PARIS - ESA’s fourth Automated Transfer Vehicle, Albert Einstein, completed a flawless rendezvous with the International Space Station on 15 June when it docked smoothly with orbital outpost at 14:07 GMT (16:07 CEST). The Automated Transfer Vehicle (ATV) is now connected to the Space Station.“Bravo Europe, bravo ESA, bravo ATV. Thank you Member States, thank you industry, thank you CNES, thank you Russian partner,” commented Jean-Jacques Dordain, Director General of ESA.
“With the fourth ATV now ready to support and supply the Space Station with essential supplies and scientific experiments, ESA again proves itself to be a reliable partner in the international station upon which the future can be developed.”
The 20-tonne ferry, the heaviest spacecraft ever launched by Europe, flew autonomously and docked with the 420-tonne complex with a precision of a few cm as both circled Earth at 28 000 km/h.
“Such a gentle contact between a spacecraft the size of a double-decker bus and a Station 20 times larger is an amazing achievement, highlighting the impressive level of control achieved by this European space system developed by our industry under ESA’s direction,” said Thomas Reiter, ESA’s Director of Human Spaceflight and Operations.
“These impressive technological capabilities will live on in the service module of NASA’s upcoming Orion crew vehicle.”
The rendezvous and docking were performed autonomously by ATV’s own computers, closely monitored by flight controllers from ESA and France’s CNES space agency at the ATV Control Centre in Toulouse, France, and by Luca Parmitano and his crewmates on the Station. Like its predecessors, ATV-4 is much more than a simple supply vessel: it is a space tug, a tanker, a freighter and a temporary habitation module.
To compensate for the natural decay in altitude of the Station’s orbit caused by atmospheric drag, it is loaded with 2580 kg of propellant to perform regular reboosts. It can even move the entire space complex out of the path of hazardous space debris. ATV also provides attitude control when other spacecraft are approaching the Station.
In its tanks, it carries 860 kg of propellant, 100 kg of oxygen and air, and 570 kg of drinking water, all to be pumped into the Station’s tanks. In its pressurised cargo module, it carries more than 1400 items packed into 141 bags, including 2480 kg of dry cargo such as scientific equipment, spare parts, food and clothes for the astronauts.
During its four months attached to the Station, ATV will provide 45 cubic metres of extra crew quarters. On previous missions, the addition was welcomed by the astronauts as “the quietest place in the Station” and was often the preferred area for working.
At the end of its mission, scheduled for 28 October, ATV-4 will separate from the Station, packed with waste bags. The following day, it will be directed to burn up safely in the atmosphere during reentry over the South Pacific Ocean.
PARIS - The module carrying the telescope and scientific instruments of ESA’s Euclid ‘dark Universe’ mission is now being developed by Astrium in Toulouse, France. Euclid will be launched in 2020 to explore dark energy and dark matter in order to understand the evolution of the Universe since the Big Bang and, in particular, its present accelerating expansion.Dark matter is invisible to our normal telescopes but acts through gravity to play a vital role in forming galaxies and slowing the expansion of the Universe.
Dark energy, however, causes a force that is overcoming gravity and accelerating the expansion seen around us today.
Together, these two components are thought to comprise 95% of the mass and energy of the Universe, with ‘normal’ matter, from which stars, planets and we humans are made, making up the remaining small fraction. Their nature remains a profound mystery.
“Euclid will address the cosmology-themed questions of ESA’s Cosmic Vision 2015–25 program with advanced payload technologies, enabling Europe to become a world leader in this field of research,” says Thomas Passvogel, Head of the Project Department in ESA’s Directorate of Science and Robotic Exploration.
Astrium will deliver a fully integrated payload module incorporating a 1.2 m-diameter telescope feeding the mission’s two science instruments, which are being developed by the Euclid Consortium.
The two state-of-the art, wide-field instruments – a visible-light camera and a near-infrared camera/spectrometer – will map the 3D distribution of up to two billion galaxies and the associated dark matter and dark energy, spread over more than a third of the whole sky.
By surveying galaxies stretched across ten billion light-years, the mission will plot the evolution of the very fabric of the Universe and the structures within it over three-quarters of its history.
