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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Scientists have spied a new exoplanet–and not only is it the biggest one yet, but it’s also moving the wrong direction. Unlike other planets, which orbit the same way their stars rotate, WASP-17 moves the opposite way, according to a study published in Astrophysical Journal.
Planets are born from the same ball of rotating gas that creates their parent star, which is why they usually orbit — and spin — in the same direction as their star. While WASP-17 is the first planet known to orbit backwards, some planets in our own solar system, such as Venus, are spinning backwards [Wired]. WASP-17′s backwards motion is known by astronomers as a retrograde orbit.
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Space aficionados are getting ready for the Perseid meteor shower, a show of shooting stars that occurs each year in the middle of August. This year, the event is expected to produce more shooting stars than usual; however, they may be slightly harder to see because of the moon’s unusual brightness due to the phase it will be in during the showers.
The Perseid Meteor Shower, which consists of debris from the Swift-Tuttle comet, became active on July 17, but have largely been so disperse and faint to see. [A] noticeable upswing in Perseid activity traditionally begins during the second week of August, leading up to their peak. They are typically fast, bright and occasionally leave persistent trains. And every once in a while, a Perseid fireball will blaze forth, bright enough to be quite spectacular and more than capable to attract attention even in bright moonlight [Space.com]. Like other meteor showers, Perseid’s fiery show is the result of particles disintegrating as they speed into the Earth’s atmosphere.
In other years, stargazers have been able to see up to 200 meteors per hour. But because the moon will be at last quarter the night of Aug. 13 and it will be at a rather bright waning gibbous phase a night or two earlier, seriously hampering observation of the peak of the Perseids, predicted to occur late on the nights of Aug. 11 and 12. [Space.com]. Still, although the moon’s brightness could hamper visibility, astronomers say the meteor shower should still be exciting to watch.
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NASA’s Kepler spacecraft has only been in operation for 10 days, but it’s already spotted a planet, according to a report in Science. That leaves experts optimistic about the craft’s potential to find other Earth-like planets.
Scientists already knew that the planet Kepler found existed. It’s called HAT-P-7b, and it’s a planetary body that’s too heavy and too hot to support life. Still, Kepler gave scientists new details about the planet, including that the planet has a hazy, ozone-like atmosphere. The analysis proves that Kepler’s onboard telescope and light-detecting instruments are at least 100 times more precise than the ground-based detectors that originally found HAT-P-7b [L.A. Times], because Earth-based telescopes must wrestle with distortion from the atmosphere, while Kepler only looks through the clear near-vacuum of space.
Scientists say that Kepler’s capabilities should be sufficient to find Earth-like planets in the “habitable zone” of a star system–that is, the ring where temperatures climb high enough to allow liquid water to exist, but aren’t so scorching as to burn up the surface of the planet.
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A panel evaluating NASA‘s goals has made some bold suggestions for the agency, including yearlong missions into deep space and even landing on Mars‘ moon, Phobos.
NASA’s current goal is to land humans on the moon once again by 2020, but the panel, which was set up by the White House, has suggested other possible ventures that could speed NASA towards another goal: a manned mission to Mars. For example, long missions to deep space would help scientists learn how to manage long-duration space missions far from Earth, which human missions to Mars would require…”It is true we need to gain experience exploring planetary surfaces, but in fact we’ve done some of that…. What we actually have almost no experience at all with is operations in deep space” [New Scientist], said committee member Edward Crawley. Missions into deep space would require further research into how to protect humans from space radiation, the harmful charged particles from which lower-orbit missions are shielded by the Earth’s magnetic field.
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A comet from the deep space far beyond Pluto probably won’t smash into the Earth and obliterate all life, reassuring researchers said today. New calculations have determined that most extinction events that have occurred over our planet’s history probably weren’t caused by killer comet showers, which bodes well for the future, too. The findings are both welcome and well-timed since only last week an object dramatically smashed into Jupiter; many researchers believe the culprit was a comet.
