April 30, 2013
The Herschel Space Telescope was never meant for hot astronomy topics. It was meant for the cool ones. The European Space Agency spacecraft officially ended its observations yesterday when the last of its liquid helium, used to keep the telescope’s temperature close to absolute zero, was exhausted after three years of operation.
Herschel was launched in 2009 and spent its mission orbiting at L2, one of five Lagrangian points in the Earth-Sun system that are gravitationally stable. L2 is nearly a million miles farther from the sun than Earth is — ESA’s Planck Space Telescope, among others, is already stationed there, and it’s the future location of NASA’s James Webb Space Telescope. That far from the Sun is an ideal place to look at cool objects.
Observing in a broad spectral range from the far infrared to submillimeter wavelengths, Herschel could study dim objects, like asteroids in the Kuiper belt at the edge of our solar system, or debris disks where planets are forming around other stars. It also saw red-shifted light from early and active star-forming galaxies. Herschel hunted for water around the universe, finding ice particles heated by ultraviolet light from stars in many protoplanetary disks, and discovering that nearly all the water in Jupiter’s atmosphere was brought to the planet by comet Shoemaker-Levy 9 in 1994.
Herschel had the largest infrared mirror ever launched into space — at 3.5 meters in diameter, it’s more than a meter bigger than the Hubble Space Telescope’s. (JWST’s mirror, however, will be almost twice as big as Herschel’s.) Scientists are still reviewing data from the space observatory, so even though the spacecraft has gone dead, discoveries will likely still be made. Indeed, astronomers are hoping that a brand new ground-based observatory can leapfrog off of Herschel’s contributions in studying the “cool” universe: ALMA, the Atacama Large Millimeter/submillimeter Array in Chile, began operating earlier this year and should be fully operational in September. Combining their data should tell us much about the early universe and galaxy formation.
April 11, 2013
You’re going to need a clock. That’s what the National Air and Space Museum wants to get across to visitors with its new permanent exhibit, Time and Navigation, opening tomorrow.
“If you want to know where you are, or if you want to know where you’re going, you need a reliable clock,” said Carlene Stephens, a curator at the National Museum of American History, which houses the Smithsonian’s collection of clocks and contributed to the exhibit. Appropriately, visitors enter the exhibit by walking under a beautiful blue and gold clock, in the “spirit of the early and truly magnificent European clocks,” says exhibit designer Heidi Eitel. She wanted to include the automaton clock that comes to life every quarter hour to tell “the story of when people began sharing time.”
The exhibit takes you through three eras, starting with Navigating at Sea, when sailors first used sextants and star charts to find their way across vast oceans. Though ships have had navigators since the 1600s, it wasn’t until the early 1800s that they had marine chronometers that kept reliable time at sea and allowed navigation with any precision. Galileo’s pendulum clock and an interactive 19th-century ship’s sextant that lets visitors navigate by the stars are highlights.
Next, the exhibit takes flight. Even aviation heros like Charles Lindbergh got lost before Navy Lieutenant Commander P.V.H. Weems developed air navigation techniques. Overhead, visitors can see the Lockheed Vega Winnie Mae, which Wiley Post and famed navigator Harold Gatty flew around the world in 1931 in just eight days — a feat that could not have been accomplished without precise location-determining skills.
In the third and final era, navigation gets three-dimensional as it moves into space. Throughout this section of the exhibit are star charts where Earth becomes just another potential destination on the map. Our education on space navigation starts with the story of NASA’s nine Ranger spacecraft, notorious for their failures to reach the moon, including two that completely missed the mark. But astronauts eventually made it to the surface, and visitors can see the Apollo sextant and space shuttle star tracker here. “When we go back into deep space,” said curator Andrew Johnston, “it’ll be very interesting to see how far we’ve come with navigation.” With the technology available today, the exhibit explains, spacecraft missions in 2012 were 100,000 times more accurate than they were in the 1960s.
Finally, the exhibit shows us how we navigate today. Atomic clocks (one is on view in case you need to set your watch) that keep time to three billionths of a second, GPS satellites that can be accessed from anywhere in the world, and smartphones that crunch all sorts of data have replaced chronometers and sextants and bulky books of charts. In fact, navigation today doesn’t even need people: Stanford’s driverless-car Stanley is also on display. It won DARPA’s 2005 Grand Challenge by navigating an off-road 132-mile race. But proving its necessity in our everyday modern lives, Time and Navigation ends with stories from today — a farmer, a fireman and a student explain how their livelihoods are affected by the technology developed since the first sailor located the North Star.
February 14, 2013
Asteroids asteroids asteroids. Forget exoplanets. If you want to keep up with your space nerd coworkers at the water cooler, you better be up on your rocks-in-space facts. Some people want to mine them. Some people want to visit them. One or two want to smash spaceships full of paintballs into them. (Why not, really?) And then there’s the asteroid we’re all going to watch skim the treetops tomorrow.
