Moonwalking

Harrison “Jack” Schmitt was the last person to step down onto the Moon. He was also the only professional geologist to work on the lunar surface, which he did during the Apollo 17 expedition to the Taurus-Littrow Valley.

The Moon’s geology still fascinates Dr. Schmitt. Just last week, in fact, he spoke about his lunar fieldwork to scientists gathered at the 45th Lunar and Planetary Science Conference being held this week in Texas. He told his audience that the samples and field notes from the Apollo 17 mission are still useful today, but that’s not all–there’s another, newer tool available to Moon explorers: the Lunar Reconnaissance Orbiter. High-resolution images from the robotic spacecraft provide fresh perspectives from on high, such as revealing boulder tracks at the Apollo landing sites that astronauts didn’t see from the ground.

Schmitt left the Moon in 1972. No one has been back since. But thanks to the Lunar Reconnaissance Orbiter, you don’t have to be an astronaut to see lunar landscapes up close. LRO returns images with such great detail that objects as small as individual boulders, or even human-made objects like the lunar landers, are easy to spot.

My favorite LRO shots are taken at a highly oblique angle rather than looking straight down. Views like that, especially when the sun is low on the horizon, almost look like what you might see if you were standing there in person.

At the bottom of this page I’ve gathered a few of these postcards from the Moon. Each offers a nice perspective on the landscape, but to really feel like you’re getting your boots dirty at the locations they show, you’ll want to click on the small pictures in order to zoom in on the details that are only visible in the much larger versions.

For example, here’s a detail from the Hausen Crater image:

Hausen Crater Central Peaks, Detail
Hausen Crater Central Peaks, Detail – Who’s up for a hike? The central peaks in the Moon’s Hausen Crater, a detail from the much larger image below. Credit: NASA / GSFC / ASU

And here’s another example, this one from Giordano Bruno Crater:

Giordano Bruno Crater, Detail

Giordano Bruno Crater, Detail – Beware of sliding boulders! A detail from a larger image of the Moon’s Giordano Bruno Crater, as imaged by LRO. Credit: NASA / GSFC / ASU

Here are some more lunar locations. Clicking on each will lead to a page where you can enlarge the image and explore the full desolation in all its magnificence. All of these images were captured in the past couple of years, and most have not been widely published elsewhere. Happy moonwalking!

Anaxagoras Crater
Anaxagoras Crater – An oblique view into the Moon’s Anaxagoras Crater, as seen by the Lunar Reconnaissance Orbiter with the Sun low on the horizon. Anaxagoras has a diameter of about 51 km. NASA / GSFC / ASU
Giordano Bruno Crater
Giordano Bruno Crater – A view of Giordano Bruno, a 22-km-wide impact crater on the far side of the Moon. When viewed large, the high resolution and oblique angle of this Lunar Reconnaissance Orbiter image almost make it seem like you’re standing right on the edge of the crater. Credit: NASA / GSFC / ASU
Antoniadi Crater Central Peak
Antoniadi Crater Central Peak – The unusually smooth floor of Antoniadi Crater includes the lowest point on the Moon. The Lunar Reconnaissance Orbiter captured this oblique view of the peak at the center of the crater, which is 143 km wide. NASA / GSFC / ASU
Posidonius Crater
Posidonius Crater, with its rille system named Rimae Posidonius. This oblique view of the 95-km-wide crater comes from the Lunar Reconnaissance Orbiter. NASA / GSFC / ASU
Hausen Crater Central Peaks
Hausen Crater Central Peaks – Hills at the center of Hausen Crater, as seen by the Lunar Reconnaissance Orbiter. The crater is nearly four kilometers deep. At high resolution, the angle and details visible in this image–right down to individual boulders–offer a moonwalker’s perspective. NASA / GSFC / ASU

This article originally appeared as a guest post on The Planetary Society site.

 

Somewhere Over the Bay of Rainbows

This entry originally appeared as a guest post on The Planetary Society site.

China’s first lunar lander, which also happens to be humankind’s first in nearly four decades, is on its way to the Moon. The Chang’e 3 spacecraft departed Earth on December 2 local China time, carrying the Yutu (Jade Rabbit) rover.

