History > 2007 > USA > Space (IV)

Chance of Asteroid

Hit on Mars Increases

December 28, 2007
Filed at 6:38 p.m. ET
By THE ASSOCIATED PRESS
The New York Times

LOS ANGELES (AP) -- The chance of a football field-sized asteroid plowing into Mars next month has been increased to 4 percent, scientists said Friday after analyzing archival data.

Though still a long shot, some researchers are hoping for a cosmic smash.

''I think it'll be cool,'' said Don Yeomans, who heads the Near-Earth Object Program at NASA's Jet Propulsion Laboratory. ''Usually when an asteroid is headed toward Earth, I'm not rooting for an impact.''

The space rock, known as the nondescript 2007 WD5, was discovered in late November by the NASA-funded Catalina Sky Survey in Arizona. Based on the latest information available, scientists said last week there was a 1-in-75 chance the asteroid could hit Mars on Jan. 30.

The odds were increased to 1-in-25 this week after a Ph.D. student pored through the archives and plotted the asteroid's motions before its official discovery. The new information allowed scientists to improve their calculations of the asteroid's orbit and flight path.

Scientists will continue to monitor the asteroid to better predict the possibility of a Martian impact. Yeomans said he expects the odds to decrease with new observations gathered early next year.

The likelihood of an asteroid hit usually ''peaks before plummeting to zero with additional data,'' he said.

The asteroid poses no threat to Earth and is closing in on the Red Planet at 27,900 mph.

Should a collision occur, it would likely blast a half-mile-wide crater north of where the rover Opportunity has been exploring since 2004.

The impact could release energy similar to the 1908 Tunguska object that exploded over remote central Siberia and wiped out 60 million trees.

------

On the Net:

Near Earth Object Program: http://neo.jpl.nasa.gov/

Chance of Asteroid Hit on Mars Increases, NYT, 28.12.2007,http://www.nytimes.com/aponline/us/AP-Mars-Asteroid.html

Mars Rover Finding

Suggests Once Habitable Environment

December 12, 2007
The New York Times
By KENNETH CHANG

SAN FRANCISCO — The lame wheel on the NASA Mars rover Spirit has proved an invaluable science tool, turning up evidence of a once habitable environment, scientists said Monday.

Meanwhile, images from the Mars Reconnaissance Orbiter have largely unraveled the mystery of geological patterns called “spiders” that appear each spring around the south pole.

The scientists reported their findings here at a meeting of the American Geophysical Union.

The right front wheel of Spirit stopped turning in March 2006. Since then, the rover has been driving backwards, dragging the lame wheel along. This May, scientists noticed a bright spot in the trail of overturned dirt.

They turned Spirit around for a closer look, finding high levels of silica, the main ingredient of window glass. They then aimed the rover at a nearby rock, wanting to break it apart to determine if the silica was just a surface coating, or if the rock was silica all the way through.

The target rock survived Spirit’s charge, but a neighboring rock cracked open. The interior of that rock, which the scientists informally named “Innocent Bystander,” turned out to be rich in silica.

On Earth, such high concentrations of silica can form in only two places: a hot spring, where the silica is dissolved away and deposited elsewhere, or a fumarole, an environment, often near a volcano, where acidic steam rises through cracks. The acids dissolve other minerals, leaving mostly silica. On Earth, both environments teem with life.

Spirit’s twin, Opportunity, which has been exploring a spot on the other side of Mars, has found evidence of an environment once steeped in acidic groundwater. The silica discovery is the first time that Spirit has seen signs of widespread water in its surroundings, a 90-mile-wide impact crater known as Gusev Crater.

Gusev was chosen as a landing site, because, at least from orbit, it looks as if it were once a lake with what appears to be river channels flowing away from it. However, until now, the rocks that Spirit has examined have largely been volcanic basalt with little hint of water.

“This shows us a side of Mars we haven’t seen before, and my guess is that it’s more common than we had thought,” said Steven W. Squyres, the project scientist for the rovers. “Whichever of those conditions produced it, this concentration of silica is probably the most significant discovery by Spirit for revealing a habitable niche that existed on Mars in the past.”