But to mine, visit, or save ourselves from them, we have to actually find them first. There are pint-sized telescope networks hard at work and infrared space telescopes gearing up, but there’s still one small group out there plugging away, monitoring the skies, that don’t often make headlines. That’s why the Minor Planet Center at the Smithsonian Astrophysical Observatory gives out the annual Edgar Wilson Awards. The recipients, who get plaques and cash awards, are amateur astronomers who discover comets during the previous year. There were five winning discoverers in 2012, announced in late January: three from Russia, one from Australia, and one hometown skywatcher from Warrenburg, Missouri.
We asked Tim Spahr, the director of the Minor Planet Center, about the motivation for the award, which has been given out since 1999. Spahr thinks the most likely reason was that the widespread use of electronic surveys (the recent discovery of Comet ISON was made with an automated program) was “killing off some of the amateur contributions, and Mr. Wilson wanted to spur them back to their scopes.” If the surveys are making quick work of object discovery, why the need to encourage individuals with their backyard ‘scope and single pair of eyes? Spahr answered:
Right now only 5% of near-Earth asteroid discoveries (and a larger percentage–perhaps 10% of comet discoveries) are made by amateurs. It is very hard to compete with the huge telescopes and software engineers that work at these projects. Still, amateurs do contribute, and they also contribute to follow-up and observing of these objects for orbit refinement.
As the observatory noted in their announcement, “the historical naming of the comet for [the discoverer] has more meaning than any award,” but they wanted to recognize the long, unpaid hours these individuals contribute to our knowledge of what’s in the sky.
January 31, 2013
“Disaggregation” is the word you want on your bingo card if you’re following the military satellite business these days. After spending decades focused on aggregation — that is, packing as many capabilities as they can onto one satellite to get the most bang for their buck in a single launch — the military is starting to think about reversing this trend. Disaggregation, then, is sending up less complex systems in smaller packages, but larger quantities. Threats of budget sequestration have allowed supporters, who argue this strategy will cut costs, to really turn up the volume.
Yesterday, the George C. Marshall Institute and the TechAmerica Space Enterprise Council held a panel discussion in Washington, D.C. as a way to turn an idea into a full-blown conversation. The U.S. Air Force has already decided that 2015 is the go or no-go time for disaggregating two important space missions: secure communications (which includes nuclear command and control) and weather forecasting. Representatives from Boeing, Lockheed Martin, and Horizons Strategy Group (a consultant on security technology) spoke on the panel, along with the former director of space policy at the National Security Council.
There are three primary arguments for disaggregation: resiliency, promoting “tech refresh,” and affordability. A constellation of disaggregated satellites would be more resilient because if one was destroyed (by an enemy or otherwise), it would only affect that one system; whereas destruction of one of the current, larger milsats would be a massive blow to a whole host of systems. It would promote a constant refreshing of technology because lead times (and lifetimes) would be much shorter. As Horizons CEO Josh Hartman noted, instead of a satellite taking eight years to build, with a lifetime of up to 25 years — which inevitably saddles users with decades-old tech — a move to small, simple satellites that take only a year or two to build would let designers and engineers stay more current. And the potentially lower cost, meaning lower risk, of these satellites would let the engineers “push the envelope” and take chances on new technology.
Affordability seems like the easiest point to make, and this is hardly the first time someone has argued for smaller, cheaper military satellites. But not everyone agrees. Lockheed’s Marc Berkowitz held the mild dissenter’s seat at the table: “The assertion that disaggregation will save taxpayer money needs to be proven. More platforms means more launches to get them to orbit.” And while losing one small satellite is better than losing one massive satellite, Berkowitz pointed out that enemies might consider the risk for retribution lower for taking one down. Furthermore, the biggest obstacle toward disaggregation right now is simply that there isn’t really a plan for the transition, nor many models that actually analyze the resilience and cost factors. Essentially, supporters are just going by their instincts that smaller and faster is by definition better.
Hartman from Horizons explained that there are steps the military can take now to test some of these theories, most of which involve taking a current spacecraft that needs upgrades or repairs, and instead of fixing it, disaggregating it into smaller replacement satellites. Between now and 2015 the Pentagon can work on creating reliable models, based on these kinds of experiments, before deciding that swarms of smallsats are the way to go.
January 11, 2013
As the U.S. government was gearing up to send the first man into space in the 1950s, questions abounded as to how people would survive in this foreign environment: What kind of vehicle would best protect them? How should environmental controls be configured? Will people even survive the radiation levels, unprotected by the Earth’s atmosphere?
One way to prepare for the journey was to send biological material — plants and animals — to near-space on a balloon, with various instruments, and measure the effects. In 1955, doctor and writer Webb Haymaker followed around a Navy crew as they launched balloons from Minnesota and raced to recover the live payloads. He published the account in what was likely one of the more exciting articles to appear in the journal Military Medicine.
