Defense Secretary Robert Gates said Thursday the United States is prepared to share with China some of the information it has about the U.S. shootdown of a spy satellite.
His comments came hours after Beijing complained the missile strike Wednesday could cause harm to security in outer space and some countries.
"We provided a lot of information ... before it took place," Gates told reporters during a visit to Hawaii. But, the secretary also said that he is determined to be open about the U.S. operation and "we are prepared to share whatever appropriately we can."'
Debris from the obliterated satellite was being tracked over the Pacific and Atlantic oceans but appeared to be too small to cause damage on Earth, Marine Gen. James Cartwright, vice chairman of the Joint Chiefs of Staff, had said earlier Thursday.
He told a Pentagon news conference that officials have a "high degree of confidence" that the missile launched from a Navy cruiser hit exactly where intended — destroying the toxic fuel tank that officials said could kill if it fell to a populated area on Earth.
It was an unprecedented mission for the Navy, so extraordinary that the final go-ahead to launch the missile Wednesday was reserved for Gates rather than a military commander.
The elaborate intercept plan had worried some international leaders, who suggested it was a thinly disguised attempt to test an anti-satellite weapon — one that could take out other nations' orbiting communications and spy spacecraft.
Within hours of the reported hit, China said it was on the alert for possible harmful fallout from the shootdown and urged Washington to promptly release data on the action.
"China is continuously following closely the possible harm caused by the U.S. action to outer space security and relevant countries," Foreign Ministry spokesman Liu Jianchao said at news conference in Beijing. "China requests the U.S. to fulfill its international obligations in real earnest and provide to the international community necessary information and relevant data in a timely and prompt way so that relevant countries can take precautions."
Cartwright estimated there was an 80 percent to 90 percent chance that the missile struck the most important target on the satellite — its fuel tank, containing 1,000 pounds of hydrazine, which Pentagon officials say could have posed a health hazard to humans if it had landed in a populated area.
Alluding to a video clip of the missile smashing into the satellite, which he showed at the news conference, Cartwright said, "We have a fireball, and given that there's no fuel (on the tip of the missile), that would indicate that that's a hydrazine fire."
The video showed the three-stage SM-3 missile launching from the USS Lake Erie at 10:26 p.m. EST, northwest of Hawaii, and of the missile's small ''kill vehicle'' — a non-explosive device at the tip — maneuvering into the path of the satellite and colliding spectacularly.
He said the satellite and the kill vehicle collided at a combined speed of 22,000 mph about 130 miles above Earth's surface, and that the collision was confirmed at a space operations center at 10:50 p.m. EST.
Asked about the satisfaction felt among those in the military who had organized the shootdown on short notice by modifying missile software and other components, Cartwright smiled widely.
"Yes, this was uncharted territory. The technical degree of difficulty was significant here," Cartwright said. "You can imagine that at the point of intercept there were a few cheers that went up."
He cautioned, however, that more technical analysis was required to determine for certain what debris was created and where it might go. The satellite was described as the size of a school bus and weighed about 5,000 pounds.
Unlike most spacecraft that fall out of orbit and re-enter the atmosphere, this satellite had an almost full fuel tank because it lost power and became uncontrollable shortly after it reached its initial orbit in December 2006. Cartwright said the hydrazine alone was justification for undertaking the unprecedented effort to use a Navy missile interceptor to attempt to destroy the satellite in orbit.
Cartwright said experts were still watching the debris fields and he could not yet rule out that hazardous material would fall to Earth. But he said that as of Thursday morning, debris had only been seen in the atmosphere — and none had been detected surviving re-entry. He indicated that debris appeared unlikely to pose a problem.
"Thus far we've seen nothing larger than a football," he said, referring to debris in the atmosphere spotted by radar and other sensors.
The military concluded that the missile had successfully shattered the satellite because trackers detected a fireball. Cartwright said it was unlikely that the fireball could have been caused by anything other than the hydrazine in the tank.
And Cartwright cited two other sources of information that indicate the fuel tank was hit: the appearance of a vapor cloud and the results of spectral analysis, or the study of light emissions, from devices aboard two aircraft that operate from the Pacific test range associated with the Pentagon's missile defense testing.
Debris from the satellite has started re-entry and will continue through Thursday and into Friday, Cartwright said.
The size of the debris is smaller than the Pentagon had forecast and most of the satellite's intelligence value was likely destroyed, Cartwright said. Analysts had said one of the reasons for the shootdown was that officials worried that without it, larger chunks of the satellite could fall and be recovered, opening the possibility of secret technology falling into the hands of the Chinese or others.
