Humans to Asteroids: Watch Out!

A FEW weeks ago, an asteroid almost 30 feet across and zipping along at 38,000 miles per hour flew 28,000 miles above Singapore. Why, you might reasonably ask, should non-astronomy buffs care about a near miss from such a tiny rock? Well, I can give you one very good reason: asteroids don’t always miss. If even a relatively little object was to strike a city, millions of people could be wiped out.

Thanks to telescopes that can see ever smaller objects at ever greater distances, we can now predict dangerous asteroid impacts decades ahead of time. We can even use current space technology and fairly simple spacecraft to alter an asteroid’s orbit enough to avoid a collision. We simply need to get this detection-and-deflection program up and running.

President Obama has already announced a goal of landing astronauts on an asteroid by 2025 as a precursor to a human mission to Mars. Asteroids are deep-space bodies, orbiting the Sun, not the Earth, and traveling to one would mean sending humans into solar orbit for the very first time. Facing those challenges of radiation, navigation and life support on a months-long trip millions of miles from home would be a perfect learning journey before a Mars trip.

Near-Earth objects like asteroids and comets — mineral-rich bodies bathed in a continuous flood of sunlight — may also be the ultimate resource depots for the long-term exploration of space. It is fantastic to think that one day we may be able to access fuel, materials and even water in space instead of digging deeper and deeper into our planet for what we need and then dragging it all up into orbit, against Earth’s gravity.

Most important, our asteroid efforts may be the key to the survival of millions, if not our species. That’s why planetary defense has occupied my work with two nonprofits over the past decade.

To be fair, no one has ever seen the sort of impact that would destroy a city. The most instructive incident took place in 1908 in the remote Tunguska region of Siberia, when a 120-foot-diameter asteroid exploded early one morning. It probably killed nothing except reindeer but it flattened 800 square miles of forest. Statistically, that kind of event occurs every 200 to 300 years.

Luckily, larger asteroids are even fewer and farther between — but they are much, much more destructive. Just think of the asteroid seven to eight miles across that annihilated the dinosaurs (and 75 percent of all species) 65 million years ago.

With a readily achievable detection and deflection system we can avoid their same fate. Professional (and a few amateur) telescopes and radar already function as a nascent early warning system, working every night to discover and track those planet-killers. Happily, none of the 903 we’ve found so far seriously threaten an impact in the next 100 years.

Although catastrophic hits are rare, enough of these objects appear to be or are heading our way to require us to make deflection decisions every decade or so. Certainly, when it comes to the far more numerous Tunguska-sized objects, to date we think we’ve discovered less than a half of 1 percent of the million or so that cross Earth’s orbit every year. We need to pinpoint many more of these objects and predict whether they will hit us before it’s too late to do anything other than evacuate ground zero and try to save as many lives as we can.

So, how do we turn a hit into a miss? While there are technical details galore, the most sensible approach involves rear-ending the asteroid. A decade or so ahead of an expected impact, we would need to ram a hunk of copper or lead into an asteroid in order to slightly change its velocity. In July 2005, we crashed the Deep Impact spacecraft into comet Tempel 1 to learn more about comets’ chemical composition, and this proved to be a crude but effective method.

It may be necessary to make a further refinement to the object’s course. In that case, we could use a gravity tractor — an ordinary spacecraft that simply hovers in front of the asteroid and employs the ship’s weak gravitational attraction as a tow-rope. But we don’t want to wait to test this scheme when potentially millions of lives are at stake. Let’s rehearse, at least once, before performing at the Met!

The White House Office of Science and Technology Policy has just recommended to Congress that NASA begin preparing a deflection capacity. In parallel, my fellow astronaut Tom Jones and I led the Task Force on Planetary Defense of the NASA Advisory Council. We released our report a couple of weeks ago, strongly urging that the financing required for this public safety issue be added to NASA’s budget.

