Engines powered by chemical fuel? How passé. For the spacecraft with truly modern flair, an ion thruster is the only way to go. Such a system might not provide powerful and dramatic bursts of speed, but space agencies around the world are recognizing the benefits of its slow-and-steady approach, which is just what’s needed for cruising between planets.
Ion propulsion works by electrically charging, or ionizing, a gas and accelerating the resulting ions to propel a spacecraft. The concept was conceived more than 50 years ago, and the first spacecraft to use the technology was Deep Space 1 in 1998. Since then … there have only been a few other noncommercial spacecrafts that have used ion propulsion [Technology Review]. However, the technology has a clear advantage over chemical propulsion when it comes to long distance missions, because a very small amount of gas can carry a spacecraft a long way. Astronautics expert Alexander Bruccoleri explains that with chemical propulsion, “You are limited in what you can bring to space because you have to carry a rocket that is mostly fuel” [Technology Review].
Now, a European Space Agency (ESA) probe will use four ion thrusters to scoot all the way to Mercury, the planet nearest to the sun. That mission won’t launch until 2014, but ESA officials say the $37 million propulsion system will be the most efficient yet, and will also be the most ambitious test of the technology to date. The Mercury probe will be launched by a conventional rocket, and will continue to use chemical propulsion until it’s out of Earth orbit. When it begins its six-year cruise to Mercury, though, its ion thrusters will kick in. The system will draw electricity from solar panels; as the xenon ions pass through the electrified grids they accelerate to up to 50km a second (31 miles per second) and shoot from the rear in a parallel beam. On Earth, at sea level, the thrust would be just enough to lift a pound coin. In space, however, the same thrust will create a much much bigger lift [Telegraph].
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Yesterday, Russian engineers cracked the wax seal on a metal hatch, and six men emerged from the simulated space capsule where they had spent the last 105 days in experiment designed to simulate the isolation of a manned trip to Mars. The experiment is part of a larger project dubbed “Mars 500.” The three months the men spent in isolation are a precursor to another simulation to take place in 2010, when another crew will submit themselves to 520 days in isolation, the projected time it would take for a return trip to Mars [ABC News].
The four Russians, one German, and one Frenchman were chosen from among 6,000 applicants, and were paid about $21,000 each for participating. Inside the mock capsule, they conducted experiments to test their physical and psychological reactions to the isolation, and performed many of the tasks that would keep Mars-bound astronauts busy. They had no television or Internet and their only link to the outside world was communications with the experiment’s controllers — who also monitored them via TV cameras — and an internal e-mail system. Communications with the outside world had 20-minute delays to imitate a real space flight [AP].
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A European spacecraft that has been peering through the thick, roiling clouds of Venus for the past three years has found further evidence that the inhospitable planet once had oceans, volcanoes, and a system of plate tectonics similar to those at work on Earth. The Venus Express has mapped the planet’s southern hemisphere using infrared imaging, and found heat variations in the surface rocks, which allows researchers to speculate on the chemical composition of those rocks. Different surfaces radiate different amounts of heat at infrared wavelengths due to a material characteristic known as emissivity, which varies in different materials [SPACE.com].
In certain highland areas, researchers detected cooler patches of rock whose thermal signatures resemble those of granites on Earth. On our own planet, granites are made during the process of rock recycling that goes on at the edges of the great geologic plates that cover the Earth. At the boundaries of these plates, ancient rock is pulled deep into the planet, reworked with water and then re-surfaced at volcanoes. Critically, then, if there is granite on Venus, there must also have been an ocean and a process of plate movement in the past [BBC News].
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The European Space Agency’s Planck observatory has reached its operating temperature of a mere tenth of a degree above the lowest temperature theoretically possible given the laws of physics, known as absolute zero. That means it’s ready for its mission: Observing the oldest light in the universe, known as the cosmic microwave background, or CMB, to create the clearest picture yet of what the young universe looked like.
Although scientists have achieved temperatures closer than this to absolute zero in the laboratory, the spacecraft is likely the coldest object in space. Such low temperatures are necessary for Planck’s detectors to study the Cosmic Microwave Background by measuring its temperature across the sky. Over the next few weeks, mission operators will fine-tune the spacecraft’s instruments. Planck will begin to survey the sky in mid-August [SPACE.com], and the first batch of data is expected to be released next year. Planck was launched May 14 and will observe the CMB from a spot more than 930,000 miles from Earth.
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The solar probe Ulysses has circled the sun for more than 18 years–almost as long as the Greek hero Odysseus, also called Ulysses, was absent from home due to the Trojan War and his prolonged journey home–but the space probe doesn’t have a homecoming in its future. Ulysses will receive its final transmission tomorrow, as researchers say the scientific findings sent home by the failing spacecraft no longer justify the mission’s costs. After shut-off, Ulysses will continue to orbit the Sun, becoming in effect a man-made ‘comet’. “Whenever any of us look up in the years to come, Ulysses will be there, silently orbiting our star, which it studied so successfully during its long and active life” [SPACE.com], says mission manager Richard Marsden.
