On May 20th, 2018, the China National Space Agency (CNSA) launched the Queqiao spacecraft, the vehicle that would deliver the Chang’e-4mission to the Moon. This vehicle was also responsible for transporting a lesser-known mission to the Moon, known as the Longjiang twin spacecraft. This package consisted of two satellites designed to fly in formation and validate technologies for low-frequency radio astronomy.
While Queqiao flew beyond the Moon to act as a communications relay for the Chang’e-4 lander, the Longjiang satellites were to enter orbit around the moon. On July 31st, 2019, after more than a year in operation, the Longjiang-2 satellite deorbited crashed on the lunar surface. And thanks to efforts spacecraft tracker Daniel Estévez and his colleagues, the Lunar Reconnaissance Orbiter (LRO) was able to photograph the impact site.
On October 13th, 2014, the Lunar Reconnaissance Orbiter (LRO) experienced something rare and unexpected. While monitoring the surface of the Moon, the LRO’s main instrument – the Lunar Reconnaissance Orbiter Camera (LROC) – produced an image that was rather unusual. Whereas most of the images it has produced were detailed and exact, this one was subject to all kinds of distortion.
From the way this image was disturbed, the LRO science team theorized that the camera must have experienced a sudden and violent movement. In short, they concluded that it had been struck by a tiny meteoroid, which proved to a significant find in itself. Luckily, the LRO and its camera appear to have survived the impact unharmed and will continue to survey the surface of the Moon for years to come.
The LROC is a system of three cameras that are mounted aboard the LRO spacecraft. This include two Narrow Angle Cameras (NACs) – which capture high-resolution black and white images – and a third Wide Angle Camera (WAC), which captures moderate resolution images that provide information about the properties and color of the lunar surface.
The NACs works by building an image one line at a time, with thousands of lines being used to compile a full image. In between the capture process, the spacecraft moves the camera relative to the surface. On October 13th, 2014, at precisely 21:18:48 UTC, the camera added a line that was visibly distorted. This sent the LRO team on a mission to investigate what could have caused it.
Led by Mark Robinson – a professor and the principal investigator of the LROC at Arizona State University’s School of Earth and Space Exploration – the LROC researchers concluded that the left Narrow Angle Camera must have experienced a brief and violent movement. As there were no spacecraft events – like a solar panel movement or antenna tracking – that might have caused this, the only possibility appeared to be a collision.
“There were no spacecraft events (such as slews, solar panel movements, antenna tracking, etc.) that might have caused spacecraft jitter during this period, and even if there had been, the resulting jitter should have affected both cameras identically… Clearly there was a brief violent movement of the left NAC. The only logical explanation is that the NAC was hit by a meteoroid! How big was the meteoroid, and where did it hit?”
To test this, the team used a detailed computer model that was developed specifically for the LROC to ensure that the NAC would not fail during the launch of the spacecraft, when severe vibrations would occur. With this model, the LROC team ran simulations to see if they could reproduce the distortions that would have caused the image. Not only did they conclude it was the result of a collision, but they were also able to determine the size of the meteoroid that hit it.
The results indicated that the impacting meteoroid would have measured about 0.8 mm in diameter and had a density of a regular chondrite meteorite (2.7 g/cm³). What’s more, they were able to estimate that it was traveling at a velocity of about 7 km/s (4.3 miles per second) when it collided with the NAC. This was rather surprising, given the odds of collisions and how much time the LRO spends gathering data.
Typically, the LROC only captures images during daylight hours, and for about 10% of the day. So for it to have been hit while it was also capturing images is statistically unlikely – only about 5% by Robinson’s own estimate. Luckily, the impact has not caused any technical problems for the LROC, which is also something of a minor miracle. As Robinson explained:
“For comparison, the muzzle velocity of a bullet fired from a rifle is typically 0.5 to 1.0 kilometers per second. The meteoroid was traveling much faster than a speeding bullet. In this case, LROC did not dodge a speeding bullet, but rather survived a speeding bullet! LROC was struck and survived to keep exploring the Moon, thanks to Malin Space Science Systems’ robust camera design.”