This is, surprisingly, not an expensive undertaking. Adding just $250 million to $300 million to NASA’s budget would, over the next 10 years, allow for a full inventory of the near-Earth asteroids that could do us harm, and the development and testing of a deflection capacity. Then all we’d need would be an annual maintenance budget of $50 million to $75 million.

By preventing dangerous asteroid strikes, we can save millions of people, or even our entire species. And, as human beings, we can take responsibility for preserving this amazing evolutionary experiment of which we and all life on Earth are a part.

Russell Schweickart, a former astronaut, was the co-chairman of the Task Force on Planetary Defense of the NASA Advisory Council.


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Two Exoplanets May Support Life

The Twin Earths of Gliese 581

An artist’s conception of the four inner planets surrounding Gliese 581, a red dwarf star 20 light years away from Earth. The large earth-like planet in the foreground is the recently discovered “Gliese 581 g,” which has an orbit of 36.6 days in the middle of the star’s habitable zone.

Two planets similar to Earth have been discovered circling the dwarf star Gliese 581. Scientists believe the pair could be inhabitable and using new, super telescopes, astronomers are now searching for signs of life.

The alien sun, glowing blood-red in the sky, provides little light and heat. But it does shine day and night throughout the year, which lasts only about two Earth months on this distant planet.

The other side of the planet, however, is in constant darkness, never illuminated by the dwarf star. Extreme temperature differences trigger mega-storms that make terrestrial hurricanes look like gentle breezes, as powerful winds drive massive waves against the coastlines.

There is no doubt about it: this is not a cozy place. And yet it is quite possible that it supports life.

Looking for Earth’s Twin

This is the exciting conclusion that was reached by Harvard astronomer Lisa Kaltenegger and her research team. The scientists performed an extensive simulation of the planet Gliese 581 d, the results of which will be described in an upcoming issue of the Astrophysical Journal. “It’s a fascinating new world,” says Kaltenegger, who has been conducting her research at the Max Planck Institute for Astronomy (MPIA) in Heidelberg, Germany since the end of September. “There is actually a possibility that it’s habitable.”

Water Could Flow

Gliese is considered the most exciting planetary system astronomers have discovered to date outside our own solar system. A total of six planets orbit the red sun in the Libra constellation. Only last week, US scientists announced that they had discovered another planet in the system that’s even more similar to Earth. The smaller, rocky planet Gliese 581 g also appears to orbit its sun in the “habitable zone.” Kaltenegger has already begun calculating the climate for this satellite.

The most important requirement to allow for the development of life as we know it is that a planet is heated by its sun to a sufficiently moderate degree that liquid water can form there. “If the ingredients are right,” says MPIA Director Thomas Henning, “it could happen almost automatically.”

Now the calculations of Kaltenegger’s team are fueling the suspicion that there might even be a few oases of life among the roughly 500 planets already discovered outside our solar system, that have remained unnoticed until now.

At first Gliese 581 d, which was discovered in 2007, was also believed to be an icy planet incapable of supporting life. Initial estimates indicated that its orbital path was in fact too far from its star, meaning it was but a flying ball of ice with temperatures constantly hovering around minus 40 degrees Celsius (minus 40 degrees Fahrenheit).

But there was one factor the astronomers hadn’t taken sufficiently into account: the greenhouse effect.

The Aliens Would Need More Muscles

Gliese 581 d is seven times as heavy as the Earth, which puts it in the class of the so-called super-Earth planets. There is every indication that because of the massive rocky planet, powerful volcanoes once spewed massive amounts of CO2 into the atmosphere, far more CO2, in fact, than exists in our atmosphere. This could have produced a dense envelope of air under high atmospheric pressure. The resulting greenhouse gas effect would have caused temperatures to rise significantly above freezing, leading to a thaw on the icy planet.

Based on her model calculations, Kaltenegger speculates that atmospheric pressure on the planet could even be as high as seven or eight bars, a level found on Earth at the bottom of lakes. “It would certainly be extremely difficult to move around there,” the astronomer explains, “sort of like constantly wading in deep water.”