In particular, Euclid will address one of the most important questions in modern cosmology: why is the Universe expanding at an accelerating rate today, rather than slowing down due to the gravitational attraction of all the matter in it?
The discovery of this cosmic acceleration in 1998 was rewarded with the Nobel Prize for Physics in 2011 and yet there is no accepted explanation for it.
By using Euclid to study its effects on the galaxies and clusters of galaxies across the Universe, astronomers hope to come much closer to understanding the true nature and influence of this mysterious dark energy.
“We are excited that Euclid has reached this important milestone, allowing us to progress towards launch in 2020, and bringing us ever closer to uncovering some of the Universe’s darkest secrets,” says Giuseppe Racca, ESA’s Euclid Project Manager.
PASADENA, Calif. -- Researchers using NASA's Mars Reconnaissance Orbiter have found that temperatures in the Martian atmosphere regularly rise and fall not just once each day, but twice.
"We see a temperature maximum in the middle of the day, but we also see a temperature maximum a little after midnight," said Armin Kleinboehl of NASA's Jet Propulsion Laboratory in Pasadena, Calif., who is the lead author of a new report on these findings.
Temperatures swing by as much as 58 degrees Fahrenheit (32 kelvins) in this odd, twice-a-day pattern, as detected by the orbiter's Mars Climate Sounder instrument.
The new set of Mars Climate Sounder observations sampled a range of times of day and night all over Mars. The observations found that the pattern is dominant globally and year-round. The report is being published in the journal Geophysical Research Letters.
Global oscillations of wind, temperature and pressure repeating each day or fraction of a day are called atmospheric tides. In contrast to ocean tides, they are driven by variation in heating between day and night. Earth has atmospheric tides, too, but the ones on Earth produce little temperature difference in the lower atmosphere away from the ground. On Mars, which has only about one percent as much atmosphere as Earth, they dominate short-term temperature variations throughout the atmosphere.
Tides that go up and down once per day are called "diurnal." The twice-a-day ones are called "semi-diurnal." The semi-diurnal pattern on Mars was first seen in the 1970s, but until now it had been thought to appear just in dusty seasons, related to sunlight warming dust in the atmosphere.
"We were surprised to find this strong twice-a-day structure in the temperatures of the non-dusty Mars atmosphere," Kleinboehl said. "While the diurnal tide as a dominant temperature response to the day-night cycle of solar heating on Mars has been known for decades, the discovery of a persistent semi-diurnal response even outside of major dust storms was quite unexpected, and caused us to wonder what drove this response."
He and his four co-authors found the answer in the water-ice clouds of Mars. The Martian atmosphere has water-ice clouds for most of the year. Clouds in the equatorial region between about 6 to 19 miles (10 to 30 kilometers) above the surface of Mars absorb infrared light emitted from the surface during daytime. These are relatively transparent clouds, like thin cirrus clouds on Earth. Still, the absorption by these clouds is enough to heat the middle atmosphere each day. The observed semi-diurnal temperature pattern, with its maximum temperature swings occurring away from the tropics, was also unexpected, but has been replicated in Mars climate models when the radiative effects of water-ice clouds are included.
"We think of Mars as a cold and dry world with little water, but there is actually more water vapor in the Martian atmosphere than in the upper layers of Earth's atmosphere," Kleinboehl said. "Water-ice clouds have been known to form in regions of cold temperatures, but the feedback of these clouds on the Mars temperature structure had not been appreciated. We know now that we will have to consider the cloud structure if we want to understand the Martian atmosphere. This is comparable to scientific studies concerning Earth's atmosphere, where we have to better understand clouds to estimate their influence on climate."
JPL, a division of the California Institute of Technology in Pasadena, provided the Mars Climate Sounder instrument and manages the Mars Reconnaissance Orbiter project for NASA's Science Mission Directorate, Washington.