It was only after the team deduced that no damage had been caused that prompted the announcement. According to John Keller, the LRO project scientist from NASA’s Goddard Space Flight Center, the real story here was how the imagery that was being acquired at the time was used to deduce how and when the LRO had been struck by a meteoroid.
“Since the impact presented no technical problems for the health and safety of the instrument,” he said, “the team is only now announcing this event as a fascinating example of how engineering data can be used, in ways not previously anticipated, to understand what is happening to the spacecraft over 236,000 miles (380,000 kilometers) from the Earth.”
In addition, the impact of a meteoroid on the LRO demonstrates just how precious the information that missions like the LRO provides truly is. Beyond mapping the lunar surface, the orbiter was also able to let its science team know exactly and when its images were comprised, all because of the high-quality data it collects.
Since it launched in June of 2008, the LRO has collected an immense amount of data on the lunar surface. The mission has been extended several times, from its original duration of two years to the just under nine. Its ongoing performance is also a testament to the durability of the craft and its components.
Be sure to enjoy this video of the images obtained by the LRO, courtesy of the LROC team:
That’s Earth. That’s us. Way off in the distance as a fairly small, blue and swirly white sphere. This is the newest so-called “Earthrise” image, and it was taken on February 1, 2014 by the Lunar Reconnaissance Orbiter.
“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,” wrote LROC Principal Investigator Mark Robinson on the instrument’s website. “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).”
Robinson went on to explain that the Earth is a color composite from several frames and the colors are very close to what the average person would see if they were looking back at Earth themselves from lunar orbit. “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,” Robinson said.
Below is a gif image that demonstrates how images are combined over several orbits to create a full image from the Wide Angle Camera.
The frames were acquired at two second intervals, so the total time to collect the sequence was 5 minutes. The video is faster than reality by a factor of about 20.
OMG – breathtaking! That was my reaction when I clicked on this incredible new interactive map of the moon’s north polar region. Be prepared to be amazed. It took four years and 10,581 images for the LROC (Lunar Reconnaissance Orbiter Camera) team to assemble what’s believed to be the largest publicly available image mosaic in existence. With over 650 gigapixels of data at a resolution of 2 meters per pixel, you’ll feel like you’re dropping in by parachute to the lunar surface.
When you call up the map, be sure to click first on the full-screen button below the zoom slider. Now you’re ready for the full experience. With mouse in hand, you’re free to zoom and pan as you please. Take in the view of Whipple Crater shadowed in polar darkeness or zoom to the bottom of Karpinskiy Crater and fly like a bird over its fractured floor.
The images are so detailed and the zoom so smooth, there’s nothing artificial about the ride. Except the fact you’re not actually orbit. Darn close though. All the pictures were taken over the past few years by NASA’s Lunar Reconnaissance Orbiter which can fly as low as 50 km (31 miles) over the lunar surface and resolve details the size of a desk.
There are 10 snapshots along the bottom of the map – click them and you’ll be swiftly carried directly to that feature. One of them is the lunar gravity probe GRAIL-B impact site.
To create the 2-D map, a polar stereographic projection was used in to limit mapping distortions. In addition, the LROC team used information from the LOLA and GRAIL teams and an improved camera pointing model to accurately project each image in the mosaic to within 20 meters. For more information on the project, click HERE.
Yutu rover drives around Chang’e-3 lander – from Above And Below
Composite view shows China’s Yutu rover and tracks driving in clockwise direction around Chang’e-3 lander from Above And Below (orbit and surface). The Chang’e-3 timelapse lander color panorama (bottom) and orbital view (top) from NASA’s LRO orbiter shows Yutu rover after it drove down the ramp to the moon’s surface and began driving around the landers right side, passing by craters and heading south on Lunar Day 1. It then moved northwest during Lunar Day 2. Arrows show Yutu’s positions over time.
