ESA finds that Venus has an ozone layer too

ESA - Venus Express Mission patch.

6 October 2011

ESA’s Venus Express spacecraft has discovered an ozone layer high in the atmosphere of Venus. Comparing its properties with those of the equivalent layers on Earth and Mars will help astronomers refine their searches for life on other planets.

Venus Express made the discovery while watching stars seen right at the edge of the planet set through its atmosphere. Its SPICAV instrument analysed the starlight, looking for the characteristic fingerprints of gases in the atmosphere as they absorbed light at specific wavelengths.

Stellar occultation at Venus

The ozone was detectable because it absorbed some of the ultraviolet from the starlight.

Ozone is a molecule containing three oxygen atoms. According to computer models, the ozone on Venus is formed when sunlight breaks up carbon dioxide molecules, releasing oxygen atoms.

These atoms are then swept around to the nightside of the planet by winds in the atmosphere: they can then combine to form two-atom oxygen molecules, but also sometimes three-atom ozone molecules.

"This detection gives us an important constraint on understanding the chemistry of Venus' atmosphere," says Franck Montmessin, who led the research.

It may also offer a useful comparison for searching for life on other worlds.

Venus Express

Ozone has only previously been detected in the atmospheres of Earth and Mars. On Earth, it is of fundamental importance to life because it absorbs much of the Sun's harmful ultraviolet rays. Not only that, it is thought to have been generated by life itself in the first place.

The build-up of oxygen, and consequently ozone, in Earth's atmosphere began 2.4 billion years ago. Although the exact reasons for it are not entirely understood, microbes excreting oxygen as a waste gas must have played an important role.

Along with plant life, they continue to do so, constantly replenishing Earth's oxygen and ozone.

As a result, some astrobiologists have suggested that the simultaneous presence of carbon dioxide, oxygen and ozone in an atmosphere could be used to tell whether there could be life on the planet.

This would allow future telescopes to target planets around other stars and assess their habitability. However, as these new results highlight, the amount of ozone is crucial.

The small amount of ozone in Mars' atmosphere has not been generated by life. There, it is the result of sunlight breaking up carbon dioxide molecules.

Animation of planet Venus

Venus too, now supports this view of a modest ozone build-up by non-biological means. Its ozone layer sits at an altitude of 100 km, about four times higher in the atmosphere than Earth's and is a hundred to a thousand times less dense.

Theoretical work by astrobiologists suggests that a planet's ozone concentration must be 20% of Earth's value before life should be considered as a cause.

These new results support that conclusion because Venus clearly remains below this threshold.

"We can use these new observations to test and refine the scenarios for the detection of life on other worlds," says Dr Montmessin.

Yet, even if there is no life on Venus, the detection of ozone there brings Venus a step closer to Earth and Mars. All three planets have an ozone layer.

"This ozone detection tells us a lot about the circulation and the chemistry of Venus' atmosphere," says Håkan Svedhem, ESA Project Scientist for the Venus Express mission.

"Beyond that, it is yet more evidence of the fundamental similarity between the rocky planets, and shows the importance of studying Venus to understand them all."

Related links:

This story in depth: http://sci.esa.int/jump.cfm?oid=49412

ESApod: Venus Express: http://www.esa.int/SPECIALS/Venus_Express/SEMHXANFGLE_0.html

Looking at Venus: http://www.esa.int/SPECIALS/Venus_Express/index.html

Image, Text, Credits: ESA / C. Carreau / Animations by AOES Medialab.

Greetings, Orbiter.ch

Did Earth's oceans come from comets?

ESA - Herschel Mission patch.

5 October 2011

ESA's Herschel infrared space observatory has found water in a comet with almost exactly the same composition as Earth's oceans. The discovery revives the idea that our planet's seas could once have been giant icebergs floating through space.

The origin of Earth's water is hotly debated. Our planet formed at such high temperatures that any original water must have evaporated. Yet today, two-thirds of the surface is covered in water and this must have been delivered from space after Earth cooled down.

Comet Hartley 2 observed by ESA’s Herschel

Comets seem a natural explanation: they are giant icebergs travelling through space with orbits that take them across the paths of the planets, making collisions possible. The impact of comet Shoemaker-Levy 9 on Jupiter in 1994 was one such event. But in the early Solar System, when there were larger numbers of comets around, collisions would have been much more common.