Beijing – The Shenzhou-10 crew, who successfully launched out of the Jiuquan Satellite Launch Center yesterday aboard a modified Long March 2B booster, spent their first full day in space today offering the country Dragon Festival (Chinese New Year) greetings from within the spacecrafts descent module. Astronauts Nie Haisheng, Zhang Xiaoguang and Wang Yaping appeared on camera around 1pm local time today to thank those who were stuck working because they were in orbit and to send greetings to the rest of the country.
"We wish all Chinese around the world a happy Dragon Boat Festival," the astronauts said while holding a banner reading "Happy Dragon Boat Festival." Within the next day or two the crew should reach their destination – the Tiangong-1 space laboratory. Chinese technicians describe Tiangong-1 as a “mini Space Station”, a uniquely Chinese construction where Chinese astronauts can begin honing their skills before graduating to a full sized space station before the year 2020.
Tiangong 1 is 35 feet long and is 11 feet in diameter at its widest part. It weighs just 8.5 tons (compare that to the first Russian space station which weighed 25 tons). It is made up of two major modules. At the front is a docking port. Tiangong 1 has been fitted with a modified APAS-89 docking unit. The same unit currently used by Russia and the United States to dock with the International Space Station. It is believed that the Chinese chose this system deliberately in order to make their spacecraft compatible with ISS.
From the docking port, a cone shaped adapter leads to the first module known as the “experiment” module. This is a two steeped pressurized module with the back half being slightly larger than the front. This is the area in which the crew will do most of their work. The experiment module is connected to the second module, known as the resource module, via a second cone like structure. The resource module is a cylinder which contains all of the crew’s life support systems as well as all of the mechanical systems and fuel. Power is generated using two foldable solar panels that attach to the module. There are also at least two maneuvering engines in the back. It is entirely possible that this section is a modified Shenzhou service module. This would be similar to how the Russians used modified Soyuz service modules on their early space stations.
Shenzhou – 10 is the first operational flight of a Shenzhou spacecraft. Up to this point, the Chinese have been using each manned mission to develop certain key technologies. First was to simply fly a man in space, then to fly a crew into space, next was to conduct a spacewalk, and after that was to dock with an orbiting lab (Tiangong-1). Now they are seeking to utilize these key technologies to begin living and working in space.
High on the priority list for Shenzhou-10 will be docking operations. In fact this is mission critical objective. Once Shenzhou-10 reaches Tiangong-1 the crew will attempt to dock with it. This will be done autonomously from the ground. If Shenzhou-10 fails to dock the mission will be over. Upon docking the crew will enter Shenzhou-10’s orbital module. Unlike the Russian Soyuz and the American Space Shuttle, which normally stay passive during docked operations, Shenzhou-10 will play a very active roll. One of the Unique capabilities of the Shenzhou system is the fact that the orbital module can function independent of the rest of the spacecraft. It acts like a third module housing the kitchen, bathroom, and a single sleep station (two more are on the lab). It is interesting to note that on this particular mission the crew will be using a new and improved toilet as well as testing out new food.
Once the post docking checks are complete the crew will open the hatch and one of them, most likely the commander, will enter the lab. The first thing he will do is give the interior a thorough look over. Tiangong-1 has been in space now for over 600 days, during this time it has only been visited once. Early Russian space stations that were left un-occupied so long were often found to have mold or slime growing on the walls by the next crew. Chinese scientists believe that they have that problem under control but they want to make sure. Following his inspection the commander will invite the other two astronauts inside where they will hold a brief news conference before beginning work.
Over the course of the next few days the crew will work to resupply the station (something the Chinese have never done before) and begin work on science experiments. Earth observations and observations of China’s farm lands will be conducted using a special hyperspectral camera that has been installed inside the experiment module. The camera will enable scientists to monitor such things as heavy metal pollution, pesticide residue, and plant disease. In addition to the camera, the spacecraft comes equipped with facilities to study photonic crystals, a material that is expected to revolutionize information technologies here on Earth, and other experiments involving life sciences.
Taking a que from NASA, the crew plans to host a live broadcast with school children in China. Astronaut Wang Yaping plans to give Chinese primary and middle school students on Earth a lesson in the effects of the zero-gravity environment. This is intended to inspire them to pursue careers in science or mathematics.
