ASU Archives

March 3, 2022March 3, 2022 by Matt Williams

How to Search for Life as we Don’t Know it

Artist's concept of Earth-like exoplanets, which (according to new research) need to strike the careful balance between water and landmass. Credit: NASA

The fields of extrasolar planet studies and astrobiology have come a long way in recent years. To date, astronomers have confirmed the existence of 4,935 exoplanets in 3,706 star systems, with another 8,709 candidates awaiting confirmation. With so many planets to study, next-generation instruments, and improved data analysis, the focus is transitioning from discovery to characterization. With the James Webb Space Telescope now deployed, these fields are about to advance much farther!

In particular, scientists anticipate that the characterization of planetary atmospheres may lead to the discovery of “biosignatures” – signs we associate with life and biological processes. The challenge will be how to recognize signatures that don’t conform to “life as we know it.” In a recent study, researchers from the School of Earth and Space Exploration (SESE) at Arizona State University (ASU) investigate possible tools for searching for life “as we don’t know it.”

December 30, 2013December 23, 2015 by Jason Major

China’s Lunar Lander Spotted by Orbiting Spacecraft

Image of Chang'e-3 (top arrow) and Yutu rover captured by NASA's Lunar Reconnaissance Orbiter on Dec. 25 UTC

Not much on the Moon escapes the eyes of NASA’s Lunar Reconnaissance Orbiter, and China’s Chang’e-3 lander and Yutu rover are no exception! The pair touched down on the lunar surface on Dec. 14, and just over a week later on Dec. 25 LRO acquired the image above, showing the lander and the 120-kg (265-lb) “Jade Rabbit” rover at their location near the Moon’s Sinus Iridum region.

The width of the narrow-angle camera image is 576 meters; north is up. LRO was about 150 km (93 miles) from the Chang’e-3 site when the image was acquired.

So how can we be so sure that those bright little specks are actually human-made robots and not just a couple of basaltic boulders? Find out below:

According to School of Earth and Space Exploration professor Mark Robinson’s description on Arizona State University’s LROC blog:

The rover is only about 150 cm wide, yet it shows up in the NAC images for two reasons: the solar panels are very effective at reflecting light so the rover shows up as two bright pixels, and the Sun is setting thus the rover casts a distinct shadow (as does the lander). Since the rover is close to the size of a pixel, how can we be sure we are seeing the rover and not a comparably sized boulder? Fortuitously, the NAC acquired a “before” image of the landing site, with nearly identical lighting, on 30 June 2013. By comparing the before and after landing site images, the LROC team confirmed the position of the lander and rover, and derived accurate map coordinates for the lander (44.1214°N, 340.4884°E, -2640 meters elevation).

Before-and-after LROC images of Chang'e-3's landing site — Before-and-after LROC images of Chang’e-3’s landing site: June 30 vs. Dec. 25, 2013

LRO circles the Moon in a polar orbit at an average altitude of 50 km (31 miles). The LROC instrument contains two narrow-angle camera heads (NACs) providing 0.5-meter/pixel panchromatic images over a 5-km swath, a wide-angle camera head (WAC) providing images at a scale of 100 meters in seven-color bands.

Both the Chang’e-3 lander and Yutu rover are reported to be in good health and performing well. The solar-powered rover went into sleep mode on Dec. 26 to wait out the 14-day lunar night, during which time the temperatures on the lunar surface can drop to -180ºC (-292ºF). Yutu’s radioisotope heat source will keep it from freezing, but it won’t be able to generate power from its solar arrays. (Source)

Read more on ASU’s LROC website, and check out Ken Kremer’s article featuring a video of Yutu’s rollout here.