The craft has already exceeded expectations. In February 2008, mission engineers announced with great solemnity and with heaps of praise for the orbiter that the craft would fall silent within a few months. Its power supply had grown too weak to keep the craft’s fuel lines from freezing. Not so fast: Engineers figured out that they could keep the lines warm by firing the craft’s thrusters in short bursts every couple of hours [The Christian Science Monitor]. Using that clever fix, Ulysses soldiered on for another year.
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NASA’s astronauts blasted off just yesterday on a final repair mission to the Hubble Space Telescope, but two space-based telescopes scheduled to rocket into space tomorrow may soon steal the spotlight from the Hubble. The two European Space Agency observatories, named Herschel and Planck, may revolutionize our understanding of how galaxies formed in the young universe, shortly after the Big Bang. Once the telescopes are in place, says ESA science director David Southwood, the next era of space-based astronomy will then be well and truly upon us. “They are at a pivotal point,” he says. “From now on astronomy is going to be done from deep space” [Nature News].
Both telescopes will be carried into space by the same Ariane 5 rocket, which is expected to launch tomorrow from a spaceport in French Guiana. The destination for both telescopes is a remarkable position in space known as the second Lagrangian point (L2). It is one of five gravitational “sweet-spots” around the Sun-Earth system where satellites can maintain station by making relatively few orbital corrections. L2 is some 1.5 million km from Earth on its “night side”. The observatories will circle this point [BBC News], orbiting at different distances to rule out any chance of a collision. At that stable location, the telescopes will be protected from temperature swings; a crucial point since both telescopes must be kept at frigid temperatures to study the “cold universe.”
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Astronomers still haven’t discovered Earth’s twin orbiting another star out in the cosmos, but they’re beginning to find worlds with a passing resemblance to our own. New studies of the red dwarf star Gliese 581 have revealed a small, rocky exoplanet with only twice the mass of Earth, and have also shed new light on a larger planet orbiting farther out, which researchers now say could have liquid water. Team member Stephane Udry believes that the larger planet could have a “large and deep” ocean. “It is the first serious ‘water-world’ candidate,” Udry said [AP].
Researchers had previously discovered three planets orbiting the star, including the potential water world, Gliese 581 d. Based on earlier observations, researchers thought that the planet took 83 days to orbit its star, which would indicate that the planet was too far from the red dwarf’s weak heat to have liquid water. But more extensive observations have shown that the planet actually has an orbital period of 66 days, putting the planet just inside the star’s “habitable zone.” Lead researcher Michel Mayor says the planet may be warm enough to bear oceans that are thousands of miles deep. “Maybe this is the first of a new class of ocean planets. That is my favourite interpretation,” says Mayor. “Whether there is life or not, I don’t know” [New Scientist]. However, not everyone is convinced that Gliese 581 d is wet and wild. Other experts say it’s more likely to be an ice giant, like Neptune and Uranus.
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A sophisticated satellite has been carefully placed into orbit just beyond the Earth’s atmosphere, and this week engineers switched on the super-sensitive instrument that will make ultra-fine measurements of Earth’s gravity. The sophisticated gradiometer will feel the subtle variations in Earth’s tug as it sweeps around the globe [BBC News].
The GOCE satellite, built by the European Space Agency (ESA), was launched on March 17, and mission controllers are now busy testing instruments and its cutting-edge propulsion system. In August or September, they will begin the scientific mission. Because the Earth’s mass is not distributed evenly around the planet (think of the mountains and the oceanic rifts), its gravity is not uniform. Mapping these variations has many applications but perhaps the biggest knowledge gains will come in the study of ocean behaviour. Understanding better how gravity pulls water – and therefore heat – around the globe will improve computer models that try to forecast climate change [BBC News].
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Which celestial bodies are more likely to host extraterrestrial life: Saturn’s hazy moon Titan and water-spewing moon Enceladus, or Jupiter’s icy moons Europa and Ganymede, which may have liquid oceans beneath their frozen crusts? That’s the difficult question facing NASA and the European Space Agency (ESA) as they try to decide where to send the next planetary probe. By the end of this month, agency officials plan to pick a destination for a massive mission, costing nearly US$4 billion, to be launched around 2020 for the distant reaches of the Solar System. The battle pits Titan, which recent discoveries have made the cool new kid on the block, against Jupiter’s moon Europa, which has long sat atop community wish lists [Nature News].
In advance of that decision, the space agencies have released details of the dueling proposals. The potential Saturn mission would follow up the remarkable discoveries made by the Nasa/Esa Cassini-Huygens mission which continues to operate at the ringed planet…. Cassini has sent back data that indicates Titan is akin to a primitive – albeit frozen – Earth. It has a thick atmosphere and is rich in organic (carbon-rich) molecules [BBC News]. The plan calls for an orbiter that would release a hot air balloon to drift in Titan’s hazy atmosphere and would drop a lander to the surface, where it could float on one of moon’s lakes of liquid ethane and methane. The orbiter would also dip into the atmosphere of Enceladus, which has fired imaginations with the revelation that it has geysers that spew jets of icy water into space.