However, until now, astronomers' observations have failed to back up the idea that comets provided Earth's water. The key measurement they make is the level of deuterium – a heavier form of hydrogen – found in water.
All the deuterium and hydrogen in the Universe was made just after the Big Bang, about 13.7 billion years ago, fixing the overall ratio between the two kinds of atoms. However, the ratio seen in water can vary from location to location. The chemical reactions involved in making ice in space lead to a higher or lower chance of a deuterium atom replacing one of the two hydrogen atoms in a water molecule, depending on the particular environmental conditions.

Comet Hartley 2’s orbit in context

Thus, by comparing the deuterium to hydrogen ratio found in the water in Earth's oceans with that in extraterrestrial objects, astronomers can aim to identify the origin of our water.

All comets previously studied have shown deuterium levels around twice that of Earth's oceans. If comets of this kind had collided with Earth, they could not have contributed more than a few percent of Earth's water. In fact, astronomers had begun to think that meteorites had to be responsible, even though their water content is much lower.

Now, however, Herschel has studied comet Hartley 2 using HIFI, the most sensitive instrument so far for detecting water in space, and has shown that at least this one comet does have ocean-like water.

"Comet Hartley's deuterium-to-hydrogen ratio is almost exactly the same as the water in Earth's oceans," says Paul Hartogh, Max-Planck-Institut für Sonnensystemforschung, Katlenburg-Lindau, Germany, who led the international team of astronomers in this work.

The Heterodyne Instrument for the Far Infrared (HIFI)

The key to why comet Hartley 2 is different may be because of where it was born: far beyond Pluto, in a frigid region of the Solar System known as the Kuiper Belt.

The other comets previously studied by astronomers are all thought to have formed near to Jupiter and Saturn before being thrown out by the gravity of those giant planets, only to return much later from great distances.

Thus the new observations suggest that perhaps Earth's oceans came from comets after all – but only a specific family of them, born in the outer Solar System. Out there in the deep cold, the deuterium to hydrogen ratio imprinted into water ice might have been quite different from that which arose in the warmer inner Solar System.

Herschel is now looking at other comets to see whether this picture can be backed up.

"Thanks to this detection made possible by Herschel, an old, very interesting discussion will be revived and invigorated," says Göran Pilbratt, ESA Herschel Project Scientist.

"It will be exciting to see where this discovery will take us."

Related links:

Herschel: ESA's giant infrared observatory: http://www.esa.int/SPECIALS/Herschel/index.html

Herschel overview: http://www.esa.int/SPECIALS/Herschel/index.html

Online Showcase of Herschel Images OSHI: http://oshi.esa.int/

This story in depth: http://sci.esa.int/jump.cfm?oid=49008

Herschel in depth: http://sci.esa.int/science-e/www/area/index.cfm?fareaid=16

Images, Text, Credits: ESA / C. Carreau / AOES Medialab / Herschel / HssO Consortium.

Greetings, Orbiter.ch

Trigger-Happy Star Formation

NASA - Chandra X-ray Observatory patch.

Oct. 5, 2011

This composite image, created using data from the Chandra X-ray Observatory and the Spitzer Space Telescope, shows the molecular cloud Cepheus B, located in our galaxy about 2,400 light years from the Earth. A molecular cloud is a region containing cool interstellar gas and dust left over from the formation of the galaxy and mostly contains molecular hydrogen. The Spitzer data, in red, green and blue shows the molecular cloud (in the bottom part of the image) plus young stars in and around Cepheus B, and the Chandra data in violet shows the young stars in the field.

The Chandra observations allowed the astronomers to pick out young stars within and near Cepheus B, identified by their strong X-ray emission. The Spitzer data showed whether the young stars have a so-called "protoplanetary" disk around them. Such disks only exist in very young systems where planets are still forming, so their presence is an indication of the age of a star system.

These data provide an excellent opportunity to test a model for how stars form. The new study suggests that star formation in Cepheus B is mainly triggered by radiation from one bright, massive star (HD 217086) outside the molecular cloud. According to the particular model of triggered star formation that was tested -- called the radiation- driven implosion (RDI) model -- radiation from this massive star drives a compression wave into the cloud triggering star formation in the interior, while evaporating the cloud's outer layers.

Different types of triggered star formation have been observed in other environments. For example, the formation of our solar system was thought to have been triggered by a supernova explosion, In the star-forming region W5, a "collect-and-collapse" mechanism is thought to apply, where shock fronts generated by massive stars sweep up material as they progress outwards. Eventually the accumulated gas becomes dense enough to collapse and form hundreds of stars.