Kaltenegger’s calculations also indicate that gravity is higher on the planet. Even a slender earthling would weigh about as much as an adult male gorilla on Gliese 581 d.

“For land dwellers, in particular, it would certainly be advantageous to have a few extra muscles,” Kaltenegger speculates. “Or else the aliens would have to crawl along the ground like snakes.”

Shrubs Could Have Leaves Black As Coal

A noticeably more earth-like gravitational environment is likely to prevail on the newly discovered neighboring planet, Gliese 581 g, with a mass only three to four times that of the Earth. However, it is not yet clear whether the planet’s climate can support life. According to initial rough estimates, temperatures on Gliese 581 g, which presumably lacks a significantly warming greenhouse effect, are more freezer-like.

The possibility of vegetation on the Gliese planets is also a source of speculation. If plant-like beings did exist there, they would probably look extremely exotic to our eyes. But because the star provides so little light, the alien plants would have to utilize all available light for their photosynthesis. The consequence, as US scientist Nancy Kiang has discovered, would be bizarre. According to Kiang, for grasses or shrubs to thrive under a red sun, their blades and leaves would have to be black as coal.

All of this, so far, is little more than conjecture, albeit with scientific underpinnings. But with the right telescopes and measuring instruments, it would, in fact, be possible, one day, to determine whether there are trees and other vegetation growing on the two earth-like Gliese planets.

To reach this determination, scientists would have to capture the light from the planet and use it to decode the chemical composition of their atmospheres. A high oxygen concentration alone would indicate that life exists there, because oxygen is a highly reactive gas that can only exist in small amounts in the atmosphere of an uninhabited planet. A high oxygen concentration would mean that there must be organisms like bacteria and plants on the planet to constantly produce more oxygen.

The Firefly And The Headlight

But analyzing the light coming from an extrasolar planet, or exoplanet, remains an enormous technical challenge. Normal stars shine millions of times more brightly than their dimly lit satellites. The task of detecting a planet the size of Earth near a distant sun is about equivalent to detecting a firefly flying next to a car headlight in Cairo — from Berlin.

Scientists have a long way to go before they can unlock the secrets of the atmospheres of rocky planets like Gliese 581 d or Gliese 581 g, which makes the breakthroughs astronomers have been able to announce in recent years all the more astonishing. They have already been able to study the atmospheres of larger exoplanets, at least indirectly. To do this, they take advantage of mini solar eclipses that occur when a distant planet passes in front of its sun. When this happens, the planet is uniformly illuminated, leaving its chemical fingerprint on the light emitted by the star.

For now, this trick only works with gas planets, which have enormous atmospheres. The atmospheres of exoplanets analyzed to date contain mostly hydrogen and helium, a composition very similar to that of Jupiter and Saturn. This confirms that our solar system is not an exception in the Milky Way.

Early this year, MPIA scientists even managed, for the first time, to directly capture and analyze the light coming from a distant planet. To do so, they used the world’s most advanced observatory, the European-run “Very Large Telescope” in Chile’s Atacama Desert. Its eight-meter mirrors are so photosensitive that they could detect a flashlight on the moon. But even this is only good enough for only a very few of the exoplanets. The impressive achievement was only possible because the planet the scientists were studying, the gas giant HR 8799 c, is unusually bright. HR 8799 c is still very young and as hot as a flamethrower.

New Telescopes on The Horizon

Astrophysicists are confident in their ability to make rapid headway in pushing the boundaries even farther, and they are eager to directly photograph smaller and colder planets. “We are moving forward much more quickly than expected,” says Max Planck scientist Henning. “In as little as five years, we could be far enough along to measure the atmospheres of super-Earth planets orbiting small, relatively dim suns for the first time.”

Scientists like Henning are pinning their hopes on the next generation of eyes in the sky. The James Webb Space Telescope, the successor of the legendary Hubble Space Telescope, could be sent into space by as early as 2014. The Europeans, for their part, plan to build another observatory, the “Extremely Large Telescope,” in the Atacama Desert. With its 42-meter mirror, it would be the biggest telescope ever built. There are even plans in the works to build a 100-meter telescope.