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A starlit sky may look serene, but those stars are actually quivering and quaking; now, researchers have recorded the stellar vibrations of distant stars for the first time. The pulsations reflect changes in temperature caused when roiling heat makes the outer surface of the star vibrate. Portions of the surface expand and cool, while others contract and get warmer [New Scientist].
The initial discovery of oscillations in our Sun in the late 1970’s led to the creation of “solar seismology,” which has since been used to measure the movement and transport of heat around the Sun. Solar seismology led to rapid progress in understanding the Sun’s internal structure, but eventually researchers hit a wall [COSMOS]. For accurate measurements, researchers need a long stretch of uninterrupted observations, which is impossible from ground-based telescopes.
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In a setback to Europe’s space program, the European Space Agency’s flagship mission to Mars will be delayed three years while the space agency tries to cobble together funding for the ambitious rover, the ExoMars. The mission had already been postponed once and was most recently scheduled to launch in 2013, but cost overruns are forcing the space agency to push back to a launch date in 2016.
Approved by space ministers in 2005, the rover was supposed to be a fairly small venture costing no more than 650m euros. But as the project developed, it was decided the endeavour should be upgraded, to provide a bigger, more capable vehicle; and one that could carry a much broader range of science instruments [BBC News]. The ExoMars is slated to include a drill that can bore down two meters into the icy soil, and is expected to search for evidence of Martian life, past or present. However, the rover’s scientific ambition pushed costs up to the current estimate of 1.2 billion euros, and Italy, the mission’s lead financier, has refused to meet those costs. Thus far, no other nation has stepped forward to pick up the tab.
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This week, an international group of astronauts and legal experts met to consider a dire but hypothetical threat to life on earth: another massive asteroid impact, like the one that researchers believe ended the reign of the dinosaurs 65 million years ago. The group, the Association of Space Explorers (ASE), concluded their meeting by asking the United Nations to prepare an international response for when a dangerous object is detected heading towards our planet. Says astronaut Rusty Schweickart, who flew into orbit with the Apollo 9 mission: “Until we have a response in place, we’re as vulnerable as the dinosaurs” [The Register].
In the report, titled Asteroid Threats: A Call for Global Response, the team reminds the public of the asteroid Apophis, which gave humanity a brief scare in 2004 when researchers calculated that it had a 1 in 37 chance of hitting the earth in the year 2029. That calamitous prediction was soon refuted by further data on Apophis’ trajectory, but the new report notes that the asteroid, also known as a “near earth object” or NEO, has a 1-in-45,000 chance of striking Earth in 2036. Currently, NASA is watching 209 NEOs, none of which is considered to be dangerous. But a threat is likely to be detected within the next 15 years, according to the ASE. “New telescopes coming online will increase these discoveries by a factor of 100,” said Ed Lu, astronaut on space shuttle Atlantis [New Scientist].
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The solar wind, a steady stream of charged subatomic particles that stream out from the sun at a speed of one million miles per hour, has dwindled to its weakest state since recording began, researchers say. While researchers already knew that solar winds fluctuate in 11-year cycles, the current doldrums trump the declines seen over the past 50 years. “We know that the sun has been this cool before, this inactive before,” said [physicist] Nancy Crooker…. “But that was prior to the Space Age, so we didn’t have actual physical measurements until now” [SPACE.com].
The data was collected by the first solar explorer, the Ulysses probe, which was launched in 1990 as a joint venture between NASA and the European Space Agency. The 17-year-old space probe, which circles the sun from a distance of about 337 million miles, has been studying the environment above and below the poles of the sun. It is just months away from shutting down because of freezing fuel [AP].
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The European Space Agency (ESA) is considering a space mission called Marco Polo, in which a spacecraft would land on a small asteroid, drill into its surface to collect samples of rock and dust, and then fly back to Earth where it would drop its sample capsule down to the surface. Two satellite manufacturing companies are currently conducting a feasibility study; if ESA signs off on the proposal, Marco Polo could sail off into space in 2017.
Asteroids are chunks of debris left over from the chaotic mass that spun around the young Sun during the formation of the Solar System about 4.6 billion years ago. The rest of the material coalesced into planets [The Daily Mail]. Researchers say that studying the composition of an asteroid could give them insight into how the solar system formed. The roughly $430 million mission would also serve as a warm-up for a hypothetical round-trip journey to Mars, as it would enable the development of technology needed for getting up and down from a large planetary body with a much bigger gravitational pull [Telegraph].
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Tiny invertebrates known as water bears are in one sense far tougher than humans who can crush hundreds of them underfoot: A new study has shown that the water bears can survive the vacuum and radiation of space. The water bears, who are more properly known as tardigrades, were launched into orbit aboard a European Space Agency satellite, where they were exposed for 10 days to the cold, low pressure, and intense radiation of space before being brought back down to Earth to study.
Researchers already knew that water bears were unusually tough critters. [T]hey prefer to spend their days in water, perhaps on a beach or a dewy patch of moss. But when the water dries up, the millimetre-long ‘bears’ can contract into a dried-out state and survive like that for years. They are also one of the few animals that survive year-round on continental Antarctica, and are among the most radiation-resistant animals known [Nature News].
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