The RDI mechanism is also thought to be responsible for the formation of dozens of stars in W5. The main cause of star formation that does not involve triggering is where a cloud of gas cools, gravity gets the upper hand, and the cloud falls in on itself.

For more information about the Chandra mission and this result, including images and other multimedia, visit: http://www.nasa.gov/chandra and http://chandra.si.edu

Image, Text, Credit: X-ray: NASA / CXC / PSU / K. Getman et al.; IRL NASA / JPL-Caltech / CfA / J. Wang et al.

Greetings, Orbiter.ch

Very southern science at Concordia

IPEV - PNRA Concordia Antartica Base patch.

5 October 2011

Antarctica is a place of extremes: isolated, cold and dark during the southern winter. In short, it is a perfect location for unique science. ESA is again asking European scientists to submit ideas for research projects at Concordia station.

The Concordia research station in Antarctica is run by the French Polar Institute and the Italian Antarctic Programme, while ESA adds its space expertise in medical monitoring, testing life-support technologies and psychological training of crews staying over the long winter under extreme conditions.

A stunning view from the Concordia research station

Fundamental research on human adaptation in harsh environments is a pillar of Concordia’s work: the location provides many of the stresses that will be faced by future long missions to the Moon or Mars.

To this end, ESA is coordinating regular Announcements of Opportunity for all research in medicine, physiology and psychology at Concordia. This is the fourth announcement since 2003.

Announcement of Opportunity

Duration of the experiments should be up to two years; longer projects must be resubmitted after this period. Multidisciplinary research is welcome.

Image above: The Concordia Station is a scientific base built in Antarctica by the French Polar Institute (IPEV) and the Italian Antarctic Programme (PNRA).

Interested scientists are asked to send Letters of Intent before 4 November; a proposal workshop will be held at ESTEC in the Netherlands on 21 November.

The final proposals are due on 9 January 2012.

Depending on their complexity, some proposals may be implemented for the 2013 winter season, implying shipping of equipment and crew training in autumn 2012. The other selected projects will begin in the following seasons.

Concordia station

The flat landscape around Concordia is 3200 m above sea level. Equal to equatorial altitude of almost 4000 m, the air pressure is only 645 hPa, leading to chronic hypobaric hypoxia.

Concordia's location

During the winter, Concordia is under almost total darkness. With an average temperature of –51°C and a record low of –85°C, the conditions are harsh during the winter, limiting access to the austral summer of November to February.

Studies conducted at Concordia include glaciology, atmospheric sciences, astronomy, Earth sciences, technology, human biology and medicine – all benefitting from the unique environment in the middle of the Antarctic continent.

The station houses a team of typically 12–14 during the winter, selected through strict medical and psychological screening.

ESA's doctor Alex Salam at Concordia

The team consists of technicians, scientists, a cook and at least one medical doctor. They are responsible for the scientific work and operating the station, and their stay may last up to 14 months.

The French coastal station Dumont d’Urville is 1100 km away, while the Italian Mario Zucchelli Station at Terra Nova Bay lies 1200 km distant.

Further information, contact person and other details are available in the linked Announcement of Opportunity (below).

Concordia: http://www.esa.int/SPECIALS/Concordia/index.html

Concordia Announcement of Opportunity: http://www.esa.int/SPECIALS/Concordia/SEMTI69U7TG_0.html

Announcement of Opportunity 2011 (pdf): http://esamultimedia.esa.int/docs/hsf_research/AO-11-Concordia_v2.doc

Images, Text, Credits: ESA / Alex Salam / Mark Drinkwater / IPEV.

Best regards, Orbiter.ch

Observation Completion by Advanced Microwave Scanning Radiometer-EOS (AMSR-E)

JAXA logo labeled.

October 5, 2011

The Japan Aerospace Exploration Agency (JAXA) has been operating the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) for over nine years (despite a design life of three years) as an onboard device installed in the American earth observation satellite Aqua, after its launch on May 4, 2002. Since the end of August, 2011, however, the continuous increase of relatively large antenna rotation friction was detected twice, thus JAXA has been monitoring the condition. At 3:58 p.m. on October 4, 2011 (Japan Standard Time,) the AMSR-E reached its limit(*1) to maintain the rotation speed necessary for regular observations (40 rotations per minute), and the radiometer automatically halted its observations and rotation.

