NASA LRO: Apollo Footprints on the Moon

NASA LRO Images Offer Sharper Views of Apollo Landing Sites

NASA's Lunar Reconnaissance Orbiter (LRO) captured the sharpest images ever taken from space of the Apollo 12, 14 and 17 landing sites.

Images show the twists and turns of the paths made when the astronauts explored the lunar surface.

At the Apollo 17 site, the tracks laid down by the lunar rover are clearly visible, along with the last foot trails left on the moon. The images also show where the astronauts placed some of the scientific instruments that provided the first insight into the moon's environment and interior.

"We can retrace the astronauts' steps with greater clarity to see where they took lunar samples," said Noah Petro, a lunar geologist at NASA's Goddard Space Flight Center in Greenbelt, Md., who is a member of the LRO project science team.

All three images show distinct trails left in the moon's thin soil when the astronauts exited the lunar modules and explored on foot. In the Apollo 17 image, the foot trails, including the last path made on the moon by humans, are easily distinguished from the dual tracks left by the lunar rover, which remains parked east of the lander.

"The new low-altitude Narrow Angle Camera images sharpen our view of the moon's surface," said Arizona State University researcher Mark Robinson, principal investigator for the Lunar Reconnaissance Orbiter Camera (LROC). "A great example is the sharpness of the rover tracks at the Apollo 17 site. In previous images the rover tracks were visible, but now they are sharp parallel lines on the surface."

http://www.nasa.gov/mission_pages/LRO/news/apollo-sites.html

Did the Earth Have Two Moons?

A paper just published in the journal Nature speculates that our home planet may have just one lonely moon now, but long ago, like Mars and Sylvia, we had two.

"Whether it's right or not, I don't know," says Maria Zuber, a planetary scientist at MIT who wrote an opinion piece accompanying the new study. "But I think it's very plausible."

The idea, cooked up by astronomers Martin Jutzi and Erik Asphaug, of the University of California at Santa Cruz, started out as an attempt to explain why our moon has so asymmetrical a surface.

The part that faces us is relatively smooth, with vast expanses of ancient lava forming flat, dark, low-lying plains that earlier astronomers mistook for oceans but when space probes first circled the moon in the early 1960s, scientists learned that the far side is mostly covered with rugged mountains and craters.

Nobody has ever been able to explain with certainty why the moon should be so lopsided: maybe it had to do with some kind of massive impact that violently rearranged the surface, much like what happened to the asteroid Vesta.

Maybe it was a slightly off-center core that caused the crust to be thinner on the Earth-facing half of the moon, which made that hemisphere more susceptible to lava bleeds.

But then Jutzi and Asphaug began thinking. "It looked to us a little bit as though the highlands on the far side accreted" — which is to say, they were added on top of the pre-existing surface.

The astronomers thought a bit more, and realized that this idea was consistent with scientists' beliefs about how the moon formed in the first place. Thanks to the analysis of moon rocks that were brought back by the Apollo missions, planetary scientists are pretty sure that our satellite was born billions of years ago when a Mars-size planetoid smashed into the young Earth.

The impact blasted off a cloud of debris from both of the objects and sent it spinning into space, where it eventually congealed into the moon. There could have been other, smaller pieces as well, says Zuber, but their orbits would have been unstable, causing them either to be flung away or to fall into Earth or the moon pretty much immediately.

Except, that is, if they happened to end up at a Trojan point — a place in the same orbit as the moon, but either well ahead of or well behind it, that's gravitationally stable — or relatively so anyway. Just last week, astronomers announced the discovery of a Trojan asteroid leading the planet Earth around the sun. There's no reason a Trojan moon couldn't lead or follow our moon around the Earth.

After a few tens of millions of years, Moon Jr. would become unstable, almost certainly falling into Moon Sr. But Jutzi and Asphaug's computer simulations of how that would play out showed that the short-lived satellite would have fallen surprisingly gently, at only a few miles per second, making more of a splat than a bang.

At a more typical impact speed, which would be at least 10 times faster, says Zuber, "you'd make a big hole and fling off ejecta" — in short form, a massive crater.