These super observatories should allow scientists to solve the mysteries of the Gliese planets. And what if their remote diagnosis reveals that there are, in fact, unknown life forms there? Could mankind launch an expedition to explore the alien worlds?

The Gliese system is only 20.5 light-years away from Earth, making the red dwarf star one of the 100 closest fixed stars — a cosmic neighbor, so to speak.

But even this relatively small interstellar chasm could not be crossed with conventional rockets. To reach the twin earthlike planets, terrestrial astronauts would have to travel for 400,000 years. Man has only existed for half as long.


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In the Habitable Zone

A planet orbiting a star causes a slight disturbance in the star’s rotation, the effect of the gravitational tug between the star and the planet. Astronomers have been studying the wobbling of stars for a couple of decades, in hopes of finding an exoplanet — a planet beyond our solar system — that might offer the possibility of sustaining human life. Now, after 11 years of searching with specialized instruments in Chile and Hawaii, a team of American astronomers has announced in the Astrophysical Journal that it has found the first likely candidate.

The planet is called Gliese 581g after its sun, Gliese 581, a red dwarf vastly dimmer than our sun and about 20 light-years from Earth. Potentially habitable does not mean Earthlike. It means that Gliese 581g is the right distance from its sun to be in the habitable zone, able to sustain liquid water and with enough gravity to retain an atmosphere. Gliese 581g orbits its sun in a bit more than 36 days and is almost certainly tidally locked, meaning the same side of the planet always faces the sun. That probably means wide extremes in temperature and a permanent twilight zone between night and day where the climates are more moderate.

What makes this discovery so important is that it happened so early in the search for exoplanets and after examining only a tiny sample of small candidate stars as close to Earth as Gliese 581. In the paper reporting their discovery, the astronomers discuss the probable implications with carefully calibrated language that still doesn’t hide their excitement. “If the local stellar neighborhood,” they write, “is a representative sample of the galaxy as a whole, our Milky Way could be teeming with potentially habitable planets.” We are intrigued, too.


Editorial, New York Times


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Don’t talk to aliens, warns Stephen Hawking

Hawking has depicted what kinds of alien could be out there

THE aliens are out there and Earth had better watch out, at least according to Stephen Hawking. He has suggested that extraterrestrials are almost certain to exist — but that instead of seeking them out, humanity should be doing all it that can to avoid any contact.

The suggestions come in a new documentary series in which Hawking, one of the world’s leading scientists, will set out his latest thinking on some of the universe’s greatest mysteries.

Alien life, he will suggest, is almost certain to exist in many other parts of the universe: not just in planets, but perhaps in the centre of stars or even floating in interplanetary space.

Hawking’s logic on aliens is, for him, unusually simple. The universe, he points out, has 100 billion galaxies, each containing hundreds of millions of stars. In such a big place, Earth is unlikely to be the only planet where life has evolved.

“To my mathematical brain, the numbers alone make thinking about aliens perfectly rational,” he said. “The real challenge is to work out what aliens might actually be like.”

The answer, he suggests, is that most of it will be the equivalent of microbes or simple animals — the sort of life that has dominated Earth for most of its history.

One scene in his documentary for the Discovery Channel shows herds of two-legged herbivores browsing on an alien cliff-face where they are picked off by flying, yellow lizard-like predators. Another shows glowing fluorescent aquatic animals forming vast shoals in the oceans thought to underlie the thick ice coating Europa, one of the moons of Jupiter.

Such scenes are speculative, but Hawking uses them to lead on to a serious point: that a few life forms could be intelligent and pose a threat. Hawking believes that contact with such a species could be devastating for humanity.