JAXA will continue to analyze this problem, and take necessary measures to correct the situation. We will also launch the successor to the AMSR-E, the Global Change Observation Mission 1st- Water "SHIZUKU" (GCOM-W1.)

*1) When rotation friction occurs, it is necessary to produce a turning force (torque) to offset the friction in order to maintain the rotation speed. The limit in this context means the maximum value of the torque (4.5 Nm,) which the AMSR-E's motor can produce.

Aqua/AMSR-E

(Reference) AMSR-E achievements

The AMSR-E is a microwave scanning radiometer with the world's highest performance. It can observe global-scale water, including ocean ice, surface temperatures, vapors, precipitation and soil water, regardless of weather conditions or if it is day or night by measuring faint radio waves emitted from the Earth.

(1) Contributing to practical areas

The AMSR-E contributed to accuracy improvement of weather forecasts by meteorological agencies around the world such as the Japan Meteorological Agency as its data was used for numerical weather predictions and for determining the center of a typhoon.

It was also helpful for more efficient operations of fishing boats as the data was used for compiling ocean condition information for fishing by a fishing industry information service center and other organizations.
   
The radiometer also contributed to monitoring the Sea of Okhotsk by the Japan Coast Guard and editing a report on overseas food demands through studying global drought conditions by the Ministry of Agriculture, Forestry and Fisheries.

(2) Usefulness to water circulation and climate change fields

Through long-time continuous observations of the Arctic ice, the AMSR-E was very helpful for understanding the impact of global warming by clarifying the smallest Arctic ice area in the observation history in the summer of 2007, and the second largest decrease of the area in the observation history in the summer of 2011.

With data observed by other satellites, the radiometer's data greatly contributed to the global precipitation map. The data was also very useful for international climate change research.

For other AMSR-E achievements in the past, please also refer to the Space Activities Commission (SAC) report issued on Aug. 31, 2005.

SAC Report on Aug. 31, 2005 (Japanese language only):
http://www.jaxa.jp/press/2005/08/20050831_sac_amsr-e_j.html

Earth Observation Center: http://www.eorc.jaxa.jp/en/index.php

Mission website:

"Aqua" Earth Observation Satellite: http://www.jaxa.jp/projects/sat/aqua/index_e.html

Image, Text, Credit: Japan Aerospace Exploration Agency (JAXA).

Greetings, Orbiter.ch

Arctic Sea Ice Continues Decline, Hits Second-Lowest Level

NASA - Operation IceBridge patch.

Oct. 4, 2011

Last month the extent of sea ice covering the Arctic Ocean declined to the second-lowest extent on record. Satellite data from NASA and the NASA-supported National Snow and Ice Data Center (NSIDC) at the University of Colorado in Boulder showed that the summertime sea ice cover narrowly avoided a new record low.

Image above: NASA satellite data reveals how this year's minimum sea ice extent, reached on Sept. 9 as depicted here, declined to a level far smaller than the 30-year average (in yellow) and opened up Northwest Passage shipping lanes (in red). (Credit: NASA Goddard's Scientific Visualization Studio).

The Arctic ice cap grows each winter as the sun sets for several months and shrinks each summer as the sun rises higher in the northern sky. Each year the Arctic sea ice reaches its annual minimum extent in September. It hit a record low in 2007.

The near-record ice-melt followed higher-than-average summer temperatures, but without the unusual weather conditions that contributed to the extreme melt of 2007. "Atmospheric and oceanic conditions were not as conducive to ice loss this year, but the melt still neared 2007 levels," said NSIDC scientist Walt Meier. "This probably reflects loss of multiyear ice in the Beaufort and Chukchi seas as well as other factors that are making the ice more vulnerable."

Joey Comiso, senior scientist  at NASA's Goddard Space Flight Center in Greenbelt, Md., said the continued low minimum sea ice levels fits into the large-scale decline pattern that scientists have watched unfold over the past three decades.

"The sea ice is not only declining, the pace of the decline is becoming more drastic," Comiso said. "The older, thicker ice is declining faster than the rest, making for a more vulnerable perennial ice cover."

This video shows Arctic sea ice from March 7, 2011, to Sept. 9, 2011, ending with a comparison of the 30-year average minimum extent (in yellow) and the Northwest Passage (shown in red). (Credit: NASA's Goddard Space Flight Center).