After a period of time the crew will once again enter Shenzhou-10 and un-dock from the station. After performing a series of maneuvers meant to simulate relocating a spacecraft from one station port to another, the crew will re-dock with the station only this time they will do it manually.
The crew will spend the rest of the mission finishing up their experiments and packing away the results. During the time between the last Shenzhou visit and this one, the station has been working autonomously so there is a lot of data to collect. The crew will then return to Earth. The entire mission is expected to last 15 days.
This will probably be the last time a Chinese spacecraft visits Tiangong-1. The spacecraft is getting old and China is already working on the Tiangong-2 follow-up module. Tiangong-2 will be more capable and able to support crews for longer stays than Tiangong-1 could. This is expected to be followed by Tiangong-3.
PASADENA, Calif. -- NASA research indicates hunks of frozen carbon dioxide -- dry ice -- may glide down some Martian sand dunes on cushions of gas similar to miniature hovercraft, plowing furrows as they go.
Researchers deduced this process could explain one enigmatic class of gullies seen on Martian sand dunes by examining images from NASA's Mars Reconnaissance Orbiter (MRO) and performing experiments on sand dunes in Utah and California.
"I have always dreamed of going to Mars," said Serina Diniega, a planetary scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif., and lead author of a report published online by the journal Icarus. "Now I dream of snowboarding down a Martian sand dune on a block of dry ice."
The hillside grooves on Mars, called linear gullies, show relatively constant width -- up to a few yards, or meters, across -- with raised banks or levees along the sides. Unlike gullies caused by water flows on Earth and possibly on Mars, they do not have aprons of debris at the downhill end of the gully. Instead, many have pits at the downhill end.
"In debris flows, you have water carrying sediment downhill, and the material eroded from the top is carried to the bottom and deposited as a fan-shaped apron," said Diniega. "In the linear gullies, you're not transporting material. You're carving out a groove, pushing material to the sides."
Images from MRO's High Resolution Imaging Science Experiment (HiRISE) camera show sand dunes with linear gullies covered by carbon-dioxide frost during the Martian winter. The location of the linear gullies is on dunes that spend the Martian winter covered by carbon-dioxide frost. By comparing before-and-after images from different seasons, researchers determined that the grooves are formed during early spring. Some images have even caught bright objects in the gullies.
Scientists theorize the bright objects are pieces of dry ice that have broken away from points higher on the slope. According to the new hypothesis, the pits could result from the blocks of dry ice completely sublimating away into carbon-dioxide gas after they have stopped traveling.
"Linear gullies don't look like gullies on Earth or other gullies on Mars, and this process wouldn't happen on Earth," said Diniega. "You don't get blocks of dry ice on Earth unless you go buy them."
That is exactly what report co-author Candice Hansen, of the Planetary Science Institute in Tucson, Ariz., did. Hansen has studied other effects of seasonal carbon-dioxide ice on Mars, such as spider-shaped features that result from explosive release of carbon-dioxide gas trapped beneath a sheet of dry ice as the underside of the sheet thaws in spring. She suspected a role for dry ice in forming linear gullies, so she bought some slabs of dry ice at a supermarket and slid them down sand dunes.
That day and in several later experiments, gaseous carbon dioxide from the thawing ice maintained a lubricating layer under the slab and also pushed sand aside into small levees as the slabs glided down even low-angle slopes.
The outdoor tests did not simulate Martian temperature and pressure, but calculations indicate the dry ice would act similarly in early Martian spring where the linear gullies form. Although water ice, too, can sublimate directly to gas under some Martian conditions, it would stay frozen at the temperatures at which these gullies form, the researchers calculate.
"MRO is showing that Mars is a very active planet," Hansen said. "Some of the processes we see on Mars are like processes on Earth, but this one is in the category of uniquely Martian."
Hansen also noted the process could be unique to the linear gullies described on Martian sand dunes.
"There are a variety of different types of features on Mars that sometimes get lumped together as 'gullies,' but they are formed by different processes," she said. "Just because this dry-ice hypothesis looks like a good explanation for one type doesn't mean it applies to others."