Credit: CNSA/NASA/Ken Kremer/Marco Di Lorenzo/Mark Robinson
See below more mosaics and LRO imagery
The powerful telescopic camera aboard NASA’s Lunar Reconnaissance Orbiter (LRO) has captured spectacular new images detailing the traverse of China’s Yutu moon rover around the landing site during its first two months exploring the Moon’s pockmarked grey terrain.
The newly released high resolution LRO images even show Yutu’s tracks cutting into the lunar surface as the world famous Chinese robot drove in a clockwise direction around the Chang’e-3 lander that delivered it to the ground in mid-December 2013.
You can precisely follow Yutu’s movements over time – from ‘above and below’ – in our new composite view (shown above) combining the latest LRO image with our timelapse mosaic showing the rover’s history making path from the touchdown point last December to today’s location.
Yutu is China’s first ever Moon rover and successfully accomplished a soft landing on the Moon on Dec. 14, 2013, piggybacked atop the Chang’e-3 mothership lander.
Barely seven hours after touchdown, the six wheeled moon buggy drove down a pair of ramps onto the desolate gray plains of the lunar surface at Mare Imbrium (Sea of Rains) covered by volcanic material.
Altogether three images of the rover and lander have been taken to date by the Lunar Reconnaissance Orbiter Camera (LROC) aboard LRO – specifically the hi res narrow angle camera (NAC).
The LROC NAC images were captured on Dec. 25, 2013, Jan. 21, 2014 and Feb. 17, 2014 as LRO soared overhead.
The four image LRO composite below includes a pre-landing image taken on June 30, 2013.
Since the solar incidence angles were different, the local topography and reflectance changes between images showing different levels of details.
“In the case of the Chang’e 3 site, with the sun higher in the sky one can now see the rover Yutu’s tracks (in the February image),” wrote Mark Robinson, Principal Investigator for the LROC camera in an LRO update.
The solar powered rover and lander can only operate during periods of lunar daylight, which last 14 days each.
During each lunar night, they both must power down and enter hibernate mode since there is no sunlight available to generate power and no communications are possible with Earth.
Here is a gif animation from the NASA LRO team combining all four LROC images.
During Lunar Day 1, Yutu drove down the landers ramps and moved around the right side in a clockwise direction.
By the end of the first lunar day, Yutu had driven to a position about 30 meters (100 feet) south of the Chang’e-3 lander, based on the imagery.
See our complete 360 degree timelapse color panorama from Lunar Day 1 herein and at NASA APOD on Feb. 3, 2014 – assembled by Marco Di Lorenzo and Ken Kremer.
After awakening for Lunar Day 2, Yutu then moved northwest and parked about 17 meters (56 feet) southwest of the lander, according to Robinson.
By comparing the Janaury and February images “it is apparent that Yutu did not move appreciably from the January location,” said Robinson.
At this moment Yutu and the companion Chang’e-3 lander are sleeping through their 3rd Lunar Night.
They entered hibernation mode on Feb. 22 and Feb. 23, 2014 respectively.
Hopefully both probes will awaken from their slumber sometime in the next week when the Moon again basks in daylight glow to begin a 4th day of lunar surface science operations.
“We all wish it would be able to wake up again,” said Ye Peijian, chief scientist of the Chang’e-3 program, according to CCTV, China’s state run broadcaster.
However, the hugely popular ‘Yutu’ rover is still suffering from an inability to maneuver its life giving solar panels. It is also unable to move – as I reported here.
The 140 kg rover is now nearing its planned 3 month long life expectancy on a moon roving expedition to investigate the moon’s surface composition and natural resources.
China is only the 3rd country in the world to successfully soft land a spacecraft on Earth’s nearest neighbor after the United States and the Soviet Union.
Stay tuned here for Ken’s continuing Chang’e-3, Orion, Orbital Sciences, SpaceX, commercial space, LADEE, Mars and more planetary and human spaceflight news. Learn more at Ken’s upcoming presentations at the NEAF astro/space convention on April 12/13.
