Scientists Bounce Laser Beams Off Old Soviet Moon Rover

Scientists have successfully bounced a laser off the Soviet Union's old Lunokhod 1 rover, which trekked across the moon's landscape more than four decades ago.

Lunokhod 1 was the first remote-controlled rover ever to land on another celestial body. The wheeled vehicle was carried to the lunar surface by a spacecraft called Luna 17, touching down in the Sea of Rains on Nov. 17, 1970.

Among its instruments, the rover toted a French-built laser retroreflector consisting of 14 corner cubes that can reflect laser light beamed from Earth. [The Moon: A Space Dumping Ground (Infographic)]

Attempts to contact the rover after the lunar night that began on Sept. 14, 1971, were unsuccessful, apparently due to a component failure on the rover. Lunokhod 1's days of rambling around the moon formally ended on Oct. 4, 1971, after 11 lunar day-night cycles (322 Earth days).

Laser ranging observations

For the most part, those working in the laser ranging field have cautioned over the years not to spend time on Lunokhod 1, calling the rover a nearly impossible target.

"And during 30 years, nobody tried to range on Lunokhod 1," Jean-Marie Torre, research engineer at the Côte d'Azur Observatory in France, told SPACE.com.

But Torre and his colleagues tried anyway, using the Grasse (MéO) laser-ranging station in Calern, France, which is run by the Côte d’Azur Observatory. In March, they received return signals from the Lunokhod 1 reflector for the first time since the start of their lunar laser ranging observation campaigns in the early 1980s.

The results were obtained over three nights, using a new instrumental configuration at the MéO station.

The historical difficulty of ranging on Lunokhod 1 may have been due to a number of factors. The reflector may have been dusty, or its cover could have closed. Or the rover may not have been parked in view of Earth, Torre said.

In the end, however, "it was more a problem of lack of confidence than to a technical difficulty," Torre said.

Poor weather conditions prevented the scientists from getting a good determination of the Lunokhod 1 reflector's efficiency. Still, the results have buoyed the interest of Earth-based scientists to continue beaming their lasers at the long-dead rover.

A retroreflector array was also left on the moon by the landing crew of NASA's Apollo 11 mission in 1969, while two more retroreflector arrays were set up by Apollo 14 and Apollo 15 moonwalkers.

In fact, Torre and a colleague were ranging successfully the Apollo 15 site when Torre suggested trying Lunokhod 1. [NASA's Apollo Moon Missions in Pictures]

"Fortunately, we had immediate echoes ... and if not, we might not have tried again for one or many years!"

Pinpointing Lunokhod's locale

The final end-of-mission location of Lunokhod 1 was uncertain until 2010. But thanks to images snapped by NASA’s Lunar Reconnaissance Orbiter (LRO), both the Luna 17 lander and Lunokhod 1 were spotted.

Lunokhod 1 came to its final stop on a site situated around 1.4 miles (2.3 kilometers) north of its point of landing.

The success last month by the Grasse station was not the first laser ranging effort targeting the "lost" Lunokhod 1 reflector.

In April 2010, specialists at the Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) in southern New Mexico used the LRO images to first pinpoint the locale of Lunokhod 1, closely enough for laser range measurements.

Surprisingly, the APOLLO researchers reported that the craft’s retroreflector was returning much more light than other reflectors on the moon.

"In normal conditions, the difficulty to range this [Lunokhod 1] reflector is the making of the corner cube [which is] silver coated. They are very good in the dark, from a few days after the new moon to the quarter. It is better to range the reflector from March to May," when the on-the moon reflector is the highest in the sky, Torre said.

A better understanding of the moon

Lunar laser ranging has been made possible by combining advances in laser technology, data processing and precision timing via atomic clocks, according to the International Laser Ranging Service, a service of the International Association of Geodesy.

Lunar laser ranging uses short-pulse lasers and state-of-the-art optical receivers and timing electronics to measure how long it takes light beamed from ground stations to travel to retroreflector arrays on the moon and back again.

It takes just two and a half seconds for light to make this roundtrip trek, requiring use of an atomic clock.

Because the reflectors on the moon are relatively small and a laser beam naturally loses its intensity with distance, only a tiny fraction of the signal makes it back. However, the information is sufficient for precise calculation of the Earth and moon's movement: speed of rotation, axial variation and orbital deviation (taking into account, of course, the influence of other celestial bodies such as the sun).

Torre said that thanks to Lunokhod 1's position on the moon -- closer to the moon’s limb than any other reflectors — it allows researchers to detect more precisely small libration effects. Laser ranging on the rover can improve researchers' understanding of the moon's internal structure and rotation, he added.