The University of Arizona Lunar and Planetary Laboratory operates the HiRISE camera, which was built by Ball Aerospace & Technologies Corp. of Boulder, Colo. JPL, a division of the California Institute of Technology in Pasadena, manages MRO for NASA's Science Mission Directorate in Washington. Lockheed Martin Space Systems, Denver, built the orbiter.
The other night I was having drinks with some friends and as usual we were talking about space. The waitress, a woman pushing 20 something, overheard our conversation and after listening politely for a while offered up the comment "ya that's the last thing we need to do right now - spend billions of dollars on a ----ing spaceship!" Wow! that hurt.
My first thought was to rebut her with crys of blasphemy! But I bit my tongue and smiled politely as she walked away. Later that night I was at home relaxing before bed and as my mind began to wander, awash with memories of good friends and fine food, I began to think about that waitress again. " Ya that's the last thing we need to do right now..." It was irritating me! But as the night progressed my irritation passed and I began to think and suddenly it dawned on me – she actually had a point.
If you watch the coverage of any major space event, almost universally the event is hailed as a technological wonder, a scientific triumph, and a source of national pride. The roots of this behavior go back to the Apollo days when the United States and the Soviet Union were fighting a cold war for the hearts and minds of the world. Space exploration was a tool used by both sides to promote their national interests and the news media simply picked up the ball and ran with it.
But to a young woman living in 2013 who is underemployed, single, and has two children to feed, the fact that its "cool" and makes her country "look good" just isn’t enough to justify the expense. Is it going to feed my children? To her there is simply nothing practical here and the entire endeavor seems purely academic. Is it?
Think about it like this. Lets say you have lived in a house all of your life. The house is old and the glass on the windows has become somewhat yellowed and dingy making it hard to see outside. Then one day you discover a door and when you open it you are bathed in a blinding light that likes of which you have never seen before! As your eyes adjust you find that you can see things in the distance - things that look a lot like other houses.
Eventually you venture outside and begin walking down the street and you discover that there is an entire neighborhood out there! As you continue to explore you learn more and more about the houses around you. Some have problems with their roof, others have termites, and still others have been destroyed all together! As you return home something strange happens. Your house no longer looks the same - your roof is sagging and there are questionable mounds in your front yard! If you had never left your house you would have never even known to look for these things.
Space exploration is that door and that light is the light of truth – as revealed by basic science!
Back in 1962 the United States sent the first space probe to the planet Venus. At the time, scientists expected the spacecraft to report almost Earth like conditions all be it a little warmer because the planet was a little closer to the Sun. When the probe got there it reported surface temperatures in excess of 800 degrees F - hot enough to melt lead! At first many scientists insisted that the probe had to be wrong but as time wore on the spacecraft's data was confirmed - Venus wasn't like Earth at all. It was more like hell.
So what happened? Why was Venus so different? As it turns out the planet's atmosphere was to blame. It was thick and composed mostly of a gas called carbon dioxide. As sunlight entered the planet's atmosphere it hit the surface and was being reflected back out into space. But, instead of leaving the planet as it does here on Earth, the light was captured by the carbon dioxide and its energy reflected back down to the surface in the form of heat. The carbon dioxide was acting like the glass in a greenhouse. The problem on Venus seems to be that this “greenhouse effect” has gotten out of control and superheated the surface. Thus was born the term "runaway greenhouse effect".
Today there is strong debate about the effects greenhouse gases like carbon dioxide are having on the Earth but we know one thing for certain – we are poring tons of these gases into our atmosphere everyday and the Earth is beginning to heat up. Could a runaway greenhouse effect happen on Earth? What causes it in the first place? There is lively debate on the subject but we would never have known to even ask the question if we had not gone to the planet Venus.
The more we learn about the worlds around us the more we learn about ourselves. The Earth enjoys an intimate relationship with the worlds around it especially the Sun, our parent star who could annihilate us all yet, upon whom we all depend for life itself.
The fact is basic science doesn't shout, it whispers. Like sediments falling silently through the great ocean of history, basic science slowly drifts into our lives bit by bit, un-noticed at first, but eventually forming the bedrock upon which everything else is built and space exploration is basic science at its best.