From far above the surface, the Mars Reconnaissance Orbiter has been taking a closer look at radial patterns of “spider” gullies, as well as bright and dark fan-like features that appear in the Martian landscape each spring.

Scientists first spotted the gullies several years ago in images taken by the Mars Global Surveyor. With the much higher resolution of Reconnaissance Orbiter, scientists saw for the first time that the gullies were wider at the center of the pattern. Another instrument allowed them to map the images onto the Martian topography; the centers of the spiders were at the top of the small hills. Those two bits of information indicated that the gullies were carved by something flowing uphill — and that pointed to carbon dioxide.

At a news conference on Tuesday, Candice Hansen, deputy principal investigator for the orbiter’s high-resolution camera, said it now appeared that a layer of translucent carbon dioxide ice, perhaps half a yard thick, formed over the south polar terrain during the winter months.

In the spring, sunlight warms the ground, vaporizing carbon dioxide at the base of the ice layer. The gas flows uphill, carving channels in the underlying soil. At weak points in the ice, the gas erupts in small geysers. The release of pressure causes the carbon dioxide gas to freeze solid and fall as white snow — the white parts of the fan-like patterns. Dust blown out with the carbon dioxide falls on the ground to form the dark parts of the fans.

“It is unlike anything on Earth,” Dr. Hansen said, though similar patterns have been seen on the Neptunian moon of Triton.

    Mars Rover Finding Suggests Once Habitable Environment, NYT, 12.12.2007, http://www.nytimes.com/2007/12/12/science/space/12mars.html

Space Shuttle Widow

Is Ready to Move on

From Rituals of Loss

December 5, 2007
The New York Times
By SARAH KERSHAW

ANNAPOLIS, Md., Dec. 3 — By now, nearly five years after her husband died when the space shuttle Columbia broke apart over Texas just 16 minutes before its scheduled landing at Cape Canaveral, the astronaut’s widow has a meticulous list of the things to pack for remembering him in public.

The American flag that was draped over his coffin; the flight patch recovered from the shuttle debris in East Texas; the Tolstoy quotation he carried in his wallet, inscribed now over a laminated photograph of the seven-member crew; his T-38 flight helmet; portraits of him in his orange NASA suit; some of his many e-mail messages to her from his 16 days in space.

An hour before what she called the final large public memorial here on Sunday for her husband, Cmdr. William C. McCool, 41, the pilot of the shuttle that was lost on Feb. 1, 2003, Lani McCool was frantically making mental checklists: Who has the flag? The white scarf used to cover the flag? A plastic bag to protect the photographs and e-mail messages from the rain? The Columbia mission lapel pins?

This moment had been building for years; it was the last big tribute planned, and she and her three grown sons were tired. Mrs. McCool, who sometimes describes herself to friends as “the woman in a bubble,” is reclusive, and the spotlight makes her uneasy.

After the Annapolis service was over, she said, she would finally catalog this mobile collage of his life and her grief and put it into storage.

“My reason for having so much of Willie’s stuff around me still is that it’s like an art piece,” she said. “But when a date for this was set, I started archiving things — not exactly cleansing, but it was nice, kind of moving forward.”

And now, in quiet moments, she can finally turn to the question of what to do at Commander McCool’s unmarked grave, a patch of grass in a cemetery in her hometown, Anacortes, Wash.

Mrs. McCool, a photographer and artist, regularly visits the grave and adorns it with temporary tributes, including a peace sign made of rose petals and 46 red balloons for his 46th birthday last September.

When she got to Annapolis, where Commander McCool’s funeral was held in 2003, at the Naval Academy chapel, she said: “Coming here, it feels like the final burial. I’ll pat the dirt, and I can finally be at peace.”

Sunday’s service was held on the cross-country course at the Naval Academy, where Mr. McCool, a midshipman who graduated in 1983, was a runner and team captain. The academy unveiled a seven-foot-high granite marker, with a bronze bas relief of Mr. McCool running on one side and the words “Sixteen Minutes From Home,” engraved on the other, near a replica of his flight patch.