Chang’e-3 lander and Yutu rover – from Above And Below
Composite view shows China’s Chang’e-3 lander and Yutu rover from Above And Below (orbit and surface) – lander color panorama (top) and orbital view from NASA’s LRO orbiter (bottom). Chang’e-3 lander color panorama shows Yutu rover after it drove down the ramp to the moon’s surface and began driving around the landers right side to the south. Yellow lines connect craters seen in the lander panorama and the LROC image from LRO (taken at a later date after the rover had moved), red lines indicate approximate field of view of the lander panorama. Credit: CNSA/NASA/Ken Kremer/Marco Di Lorenzo/Mark Robinson
See further composite and panorama views below
Story updated See our Yutu timelapse pano at NASA APOD Feb. 3, 2014: http://apod.nasa.gov/apod/ap140203.html[/caption]
China’sChang’e-3 lander and Yutu moon rover have been imaged from above and below – in one of those rare, astounding circumstances when space probes from Earth are exploring an extraterrestrial body both from orbit and the surface. And it’s even more amazing when these otherworldly endeavors just happen to overlap and involve actual work in progress to expand human knowledge of the unknown.
And it’s even rarer, when those images stem from active space probes built by two different countries on Earth.
Well by combining imagery from America’s space agency, NASA, and China’s space agency, CNSA, we are pleased to present some breathtaking views of ‘Chang’e-3 and the Yutu rover from Above and Below.’
Check out our composite mosaic (above) combining the view from the Moon’s orbit snapped by the hi res camera aboard NASA’s Lunar Reconnaissance Orbiter (LRO) with our new color panoramas from the Moon’s surface, compiling imagery from the landing site of China’s Chang’e-3 lander – with Yutu in transit in mid-Dec. 2013 soon after the successful touchdown.
See below an earlier composite mosaic using the first black and white panorama from the Chang’e-3 Moon lander.
The composite mosaic combines the efforts of Mark Robinson, Principal Investigator for the LRO camera, and the imaging team of Ken Kremer and Marco Di Lorenzo.
On Christmas eve, Dec. 24, 2013, NASA’s LRO captured it’s first images of China’s Chang’e-3 lander and Yutu moon rover – barely 10 days after the history making touchdown on Mare Imbrium (Sea of Rains) and just 60 meters east of the rim of a 450 meter diameter impact crater.
LRO was orbiting about 150 kilometers above Chang’e-3 and Yutu when the highest resolution orbital image was taken on 24 December 22:52:49 EST (25 December 03:52:49 UT).
The orbital imagery was taken by the LRO orbiters high resolution Lunar Reconnaissance Orbiter Camera (LROC) – specifically the narrow angle camera (NAC).
See below my pre-launch cleanroom photo of LRO and the LROC cameras and other science instruments.
The Chang’e-3 lander color panorama shows the Yutu rover after it drove down the ramp to the moon’s surface and began driving a significant distance around the landers right side on its journey heading southwards.
Yellow lines connect craters seen in the lander panorama to those seen in the LROC hi res NAC image from LRO, in the composite view.
Robinson identified the lunar craters and determined the field of view on the LROC image.
The LRO image was taken at a later date (on Christmas eve) after the rover had already moved. Red lines on the orbital image indicate the approximate field of view of what is seen in the Chang’e-3 lander panorama.
Although Yutu is only about 150 cm wide – which is the same as the pixel size – 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),” says NASA in a statement.
In a historic first for China, the Chang’e-3 spacecraft safely touched down on the Moon at Mare Imbrium near the Bay of Rainbows nearly seven weeks ago on Dec. 14, 2013.
Seven hours later, the piggybacked 140 kg Yutu robot drove off a pair of ramps, onto the Moon and into the history books.
Yutu was about 10 meters away from the 1200 kg stationary lander when the lander panoramic images were taken.