Leonard David has been reporting on the space industry for more than five decades. He is former director of research for the National Commission on Space and is co-author of Buzz Aldrin’s new book “Mission to Mars — My Vision for Space Exploration” out in May from National Geographic. Follow us @Spacedotcom, Facebook or Google+. Originally published on SPACE.com.

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Rare Sight: Giant Black Hole Devours Star, Fires Beams at Earth (SPACE.com)

A powerful beam of energy has been spotted blasting out from the center of a massive black hole as it rips apart and devours a star in a rare sight that astronomers say likely happens only once every 100 million years, a new study finds.

When a NASA satellite first detected the intensely bright flash deep in the cosmos, astronomers initially thought it was a powerful burst of gamma rays from a collapsing star, one of the most powerful types of explosions in the universe. But, when the tremendous amount of energy could still be seen months later, they realized something more mysterious was going on.

"This is a really, really unusual event," study co-author Joshua Bloom,assistant professor of Astronomy at University of California, Berkeley, told SPACE.com. "It's now about two-and-a-half months old, and the fact that it just continues on and is only fading very slowly is the one really big piece of evidence that tells us this is not an ordinary gamma-ray burst." [Photos: Black Holes of the Universe]

NASA’s Swift Gamma Burst Mission spacecraft first detected the gamma-ray flash, called Sw 1644+57, within the constellation Draco, at the center of a galaxy nearly 4 billion light-years away.

Using Swift observations and others by the Hubble Space Telescope and the Chandra X-ray Observatory, Bloom and his colleagues concluded that the strange activity they were seeing was likely from a star being ripped apart by a massive black hole, rather than the effects of a gamma-ray burst, which typically can only be observed for about a day.

"This burst produced a tremendous amount of energy over a fairly long period of time," Bloom said. "That's because as the black hole rips the star apart, the mass swirls around like water going down a drain, and this swirling process releases a lot of energy."

These findings are published online in the June 16 issue of the journal Science.

Death of a star

Bloom's research showed that the highly energetic and long-lasting X-rays and gamma-rays were produced as a star about the size of our sun was violently shredded by a black hole a million times more massive.

But, what makes this a rare event is that this particular black hole has not been eating up matter around it like some other active black holes in the universe, Bloom said. In fact, the researchers sifted through historical records of that region of the cosmos and could not find evidence of previous long-lived X-ray or gamma-ray emissions.

"This event was not the act of gobbling lots of gas, but instead was a sort of impulsive thing," Bloom said. "This sort of thing could happen at the center of any galaxy, but the rate at which this happens is very low. It's sort of a one-off event that really shouldn't happen again." [Top 10 Strangest Things in Space]

Astronomers were even luckier to have been able to witness the event with such detail and clarity, since the jet of X-rays and high-energy gamma rays were punched out along a rotation axis that placed Earth in the eye of the beam.

“The best explanation that so far fits the size, intensity, time scale, and level of fluctuation of the observed event, is that a massive black hole at the very center of that galaxy has pulled in a star and ripped it apart by tidal disruption," said Andrew Levan of the University of Warwick in the U.K., lead author of a companion piece that was also published in Science. "The spinning black hole then created the two jets, one of which pointed straight to Earth.”

A lucky view

Essentially, astronomers here on Earth are looking down the barrel of the jet, witnessing an event which is likely to happen about once in 100 million years in any given galaxy, Bloom said.

"This is part of the special nature of the event," he said. "What we have is a geometrical rarity on top of an already rare event. I would be surprised if we saw another one of these anywhere in the sky in the next decade."

The astronomers suspect that the gamma-ray emissions began on March 24 or 25, at a distance of about 3.8 billion light-years away. And while they are still detecting activity from this event, Bloom and his colleagues estimate that the emissions will fade over the next year.

And while this may be an incredibly rare event, it does help astronomers further understand how black holes grow.

"I think this adds another piece of evidence that black holes grow organically by gobbling not just other black holes during mergers of galaxies, which is one of the ways people think black holes grow, but they also grow by eating up their surroundings in the form of gas and stars," Bloom said. "If this picture is right, black holes grow in many different ways. It addresses some unanswered question in astrophysics: these infants aren't just feeding on one baby product, namely merging with brethren, but they're gobbling up different types of foodstuffs."

You can follow SPACE.com Staff Writer Denise Chow on Twitter @denisechow. Follow SPACE.com for the latest in space science and exploration news on Twitter @Spacedotcom and on Facebook.

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