Unlocking the Secrets of an Alien World's Magnetic Field

The strength of an alien world's magnetic field may have been deduced for the first time, by analyzing extraordinarily fast winds slamming against it from the planet's star, researchers say.

This research could help gauge the strength of other exoplanets' magnetic fields as well, scientists say.

The magnetic field of a planet can influence its evolution in crucial ways. "It works as a shield against stellar wind particles, which erode the atmosphere, so it is important to know if this field is big or small," said study lead author Kristina Kislyakova, a planetary scientist at the Austrian Academy of Sciences, in Graz.

In order to find out magnetic details about exoplanets — planets beyond our own solar system — Kislyakova and her colleagues investigated HD 209458b, which orbits a sunlike star in the constellation Pegasus about 150 light-years from Earth. This alien world is only about 70 percent the mass of Jupiter, but nearly 40 percent wider.

HD 209458b is a "hot Jupiter," a gas giant that orbits its star closer than Mercury does to the sun — specifically, HD 209458b circles its star at a distance of less than one-twentieth the distance between the sun and Earth. The extraordinary roasting that HD 209458b endures makes its atmosphere blow away like the tail of a comet. Astronomers have informally dubbed the world "Osiris," after the Egyptian god torn to pieces by his evil brother Set.

The researchers used NASA's Hubble Space Telescope to analyze the spectrum of light from HD 209458b as it passed in front of its star. Oddly, the data revealed hydrogen atoms moving away extremely quickly from the exoplanet in a lopsided manner.

To help explain the unusual way in which the hydrogen is blowing off HD 209458b, the scientists built a 3D model to account for all the known interactions between planetary atmospheres and stellar winds, the flow of particles that stream off stars. The model suggested the exoplanet had a magnetic field about 10 percent as strong as Jupiter's, and that the stellar wind blowing onto the planet was moving at about 895,000 mph (1.44 million km/h).

"The implication of these findings is improvement of our understanding of the worlds outside the solar system — some new light shed on bodies many light-years away from us," Kislyakova told Space.com.

These findings support prior research suggesting that hot Jupiters have relatively weak magnetic fields compared with their cooler gas giant cousins. Since hot Jupiters orbit very near their stars, they experience powerful gravitational pulls that likely slow the rates at which these hot Jupiters spin. This slower rotation should result in weaker magnetic fields, because a planet's magnetic field "is generated most effectively in fast-rotating cores of planets," Kislyakova said.

Is Russian Mystery Object a Space Weapon?

The orbital maneuvers of a mysterious object Russia launched earlier this year have raised concerns that the satellite may be a space weapon of some sort.

The speculation centers on "Object 2014-28E," which Russia lofted along with three military communications satellites in May. The object was originally thought to be space junk, but satellite trackers have watched it perform a number of interesting maneuvers over the past few weeks, the Financial Times .

Last weekend, for example, 2014-28E apparently met up with the remnants of a rocket stage that helped the object reach orbit.

As a result, some space analysts wonder if Object 2014-28E could be part of an anti-satellite program — perhaps a revived version of the Cold War-era "Istrebitel Sputnikov" ("satellite killer") project, which Russian officials have said was retired when the Soviet Union collapsed in the early 1990s.

Military officials have long regarded the ability to destroy or disable another country's satellites as a key national-security capability. The Soviet Union is not the only nation known to have worked on developing such technology; China destroyed one of its own weather satellites in a 2007 test that spawned a huge cloud of orbital debris, and the United States blew up one of its own defunct spacecraft in 2008.

The concern about Object 2014-28E is legitimate, said Joan Johnson-Freese, a professor of national security affairs at the U.S. Naval War College in Newport, Rhode Island. But she cautioned against jumping to conclusions, saying that Russia could have a number of purposes in mind for the technology that 2014-28E may be testing out.

"Any satellite with the capability to maneuver has the potential to be a weapon," Johnson-Freese told Space.com. "But does that mean necessarily that all maneuverable satellites are weapons? No."

The United States has also worked to develop maneuverable-satellite technology, she noted, citing the Air Force's Experimental Satellite System-11 (XSS-11) and NASA's DART (Demonstration for Autonomous Rendezvous Technology) spacecraft, both of which launched in 2005. Further, the Defense Advanced Research Projects Agency (DARPA) managed a mission called Orbital Express, which launched in 2007 to test out satellite-servicing tech.

"When we did DART and XSS-11, other countries went into panic mode — you know, 'The U.S. has space weapons,'" Johnson-Freese said. "The first thing we did was assuage those concerns and say, 'No, no. That's not what it is. It's just a maneuverable satellite.' But any time you have dual-use technology, there are going to be concerns."

And pretty much all space technology is dual-use, said Brian Weeden, a technical adviser with the Secure World Foundation (a nonprofit organization dedicated to space sustainability) and a former orbital analyst with the Air Force. For example, spacecraft capable of orbital rendezvous operations could help a nation inspect, service and refuel its satellites, or deorbit defunct craft to help mitigate the growing space-junk problem.

Weeden thinks it's unlikely that Object 2014-28E is up to anything nefarious.

"The activities are much more in line with an inspection mission than with any sort of destruction mission," he told Space.com.

The secrecy surrounding the spacecraft helps fuel speculation about its mission, as does the fact that U.S.-Russian relations have deteriorated in the wake of Russia's military intervention in Ukraine this year, Weeden said.

"I think if this had happened in a different context, the speculation would be different," Weeden said. "But because it's occurring in the context of heightened tensions, there's more of a proclivity to assume the worst."

Russia likely regards Object 2014-28E's mission as a national-security activity in space, he added. The secrecy is thus unsurprising, as Russia tends to keep a tight lid on such missions as a matter of policy.

And Russian officials may be happy to keep quiet and let the mystery and speculation continue to build, Johnson-Freese said.

"I think that anything the Russians can do to provoke the United States right now, their government is supportive of," she said. "If this can cause concern in the United States, they're all for it."