I don’t see how anything could be more practical.
1000 years from now nobody is going to remember most of the things we consider to be important today however, you can rest assured, they will all remember one thing above all others - we were the first generation to venture into space. RG
Editors Note: Send your comments to Robert@interspacenews.com
PARIS - Despite requests to take a "strategic pause" to re-evaluate its design, ESA officials are moving ahead with the design of its Ariane 6 booster which is intended to cement Europe's lead in the launch services market.
The controversy centers around the boosters solid propellant first stage. Many, including Europe’s Air & Space Academy, believe that mounting a cryogenic upper stage atop two solid rocket boosters is not a sound design and are urging ESA to take time to develop a "more powerful liquid fueled alternative". But ESA Launch Vehicle Director Antonio Fabrizi disagrees stating that the design "received the specific endorsement of ESA’s governments last November and cannot simply be set aside."
The current plan calls for freezing the design in July of this year and then beginning construction in late 2014. First flight will be in 2021 although several issues still need to be hammered out. These include the size of the payload fairing and the number of solid boosters that will be used (2 or 4). There is also the tedious process of deciding which nations get to build what components - the entire project is worth 4 billion euros so there will be a lot of fighting about who gets to build the big parts. In the mean time ESA is moving ahead with a 2 billion Euro upgrade to its existing Ariane V booster. This upgrade, intended to be complete by 2017 and known as the Ariane V ME, will increase the boosters lift by providing it with a reignitable upper stage upper stage.
In defense of the solid booster configuration, Arianespace officials are quick to point out that there has never been a problem with the Atiane V Solid Rocket Boosters and that they are considered to be one of the most reliable components of the Ariane V stack. Also synergies between ESA's solid fuel Vega booster and the new Ariane 6 would benefit both projects.
Currently, Arianespace considers itself to be hamstrung by the need to provide two satellites every two or three months for the Ariane V and yet remain within the vehicles performance range. Currently, customers have to wait until a compatible partner can be found for the launch. The new Ariane 6 system will launch a single satellite at a time allowing for more flexibility and less wait time for the customers. Ariane 6 will be able to orbit payloads weighing as much as 6.5 tones making it competitive with most of the worlds planed commercial launch systems.
Although Arianespace is currently the worlds leading launch services provider it realizes that the market is changing dramatically. SpaceX's Falcon launch vehicle, along with China's Long March series of rockets, India's GSLV and PSLV boosters, Japan's H-2, and Ukraine's Zenit are all set to enter the commercial launch services market within the next few years. Combined with the company's traditional competitors, the American Atlas V and Delta IV, Russia's Proton, and Japan's H-2 , these factors threaten the company's leadership position in the market. As a result the company has decided to construct a new booster custom designed to fit the future market. The Ariane 6 has been under development since 2009.
PASADENA, Calif. - Approaching its 10th anniversary of leaving Earth, NASA's Mars Exploration Rover Opportunity is on the move again, trekking to a new study area still many weeks away.
The destination, called "Solander Point," offers Opportunity access to a much taller stack of geological layering than the area where the rover has worked for the past 20 months, called "Cape York." Both areas are raised segments of the western rim of Endeavour Crater, which is about 14 miles (22 kilometers) in diameter.
"Getting to Solander Point will be like walking up to a road cut where you see a cross section of the rock layers," said Ray Arvidson of Washington University, St. Louis, deputy principal investigator for the mission.
Solander Point also offers plenty of ground that is tilted toward the north, which is favorable for the solar-powered rover to stay active and mobile through the coming Martian southern-hemisphere winter.
"We're heading to a 15-degree north-facing slope with a goal of getting there well before winter," said John Callas of NASA's Jet Propulsion Laboratory, Pasadena, Calif., project manager for the Mars Exploration Rover Project. The minimum-sunshine days of this sixth Martian winter for Opportunity will come in February 2014.
NASA's Mars Exploration Rover Project launched twin rovers in 2003: Spirit on June 10 and Opportunity on July 7. Both rovers landed in January 2004, completed three-month prime missions and began years of bonus, extended missions. Both found evidence of wet environments on ancient Mars. Spirit ceased operations during its fourth Martian winter, in 2010. Opportunity shows symptoms of aging, such as loss of motion in some joints, but continues to accomplish groundbreaking exploration and science.