The lander and Yutu were just completing their 1st Lunar Day of explorations when the LROC images were taken, and entered their first period of hibernation soon thereafter on Dec. 25 (Christmas Day) and Dec 26 respectively coinciding with the start of their 1st Lunar Night.
Yutu’s fate will remain unknown until the 3rd Lunar Day starts around Feb. 8 or 9.
So, What’s the terrain like at the Mare Imbrium landing site?
Chang’e-3 landed on a thick deposit of volcanic material.
“A large scale wrinkle ridge (~100 km long, 10 km wide) cuts across the area and was formed as tectonic stress caused the volcanic layers to buckle and break along faults. Wrinkle ridges are common on the Moon, Mercury and Mars,” says Robinson.
“The landing site is on a blue mare (higher titanium) thought to be about 3.0 billion years old.”
Older red mare about from 3.5 billion years is only 10 km to the north, he notes.
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:
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).
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.
On December 17, 2012, the GRAIL mission came to an end, and the two washing machine-sized spacecraft performed a flying finale with a planned formation-flying double impact into the southern face of 2.5-kilometer- (1.5-mile-) tall mountain on a crater rim near the Moon’s north pole. The Lunar Reconnaissance Orbiter has now imaged the impact sites, which show evidence of the crashes.
But surprisingly, these impacts were not what was expected, says the LRO and GRAIL teams. The ejecta around both craters is dark. Usually, ejecta from craters is lighter in color – with a higher reflectance – than the regolith on surface.
“I expected the ejecta to be bright,” said LROC PI Mark Robinson at a press conference from the Lunar and Planetary Science Conference today, “because everybody knows impact rays on the Moon are bright. We are speculating it could be from hydrocarbons from the spacecraft.”
Typically ejecta from craters is brighter, since subsurface regolith tends to have a higher reflectance. The lunar regolith on the surface tends to be darker because of its exposure to the vacuum of space, cosmic radiation, solar wind bombardment, and micrometeorite impacts. Slowly over time, these processes tend to darken the surface soil.
Robinson said the hydrocarbons could have come from fuel left in the fuel lines (JPL estimated a quarter to half a kilogram of fuel may have remained in the spacecraft – so, not very much) or from the spacecraft itself, which is made out of carbon material.
Additionally, the impact craters’ shapes were not as expected. The impacts formed craters about 5 m (15 ft) in diameter, and there is little ejecta to the south – the direction from which the spacecraft were traveling. “The spacecraft came in at a 1 or 2 degree impact angle,” said Robinson, “so this not a normal impact, as all the ejecta went upstream in the direction of travel.”
“I was expecting to see skid marks, myself,” said GRAIL principal investigator Maria Zuber. She added that she was committed to using every bit of fuel to mapping the gravity field at as low an altitude as possible. “I was determined that we would not end the mission with unused fuel because that would have meant we could mapped it even lower.
Robinson said he was skeptical that they could find the impact craters, since the team has yet to find the impact sites of the Apollo ascent stages, which should be much bigger than the GRAIL impacts.
“Finding the impact crater was like finding a needle in haystack,” Robinson said, “as the images are looking at an area that is about 8 km wide and 30 to 40 km tall, and we were looking for something that is a couple of pixels wide.”
Robinson said he spent hours looking for it with no luck, only to see it later when he was on a conference call and was just looking at it out of the corner of his eye.
“It was really fun to find the craters,” he said. LRO did take images in early January, but better images were taken on February 28, 2013.
While LRO’s camera was not able to image the actual impact since it occurred on the night-side of the Moon, the LAMP instrument (Lyman Alpha Mapping Project) on LRO was able to detect the plumes of the impacts.
Kurt Retherford, PI of LAMP said the UV spectrograph was pointed towards the limb of the Moon — and actually looking in the direction of the constellation Orion at the time of the GRAIL impact — to observe the gases coming out of the plumes. They did detect the two impact plumes which clearly showed an excess of emissions from hydrogen atoms. “We were excited to see this detection of atomic hydrogen coming from the impact sites,” Retherford said. “This is our first detection of native hydrogen atoms from the lunar environment.”