He suggests that aliens might simply raid Earth for its resources and then move on: “We only have to look at ourselves to see how intelligent life might develop into something we wouldn’t want to meet. I imagine they might exist in massive ships, having used up all the resources from their home planet. Such advanced aliens would perhaps become nomads, looking to conquer and colonise whatever planets they can reach.”

He concludes that trying to make contact with alien races is “a little too risky”. He said: “If aliens ever visit us, I think the outcome would be much as when Christopher Columbus first landed in America, which didn’t turn out very well for the Native Americans.”

The completion of the documentary marks a triumph for Hawking, now 68, who is paralysed by motor neurone disease and has very limited powers of communication. The project took him and his producers three years, during which he insisted on rewriting large chunks of the script and checking the filming.

John Smithson, executive producer for Discovery, said: “He wanted to make a programme that was entertaining for a general audience as well as scientific and that’s a tough job, given the complexity of the ideas involved.”

Hawking has suggested the possibility of alien life before but his views have been clarified by a series of scientific breakthroughs, such as the discovery, since 1995, of more than 450 planets orbiting distant stars, showing that planets are a common phenomenon.

So far, all the new planets found have been far larger than Earth, but only because the telescopes used to detect them are not sensitive enough to detect Earth-sized bodies at such distances.

Another breakthrough is the discovery that life on Earth has proven able to colonise its most extreme environments. If life can survive and evolve there, scientists reason, then perhaps nowhere is out of bounds.

Hawking’s belief in aliens places him in good scientific company. In his recent Wonders of the Solar System BBC series, Professor Brian Cox backed the idea, too, suggesting Mars, Europa and Titan, a moon of Saturn, as likely places to look.

Similarly, Lord Rees, the astronomer royal, warned in a lecture earlier this year that aliens might prove to be beyond human understanding.

“I suspect there could be life and intelligence out there in forms we can’t conceive,” he said. “Just as a chimpanzee can’t understand quantum theory, it could be there are aspects of reality that are beyond the capacity of our brains.”


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Reaching for the Stars When Space Was a Thrill

Using aviation industry ads, a new book revisits a time when outer space still thrilled, and cold war paranoia reigned.

The years from 1957 to 1962 were a golden age of science fiction, as well as paranoia and exhilaration on a cosmic scale. The future was still the future back then, some of us could dream of farms on the moon and heroically finned rockets blasting off from alien landscapes. Others worried about Russian moon bases.

Scientists debated whether robots or humans should explore space. Satellites and transistors were jazzy emblems of postwar technology, and we were about to unravel the secrets of the universe and tame the atom (if it did not kill us first).

Some of the most extravagant of these visions of the future came not from cheap paperbacks, but from corporations buffing their high-tech credentials and recruiting engineering talent in the heady days when zooming budgets for defense and NASA had created a gold rush in outer space.

In the pages of magazines like Aviation Week, Missiles and Rockets and even Fortune, companies, some famous and some now obscure, were engaged in a sort of leapfrog of dreams. And so, for example, Republic Aviation of Farmingdale, N.Y. — “Designers and Builders of the Incomparable Thundercraft” — could be found bragging in Aviation Week and Space Technology magazine in 1959 about the lunar gardening experiments it was doing for a future Air Force base on the moon.

Or the American Bosch Arma Corporation showing off, in Fortune, its “Cosmic Butterfly,” a solar-powered electrically propelled vehicle to ferry passengers and cargo across the solar system.

Most Americans never saw these concoctions, but now they have been collected and dissected by Megan Prelinger, an independent historian and space buff, in a new book, “Another Science Fiction: Advertising the Space Race 1957-1962.” It is being published on May 25 by Blast Books.

Ms. Prelinger and her husband, Rick, operate the Prelinger Library, a private research library in San Francisco with a heavy emphasis on media, technology and landscape history.

In an e-mail message, Ms. Prelinger said she had grown up “on a cultural diet of science fiction and space,” memories of the moon landings and “Star Trek” merging in her mind. “As a result,” she said, “I grew up believing that I was a junior member of an advanced technological society.”