Chang’e 3 is headed for a mid-December landing on a broad plain called Sinus Iridum, “The Bay of Rainbows.” Sinus Iridum is found at the northwest edge of Mare Imbrium, or “Sea of Rains.” It’s an impact basin a couple of hundred kilometers wide that was filled in by floods of basaltic lava. At its “shores” is a semi-circular ring of dramatic mountains called Montes Jura, with the Heraclides Promontory at its western tip and the Laplace Promontory at the eastern tip.

Sinus Iridum
Sinus Iridum – A terrain model of the Moon’s Sinus Iridum, the Bay of Rainbows, a 236-km wide impact basin filled with basaltic lava. Credit: NASA / ASU / Bill Dunford

This area is over 1,000 kilometers from the nearest Apollo landing site, and it could provide lunar explorers with a rich set of information about the Moon and its history.

Thanks to NASA’s Lunar Reconnaissance Orbiter, we can make an advance visit of our own. Following are a few extreme close-ups of the Bay of Rainbows, courtesy of LRO’s sharp-eyed cameras, which can make out objects as small as the equipment left of the surface by the Apollo astronauts, and even their foot trails.

One of the first things that becomes apparent when looking through LRO’s Sinus Iridum data is that this plain, which looks so smooth from a distance, is a little more…complicated than you might think. I purposely chose the most featureless section of the bay that I could see, and found that images from this area typically look like the following.

Rough Features of a Smooth Plain
Rough Features of a Smooth Plain – Sinus Iridum, “The Bay of Rainbows,” is one of the smoothest areas of the Moon, and parts of it appear almost featureless from a distance. But when the Lunar Reconnaissance Orbiter trains its high-resolution camera on even the flattest sections of the plain, it reveals a complex surface of craters, ejecta, and boulders. Credit: NASA / GSFC / ASU

There will be no shortage of rocks and craters for Yutu to explore.

Here’s one interesting crater among many, an apparently (relatively) young example with bright ejecta and what looks like rings of melted rock.

Bright Unnamed Crater in Sinus Iridum
Bright Unnamed Crater in Sinus Iridum – A relatively recent impact has exposed light material from beneath the surface of Sinus Iridum on the Moon, as seen in detail by the Lunar Reconnaissance Orbiter. Credit: NASA / GSFC / ASU

If the Jade Rabbit wandered far enough to reach the edge of the bay, it would be able to explore Promontorium Laplace, a cape marked by mountains that rise as much as 2600 meters above the lava plains. It was named for Pierre Simon marquis de Laplace, who was a French astronomer in the 18th century.

Here’s a close look at the exact point where the plains meet the Laplace headlands and its intriguing geology.

Edge of the Bay
Edge of the Bay – The eastern edge of the Moon’s Sinus Iridum plain where it meets the mountains of Promontorium Laplace. The promontory reaches about 2600 meters above the plains at its highest point. The boulders at the foot of the wall in this image are a few tens of meters across. Imaged by the Lunar Reconnaissance Orbiter. Credit: NASA / GSFC / ASU

Imagine the view from on top of the hill!

If the Chang’e 3 landing goes well, we won’t have to imagine the view from the plains, as we follow along with Yutu’s adventures on the surface of the Moon.

The Strangest Place on the Moon?

This entry originally appeared as a guest post on The Planetary Society site.

It’s always rewarding to wander the surface of the Moon using the archive of images captured by the Lunar Reconnaissance Orbiter. It’s full of pictures that show off the Moon’s stark beauty, pictures so sharp you can see right down to individual boulders on the surface. Exploring the craters, ridges, and rilles seen in the archive usually elicits a “Nice” or sometimes even a “Wow!”

It’s more unusual to find a “What the hell is that?”

But that’s what I said when I stumbled across this recent view of Lacus Felicitatis (the “Lake of Happiness”). There’s a D-shaped depression about two kilometers wide and 30 meters deep. It’s filled with domes of smooth, dark material rising above rough, mostly crater-less light material. Its features look unusually sharp (and therefore probably relatively young).

Ina crater on the moon
Oblique Ina – The Lunar Reconnaissance Orbiter captured this new perspective on an unusual feature: the D-shaped “Ina” with its domes and fresh terrain. Ina is about 2 kilometers wide. North is to the right. NASA/GSFC/ASU

I discovered I wasn’t the first one to notice this place. Apollo astronauts took note and photographed it from orbit. The feature came to be known as Ina.