In this case, you'd form just a pile of extra stuff on one side, as though you slapped a handful of mud onto a basketball. And if the minimoon were about 750 miles (1,200 km) across, with about a third as much mass as its big brother, it could account for most of the extra material we now see on the far side.

The scenario could also explain why the near side is paved over with so much lava. At the time of impact, the moon would have cooled from its original molten state to form a thin crust, with an ocean of magma underneath.

All the extra mass added to the far side could have squeezed most of the subsurface magma around to the side that faces us, providing an ample supply of molten rock for later eruptions. "Every once in a while I read a paper I really enjoy," says Zuber.

"This is a genuinely new idea. That's what really struck me."

A new theory in science isn't worth much, however, unless you can test it somehow. The best way would be to look for the mineralogical signature of such an event in rocks brought back from the far side of the moon.

Unfortunately, no such mission is in the works anytime soon. But the Lunar Reconnaissance Orbiter, or LRO, which is circling the moon even now, has detectors that can get at least a sense of the minerals below.

And in September, another moon probe will be on its way, with Zuber as principal investigator. It's called GRAIL, for Gravity Recovery and Interior Laboratory.

Actually, it's a pair of probes that will orbit in tandem; changes in the distance between them will measure the local lunar gravity with extraordinary precision.

That will give Zuber and her team a detailed look at the moon's geological (or technically, selenological) structure and history, and when combined with LRO's data, could make or break Jutzi and Asphaug's idea.

NASA Lunar Reconnaissance Orbiter: Sunrise on the Moon

On June 10, 2011, NASA's Lunar Reconnaissance Orbiter angled its orbit 65° to the west, allowing the spacecraft's cameras to capture a dramatic sunrise view of the moon's Tycho crater.

A very popular target with amateur astronomers, Tycho is located at 43.37°S, 348.68°E, and is about 51 miles (82 km) in diameter.

The summit of the central peak is 1.24 miles (2 km) above the crater floor. The distance from Tycho's floor to its rim is about 2.92 miles (4.7 km).

Tycho crater's central peak complex, shown here, is about 9.3 miles (15 km) wide, left to right (southeast to northwest in this view).

Image Credit: NASA/Goddard Space Flight Center/Arizona State University

Apollo Moon Landing Sites Captured on LRO Camera

Images of five of the six Apollo landing sites were captured by NASA's Lunar Reconnaissance Orbiter (LRO) within weeks of reaching the moon. The team hopes to see its first images of the Apollo 12 landing site next month.

LRO is currently orbiting the moon on an elliptical path that takes it some 30 km over the moon's south pole and 200 km over the north pole, but later this year it will enter a circular orbit at an altitude of about 50 km. (Illustration: NASA Goddard Space Flight Center Scientific Visualization Studio)

The lunar module Eagle, which was used to carry Apollo 11 astronauts Neil Armstrong and Buzz Aldrin down to the lunar surface on 20 July 1969 is clearly seen in the image on the left. When LRO settles into its final orbit later this year, it will deliver images that are at least twice as sharp as this one.

The lunar module Falcon from the Apollo 15 mission is visible in the image on the right. Apollo 15 astronauts, who reached the moon on 30 July 1971, were the first to use a lunar rover to explore the surface. Click here to see their trek superimposed on a map of London. (Image: NASA/GSFC/ASU)

This image of Apollo 11 astronaut Buzz Aldrin in front of the lunar module Eagle provides a sense of scale to interpret the LRO images taken from orbit. The lunar module is about 4 metres wide. (Image: NASA/Neil Armstrong)

Good lighting conditions made the 1971 Apollo 14 site particularly easy to spot, says Mark Robinson, who heads up the Lunar Reconnaissance Orbiter Camera team at Arizona State University in Tempe.

Well-worn tracks can be seen in the soil to the left of the lunar module Antares (arrow).
Click here to see the Apollo 14 crew's trek superimposed on a map of London. (Image: NASA/GSFC/ASU)

A footpath connects the Apollo 14 landing site to an experiments package that the crew members set up. The experiments station, which transmitted data back to Earth for years after the mission, boasts a reflector that can be used for laser-ranging measurements of the Earth-moon distance (see Mirrors on the moon) and a range of experiments used to study the lunar environment and interior. (Image: NASA/GSFC/ASU)

Apollo 16's Orion lunar module (left) landed in the heavily-cratered lunar highlands on 21 April 1972.