The book, she said, was inspired by a shipment of old publications to the library, including Aviation Week & Space Technology and Missiles and Rockets. “I little expected that the advertising in their pages would seize my attention more than the articles themselves,” she writes in the introduction to her book.

The ads are chock-full of modernist energy and rich in iconography in ways Ms. Prelinger is happy to elaborate on.

The late ’50s were also the years of the Organization Man. The cover illustration, from an insurance ad, shows a man in a gray flannel suit who is a dead ringer for the existentially confused Don Draper of “Mad Men,” floating alarmed and bewildered among the planets and stars. Time and again, the mountains and valleys of the moon, for example, are portrayed as if they were the mountains, canyons and deserts of the American West, making the space program just another chapter in the ongoing narrative of Manifest Destiny.

In one illustration, the hands of God and Adam from Michelangelo’s Sistine Chapel ceiling have been transformed into a giant pair of space gloves reaching for each other. In another, the silhouette of a spaceship forms a cross.

“These images suggest that the furthest reach of what humankind hoped to find in space was in fact the very essence of infinity,” Ms. Prelinger writes.

Leafing through this book is a walk down my own memory lane. I grew up in Seattle, which was a one-company town dominated by Boeing. Almost everybody worked there sooner or later. My best friend’s father helped design the Saturn V rocket that lifted humans to the moon. After limping out of M.I.T. with a physics degree in the late ’60s, I, too, worked there for a year, playing a kind of space war — shooting high-speed aluminum balls at sheets of aluminum arrayed to simulate the structures of aircraft or spacecraft, to see what the damage would be under various conditions. At the end of the day, my desk was buried in piles of sharp dented and charred sheets of aluminum. I had to count all the holes.

It’s hard to know what to be more nostalgic about, all those childhood dreams of space opera or the optimism of an era in which imagination and technology were booming and every other ad ended with a pitch to come work for the thriving company of the future. “To advance yourself professionally, you should become a member of one these teams. Write to N. M. Pagan,” reads a typical notice from the Martin Company, now part of Lockheed Martin.

You don’t hear that much these days.

Back then, you, too, sitting at a drafting table or in a cubicle, designing antennas or self-locking nuts among acres of such boards and cubicles — “Reaching for the Moon, Mr. Designer?” reads a Kaylock ad — could be a space hero.

And of course it was almost exclusively men depicted in the ads. One exception was an ad from the National Cash Register Company for a new electronic machine for posting checks. “And what the POST-TRONIC does electronically the operator cannot do wrong — because she doesn’t do it at all!” says the ad showing a woman floating in space at the machine’s console.

Naturally, there was a hook to those recruitment ads, as Ms. Prelinger points out. The real business of most of those aerospace companies was not the space program but defense — building fighters, bombers, missiles and other implements of the cold war, not to mention commercial airliners. For many of these places, the space program was more of a hindrance than a boost to the bottom line, a sort of prestigious loss leader to attract cutting-edge talent.

Occasionally, as Ms. Prelinger reports, the darker side of this work bled through into the trade press and the ads, like when the Marquardt Corporation, which made small control rockets for satellites, showed a spy satellite aiming its lens down at Earth.

If the space fever began in 1957 with Sputnik, it cooled by 1962, when the basic plan for the Apollo moon missions was set and there was no more space for imaginations to run wild. Also, by then NASA’s budget was leveling off. Ms. Prelinger said that during this period about half a million engineers, scientists, draftsmen and other people followed the clarion call to blend their talents into the new age, swelling the ranks of aerospace workers to more than a million.

Some of them might have wound up like me. When the “impact mechanics” group was downsized, I was sent to the “weights and measures” group. Our job was to scrutinize rocket blueprints to determine the position and weight of every nut, bolt, washer and any other item on a small upper-stage booster that was to deliver an unknown payload to orbit. The information could be entered into a computer program that would calculate the center of gravity and other dynamical properties of the rocket package.

