Rosetta’s comet

ESA - Rosetta Mission patch.

Jan. 20, 2013

Comet 67P/CG on 5 Oct 2013

ESA’s Rosetta spacecraft will wake up today, 20 January, after 31 months in deep space hibernation, to catch up with comet 67P/Churyumov–Gerasimenko.

This image shows the most recent observations of the 4 km-wide comet, taken on 5 October 2013 by the Very Large Telescope of the European Southern Observatory (ESO) in Chile. The comet was around 500 million kilometres from Earth, before it passed behind the Sun and out of view from Earth’s perspective.

For this image, a long series of observations was processed to reveal both the comet without the background stars (on the left panel), and the star field with the track of the comet marked (on the right). Viewed against a crowded star field in a direction towards the centre of the Milky Way, the comet appears as a simple spot.

The observation marks the start of a close collaboration between ESA and ESO to monitor the comet from the ground during Rosetta’s encounter later this year.

Rosetta was launched in 2004 and will become the first space mission to rendezvous with a comet, the first to attempt a landing on a comet and the first to follow a comet as it swings around the Sun.

Rosetta spacecraft deep space wake-up

The comet is on a 6.5-year orbit around the Sun and is currently moving towards the inner Solar System, inside the orbit of Jupiter. It will be closest to the Sun – roughly between the orbits of Earth and Mars – in August 2015. During this approach, the surface will warm up and its ices will sublimate, dragging out dust into a tail and likely causing jets from the surface.

Although there is no evidence in this image to suggest that the comet is already active, scientists will be keen to check in on the comet again in February, when it is next observable by the  Very Large Telescope.

In the meantime, the observations carried out late last year have been used to confirm the comet’s orbit ahead of a major manoeuvre planned for Rosetta in May, to line it up for its rendezvous in August. Further calculations will be made once Rosetta sights the comet in its own imaging system.

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

Images, Text, Credits: ESA / ESO / C. Snodgrass (Max Planck Institute for Solar System Research, Germany).

Best regards, Orbiter.ch

The correction of the orbit of the International Space Station

ISS - International Space Station patch.

18/01/2014

January 18, 2014 the correction of the orbit of the International Space Station.

According to calculations by the ballistic and navigation support Mission Control Center FSUE TsNIIMash engines cargo spacecraft Progress M-21M were included in the 09 4:00 Moscow time and worked 528 seconds. As a result, ISS received a velocity increment of 1.18 m/s. The average height of its orbit increased by 2.8 km and reached 417.25 km.

Progress-M reboost ISS

According to the service ballistic and navigation support MCC after the ISS orbit maneuver parameters were as follows:

- The minimum height - 415.29 km
- Maximum height - 436.72 km
- Period - 92.855 min
- Inclination - 51,67°.

ROSCOSMOS Press Release: http://www.federalspace.ru/20139/

Image, Text, Credits: Roscosmos press service and DRM TsNIIMash / NASA / Translation: Orbiter.ch Aerospace.

Greetings, Orbiter.ch

NASA Searches for Climate Change Clues in the Gateway to the Stratosphere

NASA - ATTREX Mission patch.


Jan. 17, 2014

NASA's uncrewed Global Hawk research aircraft is in the western Pacific region on a mission to track changes in the upper atmosphere and help researchers understand how these changes affect Earth's climate.

Deployed from NASA's Dryden Flight Research Center in Edwards, Calif., the Global Hawk landed at Andersen Air Force Base in Guam Thursday at approximately 5 p.m. EST and will begin science flights Tuesday, Jan. 21. Its mission, the Airborne Tropical Tropopause Experiment (ATTREX), is a multi-year NASA airborne science campaign.

ATTREX will measure the moisture levels and chemical composition of upper regions of the lowest layer of Earth's atmosphere, a region where even small changes can significantly impact climate. Scientists will use the data to better understand physical processes occurring in this part of the atmosphere and help make more accurate climate predictions.

"We conducted flights in 2013 that studied how the atmosphere works and how humans are affecting it," said Eric Jensen, ATTREX principal investigator at NASA’s Ames Research Center in Moffett Field, Calif. "This year, we plan to sample the western Pacific region which is critical for establishing the humidity of the air entering the stratosphere."

Image above: NASA's Global Hawk 872 on a checkout flight from Dryden Flight Research Center, Edwards, Calif., in preparation for the 2014 ATTREX mission over the western Pacific Ocean. Image Credit: NASA/Tom Miller.