At the foot of the marker, which was financed with private donations, one of Commander McCool’s e-mail messages is engraved in a cobblestone: “I’ve been reflecting about there being a clue to peace from this vantage point,” it said. “The answer is very obvious from here.”

During the service on Sunday, which drew about 150 people, including NASA’s administrator, Michael D. Griffin, Mrs. McCool was able to muster the calm to speak. Her voice broke and she said, “I’m sorry,” as she was reading from her husband’s e-mail.

Over the years, at many of the dozen or so public memorial services and tributes to her husband, the events have felt like a mix between a wedding and a funeral, she said.

The Annapolis service had that feel — the excitement of touching the flight patch replica on the granite marker, which Mrs. McCool had the artist place at her “kissing height,” about five feet. But she also listened to a midshipman play “Amazing Grace” on bagpipes to close the service, and wore dark sunglasses, even in the rain, to hide her tears.

A constant for Mrs. McCool at these events is her close friend Rona Ramon, the widow of another astronaut on the Columbia, Col. Ilan Ramon, the first Israeli astronaut in space. Mrs. McCool goes to Israel for Colonel Ramon’s memorials, and Mrs. Ramon comes to the United States for Commander McCool’s.

Mrs. Ramon, who came to Annapolis with two of her four children, said: “In Hebrew we say there’s nothing by coincidence. These two events are so connected; it’s been a time to think about peace.”

When the Sunday service was over, Mrs. McCool’s son Cameron, 20, said of his mother, “I feel relief for her; I can always feel the stress in her voice.”

Before she goes back home this week, Mrs. McCool plans to go to back to the Willie McCool marker alone. She said she would take the shells from the 21-gun salute at his funeral, spread them out around the granite stone and take a photograph for her collection.

Space Shuttle Widow Is Ready to Move on From Rituals of Loss, NYT, 5.12.2007, http://www.nytimes.com/2007/12/05/us/05shuttle.html

One Last Ride to the Hubble

December 4, 2007
The New York Times
By DENNIS OVERBYE

GREENBELT, Md. — It’s the last roundup for the People’s Telescope.

Next August, after 20 years of hype, disappointment, blunders, triumphs and peerless glittering vistas of space and time, and four years after NASA decided to leave the Hubble Space Telescope to die in orbit, setting off public and Congressional outrage, a group of astronauts will ride to the telescope aboard the space shuttle Atlantis with wrenches in hand.

That, at least, is the plan.

“It’s been a roller coaster ride from hell,” Preston Burch, the space telescope’s project manager, said in his office here at the Goddard Space Flight Center of the controversy and uncertainty.

In a nearby building, the Hubble’s astronaut knights — dressed as if for surgery, in white gowns, hoods and masks —swarmed through a giant clean room to kick the tires, so to speak, of new instruments destined for the Hubble and to try out techniques and tools under the watchful eye of the Goddard engineers. They practiced sliding a new wide-field camera 3, suspended in air like a magician’s grand piano, in and out of its slot on a replica of the telescope that is mechanically and electrically exact down to the tape around the doors. “We have to train their minds and bodies,” said Michael Weiss, the deputy project manager of Hubble, adding that when the astronauts see the real telescope in orbit, “they say they’ve seen it before.”

Spacewalking astronauts have refurbished the Hubble four times in the last two decades; but the trip planned for August, almost everybody agrees, really will be the last service call. The shuttles are scheduled to stop flying in 2010, and without periodic maintenance, the telescope’s gyroscopes and batteries are expected die within about five years.

Astronauts, engineers and scientists here say they are resolved to pull off the most spectacular rejuvenation of the telescope yet, one, they say, that will leave it operating at the apex of its abilities well into the next decade so that it can go out in a blaze of glory.

“It will be a brand new telescope, practically,” said Matt Mountain, director of the Space Telescope Science Institute on the Johns Hopkins campus in Baltimore. He added, “We want to return crackerjack science we can be proud of.”

The last visit, Dr. Mountain explained, is unique. “You don’t have to do routine maintenance,” he said. “It’s like a car you’re only going to keep another 20,000 miles. You don’t buy new tires.”