It was essential but brain-numbing work, and I learned a lot about shooting rubber bands from the wars that broke out every day after lunch.

But it was men and women like these, working in cubicles, who saved the astronauts of Apollo 13 in 1969, by figuring out how to bring them back from the moon alive in a crippled spacecraft.

In the wake of the moon landings and then the end of the cold war, many of those jobs, exciting or not, disappeared, as did many of the companies that advertised them. What has not disappeared in all these years and decades is the yearning and arguing about space.

We’re still fighting about what NASA should do as far as human exploration of the universe is concerned, collectively looking more and more like that bewildered advertising man floating in space on the cover of Ms. Prelinger’s fascinating book. The argument has been going on for my whole life. Since those advertisements appeared, the United States invaded Vietnam and left; the Soviet Union crumbled and China rose; the whole nation stopped smoking.

We never did find the essence of infinity — at least not yet.

Dennis Overbye, New York Times


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From the Clash of White Dwarfs, the Birth of a Supernova

STAR A Type 1a supernova is seen to the bottom left of a galaxy in the Virgo cluster.

How many ways can a star go “kaboom!”? It might depend on what kind of galaxy the star lives in, astronomers said last week.

For the last 20 years, astronomers seeking to measure the cosmos have used a special type of exploding star, known as Type 1a supernovas, as distance markers. They are thought to result when stars known as white dwarfs grow beyond a certain weight limit, setting off a thermonuclear cataclysm that is not only bright enough to be seen across the universe but is also remarkably uniform from one supernova to the next. Using them, two teams of astronomers a little more than a decade ago reached the startling and now widely held conclusion that some “dark energy” was speeding up the expansion of the universe.

But astronomers, to their embarrassment, have not been able to agree on how the white dwarf gains its fatal weight and explodes, whether by slowly grabbing material from a neighboring star or by crashing into another white dwarf.

In a telephone news conference on Wednesday and a paper published Thursday in the journal Nature, Marat Gilfanov and his colleague, Akos Bogdan, both of the Max Planck Institute for Astrophysics in Garching, Germany, said that for at least one class of galaxies in the universe, the roundish conglomerations of older, redder stars known as ellipticals, these supernovas are mostly produced by collisions.

“We have revealed the source of the most important explosions in cosmology,” Dr. Gilfanov said, adding that until now “we didn’t know exactly what they were.”

Reasoning that white dwarfs slowly gobbling gas from neighbors would emit X-rays as the captured gas fell and was heated, Dr. Gilfanov and Dr. Bogdan used NASA’s Chandra X-Ray Observatory to look at five elliptical galaxies and the central bulge of the nearby Andromeda galaxy — all of which are composed of older stars. The satellite recorded only about one-thirtieth to one-fiftieth of the X-rays that would be expected from such white dwarfs, leading the astronomers to conclude that no more than 5 percent of the supernovas in those types of stellar systems could be produced by accreting white dwarfs.

The observations leave open the possibility that accreting dwarfs might be responsible for more of the supernovas in spiral galaxies like our own, which tend to have younger, more massive stars.

That leaves open the possibility of two different kinds of Type 1a supernovas at loose in the universe and could add extra uncertainty into efforts to use exploding stars as standard candles to make precise measurements of the universe. Accreting white dwarfs go off at a precisely determined mass known as the Chandrasekhar limit, but a pair of colliding dwarfs could have a range of masses.

Mario Livio, a theorist at the Space Telescope Science Institute, said that while the new results and the idea of two classes of supernovas “muddies the water,” they would not affect the measurements of dark energy. Most of the supernovas in those studies, he said, came from spiral galaxies, and the astronomers, moreover, were very careful to calibrate their data.

“The main results so far will remain unchanged,” Dr. Livio said.

Adam Riess, of Johns Hopkins University and the Space Telescope Science Institute and a first-rate dark energy hunter, called the new paper “an interesting study.” He compared the two theories of supernovas to lighting a stick of dynamite with a fuse versus banging them together to see if they would go off. “If we find a connection to where nature does it one way versus the other, we could use that information to improve the use of these candles,” Dr. Riess wrote in an e-mail message. “I think we are getting close to that point now.”