“Operation Stratomouse,” as Haymaker dubbed it, began with the biggest foil of balloon launches: the weather. The many last-minute “no-gos” finally started to turn the anxious crew members against each other. “Once, after a favorable forecast had ushered in utterly impossible weather, and a crew member had remarked that ‘that crowd of parasitic bandits over in the weather station ought to be sent up in one of the balloons,’ [launching chief Ed] Lewis squelched him by commenting quietly that he would be dispatching them in the wrong direction!”
Mice, those perennial lab creatures, were among the payloads to be studied for any effect from cosmic rays. Project lead Otto Winzen noted that although they had “sent balloons up for many purposes, even some with rockets dangling from them which are fired into the upper stratosphere when the balloons reach 80,000 feet… the flights to come have a particular significance because of their living cargoes.”
And those living cargoes required special packing:
They were in a flat wire mesh cage, each in its own compartment, gnawing away on pieces of raw potato, which would quench their thirst on the long cruise. The cage was placed on the platform which covers the lower hemisphere of the gondola. Then the two hemispheres were sealed airtight by means of 134 bolts and nuts, and around the sphere went a thick shell of insulating plastic and over that a layer of shiny aluminum foil to reflect the sun’s rays. The oxygen tanks were strapped into place, and filled to capacity. The gondola purred from the vibration of its cooling fans like something alive.
While certainly risky for the near-space-traveling mice, it wasn’t always a safe venture for the human crew, either.
[Balloon] Evelyn A leaped skyward, giving off an agonizing, crashing, echoing sound. As she moved swiftly in the direction of the truck, a gust of wind caused her to hesitate; her long nylon rope then lashed out to one side in an undulating movement as though it were a whip being cracked. Agile little Herk Ballman, standing at the level of the beacon, just managed to jump out of its way. An old hand at balloon launching, he had always been successful at outwitting a rampaging balloon. His close call brought to mind a launching in Europe in which one crewman had had his scalp ripped from one end to the other by a rising gondola, and another his forearm mangled and his shoulder dislocated by a swerving nylon rope which had momentarily looped itself around his arm.
Once aloft, the 175 foot-diameter balloon was quite the sight:
“There’s something eloquent about a gigantic balloon when being launched, whether it slips away tranquilly into the unknown or goes charging forward like an enraged elephant,” Winzen went on to say. “Each has a personality of its own and every one is a solo performer. From where I stand on the launch platform, I can catch from one balloon the satiny swish of a wedding gown as a breeze twists it, and from another the full resilience of a four-master after it has lurched suddenly before a gust of wind.”
The team had a C-47 at their disposal to chase the balloon, which would travel hundreds of miles away, giving the gondola payload extended exposure to near-space. Meanwhile, calls of flying saucer sightings came pouring in to newspapers and even the FBI as the balloon floated over farms and nearby towns. But Haymaker was taken with the romance of the sight:
Brilliantly lighted by the setting sun, she looks like the evening star. A little later, having taken on a harvest moon hue, she is outshone by Venus. A pity that she is expendable! Tomorrow, after she has accomplished her noble mission, a segment of her wall will be ripped out by a line attached to the top of the falling parachute, and she will wallow and sink, like a harpooned whale, and ultimately be found in farmers’ refrigerators, reduced to vegetable bags.
The Navy boys were just as excited, but less moony-eyed, as one sergeant observed “that she is ’tighter’n a bullfighter’s pants,’ and should be belching off some gas soon.” Eventually, the gondolas were cut from the balloons and parachuted to the ground, where the crew frantically searched for it before time — that is, the oxygen — ran out. “They are looking for congregations of cows, who are curious about gondolas, and for a line-up of cars along a road, for farmers, too, take advantage of extraordinary diversions such as this.”
Sometimes it was good news, such as when the gondola from Evelyn A was recovered: “There they were, all 60 mice cocking their eyes at the warden and me as though asking for food.” Other times, it was total loss, such as when the gondola on Emma V didn’t sever properly, the payload clinging on far too long for the animals to survive. Emma V continued on its flight, making newspapers around the region as the crew tried anything to get it down:
Our Emma V was described as an unruly giant. The following morning the account was continued, the caption reading, ”Balloon Dips But Evades Plane Guns”… On the fifth morning there was this surprising announcement: ”Wandering Balloon is First Satellite.” The Emma V was sighted over Bathhurst, New Brunswick, and was headed over the Atlantic for ”a high-altitude European tour.”
Haymaker grandly concluded his story about the ballooners, championing their role in future spaceflight:
Up there, in the as yet hostile and forbidding fringes of space, where it is always night, the ubiquitous mouse has gained a foothold. Before man can do likewise, or, indeed, pierce the stratosphere and travel through the black unknown beyond, he will continue to need balloon-borne animals as forerunners-unless, per chance, man himself is willing to serve as “guinea pig” for his fellowman.
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