Nasa Earthrise
Germaine Greenweig
LRO experiences twelve earthrises every day, however LROC is almost always busy imaging the lunar surface so only rarely does an opportunity arise such that LROC can capture a view of the Earth. On the first of February of this year LRO pitched forward while approaching the north pole allowing the LROC WAC to capture the Earth rising above Rozhdestvenskiy crater (180-km diameter).
The LROC Wide Angle Camera (WAC) is very different than most digital cameras. Typically resolution is reported as the number pixels in a single image, a cell phone camera today has more than 5 million pixels (5 megapixels). A single WAC frame has only 9856 pixels, however the WAC builds up a much larger image by exposing a series of images (or frames) as LRO progresses in its orbit; this type of imaging is called "push-frame". Over a full month as the LRO orbit track progresses around the Moon the WAC builds up a collection of images that covers the entire globe.
Occasionally LRO points off into space to acquire observations of the exosphere and perform instrument calibration measurements. During these slews sometimes the Earth (and other planets) pass through the WAC's field of view and dramatic images such as the one shown here are acquired. In the opening image the Moon is a greyscale composite of the first six frames of the WAC observation (while the spacecraft was still actively slewing), using visible bands 604 nm, 643 nm, and 689 nm. The Earth is a color composite of later frames, using the 415 nm, 566 nm, and 604 nm bands as blue, green, and red, respectively. These wavelengths were picked as they match well the response of the human eye, so the colors are very close to true, that is what the average person might see. Also, in this image the relative brightness between the Earth and the Moon is correct, note how much brighter the Earth is relative to the Moon.
"The image is simply stunning," said Noah Petro, Deputy Project Scientist for LRO at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "The image of the Earth evokes the famous 'Blue Marble' image taken by Astronaut Harrison Schmitt during Apollo 17, 43 years ago, which also showed Africa prominently in the picture."
In this composite image we see Earth appear to rise over the lunar horizon from the viewpoint of the spacecraft, with the center of the Earth just off the coast of Liberia (at 4.04 degrees North, 12.44 degrees West). The large tan area in the upper right is the Sahara Desert, and just beyond is Saudi Arabia. The Atlantic and Pacific coasts of South America are visible to the left. On the moon, we get a glimpse of the crater Compton, which is located just beyond the eastern limb of the moon, on the lunar farside.
LRO was launched on June 18, 2009, and has collected a treasure trove of data with its seven powerful instruments, making an invaluable contribution to our knowledge about the moon. LRO experiences 12 earthrises every day; however the spacecraft is almost always busy imaging the lunar surface so only rarely does an opportunity arise such that its camera instrument can capture a view of Earth. Occasionally LRO points off into space to acquire observations of the extremely thin lunar atmosphere and perform instrument calibration measurements. During these movements sometimes Earth (and other planets) pass through the camera's field of view and dramatic images such as the one shown here are acquired.
This image was composed from a series of images taken Oct. 12, when LRO was about 83 miles (134 kilometers) above the moon's farside crater Compton. Capturing an image of the Earth and moon with LRO's Lunar Reconnaissance Orbiter Camera (LROC) instrument is a complicated task. First the spacecraft must be rolled to the side (in this case 67 degrees), then the spacecraft slews with the direction of travel to maximize the width of the lunar horizon in LROC's Narrow Angle Camera image. All this takes place while LRO is traveling faster than 3,580 miles per hour (over 1,600 meters per second) relative to the lunar surface below the spacecraft!
The high-resolution Narrow Angle Camera (NAC) on LRO takes black-and-white images, while the lower resolution Wide Angle Camera (WAC) takes color images, so you might wonder how we got a high-resolution picture of the Earth in color. Since the spacecraft, Earth, and moon are all in motion, we had to do some special processing to create an image that represents the view of the Earth and moon at one particular time. The final Earth image contains both WAC and NAC information. WAC provides the color, and the NAC provides high-resolution detail.
"From the Earth, the daily moonrise and moonset are always inspiring moments," said Mark Robinson of Arizona State University in Tempe, principal investigator for LROC. "However, lunar astronauts will see something very different: viewed from the lunar surface, the Earth never rises or sets. Since the moon is tidally locked, Earth is always in the same spot above the horizon, varying only a small amount with the slight wobble of the moon. The Earth may not move across the 'sky', but the view is not static. Future astronauts will see the continents rotate in and out of view and the ever-changing pattern of clouds will always catch one's eye, at least on the nearside. The Earth is never visible from the farside; imagine a sky with no Earth or moon - what will farside explorers think with no Earth overhead?"
NASA's first Earthrise image was taken with the Lunar Orbiter 1 spacecraft in 1966. Perhaps NASA's most iconic Earthrise photo was taken by the crew of the Apollo 8 mission as the spacecraft entered lunar orbit on Christmas Eve Dec. 24, 1968. That evening, the astronauts -- Commander Frank Borman, Command Module Pilot Jim Lovell, and Lunar Module Pilot William Anders -- held a live broadcast from lunar orbit, in which they showed pictures of the Earth and moon as seen from their spacecraft. Said Lovell, "The vast loneliness is awe-inspiring and it makes you realize just what you have back there on Earth."
The cost to transport materials to the Moon from Earth is about $1 million per kilogram. Here, Earth is seen from the Moon in one of the iconic "earthrise" photos taken during the Apollo 8 mission. (Photo courtesy of NASA)
Cannon is leading an interdisciplinary team of Mines researchers that recently received $2 million in NASA funding to advance technology for the extraction of one of the more bountiful metals found in lunar soil, or regolith: aluminum.
With the funding from NASA, the Mines researchers will develop a tapping system that can siphon off the molten metals from the MRE reactor. That system will be integrated with an aluminum-refinement reactor and a wire-casting system to create high-purity aluminum wire that could be used as a feedstock for additive manufacturing on the surface of the Moon.
One of the key questions the researchers hope to answer is material compatibility. In order to function on the Moon, the reactor will need to be made of a material that can withstand the extreme temperatures required to melt the regolith, keep its strength and not get corroded by the lava.
NASA's Lunar Reconnaissance Orbiter captured the image on Feb. 1 with its wide-angle camera, depicting a colorized view of the Earth rising over the 112-mile-wide (180 kilometers) Rozhdestvenskiy crater. NASA released a colorized version of thThe event was one of 12 such "earthrises" that occur every day from the perspective of the moon.
The LRO spacecraft's wide-angle camera takes images in a different way than most digital cameras. A typical cellphone camera has more than 5 million pixels, whereas a single frame of the LRO camera has fewer than 10,000 pixels. [Amazing Photos of Earth from Space]
But the LRO camera builds up a much larger image by taking multiple exposures as the spacecraft orbits, a technique known as "push-frame" imaging. Over the course of a month, the orbiter camera collects enough images to cover the whole moon.
The LRO usually spends its time staring at the lunar surface looking for signs of water or ice in permanently shadowed craters. But occasionally the spacecraft points into space to image the moon's exosphere, the thin atmosphere-like layer surrounding it, or to calibrate the craft's instruments. Sometimes, the spacecraft captures images of Earth (like this one) or other planets making their progress across the heavens.
In the image, Earth is a color composite of several frames, optimized for the colors blue, green and red. These colors match what the human eye detects, so they are true to what an average person might see.
Monitor journalism changes lives because we open that too-small box that most people think they live in. We believe news can and should expand a sense of identity and possibility beyond narrow conventional expectations.
c80f0f1006