Dennis Overbye, New York Times


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Closing the new frontier

“We have an agreement until 2012 that Russia will be responsible for this,” says Anatoly Perminov, head of the Russian space agency, about ferrying astronauts from other countries into low-Earth orbit. “But after that? Excuse me, but the prices should be absolutely different then!”

The Russians may be new at capitalism, but they know how it works. When you have a monopoly, you charge monopoly prices. Within months, Russia will have a monopoly on rides into space.

By the end of this year, there will be no shuttle, no U.S. manned space program, no way for us to get into space. We’re not talking about Mars or the moon here. We’re talking about low-Earth orbit, which the United States has dominated for nearly half a century and from which it is now retiring with nary a whimper.

Our absence from low-Earth orbit was meant to last a few years, the interval between the retirement of the fatally fragile space shuttle and its replacement with the Constellation program (Ares booster, Orion capsule, Altair lunar lander) to take astronauts more cheaply and safely back to space.

But the Obama 2011 budget kills Constellation. Instead, we shall have nothing. For the first time since John Glenn flew in 1962, the United States will have no access of its own for humans into space — and no prospect of getting there in the foreseeable future.

Of course, the administration presents the abdication as a great leap forward: Launching humans will be turned over to the private sector, while NASA’s efforts will be directed toward landing on Mars.

This is nonsense. It would be swell for private companies to take over launching astronauts. But they cannot do it. It’s too expensive. It’s too experimental. And the safety standards for getting people up and down reliably are just unreachably high.

Sure, decades from now there will be a robust private space-travel industry. But that is a long time. In the interim, space will be owned by Russia and then China. The president waxes seriously nationalist at the thought of China or India surpassing us in speculative “clean energy.” Yet he is quite prepared to gratuitously give up our spectacular lead in human space exploration.

As for Mars, more nonsense. Mars is just too far away. And how do you get there without the stepping stones of Ares and Orion? If we can’t afford an Ares rocket to get us into orbit and to the moon, how long will it take to develop a revolutionary new propulsion system that will take us not a quarter-million miles but 35 million miles?

To say nothing of the effects of long-term weightlessness, of long-term cosmic ray exposure, and of the intolerable risk to astronaut safety involved in any Mars trip — six months of contingencies vs. three days for a moon trip.

Of course, the whole Mars project as substitute for the moon is simply a ruse. It’s like the classic bait-and-switch for high-tech military spending: Kill the doable in the name of some distant sophisticated alternative, which either never gets developed or is simply killed later in the name of yet another, even more sophisticated alternative of the further future. A classic example is the B-1 bomber, which was canceled in the 1970s in favor of the over-the-horizon B-2 stealth bomber, which was then killed in the 1990s after a production run of only 21 (instead of 132) in the name of post-Cold War obsolescence.

Moreover, there is the question of seriousness. When John F. Kennedy pledged to go to the moon, he meant it. He had an intense personal commitment to the enterprise. He delivered speeches remembered to this day. He dedicated astronomical sums to make it happen.

At the peak of the Apollo program, NASA was consuming almost 4 percent of the federal budget, which in terms of the 2011 budget is about $150 billion. Today the manned space program will die for want of $3 billion a year — 1/300th of last year’s stimulus package with its endless make-work projects that will leave not a trace on the national consciousness.

As for President Obama’s commitment to beyond-lunar space: Has he given a single speech, devoted an iota of political capital to it?

Obama’s NASA budget perfectly captures the difference in spirit between Kennedy’s liberalism and Obama’s. Kennedy’s was an expansive, bold, outward-looking summons. Obama’s is a constricted, inward-looking call to retreat.

Fifty years ago, Kennedy opened the New Frontier. Obama has just shut it.

Charles Krauthammer, Washington Post


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