October 17, 2013
Comet ISON has been the subject of all sorts of predictions since it was discovered just over a year ago. First it was thought that ISON will be the most spectacular comet seen in a generation when it draws close to the sun late this November. Then some astronomers in Colombia insisted the comet was fizzling — that is, breaking into pieces — as comets sometimes do. But most other astronomers decided to wait and see.
Released today, new images from the Hubble Space Telescope reveal that Comet ISON is sticking together so far. “It’s overhyped, it’s underhyped. Just let it be what it is,” said astrophysicist Bonnie Meinke this afternoon during a Google Hangout with other scientists tracking the comet.
On November 28, ISON will make its closest pass to the sun, approaching just about one million miles above the surface. The “sungrazer” will be so close that the sun’s magnetic field will yank on charged dust and gas particles in the comet’s tail, likely creating “waves and puffy bits,” said Meinke, much like Comet Lovejoy in 2011. The solar observatories — SDO, SOHO, and STEREO — as well as the Mercury orbiter MESSENGER, will all turn their eyes to the comet as it passes.
September 12, 2013
The Moment actually came a year ago — on or about August 25, 2012, to be more precise. That’s when Voyager project scientists now agree that the Voyager 1 spacecraft crossed into the region where interstellar space begins, and where particles from our sun no longer dominate.
It’s been a long, strange trip — even to get to this announcement. Over the past year, several scientific papers have been published claiming that Voyager had crossed the historic boundary, only to have other researchers, including, notably, Voyager project scientist Ed Stone of Caltech, say not so fast. Today, though, they all seemed to agree: Voyager is now among the stars.
You can find the details on NASA’s Voyager site, or read the technical report in Science magazine by Don Gurnett of the University of Iowa and other Voyager investigators that appears to have closed the argument for good.
At a NASA press conference today, Gurnett played these historic first sounds from interstellar space:
Suzy Dodd, NASA’s project manager for Voyager, also showed two photos of the Voyager science team — one from the 1970s and one taken recently — that showed, in dramatically human terms, just how very long it took to escape our solar system.
August 8, 2013
We used to have to know things. Now we have smartphones.
Let’s say I’m standing in my backyard on a clear night, and I notice a bright planet about to set in the west, just over the fence. Jupiter or Saturn? With the naked eye it’s hard to tell, at least for me. But point the Google Sky phone app at the mystery dot, and I know in seconds. Jupiter. Thanks.
We should be astonished at such fact-finding power, but we rarely are. Maybe that’s because web- and phone-based tools for identifying what’s in the sky overhead are becoming more common at the same time as they’re getting easier to use. And most of them are free. NASA just released a nifty Interactive Satellite Viewer, for example, that shows you the current positions of its Earth- and space-pointing spacecraft. It’s similar to other online satellite trackers that have been around for a while, but it’s nicely done.
Even cooler are the smartphone apps that use augmented reality to display the positions of satellites wherever and whenever you happen to be looking. These include Sat Tracker for Layar and — even easier — the Satellite AR app created by Analytical Graphics, Inc. (AGI), who maintain a constantly updated database of all the orbiting objects tracked by U.S. Strategic Command. Look up for more than 15 minutes from any dark location at night, and you’ll likely spot the slow, steady track of some satellite crossing the sky overhead. With Satellite AR, you don’t have to guess which satellite it is. A cartoon-like icon will be superimposed on the real thing.
Best of all is the Google Earth version of AGI’s satellite database. Now you see not just the operating satellites, but all the bits of flotsam orbiting with them. Here’s a screen grab from my location in Virginia. Man, is there a lot of junk up there, most of it debris (DEB) from past launches and explosions. Thanks to these handy tools, I can track all of it, and watch the trash float by in real time.
Update: See the first comment below for yet another version that’s even better.