Studies show even slight changes in the chemistry and amount of water vapor in the stratosphere, the same region that is home to the ozone layer, which protects life on Earth from the damaging effects of ultraviolet radiation, can affect climate significantly by absorbing thermal radiation rising from the surface. Predictions of stratospheric humidity changes are uncertain because of gaps in the understanding of the physical processes occurring in the tropical tropopause layer.

ATTREX is studying moisture and chemical composition from altitudes of 55,000 feet to 65,000 feet in the tropical tropopause, which is the transition layer between the troposphere, or the lowest part of the atmosphere, and the stratosphere, which extends up to 11 miles above Earth's surface. Scientists consider the tropical tropopause to be the gateway for water vapor, ozone and other gases that enter the stratosphere. For this mission, the Global Hawk carries instruments that will sample the tropopause near the equator over the Pacific Ocean.

ATTREX scientists installed 13 research instruments on NASA's Global Hawk 872. Some of these instruments capture air samples while others use remote sensing to analyze clouds, temperature, water vapor, gases and solar radiation.

"Better understanding of the exchange between the troposphere and stratosphere and how that impacts composition and chemistry of the upper atmosphere helps us better understand how, and to what degree, the upper atmosphere affects Earth’s climate," Jensen said.

 NASA Deploys ATTREX To Guam to Study Climate Change

In 2013, for the first time, ATTREX instruments sampled the tropopause region in the Northern Hemisphere during winter, when the region is coldest and extremely dry air enters the stratosphere. Preparations for this mission started in 2011 with engineering test flights to ensure the aircraft and its research instruments operated well in the extremely cold temperatures encountered at high altitudes over the tropics, which can reach minus 115 degrees Fahrenheit. ATTREX conducted six science flights totaling more than 150 hours last year.

Jensen and Project Manager Dave Jordan of Ames lead the ATTREX mission. It includes investigators from Ames and three other NASA facilities: Langley Research Center in Hampton, Va., Goddard Space Flight Center in Greenbelt, Md., and the Jet Propulsion Laboratory in Pasadena, Calif. The team also includes investigators from the National Oceanic and Atmospheric Administration, the National Center for Atmospheric Research, universities and private industry.

ATTREX is one of the first research missions of NASA's new Earth Venture project. These small and targeted science investigations complement NASA's broader science research satellite missions. The Earth Venture missions are part of NASA's Earth System Science Pathfinder Program managed by Langley.

For more information about the ATTREX mission, visit: http://espo.nasa.gov/missions/attrex

An ATTREX press kit is available at http://www.nasa.gov/centers/ames/events/2013/attrex.html

Image (mentioned), Video, Text, Credits: NASA / Steve Cole / Ames Research Center / Rachel Hoover / Dryden Flight Research Center / Beth Hagenauer.

Best regards, Orbiter.ch

Expedition 38 Preparing for Mission’s Fourth Spacewalk

ISS - Expedition 38 Mission patch.


Jan. 15, 2014

Expedition 38 is working new science delivered aboard Cygnus including ongoing international and commercial research. The crew is also preparing for its fourth spacewalk in five weeks.

Japanese astronaut Koichi Wakata worked on science experiments for students and a commercial organization. Wakata first videotaped a demonstration of the difference between gravity on Earth and microgravity on International Space Station. Later he worked on NanoRacks commercial research gear in the Kibo laboratory on an experiment delivered Sunday aboard the Cygnus resupply craft.

After spending his morning exercising, Flight Engineer Rick Mastracchio spent the rest of the afternoon with maintenance work on the Waste and Hygiene Compartment. He replaced urine hydraulic components in the Harmony node’s bathroom.

Image above: Cosmonauts Oleg Kotov and Sergey Ryazanskiy work outside the station's Russian segment during a Dec. 27 spacewalk.

NASA astronaut Mike Hopkins set up the Space Linear Acceleration Mass Measurement Device (SLAMMD) to measure his body mass. Afterward, he continued work with a vaccine experiment using the commercial generic bioprocessing apparatus to help prevent infections on Earth and in space.

Read about the SLAMMD: http://www.nasa.gov/mission_pages/station/research/experiments/640.html

Commander Oleg Kotov and Flight Engineer Sergey Ryazanskiy are preparing for a spacewalk to complete unfinished work from a previous spacewalk. The cosmonaut duo is scheduled to exit the Pirs docking compartment in their Orlan spacesuits Jan. 27 at 9:10 a.m. EST.