Gates arrived in Hawaii less than two hours before the missile was launched. His press secretary, Geoff Morrell, said Gates had a conference call during his flight with Cartwright and Air Force Gen. Kevin Chilton, head of Strategic Command. They told him that "the conditions were ripe for an attempt, and that is when the secretary gave the go-ahead to take the shot, and wished them good luck," Morrell said.
At 10:35 p.m. EST, Gates spoke to both generals again and "was informed that the mission was a success, that the missile had intercepted the decaying satellite, and the secretary was obviously very pleased to learn that," said Morrell.
U.S. to Share Satellite Strike Data with China
Solar System Like Ours Found
The discovery of a Jupiter-like planet and another about the size of Saturn has astronomers suggesting that solar systems like our own may be common.
The newfound worlds both appear to be gaseous and are about 80 percent the sizes of Jupiter and Saturn, the astronomers said today. They orbit a star that is about half the size of our sun and is dimmer and much cooler.
"This is the first discovery of a multi-planet system that could be analogous to our solar system," said research team member Alison Crocker, a Dartmouth College graduate now studying at Oxford University.
Several similarities
The newfound solar system, about 5,000 light-years away, is more compact than our own. The larger planet's orbit is 2.3 times as far from its host star as the Earth is from the sun. Jupiter is 5.2 times farther from the sun than Earth.
But there are several interesting similarities:
* The ratio between the masses of the two worlds is about 3:1, similar to the Jupiter/Saturn ratio.
* The smaller planet is about twice as far from its star as the larger one, just as Saturn is roughly twice as far away from the sun as Jupiter.
* The two worlds orbit their star in 5 and 14 years, similar to the 2:5 orbit ratio of Jupiter and Saturn.
The planets were found using a technique called gravitational lensing, in which light from the faraway planets is bent and magnified by the gravity of a foreground object, in this case a another star. The technique has been used to find three other Jupiter-mass planets, each around different stars, in the past.
"This is the first time we had a high-enough magnification event where we had significant sensitivity to a second planet — and we found one," said Scott Gaudi, assistant professor of astronomy at Ohio State University. "You could call it luck, but I think it might just mean that these systems are common throughout our galaxy."
The discoveries, by an international team using 11 telescopes around the world, are detailed in the Feb. 15 issue of the journal Science. The initial observations were made by The Optical Gravitational Lensing Experiment (OGLE).
Formation theories
Even though their star emits only about 5 percent as much light as the sun, the two planets, namded OGLE-2006-BLG-109Lb and OGLE-2006-BLG-109Lc, are thought to be about the same temperatures as Jupiter and Saturn because of their tighter orbits.
"The temperatures are important because these dictate the amount of material that is available for planet formation," Gaudi said. "Most theorists think that the biggest planet in our solar system formed at Jupiter's location because that is the closest to the sun that ice can form. Saturn is the next biggest because it is in the next location further away, where there is less primordial material available to form planets."
Theorists have wondered if gas giants in other solar systems form in the same way as ours did.
"This system seems to answer in the affirmative," Gaudi said.
The leading theory is that a rocky protoplanet forms first, then if it gains enough mass, it attracts a shell of gas. Astronomers don't agree, however, whether that explains all the giant planets in our solar system. Another idea is that the giants collapse from a knot of material, much in the way a star forms.
Other worlds?
It's also plausible that there could be rocky planets around the star in orbits similar to Venus, Earth or Mars. And icy worlds like Neptune might exist in the system's outer reaches, the researchers said.
There are now about 250 known planets beyond our solar system and some 25 multiple-planet system. Among those are setups with rocky worlds just a few times the mass of Earth.
"While most planetary systems around other stars substantially differ from [our] solar system, a series of recent detections have brought us closer and closer to home," said Martin Dominik, a University of St. Andrews researcher involved in the discoveries. "Sooner rather than later, someone can be expected to discover an Earth-mass planet orbiting a star other than the sun."
One Hour Warning: Solar Storms Get More Predictable
If humans live on the moon some day, they might turn on the weather forecast just as they do on Earth. But in space, they won't fear rain storms, but sun storms.
During a solar radiation storm, the sun emits huge sprays of charged particles that can disable satellites and would harm humans in space if they're not properly protected. Although these storms are notoriously difficult to predict, a new method of forecasting storms can give up to an hour's warning.
The technique relies on measurements taken by the NASA/ESA SOHO (Solar and Heliospheric Observatory) spacecraft in orbit around the sun. SOHO, launched in 1995, has been near death more than once, but clever engineers, working with the equivalent of electronic duct tape and more than a dash of luck, have kept it running well beyond its expected lifetime. And now the probe is making fresh contributions to solar weather forecasting.