Engineers and project managers are busy mapping out five days of spacewalks.

If all goes well — never a given 350 miles above Earth — the astronauts will install a new camera and spectrograph and change out all the gyroscopes that keep it properly pointed and the batteries that keep it running. They are also planning to repair a broken spectrograph and the Hubble’s workhorse, the Advanced Camera for Surveys, which had a severe short-circuit last winter and was pronounced at the time probably beyond repair.

Dramatic turnabouts have characterized the history of the Hubble telescope, which was hailed before its launching in April 1990 as the greatest advance in astronomy since Galileo invented the telescope.

In space, the Hubble would be able to discern details blurred by the turbulent murky atmosphere. But its 94-inch diameter mirror turned out to have been polished to the wrong shape, leaving it with what astronomers call a spherical aberration. The Hubble became branded as a “technoturkey.”

In 1993, astronauts fitted the telescope with corrective lenses (at the cost of removing one of its five main instruments, a photometer), and the cosmos snapped into razorlike focus.

Three more visits by astronauts kept the Hubble running and, by replacing old instruments, actually made it more powerful. Along the way, the astronauts graduated from yanking equipment fitted with large astronaut-friendly handles to operating on instruments never meant to be repaired by people wearing the equivalent of boxing gloves in space.

In 2002, after an infrared camera named Nicmos unexpectedly ran out of coolant, the astronauts attached a mechanical refrigerator to run coolant through its pipes. A year later, the Hubble’s astronomers used the rejuvenated camera along with the advanced survey camera to record the deepest telescopic views ever obtained of the universe. The images captured galaxies as they existed a few hundred million years after the beginning of time.

“When you have an instrument that reaches so far beyond what you’ve ever had before, you make discoveries that nobody ever thought of before,” said John Grunsfeld, who will be the payload commander on the Atlantis mission. “And we see things that nobody ever saw before. As a result, you know, Hubble became not just an observatory, but an icon for all of science. And Hubble has become part of our culture.”

That status did not come cheaply.

Edward Weiler, director of the Goddard center and formerly associate administrator for science at NASA, estimated that over the years the Hubble had cost $9 billion. “There are few people, especially Americans, who won’t say it was worth it,” he said.

All this seemed doomed to a premature end after the shuttle Columbia disaster in 2003 that killed its crew of seven. Sean O’Keefe, who was then the NASA administrator, declared that a shuttle flight to the telescope was too risky because, unlike the space station, it offered no safe haven if anything went wrong with the shuttle. The public was appalled. Schoolchildren even offered to send their pennies to NASA to keep the telescope going.

Some astronomers and engineers challenged the reasoning of Mr. O’Keefe, whose background was in public administration, and not engineering. Others in the space science community, noting that the science budget was being squeezed by President Bush’s Moon-Mars initiative, suggested that it was time to move on and that the Hubble repair money might be better spent on other science projects.

“Everybody could see where he was coming from,” David Leckrone of Goddard, the Hubble’s project scientist, said, referring to Mr. O’Keefe’s distress about the Columbia and a mandate for increased emphasis on safety. But, he added, “It seemed so un-NASA-like. We would never have sent anybody to the Moon if we were so risk averse.”

“I thought we were dead,” Dr. Leckrone said. “As long as he was administrator, it stuck.”

In February 2005, however, Mr. O’Keefe resigned to become chancellor at Louisiana State University in Baton Rouge. His successor, Michael Griffin, who has a Ph.D. in aerospace engineering, instituted a rigorous risk analysis, culminating in a two-day meeting of experts that concluded it was no riskier to fly to the telescope than to go to the space station. In fall 2006, after the shuttles had begun flying again, Dr. Griffin approved the Hubble mission to a standing ovation from scientists and engineers.

“We all agree the risks are acceptable,” Dr. Leckrone said. “Griffin led us through that process with a good deal of intellectual vigor. He didn’t fake it.”

As a backup, NASA will have the shuttle Endeavor, which is scheduled for a September mission to the space station, prepped for a quick launching if a rescue is needed.