Image credits: NASA/GSFC/Arizona State University

October 16, 2013December 23, 2015 by Jason Major

This is the Moon, the Whole Moon and Nothing But the Moon

Take a look around the Moon… no, really, take a good look AROUND the Moon! This is a fantastic animation of our planetary partner in space made by the folks on the Lunar Reconnaissance Orbiter team at Arizona State University. Assembled from reflectance maps and digital terrain models created from data gathered by LRO’s wide-angle camera, this full 360-degree portrait of the Moon shows its surface as if it were receiving direct top-down sunlight on all points — a physical impossibility, yes, but it gives us a great view of pretty much everything (including the far side, which for obvious reasons most of us never get a good look at.)

In addition to shining a light on the lunar landscape (pun intended) the vast amounts of data used to create the view above can also be used to calculate the type of illumination that would be found on any point on the Moon, at any time, allowing for better targeted observation planning with LRO’s narrow-angle camera.

Read more about how this process was engineered here, and see a more recent result of these new capabilities below:

While the image above wouldn’t have been visible from anywhere on North America on October 15, 2013 at 2 p.m. EDT, it’s what would have been seen in the night sky above Mumbai — but no international calls to India were needed, as the view could simply be generated from the LRO WAC data and a ray-tracing algorithm that plots the angles of light and shadow across the lunar terrain. Voilà — it’s Insta-Moon*!

*Some assembly required.

Read more on the Arizona State University LROC site here (and to really blow your mind, watch the high-resolution version here.)

Want to explore the Moon on your Android or iPhone? Check out our Phases of the Moon app!

June 1, 2012December 23, 2015 by Jason Major

Astronomers Take “Baby Picture” of an Incredibly Distant Galaxy

False-color image of galaxy LAEJ095950.99+021219.1 (Credit: James Rhoads/ASU)

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Astronomers from Arizona State University have grabbed an image of a dim, distant galaxy, seeing it as it looked only 800 million years after the birth of the Universe. Visible above as a green blob in the center of a false-color image acquired with the Magellan Telescopes at the Las Campanas Observatory in Chile, the galaxy is seen in its infancy and, at 13 billion light-years away, is one of the ten most distant objects ever discovered.

The galaxy, designated LAEJ095950.99+021219.1, was detected by light emitted by ionized hydrogen using the Magellan Telescopes’ IMACS (Inamori-Magellan Areal Camera & Spectrograph) instrument, built at the Carnegie Institute in Washington. In order to even find such a remote object — whose existence had already been suspected — the team had to use a special narrow-band filter on the IMACS instrument designed to isolate specific wavelengths of light.

“Young galaxies must be observed at infrared wavelengths and this is not easy to do using ground-based telescopes, since the Earth’s atmosphere itself glows and large detectors are hard to make,” said team leader Sangeeta Malhotra, an associate professor at ASU who helped develop the technique.

“As time goes by, these small blobs which are forming stars, they’ll dance around each other, merge with each other and form bigger and bigger galaxies. Somewhere halfway through the age of the universe they start looking like the galaxies we see today – and not before.”

– Sangeeta Malhotra, ASU professor

LAEJ095950.99+021219.1 is seen at a redshift of 7, putting it farther away than any other objects previously discovered using the narrow-band technique.

(What is redshift? Watch “How To Measure The Universe” here.)

“We have used this search to find hundreds of objects at somewhat smaller distances. We have found several hundred galaxies at redshift 4.5, several at redshift 6.5, and now at redshift 7 we have found one,” said James Rhoads, associate professor at ASU and research team leader.

“This image is like a baby picture of this galaxy, taken when the universe was only 5 percent of its current age. Studying these very early galaxies is important because it helps us understand how galaxies form and grow.”

So why does LAEJ095950.99+021219.1 not look much like the galaxies we’re used to seeing in images?

Malhotra explains: “Somewhere halfway through the age of the universe they start looking like the galaxies we see today – and not before. Why, how, when, where that happens is a fairly active area of research.”

The team’s NSF-funded research was published in Astrophysical Journal Letters. Read more on Phys.Org News here.

February 20, 2012December 24, 2015 by Ray Sanders

Recent Geologic Activity on the Moon?