Shortly before leaving Cape York last month, Opportunity used the rock abrasion tool, the alpha particle X-ray spectrometer and the microscopic imager on its robotic arm to examine a rock called "Esperance" and found a combination of elements pointing to clay-mineral composition.
"The Esperance results are some of the most important findings of our entire mission," said Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the mission. "The composition tells us about the environmental conditions that altered the minerals. A lot of water moved through this rock."
Cape York exposes just a few yards, or meters, of vertical cross-section through geological layering. Solander Point exposes roughly 10 times as much. Researchers hope to find evidence about different stages in the history of ancient Martian environments. The rim of Endeavour Crater displays older rocks than what Opportunity examined at Eagle, Endurance, Victoria and Santa Maria craters during the first eight years of the rover's work on Mars.
JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover Project for NASA's Science Mission Directorate.
PASADENA - Stars have an alluring pull on planets, especially those in a class called hot Jupiters, which are gas giants that form farther from their stars before migrating inward and heating up.
Now, a new study using data from NASA's Kepler Space Telescope shows that hot Jupiters, despite their close-in orbits, are not regularly consumed by their stars. Instead, the planets remain in fairly stable orbits for billions of years, until the day comes when they may ultimately get eaten.
"Eventually, all hot Jupiters get closer and closer to their stars, but in this study we are showing that this process stops before the stars get too close," said Peter Plavchan of NASA's Exoplanet Science Institute at the California Institute of Technology, Pasadena, Calif. "The planets mostly stabilize once their orbits become circular, whipping around their stars every few days."
The study, published recently in the Astrophysical Journal, is the first to demonstrate how the hot Jupiter planets halt their inward march on stars. Gravitational, or tidal, forces of a star circularize and stabilize a planet's orbit; when its orbit finally become circular, the migration ceases.
"When only a few hot Jupiters were known, several models could explain the observations," said Jack Lissauer, a Kepler scientist at NASA's Ames Research Center, Moffet Field, Calif., not affiliated with the study. "But finding trends in populations of these planets shows that tides, in combination with gravitational forces by often unseen planetary and stellar companions, can bring these giant planets close to their host stars."
Hot Jupiters are giant balls of gas that resemble Jupiter in mass and composition. They don't begin life under the glare of a sun, but form in the chilly outer reaches, as Jupiter did in our solar system. Ultimately, the hot Jupiter planets head in toward their stars, a relatively rare process still poorly understood.
The new study answers questions about the end of the hot Jupiters' travels, revealing what put the brakes on their migration. Previously, there were a handful of theories explaining how this might occur. One theory proposed that the star's magnetic field prevented the planets from going any farther. When a star is young, a planet-forming disk of material surrounds it. The material falls into the star -- a process astronomers call accretion -- but when it hits the magnetic bubble around it, called the magnetosphere, the material travels up and around the bubble, landing on the star from the top and bottom. This bubble could be halting migrating planets, so the theory went.
Another theory held that the planets stopped marching forward when they hit the end of the dusty portion of the planet-forming disk.
"This theory basically said that the dust road a planet travels on ends before the planet falls all the way into the star," said co-author Chris Bilinski of the University of Arizona, Tucson. "A gap forms between the star and the inner edge of its dusty disk where the planets are thought to stop their migration."
And yet a third theory, the one the researchers found to be correct, proposed that a migrating planet stops once the star's tidal forces have completed their job of circularizing its orbit.
To test these and other scenarios, the scientists looked at 126 confirmed planets and more than 2,300 candidates. The majority of the candidates and some of the known planets were identified via NASA's Kepler mission. Kepler has found planets of all sizes and types, including rocky ones that orbit where temperatures are warm enough for liquid water.
The scientists looked at how the planets' distance from their stars varied depending on the mass of the star. It turns out that the various theories explaining what stops migrating planets differ in their predictions of how the mass of a star affects the orbit of the planet. The "tidal forces" theory predicted that the hot Jupiters of more massive stars would orbit farther out, on average.