Then in the 1990s pictures from the Clementine spacecraft showed that Ina’s colors resembled those of very young impact craters, although Ina is definitely not that kind of crater.

More recently, scientists looked at the best available pictures of Ina, and noted a relative lack of impact craters in the low-lying, light materials. They decided it must be very young. They concluded that Ina is a volcanic feature, the caldera of a low shield volcano, and speculated that perhaps it’s a site where—even today—gasses from deep underground might be escaping. Such outgassing events could even be the source of the mysterious flashes of light that amateur astronomers report seeing on the lunar surface from time to time.

Then the Lunar Reconnaissance Orbiter sent down even sharper pictures, up to ten times sharper, like this one. As happens so often in science, the new information raised more questions than it answered.

Ina crater on the moon
Closeup on Ina – A tight view of the unusual Ina formation from the powerful Lunar Reconnaissance Orbiter Camera. It can be hard to see which parts of the terrain rise and which fall. It may help to point out that the darker areas in this image are generally higher than the light areas, the lower part of the picture is closer to the camera than the top part, and the light is coming from the lower left. Credit: NASA/GSFC/ASU

Lunar explorers saw that while the lighter material is indeed probably younger that the blobs of darker material, it’s not without craters of its own, and may not be all that much younger than the surrounding plains. Rather than places where the ground collapsed, as in an earthly caldera, the lighter areas may be thick lava that flowed between the dark mounds.

We know the Moon better than any other place outside Earth. The strange topography of Ina, however, serves as a reminder that the Moon still guards some of its most interesting secrets.

The Pit

This post originally appeared as a guest blog entry on The Planetary Society web site.

One of the world’s largest open-pit mines delves into Utah’s Oquirrh Mountains. The Bingham Canyon Mine is four kilometers wide and reaches nearly a kilometer deep. You could stack two of Chicago’s Sears Tower (now called Willis Tower) one atop another inside the yawning pit. It’s just huge, and if stand at the rim and look down, the view is breathtaking.

Bingham Canyon Mine
Bingham Canyon Mine – One of the world’s largest open-pit mines, found in Utah’s Oquirrh Mountains. It reaches nearly a kilometer deep. Credit: Bill Dunford

Over the course of decades, the stair-step excavation in the copper mine exposed a colorful variety of geology inside the mountain. Imagine the boon to lunar explorers if a similar pit could be dug into the moon’s Aristarchus Plateau. That geologically diverse region of ancient lava floods and volcanic explosions is one of the Moon’s most tantalizing regions for exploration, and was once a potential target for an Apollo landing.

About 175 million years ago, an asteroid or comet did just that, slamming into the edge of the plateau and blasting out a huge pit in a single cataclysmic event. Where the Bingham Canyon Mine is four kilometers wide, Aristarchus Crater is 40. The Earthly copper mine is just shy of a kilometer deep, while the floor of Aristarchus lies about 3.5 kilometers below the rim.

The crater’s walls are marked by a distinctive stair-step shape reminiscent of the mine’s terraces. They formed when blocks of material slumped down into the crater. (By the way, the Bingham mine experienced its own massive landslide in 2013.)

Aristarchus Crater Context

Aristarchus Crater Context – A mosaic of Lunar Reconnaissance Orbiter images showing the moon’s Aristarchus Crater. Credit: NASA/GSFC/ASU

To get a better look, in 2011 engineers commanded the Lunar Reconnaissance Orbiter to lower its flight path to just 26 km above the surface, cutting its normal altitude roughly in half. The robotic spacecraft was now flying above the Moon’s surface at only about twice the height of an airliner cruising over the countryside. From this vantage point, the powerful cameras on board LRO captured an amazingly detailed glimpse inside Aristarchus Crater. Here’s one section of that mosaic, with a resolution high enough to make out individual boulders.

Aristarchus Crater Wall – An oblique, high-resolution view of the terraced wall of the Moon’s Aristarchus Crater, from rim to floor. Imaged by the Lunar Reconnaissance Orbiter. Credit: NASA/GSFC/ASU

The Apollo program never made it here, but thanks to the LRO team we get to stand on the rim of Aristarchus Crater anyway, and marvel.