Image above: Astronaut works inside the Destiny laboratory to replace gear on the Combustion Integrated Rack.

During the previous spacewalk that took place Dec. 27, Kotov and Ryazanskiy installed then removed two cameras that experienced telemetry and connectivity issues. The extra work postponed the jettisoning of experiment gear and the installation of a payload boom.

Read about the Dec. 27 Russian spacewalk: http://www.orbiterchspacenews.blogspot.ch/2013/12/station-cosmonauts-complete-spacewalk.html

Cosmonaut and veteran station resident Mikhail Tyurin reconfigured communications gear inside the Rassvet mini-research module. He spent the rest of the afternoon setting up sensors to check temperatures and air flows, checking electronics gear and downloading science data collected for the Obstanovka experiment.

Read more about Obstanovka: http://www.energia.ru/en/iss/researches/study/05.html

The six-member Expedition 38 crew teamed up for an emergency drill Wednesday morning reviewing escape paths, safety gear and communication procedures. Afterward, the crew called down to Mission Control to discuss the results of the drill.

Images, Text, Credits: NASA / NASA TV.

Greetings, Orbiter.ch

The experts behind Gaia's arrival at nothingness

ESA - Gaia Mission patch.

15 January 2014

With a final, modest, thruster burn yesterday afternoon, ESA’s billion-star surveyor finalised its entry into orbit around ‘L2’, a virtual point far out in space. But how do you orbit nothing? And who can show you how to get there, anyway?

Just after 15:30 GMT (16:30 CET) yesterday, Gaia made a short thruster burn, nudging the galactic survey craft onto its planned scientific orbit. The job had been mostly completed last week, after an almost two-hour firing took Gaia into a squiggly path about the L2 Lagrange point, 1.5 million km from Earth.

Gaia mapping the stars of the Milky Way

But this apparently simple manoeuvre belies an astonishing fact: the L2 point consists of precisely nothing. It’s simply a point in space.

Nothing there

“Lagrange points are special – it’s true there’s nothing there,” says Markus Landgraf, a mission analyst at ESOC, ESA’s operations centre in Darmstadt, Germany.

“They are points where the gravitational forces between two masses, like the Sun and Earth, add up to compensate for the centrifugal force of Earth’s motion around the Sun, and they provide uniquely advantageous observation opportunities for studying the Sun or our Galaxy.” 

As seen from this Lagrange point (there are a total of five such points in the Sun–Earth system), the Sun, Earth and Moon will always be close together in the sky, so Gaia can use its sunshield to protect its instruments from the light and heat from these three celestial bodies simultaneously.

Gaia follows a Lissajous orbit

This also helps the satellite to stay cool and enjoy a clear view of the Universe from the other side.

L2 provides a moderate radiation environment, which helps extend the life of the instrument detectors in space.

However, orbits around L2 are fundamentally unstable.

“We'll have to conduct stationkeeping burns every month to keep Gaia around L2, otherwise perturbations would cause it to ‘fall off’ the point,” says Gaia Operations Manager David Milligan.

For those used to seeing images of the International Space Station orbiting Earth, or Mars Express orbiting the Red Planet, it seems intuitive that spacecraft have to orbit something. How do you get a spacecraft to orbit around a point of nothingness?

ESA flight dynamics experts

To maintain this orbit for Gaia’s planned 5-year mission requires extremely careful work by ESA’s flight dynamics team – the experts who determine and predict trajectories, prepare orbit manoeuvres and determine satellite attitudes.

The flight dynamics experts use a range of software tools, developed and refined during decades of support to missions around Earth and across the Solar System.

To plan the orbit, the team applies mathematical models to generate an initial guess for the target orbit and how to get there. This guess must account for the requirements and constraints of the launcher and the needed telecommunications links.

Flight dynamics at ESA

Next, those initial guesses are fed into simulation software to see if the results would violate any of the constraints. Often, no solution is possible.

“That is where expertise and experience are indispensable to reconsider the assumptions and then start all over,” says Frank Dreger, Head of Flight Dynamics.

“There's no commercial source for this sort of software or expertise – it’s been built up over many years at ESOC and represents a capability that is rare in the world and unique in Europe.”