In the meantime, engineers, challenged by Mr. O’Keefe to keep the Hubble going as long as possible, learned to run it on a kind of austerity program, using two gyroscopes to keep the telescope pointed instead of the usual three (one for each dimension in space). They also learned how to preserve the batteries, which derive power from solar panels in the sunlit part of each orbit and provide electricity in the dark part. As a result, the batteries, which degraded rapidly for years, are now actually slightly stronger than before, the engineers say, and the Hubble has a healthy gyroscope in reserve in case one fails.

“If it weren’t for two-gyro science,” Mr. Weiss, the deputy project manager, said, “the next gyro failure would take us out of science.”

Besides Dr. Grunsfeld, who has been to Hubble twice, the crew includes Cmdr. Scott Altman, who led a Hubble mission in 2003; the pilot, Gregory Johnson; and the mission specialists, Andrew J. Feustel, Megan McArthur, Col. Mike T. Good and Michael J. Massimino, who also worked on the Hubble in 2003 and performed two spacewalks.

The new wide-field camera was designed to extend the Hubble’s vision into the ultraviolet wavelengths characteristic of the hottest stars and into the longer infrared wavelengths characteristic of cool stars, complementing the abilities of the advanced survey camera. It will replace the wide-field planetary camera 2, which has been in the telescope since 1993 and has been its only visible-light camera for the last year.

When the old camera is slid out, perhaps as early as the first spacewalk, will be “a heart-stopping moment,” Dr. Mountain said.

Dr. Grunsfeld’s crew will install another new instrument, the Cosmic Origins Spectrograph, into the slot now occupied by an old corrective optics package known as Costar that is no longer needed.

The instruments installed on the Hubble since the 1993 repair were built taking the mirror’s aberration into account. The new spectrograph is also designed to be sensitive to invisible ultraviolet light. Astronomers hope to use it to map a so-called “cosmic web,” stretching through intergalactic space, in which two-thirds of atoms in the universe are thought to be drifting and hiding.

Those tasks will be the easier parts.

One of the bigger challenges of the mission will be surgery on the Space Telescope Imaging Spectrograph, which can take pictures of things and break down their light to analyze their composition. The spectrograph had an electrical failure in 2004. To get inside the spectrograph, 111 screws that were never meant to be removed in space have to be unscrewed and kept from floating off. The plan is to clamp a plate over them beforehand and unscrew them through tiny holes.

No such option exists for the Advanced Camera, the choice for 70 percent of Hubble’s prospective users and the chief dark-energy-hunting instrument on or off the planet. It suffered a huge short-circuit in its power supply last winter.

In a task that could be spread over two spacewalks, the astronauts will clamp a new power supply to the outside of the camera. From there, according to ground tests, power can be fed back inside to the other parts of the camera through existing wires, unless they were damaged in the short-circuit.

In one additional piece of business, the astronauts will attach a grapple fixture to the bottom of the telescope so that a robot spacecraft could grab it and attach a rocket module in the future. The rocket would then drop the telescope into the ocean.

But that time is not yet. The telescope’s orbit will be stable through 2024, according to recent calculations.

All of this work could, in principle, be performed in the allotted five days of spacewalks. In that case, when the Atlantis pulls away and human eyes glimpse the Hubble for the last time in person, the telescope would have its full complement of instruments to dissect the light from the cosmos for the first time since 1993.

Running down a list of subjects like planets around other stars, dark energy and the structure of the universe, Dr. Leckrone called the telescope a toolkit for discovery. Noting that any astronomer in the world could propose to use it, he said: “A lot of brain power comes to Hubble. It’s mouthwatering to think of what they will do with it.”

Asked whether the astronomers were tempted to run the rejuvenated instrument frugally to prolong its life beyond its anticipated 2013 demise, Dr. Mountain said the idea was to go for broke.

“We don’t want to trade science for false longevity,” he said.

One Last Ride to the Hubble, NYT, 4.12.2007, http://www.nytimes.com/2007/12/04/science/space/04hubb.html