In the new study, published in Science, researchers focused on long-period comets, which are among the wild cards in a thick deck of cosmic threats. In contrast with short-period comets, such as Comet Halley and Comet Tempel-Tuttle, long-period comets trace insanely eccentric orbits that range out beyond Neptune, Pluto and the Kuiper Belt to a little-understood region on the solar system’s edge known as the Oort Cloud [MSNBC]. The Oort cloud, which contains billions of small, icy objects, may extend from about 93 billion miles from the sun to as far as 9 trillion miles away.
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What lies beneath the icy crust of Enceladus? Ever since the NASA space probe Cassini snapped pictures of the Saturnian moon expelling enormous jets of icy vapor from fissures near its south pole in 2005, planetary scientists have debated whether the evidence points to liquid oceans beneath the moon’s surface. Now, a new chemical analysis of the plume bolsters the oceanic theory, thanks to the detection of a mundane chemical: ammonia. Says study coauthor Jonathan Lunine: “This is the first time Cassini has actually been able to ’smell’ ammonia…. And because ammonia is an antifreeze, it probably ensures that there is liquid water in the interior of Enceladus.” And where there’s water, there could be life [Wired.com].
Last month, another team of researchers also argued for the presence of an ocean when they published their discovery of sodium salts in Saturn’s outer-most ring which is thought to originate from Enceladus’ plume material. “The two studies are complimentary and now, for the first time, we are getting an idea of the full picture of what’s happening on Enceladus,” [Chemistry World], says Frank Postberg, lead author of that earlier study. However, Postberg’s study was contested by another paper that found no traces of sodium vapor around Enceladus, leaving the debate unresolved. Sodium is thought to be an indicator of liquid water because it suggests that salt leached from rocks into the water.
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Jupiter is sporting a new, Earth-sized scar near its south pole, and NASA has confirmed that the gas giant was thumped by a massive impact over the past few days. The discovery was made Sunday night by a Australian computer programmer who uses his spare time to stargaze with his backyard telescope, and today NASA declared that the dark spot is definitely not a weather system, and is indeed evidence of a collision. It’s not yet known exactly what smacked into Jupiter; astronomers say it could have been an unknown comet, or a stray piece of ice.
This is only the second time such an impact has been observed. The first was almost exactly 15 years ago, when more than 20 fragments of comet Shoemaker-Levy 9 collided with the gas giant. “This has all the hallmarks of an impact event, very similar to Shoemaker-Levy 9,” said Leigh Fletcher, an astronomer at NASA’s Jet Propulsion Lab…. “We’re all extremely excited” [New Scientist].
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The solar system’s main asteroid belt may have taken its shape when three gas giant planets were flung into more distant orbits, scattering the remote, icy objects that were lurking at the solar system’s edge. A new study, published in Nature, suggests that the event sent “space invaders” to the belt between Mars and Jupiter that seem more like primitive frozen comets than the baked rocks that make up the overwhelming majority of asteroids [AP].
The findings support a recent theory for the solar system’s formation called the Nice model (named after the city in France), which suggests that all four gas giants originally formed near to the sun, but migrated in what “we believe was a very violent event that happened roughly 700 million years after the solar system formed,” when the solar system was in “its teenage years,” [SPACE.com], explains study coauthor Harold Levison. He says the original orbits of the gas giants weren’t stable, and “the orbits really just went kablooy”. Jupiter moved inwards, while Saturn, Uranus and Neptune all moved away from the Solar System’s centre. As they did so, they catapulted icy bodies from the early protoplanetary disc into the inner Solar System [Nature News].
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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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Does Galileo Galilei deserve yet another notch in his belt? Besides discovering four of Jupiter‘s moons, studying sunspots, observing the phases of Venus, and examining the rough mountains and craters of the moon, Galileo may also have identified the planet Neptune more than two centuries before its official discovery, one researcher is arguing.