July 17, 2013
For all the new, exotic things astronomers discover in the universe, it’s almost more exciting to find out there was something hanging out in our own neighborhood that we never knew was there. This week, the SETI Institute announced that one of its astronomers, Mark Showalter, found a never-before-seen moon around Neptune, its 14th (circled above), noting that it was even missed by Voyager 2 when it flew by and surveyed the planet’s rings and moons in 1989. He used the Hubble Space Telescope to study the planet, then re-processed and combined 150 images in sets of eight to 10.
The news sounded a bit familiar. Air & Space interviewed Showalter earlier this summer about studying the solar system, and he told us a similar story. You can read the interview in full in our feature on the Hubble Space Telescope, part of our upcoming 2013 special collector’s edition on aerospace inventions, The Genius Factor, which arrives on newsstands this August. Here’s a snippet, in which we asked him about imaging the rings of Uranus:
“Hubble remains far and away the most powerful instrument we have for studying the families of small moons orbiting the outer planets,” Showalter says. “I find it remarkable that Mab and Cupid were too small to be noticed by the Voyager spacecraft during its 1986 flyby of Uranus, but we could see them using Hubble years later.” Showalter used the same “observing trick” on Pluto and discovered two tiny moons in 2011 and 2012.
June 4, 2013
As the saying goes, it’s tough to turn a big ship. That’s why an experiment last winter that required shifting the International Space Station’s attitude became an important lesson in what it takes to move a million-pound structure in space. According to European Space Agency operations engineers Nadia This and Denis Van Hoof, an undertaking like this requires patience and preparation — not to mention a few gutsy scientists.
The move was to accommodate an ESA experiment called SOLAR, a nickname for the “Sun Monitoring on the External Payload Facility of Columbus” project, which measures sun activity and radiation. Mounted to the outside of the station, SOLAR normally can rotate to keep the sun in view for 14 days in a row — called a Sun Visibility Window. But eventually the station’s orientation changes so that it blocks the sun, sometimes for up to 25 days.
During a meeting of the SOLAR team in 2010, one of the heliophysicists mentioned it was a pity the instrument couldn’t see a full 27-day rotation of the sun, especially now that it’s in the active phase of its 11-year cycle. Couldn’t they move the space station to point the instrument at it for that long?
At least they could ask.
“For scientific investigators, the sky is the limit,” says Van Hoof. “They will propose whatever crazy idea they might have. Of course there is a filter in between. Two years ago, I talked with my team leader about this, and he said ‘let’s make a technical [description of the procedure], but I’m pretty sure this is not going to get through.’ ”
Fortunately, celestial timing favors SOLAR twice a year. Around the summer and winter solstices, when the sun reaches its highest or lowest point relative to the celestial equator, the blackout period shortens to just eight days. So if the team could move the station for just those days, they could combine two observation windows back-to-back, and see a full rotation of the sun.
Adjustments to the ISS orbit are carefully planned and executed in collaboration with the five international partners and their scientific communities. Because many sensitive instruments are mounted outside and inside, changing the station’s orientation might mean exposing them to different radiation, temperature fluctuations, drag and other hazards, not to mention changing their own planned targeting. The station can fly in three flight attitudes, but some instruments are only rated to fly a limited number of hours in certain configurations.
Station managers also needed to consider everything from the position of the station’s robotic arm to the amount of momentum stored in the station’s control gyros (read more about ISS steering here)
After two years of planning and negotiations, the move was approved. “I don’t know if we got lucky or if it’s politics now, but the ISS program is really wanting to show that they are there for science,” Van Hoof says.
Last fall, with all the parameters set and the SOLAR experiment ready, the station prepared to move. On November 19, SOLAR came out of shadow and began recording the sun. On December 1, the station spent about two hours shifting seven degrees, holding the angle for 10 days before returning to its regular position. The team was able to gather 35 straight days of observations.
The science team is still analyzing their data, but they noticed changes in the sun’s activity in extreme ultraviolet wavelengths, related to newly forming sunspots, Van Hoof says. A full rotation provides a much more complete data set that the team can use to compare with other solar-observing experiments, such as NASA’s Solar Dynamics Observatory. The team was so pleased with the results that they hope to perform the maneuver again during the summer solstice later this month.
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