While the sea ice extent did not dip below the 2007 record, the sea ice area as measured by the microwave radiometer on NASA's Aqua satellite did drop slightly lower than 2007 levels for about 10 days in early September, Comiso said. Sea ice "area" differs from extent in that it equals the actual surface area covered by ice, while extent includes any area where ice covers at least 15 percent of the ocean.

Arctic sea ice extent on Sept. 9, the lowest point this year, was 4.33 million square kilometers (1.67 million square miles). Averaged over the month of September, ice extent was 4.61 million square kilometers (1.78 million square miles). This places 2011 as the second lowest ice extent both for the daily minimum extent and the monthly average. Ice extent was 2.43 million square kilometers (938,000 square miles) below the 1979 to 2000 average.

This summer's low ice extent continued the downward trend seen over the last 30 years, which scientists attribute largely to warming temperatures caused by climate change. Data show that Arctic sea ice has been declining both in extent and thickness. Since 1979, September Arctic sea ice extent has declined by 12 percent per decade.

"The oldest and thickest ice in the Arctic continues to decline, especially in the Beaufort Sea and the Canada Basin," NSIDC scientist Julienne Stroeve said. "This appears to be an important driver for the low sea ice conditions over the past few summers."

Climate models have suggested that the Arctic could lose almost all of its summer ice cover by 2100, but in recent years, ice extent has declined faster than the models predicted.

Video above: In a taped version of a live broadcast, NASA Cryosphere Program Manager Tom Wagner shares his insights on the 2011 minimum. (Credit: NASA's Goddard Space Flight Center).

NASA monitors and studies changing sea ice conditions in both the Arctic and Antarctic with a variety of spaceborne and airborne research capabilities. This month NASA resumes Operation IceBridge, a multi-year series of flights over sea ice and ice sheets at both poles. This fall's campaign will be based out of Punta Arenas, Chile, and make flights over Antarctica . NASA also continues work toward launching ICESat-2 in 2016, which will continue its predecessor's crucial laser altimetry observations of ice cover from space.

To see a NASA data visualization of the 2011 Arctic sea ice minimum as measured by the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) on Aqua, visit: http://www.nasa.gov/topics/earth/features/2011-ice-min.html

For more information about NASA and agency programs, visit: http://www.nasa.gov

Image (mentioned), Videos (mentioned) Text, Credit: NASA's Earth Science News Team / Patrick Lynch.

Greetings, Orbiter.ch

Galileo IOV satellites fuelled for launch

ESA - Galileo IOV logo.

4 October 2011

ESA’s first two Galileo navigation satellites are both now fuelled and checked for their launch by Soyuz from French Guiana on 20 October.

The two Galileo In-Orbit Validation satellites reached Europe’s Spaceport last month. Galileo’s second flight model, FM2, touched down on 7 September on an Antonov-124 and the Galileo Protoflight Model followed it seven days later on an Ilyushin 76.

Both satellites are now fuelled and ready to be mated this week onto the dispenser that will hold them in place during launch before deploying them into their final 23 222 km orbit.

Galileo IOV satellite

The combined payload stack – the dispenser and both satellites – will then be transported from the fuelling facility to the Upper Composite Integration Facility S3B for integration with their Fregat-MT upper stage and subsequent encapsulation.

Follow the Galileo In-Orbit Validation launch campaign from the new Soyuz-Galileo IOV minisite (see below link).

Dispenser check-out with upper stage

Soyuz from French Guiana

This month’s launch will be historic: the first Soyuz launch from a spaceport outside of Baikonur in Kazakhstan or Plesetsk in Russia.

As a medium-class vehicle, Soyuz will complement Ariane and Vega to extend the flexibility and competitiveness of Europe’s launcher family.

Encapsulated under fairing

Galileo

The first two Galileo IOV satellites, launched this month, will be followed next year by two more. This quartet of satellites, built by a consortium led by EADS Astrium Germany, will form the operational nucleus of the full Galileo satnav constellation.

Galileo IOV in orbit

They combine the best atomic clock ever flown for navigation – accurate to one second in three million years – with a powerful transmitter to broadcast precise navigation signals.

Soyuz-Galileo IOV launch minisite: http://www.esa.int/SPECIALS/Galileo_IOV/

Images, Text, Credits: ESA / P. Carril / S. Corvaja.

Cheers, Orbiter.ch