More about:

Gaia overview: http://www.esa.int/Our_Activities/Space_Science/Gaia/Gaia_overview

Gaia factsheet: http://www.esa.int/Our_Activities/Space_Science/Gaia/Gaia_factsheet

Frequently asked questions: http://www.esa.int/Our_Activities/Space_Science/Gaia/Frequently_Asked_Questions_about_Gaia

Gaia brochure: http://www.esa.int/About_Us/ESA_Publications/ESA_BR-296_Gaia_ESA_s_galactic_census

Images, Text, Credits: ESA/ATG medialab; background: ESO/S. Brunier/J. Mai.

Greetings, Orbiter.ch

First Planet Found Around Solar Twin in Star Cluster

ESO - European Southern Observatory logo.

15 January 2014

Six-year search with HARPS finds three new planets in Messier 67

Artist's impression of an exoplanet orbiting a star in the cluster Messier 67

Astronomers have used ESO's HARPS planet hunter in Chile, along with other telescopes around the world, to discover three planets orbiting stars in the cluster Messier 67. Although more than one thousand planets outside the Solar System are now confirmed, only a handful have been found in star clusters. Remarkably one of these new exoplanets is orbiting a star that is a rare solar twin — a star that is almost identical to the Sun in all respects.

Planets orbiting stars outside the Solar System are now known to be very common. These exoplanets have been found orbiting stars of widely varied ages and chemical compositions and are scattered across the sky. But, up to now, very few planets have been found inside star clusters [1]. This is particularly odd as it is known that most stars are born in such clusters. Astronomers have wondered if there might be something different about planet formation in star clusters to explain this strange paucity.

 The star cluster Messier 67 in the constellation of Cancer

Anna Brucalassi (Max Planck Institute for Extraterrestrial Physics, Garching, Germany), lead author of the new study, and her team wanted to find out more. “In the Messier 67 star cluster the stars are all about the same age and composition as the Sun. This makes it a perfect laboratory to study how many planets form in such a crowded environment, and whether they form mostly around more massive or less massive stars.”

The team used the HARPS planet-finding instrument on ESO's 3.6-metre telescope at the La Silla Observatory. These results were supplemented with observations from several other observatories around the world [2]. They carefully monitored 88 selected stars in Messier 67 [3] over a period of six years to look for the tiny telltale motions of the stars towards and away from Earth that reveal the presence of orbiting planets.

Wide-field view of the open star cluster Messier 67

This cluster lies about 2500 light-years away in the constellation of Cancer (The Crab) and contains about 500 stars. Many of the cluster stars are fainter than those normally targeted for exoplanet searches and trying to detect the weak signal from possible planets pushed HARPS to the limit.

Three planets were discovered, two orbiting stars similar to the Sun and one orbiting a more massive and evolved red giant star. The first two planets both have about one third the mass of Jupiter and orbit their host stars in seven and five days respectively. The third planet takes 122 days to orbit its host and is more massive than Jupiter [4].

Zooming in on the star cluster Messier 67

The first of these planets proved to be orbiting a remarkable star — it is one of the most similar solar twins identified so far and is almost identical to the Sun (eso1337) [5]. It is the first solar twin in a cluster that has been found to have a planet.

Two of the three planets are “hot Jupiters” — planets comparable to Jupiter in size, but much closer to their parent stars and hence much hotter. All three are closer to their host stars than the habitable zone where liquid water could exist.

Flying through the star cluster Messier 67

“These new results show that planets in open star clusters are about as common as they are around isolated stars — but they are not easy to detect,” adds Luca Pasquini (ESO, Garching, Germany), co-author of the new paper [6]. “The new results are in contrast to earlier work that failed to find cluster planets, but agrees with some other more recent observations. We are continuing to observe this cluster to find how stars with and without planets differ in mass and chemical makeup.”

Panning across the star cluster Messier 67

Notes:

[1] Star clusters come in two main types. Open clusters are groups of stars that have formed together from a single cloud of gas and dust in the recent past. They are mostly found in the spiral arms of a galaxy like the Milky Way. On the other hand globular clusters are much bigger spherical collections of much older stars that orbit around the centre of a galaxy. Despite careful searches, no planets have been found in a globular cluster and less than six in open clusters. Exoplanets have also been found in the past two years in the clusters NGC 6811 and Messier 44, and even more recently one has also been detected in the bright and nearby Hyades cluster.

[2] This work also used observations from the SOPHIE instrument at the Observatoire de Haute-Provence in France, the Swiss 1.2-metre Leonhard Euler Telescope at ESO's La Silla Observatory in Chile and the Hobby Eberly Telescope in Texas, USA.