Its widely accepted that in 1612 and again in 1613 Galileo must have observed Neptune, although at the time he thought it was a star, spotted during his observation of Jupiter’s moons. But physicist David Jamieson from the University of Melbourne, Australia, says that history has judged Galileo incorrectly – and that his notebooks reveal that he knew he was looking at a planet after all [Nature blog].
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The first permanent node of the “interplanetary internet” has been installed and tested out aboard the International Space Station, in what NASA officials say is the first step to a communication system that could one day span the solar system. The interplanetary internet got its first deep space tryout last fall, when a spacecraft called EPOXI that’s on its way to a comet rendezvous used the system to send images back to its controllers on Earth. Now, researchers are ready to test it out in regular communications with the space station.
There’s a fringe benefit: In just a few months, astronauts will be able to tweet live from the international space station. “NASA is trying to leverage the popularity of Twitter to get its message out,” said [researcher] Kevin Gifford…. “To tweet from space will have a lot of glitz value” [Denver Post]. Currently, astronauts on the space station have to schedule times to send or receive data from mission control below; that’s why the first astronaut to make use of Twitter on a space shuttle flight, Mike Massimino, aka @Astro_Mike, had to send his tweets to Houston and have a NASA employee post them to his profile.
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As the second man to ever walk on the moon (he stepped out of the lunar module about 15 minutes after Neil Armstrong), Buzz Aldrin knows a little something about space exploration, about bold ambitions and great risks. Now, Aldrin is speaking out about NASA, and declaring loudly that the space agency has lost its boldness. The next step in humanity’s exploration of space must be a bootprint on Mars, he says.
Says Aldrin: “As I approach my 80th birthday, I’m in no mood to keep my mouth shut any longer when I see NASA heading down the wrong path. And that’s exactly what I see today. The agency’s current Vision for Space Exploration will waste decades and hundreds of billions of dollars trying to reach the moon by 2020—a glorified rehash of what we did 40 years ago. Instead of a steppingstone to Mars, NASA’s current lunar plan is a detour” [Popular Mechanics].
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Saturn’s moon Enceladus got humanity’s attention in 2005 when surprised astronomers detected jets of ice and gas spraying out from the moon’s icy surface, and since then researchers have eagerly investigated the possibility that the jets might emanate from liquid oceans beneath the frozen crust. A moon with liquid water would be of great interest, because it would be more likely to host extraterrestrial microbes. Now, two new studies with somewhat contradictory results have deepened the mystery of what lies beneath Enceladus’s shell of ice.
Both groups of researchers were looking for sodium near Enceladus; one found it, the other didn’t. Sodium is interesting because it indicates that deep under the ice, liquid water has been in contact with rocks, which leach salts [ScienceNOW Daily News]. The dissolved sodium, along with water, would be shot into space in the geysers, and some of the sodium would be trapped in ice crystals as they formed. The first research group found sodium traces in Saturn’s E ring, a wide band of ice particles that is believed to be replenished by Enceladus’s jets. “Those salty grains provide our current best smoking (or steaming) gun pointing to present-day liquid water near the surface of Enceladus” [Wired.com], wrote space scientist John Spencer in an essay accompanying the findings.
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Five days after their launch, NASA‘s two new lunar probes have successfully rendezvoused with their target. The Lunar Reconnaissance Orbiter fired its thrusters this morning to settle into orbit around the moon, while the Lunar Crater Observation and Sensing Satellite (LCROSS) swung past the moon, streaming live video all the while. (NASA promises to put the video playback online soon.)
The paired satellites will spend the next year mapping the moon and searching for traces of water ice, culminating in a dramatic crash when LCROSS plunges into a crater. But for now, NASA is busy celebrating the successful first steps. The $504 million LRO is the first NASA vessel to orbit the moon since 1998. “LRO has returned NASA to the moon,” a flight controller said as NASA’s LRO mission control center erupted in applause. The probe’s lunar arrival comes just under one month ahead of the 40th anniversary of NASA’s first moon landing by Apollo 11 astronauts on July 20, 1969 [SPACE.com].
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