Newly detected series of narrow linear troughs are known as graben, and they formed in highland materials on the lunar farside. These graben are located on a topographic rise with several hundred meters of relief revealed in topography derived from Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) stereo images (blues are lower elevations and reds are higher elevations). Image Credit: NASA/GSFC/Arizona State University/Smithsonian Institution

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Recent images from NASA’s Lunar Reconnaissance Orbiter Camera provide evidence that the lunar crust may be pulling apart in certain areas. The images reveal small trenches less than a kilometer in length, and less than a few hundred meters wide. Only a small number of these features, known as graben, have been discovered on the lunar surface.

There are several clues in the high-resolution images that provide evidence for recent geologic activity on the Moon.

The LROC team detected signs of contraction on the lunar surface as early as August of 2010. The contractions were in the form of lobe-shaped ridges known as lobate scarps. Based on the data, the team suggests the widely-distributed scarps indicate the Moon shrank in diameter, and may be continuing to shrink. Interestingly enough, the new image data featuring graben presents a contradiction, as they indicate lunar crust being pulled apart and theorize that the process that created the graben may have occurred within the past 50 million years.

“We think the Moon is in a general state of global contraction due to cooling of a still hot interior, said thomas Watters from the Center for Earth and Planetary Studies. “The graben tell us that forces acting to shrink the Moon were overcome in places by forces acting to pull it apart. This means the contractional forces shrinking the Moon cannot be large, or the small graben might never form.”

Based on the size of the graben, the forces responsible for contraction of the lunar surface are assumed to be fairly weak. It is further theorized that, unlike the early terrestrial planets, the Moon was not completely molten during its early history.

“It was a big surprise when I spotted graben in the farside highlands,” said Mark Robinson, LROC Principal Investigator at Arizona State University. “I immediately targeted the area for high resolution stereo images so we could create a 3-dimensional view of the graben. It’s exciting when you discover something totally unexpected. Only about half the lunar surface has been imaged in high resolution. There is much more of the Moon to be explored.”

If you’d like to learn more about the recently discovered graben on the moon, you can watch a short video by Thomas Watters below:

To learn more about the Lunar Reconnaissance Orbiter Camera, visit: http://www.lroc.asu.edu/

Source: Arizona State University News

April 15, 2011December 24, 2015 by Jason Major

Look Inside a Lunar Crater

Brightening the shadowed area reveals details of the crater floor...and even more boulders!

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The crater shown above is located in the lunar highlands and is filled with and surrounded by boulders of all sizes and shapes. It is approximately 550 meters (1800 feet) wide yet is still considered a small crater, and could have been caused by either a direct impact by a meteorite or by an ejected bit of material from another impact. Scientists studying the Moon attempt to figure out how small craters like this were formed by their shapes and the material seen around them…although sometimes the same results can be achieved by different events.

For example, when an object from space strikes the Moon, it is typically traveling around 20 km per second (12 miles/sec). If the impact site happens to have a very hard subsurface, it can make a crater with scattered bouldery chunks composed of the hard material around it. But, if a large piece of ejected material from another impact were to strike the lunar surface at a much slower speed, as ejecta typically do (since they travel slower than incoming space debris and the Moon’s escape velocity is fairly low, meaning any ejecta that does fall back to the surface must be traveling slower than 2.38 km/s,) then the ejected chunk could break apart on impact and scatter boulders of itself around the crater…regardless of subsurface composition.

Really the only way to tell for sure which scenario has taken place around a given crater – such as the one above – is to collect and return samples from the site so they can be tested. (Of course that’s much easier said than done!)

You can read more about this image on Arizona State University’s Lunar Reconnaissance Orbiter Camera site here.

And as an added treat, take a look deep into the shadows of the crater’s interior below…I tweaked the image curves in Photoshop to wrestle some of the details out of there!

Image credit: NASA/GSFC/Arizona State University. (Edited by J. Major.)

P.S.: Want to see both image versions combined? Click here. (Thanks to Mike C. for the suggestion!)