The new technique relies on SOHO's Comprehensive Suprathermal and Energetic Particle Analyzer (COSTEP), which monitors the radiation coming from the sun.
Scientists analyzed the data COSTEP recorded from sun storms during the first six years of the spacecraft's launch, and compiled a matrix that can predict a full-blown storm is coming after the less-dangerous first wave arrives. Because there is about an hour's lag time between the early arrival of electrons, and the eventual onslaught of more-damaging protons, this new forecast system gives people and spacecraft enough time to take cover.
The method was described in the journal Space Weather, and went online just in time for the recent launch of the STS-122 shuttle mission.
Radiation risk
On Earth, people are protected from the brunt of solar radiation by our planet's atmosphere and magnetic field. Even astronauts orbiting the Earth on the International Space Station are shielded from much of it since Earth's magnetic field extends far enough to cover them. The astronauts do retreat to a radiation-shielded part of the station during severe storms, however.
But when people venture beyond our planet's protective bubble, they will really be at risk of severe health effects from solar storm radiation. It was a concern even during brief lunar missions in the Apollo era.
"We know what happens when humans are exposed to a lot of radiation — Hiroshima and Nagasaki have given us an example," said Arik Posner, a senior research scientist at Southwest Research Institute in San Antonio, Texas, who developed the new forecast technique. "Humans are constantly hit by some sort of radiation, even on Earth, at very low levels. But what happens when you increase the radiation level slightly? We don't know. But the best thing to do is limit exposure."
DNA damage
The most damaging solar-storm radiation particles are fast-moving protons. These energetic particles can destroy human tissue and break strands of DNA.
The radiation is also dangerous for spacecraft. When a speeding particle hits electronics, it can cause bits to change from zeroes to ones or vice versa, prompting program malfunctions. If power is knocked out, a satellite can fail completely.
Scientists don't fully understand the physics behind solar storms. They know they are closely related to the cycles of the sun's magnetic field, and that they emerge from relatively cool, intensely magnetic regions of the solar surface called sunspots. The magnetic field is always changing — about every 11 years its magnetic north pole becomes the south pole, and vice versa. As the polarity cycles and regional instabilities develop, the sun's magnetic field lines get twisted and tangled, resulting in big knots of extremely strong magnetism.
Although the exact mechanism isn't known, somehow these magnetic field events are tied to eruptions of matter and energy.
"We don't have a really good idea of exactly how these processes happen," Posner said. "It's a very active area of research."
Huge explosions on the sun accelerate charged particles to near light-speed. The lighter particles, electrons, can speed up more easily, so they reach SOHO's radiation detector first. This allows the spacecraft to give humans about an hour's advance notice before the heavier protons and ions arrive and wreak havoc.
"The detector can only say that there is already an event in progress," Posner told SPACE.com. "It cannot predict one before it starts. But it does give you a tool to forecast these events."
After Posner and his collaborators designed the matrix to predict a coming storm, they tested it on the sun storm record from 2003, a year that did not comprise the initial data set on which the matrix was based. When it measured an increase in high-speed electrons, the program was able to successfully predict that a solar storm was coming. It forecasted all four major storms of 2003 with advance warnings ranging from 7 to 74 minutes.
Enduring craft
SOHO is a joint project between NASA and the European Space Agency (ESA). Three times it has seemed to be a doomed mission. During the most recent scare, in 2003, a stuck motor drive would not permit the craft's primary antenna to move. The antenna is used for transmitting pictures and data back to Earth, and it must be pointed toward the planet. Scientists feared lengthy blackout periods.
Engineers employed some tricks, including flipping the craft upside down during portions of its orbit, to get the data flowing again.
In 1998, changes in the spacecraft's software inadvertently sent it into a flat spin. The electricity-providing solar panels turned edge-on to the Sun, and SOHO lost power. It could not orient itself or maintain its temperature — critical in the frigid environment of space.
The mission appeared doomed.
After nearly three months, with much perseverance by the ground team, contact was re-established and the craft's orientation was fixed. Sunlight hit the panels, and SOHO was back.
Later in 1998, another problem nearly ended the mission again. The craft's last navigational gyro failed.
"In a race against time and a depleting maneuvering-fuel supply," explained SOHO Project Scientist Bernhard Fleck of ESA, engineers had to develop a software patch to get the craft back in operation without the gyro. New software was developed in early 1999 to allow a spacecraft to maintain attitude without gyros. Engineers sent it up, "making SOHO the first 3-axis stabilized spacecraft to be operated without any gyros," Fleck said.