[3] Most open clusters dissipate after a few tens of million years. However, clusters that form with a higher density of stars can stay together for much longer. Messier 67 is an example of such a long-lived older cluster and is one of the oldest and best-studied of such clusters close to the Earth.

[4] Mass estimates for planets observed using the radial velocity method are lower estimates: if the planet's orbit is highly inclined it could have a higher mass and create the same observed effects.

[5] Solar twins, solar analogues and solar-type stars are categories of stars according to their similarity to the Sun. Solar twins are the most similar to the Sun, as they have very similar masses, temperatures, and chemical abundances. Solar twins are very rare, but the other classes, where the similarity is less precise, are much more common.

[6] This detection rate of 3 planets in a sample of 88 stars in Messier 67 is close to the average frequency of planets around stars that are not members of clusters.

More information:

This research was presented in a paper entitled “Three planetary companions around M67 stars“, by A. Brucalassi et al., to appear in the journal Astronomy & Astrophysics.

The team is composed of A. Brucalassi (Max-Planck-Institut für extraterrestrische Physik, Garching, Germany [MPE]; Sternwarte, Munich, Germany), L. Pasquini (ESO, Garching, Germany), R. Saglia (MPE; Sternwarte), M.T. Ruiz (Universidad de Chile, Santiago, Chile), P. Bonifacio (GEPI, Observatoire de Paris, CNRS, Univ. Paris Diderot, France), L. R. Bedin (INAF - Osservatorio Astronomico di Padova, Padova, Italy), K. Biazzo (INAF - Osservatorio Astronomico di Catania, Catania, Italy), C. Melo (ESO, Santiago, Chile), C. Lovis (Observatoire de Geneve, Switzerland) and S. Randich (INAF - Osservatorio Astrofisico di Arcetri, Florence, Italy).

ESO is the foremost intergovernmental astronomy organisation in Europe and the world's most productive ground-based astronomical observatory by far. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world's largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world's biggest eye on the sky”.

Links:

Video: ESOcast 62: Three planets found in star cluster: http://www.eso.org/public/videos/eso1402a/

Research paper: A&A letter: http://www.eso.org/public/archives/releases/sciencepapers/eso1402/eso1402a.pdf

Photos of the ESO 3.6-metre telescope: http://www.eso.org/public/images/archive/search/?adv=&subject_name=3.6

Images, Text, Credits: ESO/L. Calçada/IAU and Sky & Telescope/Digitized Sky Survey 2/Acknowledgement: Davide De Martin/Videos: ESO/L. Calçada/N. Risinger/Digitized Sky Survey 2/N. Risinger (skysurvey.org)/Music: movetwo.

Best regards, Orbiter.ch

Ten years imaging Mars

ESA - Mars Express Mission patch.

Jan. 14, 2014

Ten years ago, on 14 January 2004, Mars Express took its very first images of Mars in colour and in 3D.

To mark the occasion, the team produced a fly-through movie of the ancient flood plain Kasei Valles. The movie is based on the 67-image mosaic released as part of the ten-years-since-launch celebrations in June 2013.

The floodwaters of Mars

The scene spans 987 km in the north–south direction, 19–36°N, and 1550 km in the east–west direction (280–310°E). It covers 1.55 million square kilometres, an area equivalent to the size of Mongolia.

Kasei Valles is one of the largest outflow channel systems on Mars, created during dramatic flood events. From source to sink, it extends some 3000 km and descends 3 km.

Kasei Valles splits into two main branches that hug a broad island of fractured terrain – Sacra Mensa – rising 2 km above the channels that swerve around it. While weaker materials succumbed to the erosive power of the fast-flowing water, this hardier outcrop has stood the test of time.

Artist's view of the Mars Express spacecraft

Slightly further downstream, the flood waters did their best to erase the 100 km-wide Sharonov crater, crumpling its walls to the south. Around Sharonov many small streamlined islands form teardrop shapes rising from the riverbed as water swept around these natural obstacles.

The Planetary Science and Remote Sensing Group at Freie Universität Berlin produced the movie. The processing of the High Resolution Stereo Camera image data was carried out at the DLR German Aerospace Center.

For more information about Mars Express Mission, visit: http://www.esa.int/Our_Activities/Space_Science/Mars_Express

Image, Video, Text, Credits: ESA / DLR / FU Berlin (G. Neukum).

Best regards, Orbiter.ch