Apollo 17's lunar module, Challenger (right), landed on the moon on 11 December 1972. Apollo 17 was the last mission to land on the moon and the first to boast a trained geologist – Harrison Schmitt. Schmitt and mission commander Eugene Cernan set records for the distance covered on the surface – 30 km – and the amount of samples collected – 110 kg – during their mission. (Image: NASA/GSFC/ASU)

40 Years After Apollo 11 Moon Landing: Neil Armstrong Talks about his thoughts

Neil Armstrong

Forty years ago men from Earth made history on the moon. On July 20, 1969, Apollo 11 astronauts Neil Armstrong and Buzz Aldrin became Earth's first human emissaries to set foot on the lunar surface while crewmate Michael Collins orbited high above.

In this retrospective for SPACE.com, the reclusive Neil Armstrong - the first human to walk on another world - recalls the heady year at the peak of the Space Race between the U.S. and Soviet Union that led to the first manned moon landing:

From a historic perspective, this is a particularly significant time in the annals of space exploration.

Sputnik, the first artificial earth satellite was launched just over a half century ago marking the beginning of the Space Age in 1957. Yuri Gagarin became the first human to orbit the Earth four years later.

Forty years ago, the Soviet Union and the United States were locked in an epic battle to be pre-eminent in space and the first to send humans to the moon.

In October of 1968, the Americans launched their first Apollo spacecraft with humans aboard. Later that same month, the Soviets launched Soyuz 3 which rendezvoused with Soyuz 2. In December, the second Apollo crew (Apollo 8) became the first humans escape the Earth's gravity and the first to circle the moon.

In January of 1969, Soyuz 4 launched and was followed by Soyuz 5 the following day. After docking, two crewmen from Soyuz 5 exited their craft and transferred outside to the other craft, Soyuz 4. They returned to Earth in Soyuz 4.

Two months later, Apollo 9 launched with two spacecraft, the normal Apollo Command Module and the new lunar landing craft, the Lunar Module. It was the first checkout flight of the ungainly machine in Earth orbit.

The lunar module flew again in May on Apollo 10, this time to the moon in a full dress rehearsal except for the descent and landing. Those two flights completed the flight test requisites mandatory prior to an attempt to achieve the Apollo goal.

On July 20, Apollo 11's crew piloted their Lunar Module to the first successful landing on the surface of the moon. In October, Soyuz 6, 7, and 8, with seven cosmonauts aboard, flew simultaneously and in November, Apollo 12 made the second of the six successful landings on the moon.

The flights of 40 years ago were among the most exciting in the history of spaceflight. We can expect a number of retrospective articles and television broadcasts to focus on this anniversary year. I look forward to remembering that memorable time.

-- Neil Armstrong

Space camp for Adults - 2009

You might think of little kids when you hear the phrase "space camp," but in fact the U.S. Space & Rocket Center in Alabama offers three-day and six-day programs for adult space enthusiasts.

After some SCUBA diving, move on to a shuttle mission and choose one of two tracks: pilot or mission specialist.

"You will rotate through the orbiter, space station and mission control on training missions which lead up to an extended duration mission," the Center promises. "You will also receive training in our high performance jet simulators and our 3G centrifuge.

Moon Missions Launched: Lunar Reconnaissance Orbiter and Crater Observation

NASA launched a pair of moon missions, the agency's first in more than 10 years, on Thursday. Intended to pave the way for the return of astronauts to the lunar surface, the Lunar Reconnaissance Orbiter will map the moon in 3D, focusing on 50 'high priority' locations that are thought to be prime landing sites.

A second mission called the Lunar CRater Observation and Sensing Satellite will orbit Earth for about 100 days before it guides the spent upper stage of the Atlas V launch vehicle into a collision with a crater on the moon's south pole.

The blast is expected to excavate more than 350 tonnes of material and could reveal whether the polar craters contain water ice, which could be used by future lunar colonists. (Image: United Launch Alliance/Pat Corkery)