The survey results matched the "tidal forces" theory and even showed more of a correlation between massive stars and farther-out orbits than predicted.
This may be the end of the road for the mystery of what halts migrating planets, but the journey itself still poses many questions. As gas giants voyage inward, it is thought that they sometimes kick smaller, rocky planets out of the way, and with them any chance of life evolving. Lucky for us, our Jupiter did not voyage toward the sun, and our Earth was left in peace. More studies like this one will help explain these and other secrets of planetary migration.
The technical paper is online at http://iopscience.iop.org/0004-637X/769/2/86/.
NASA Ames manages Kepler's ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed Kepler mission development. Ball Aerospace & Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with JPL at the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes the Kepler science data. Kepler is NASA's 10th Discovery Mission and is funded by NASA's Science Mission Directorate at the agency's headquarters in Washington.
NASA's Exoplanet Science Institute at Caltech manages time allocation on the Keck telescope for NASA. JPL manages NASA's Exoplanet Exploration program office. Caltech manages JPL for NASA.
PASADENA, Calif. - NASA's Mars Science Laboratory mission is approaching its biggest turning point since landing its rover, Curiosity, inside Mars' Gale Crater last summer.
Curiosity is finishing investigations in an area smaller than a football field where it has been working for six months, and it will soon shift to a distance-driving mode headed for an area about 5 miles (8 kilometers) away, at the base Mount Sharp.
In May, the mission drilled a second rock target for sample material and delivered portions of that rock powder into laboratory instruments in one week, about one-fourth as much time as needed at the first drilled rock.
"We're hitting full stride," said Mars Science Laboratory Project Manager Jim Erickson of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We needed a more deliberate pace for all the first-time activities by Curiosity since landing, but we won't have many more of those."
No additional rock drilling or soil scooping is planned in the "Glenelg" area that Curiosity entered last fall as the mission's first destination after landing. To reach Glenelg, the rover drove east about a third of a mile (500 meters) from the landing site. To reach the next destination, Mount Sharp, Curiosity will drive toward the southwest for many months.
"We don't know when we'll get to Mount Sharp," Erickson said. "This truly is a mission of exploration, so just because our end goal is Mount Sharp doesn't mean we're not going to investigate interesting features along the way."
Images of Mount Sharp taken from orbit and images Curiosity has taken from a distance reveal many layers where scientists anticipate finding evidence about how the ancient Martian environment changed and evolved.
While completing major first-time activities since landing, the mission has also already accomplished its main science objective. Analysis of rock powder from the first drilled rock target, "John Klein," provided evidence that an ancient environment in Gale Crater had favorable conditions for microbial life: the essential elemental ingredients, energy and ponded water that was neither too acidic nor too briny.
The rover team chose a similar rock, "Cumberland," as the second drilling target to provide a check for the findings at John Klein. Scientists are analyzing laboratory-instrument results from portions of the Cumberland sample. One new capability being used is to drive away while still holding rock powder in Curiosity's sample-handling device to supply additional material to instruments later if desired by the science team.
For the drill campaign at Cumberland, steps that each took a day or more at John Klein could be combined into a single day's sequence of commands. "We used the experience and lessons from our first drilling campaign, as well as new cached sample capabilities, to do the second drill campaign far more efficiently," said sampling activity lead Joe Melko of JPL. "In addition, we increased use of the rover's autonomous self-protection. This allowed more activities to be strung together before the ground team had to check in on the rover."
The science team has chosen three targets for brief observations before Curiosity leaves the Glenelg area: the boundary between bedrock areas of mudstone and sandstone, a layered outcrop called "Shaler" and a pitted outcrop called "Point Lake."
JPL's Joy Crisp, deputy project scientist for Curiosity, said "Shaler might be a river deposit. Point Lake might be volcanic or sedimentary. A closer look at them could give us better understanding of how the rocks we sampled with the drill fit into the history of how the environment changed."
JPL, a division of the California Institute of Technology, Pasadena, manages the Mars Science Laboratory Project for NASA's Science Mission Directorate in Washington.
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