution of our Solar System.

Related links:

Rosetta at Astrium: http://www.astrium.eads.net/en/programme/rosetta-1go.html

Rosetta at DLR: http://www.dlr.de/dlr/en/desktopdefault.aspx/tabid-10394/

Ground-based comet observation campaign: http://www.rosetta-campaign.net/home

More about...

Rosetta overview: http://www.esa.int/Our_Activities/Space_Science/Rosetta_overview

Rosetta factsheet: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_factsheet

Frequently asked questions: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Frequently_asked_questions

For more information about Rosetta missio, visit: http://www.esa.int/Our_Activities/Space_Science/Rosetta

Images Credits: Spacecraft: ESA/ATG medialab; Comet, left: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA; comet, top right: ESA/Rosetta/NavCam – CC BY-SA IGO 3.0; data: Feldman et al (2015). Video, Text, Credit: European Space Agency (ESA).

Best regards, Orbiter.ch

ESA heading towards removing space debris

ESA - Clean Space Programme logo.

2 June 2015

ESA’s goal of removing a derelict satellite from orbit is picking up pace, as a mission design is assembled to be put before European ministers next year for approval.

The e.Deorbit mission came through ESA’s Clean Space initiative, tasked with reducing the environmental impact of the space industry in both the terrestrial and orbital realms.

Space debris removal mission

Space debris levels are increasing relentlessly, as colliding objects bequeath more debris and further collisions. Conserving the heavily trafficked and valuable low orbits calls for removing the large objects at a high risk of collision.

e.Deorbit would target an ESA derelict in this region, capture it, then safely burn up both the satellite and itself through a controlled atmospheric reentry. 

Having proved this approach, multiple missions per year could be flown – and e.Deorbit is being designed with recurring flights in mind.

In space industry parlance, e.Deorbit has completed its ‘Phase-A’ preliminary analysis that began in January 2014. With many aspects already finalised, it is now moving on to ‘Phase-B1’.

The aim now is to bring e.Deorbit to a point where it is essentially ready to build if ESA’s Council of Ministers in December 2016 gives its assent for launch in 2021.

Distribution of debris

Several studies in ESA’s Concurrent Design Facility have already defined aspects of the mission, which would adapt a Vega rocket upper stage as a platform for its capture system.

The proposal to harpoon its target has been dismissed as too difficult for the time being, in favour of alternative capture options such as robotic arms or nets. The initial prospect of taking debris into higher, quieter orbits has also been ruled out in favour of downward deorbiting.

“I am very pleased with the progress we are making,” said Robin Biesbroek, managing the effort. “In this phase we will really go into detail on the concept of operations, e.Deorbit’s subsystems design, and especially the capture and deorbit phases.

Concurrent Design Facility

“Extensive simulations will be done not only for standard cases, but also for off-nominal cases.”

The work to come will define the mission’s technical specifications around various goals, the most important of which is to minimise the danger to people on the ground, down to less than one in 10 000.

e Deorbit’s next milestone will be its ‘systems requirements review’, due in May–June 2016.

Related links:

How to catch a satellite: http://www.esa.int/Our_Activities/Space_Engineering_Technology/Clean_Space/How_to_catch_a_satellite

Technologies for space debris remediation: http://www.esa.int/Our_Activities/Space_Engineering_Technology/Clean_Space/Technologies_for_space_debris_remediation

Readying ESA's 'garbage truck': Robin Biesbroek interview: http://www.esa.int/Our_Activities/Space_Engineering_Technology/Clean_Space/Readying_ESA_s_garbage_truck_Robin_Biesbroek_interview

About Clean Space:

What is Clean Space?: http://www.esa.int/Our_Activities/Space_Engineering_Technology/Clean_Space/What_is_Clean_Space

Why is it needed?: http://www.esa.int/Our_Activities/Space_Engineering_Technology/Clean_Space/Why_is_it_needed

What are its objectives?: http://www.esa.int/Our_Activities/Space_Engineering_Technology/Clean_Space/What_are_its_objectives

Q & A on Clean Space: http://www.esa.int/Our_Activities/Space_Engineering_Technology/Clean_Space/Q_A_on_Clean_Space

Images, Text, Credits: ESA/Guus Schoonewille.

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