This video shows LRO as it flies over the north pole of the Moon, where it has a very good view of the GRAIL impact. The second part is the view from LRO through LAMP’s slit, showing the impact and the resulting plume. The orbits, impact locations, terrain, LAMP field of view, and starfield are accurately rendered.
Retherford said further studies from this will help in determining the processes of how the implantation of solar wind protons on the lunar surface could create the water and hydroxyl that has been recently detected on the lunar surface by other spacecraft and in studies of lunar rocks returned by the Apollo missions.
LROC view looking obliquely of the south rim of Aristarchus from the west (NASA/GSFC/Arizona State University)
Flying over at an altitude of 135 km, NASA’s Lunar Reconnaissance Orbiter captured this lovely oblique view of the crater Aristarchus, looking down at the 40-km (25-mile) -wide crater’s southern rim from the west.
The broad flank of Aristarchus’ 300-meter (980-foot) central peak and surrounding hills can be seen at left, casting lengthening shadows in the setting sun.
Named after the Greek astronomer who first proposed a controversial heliocentric model for the Solar System in the 3rd century BCE, Aristarchus is a prominent crater located near the Moon’s northwestern limb within the geologically-diverse Oceanus Procellarum — the “Ocean of Storms.” Surrounded by rays of bright ejecta that extend down its stepped rim, the floor of Aristarchus drops 3.7 km (2.3 miles) below the surrounding lunar landscape.
The bright material seen in the ejecta streaks seems to echo the patterns of light and dark material lining the slopes of Aristarchus’ central peak, suggesting that they may be the made of similar material.
Detail of the 4.5-km-long central peak of Aristarchus (NASA/GSFC/Arizona State University)
The impact that created Aristarchus an estimated 450 million years ago excavated subsurface material, melting and spraying it tens of kilometers over the surrounding plateau. It’s thought that the central peak is likely composed of the same stuff, dredged up by the impact and frozen in place.
Future lunar explorers, should they ever visit this region, would be able to collect samples from the base of the central peak and compare them to samples from the bright rays to see if they match up, allowing researchers to learn about the composition of the material underlying the plateau from rocks scattered conveniently around the surface… this is the beauty of such (relatively) recent craters! The digging’s already been done for us.
Caption: LROC image showing the illuminated side of the still standing American flag to be captured at the Apollo 17 landing site. Credit: NASA/GSFC/Arizona State University.
Mark Robinson, Principal Investigator of the Lunar Reconnaisance Orbiter Camera (LROC) says the most often-asked questions he gets about the images LRO has taken of the Moon are about pictures of the Apollo landing sites and what is visible. Especially, Robinson said, people want to know if the flags are still standing.
Previously, Robinson has said that while the flag poles are likely still standing, he didn’t think the flags themselves survived the harsh radiation of the lunar surface environment. But new images and video show that at some of the landing sites – Apollo 12, Apollo 16, and Apollo 17 – the flags must still be intact, because they are creating shadows on the surface.
“Personally I was a bit surprised that the flags survived the harsh ultraviolet light and temperatures of the lunar surface, but they did,” Robinson wrote on the LROC website. “What they look like is another question (badly faded?).”
Caption: The flag was captured in this image of the Apollo 16 site with the spacecraft slewed 15° towards the Sun; the shadowed side of the flag is seen by LROC. Credit: NASA/GSFC/Arizona State University.
James Fincannon, a NASA engineer from Glenn Research Center, combined LROC images of each Apollo site taken at roughly the same orientation but with different Sun angles to show the travel of shadows.
“Combined with knowledge of the Apollo site maps which show where the flag was erected relative to the Lander, long shadows cast by the flags at the three sites show that the these flags are still “flying”, held aloft by the poles,” Fincannon wrote.
And so, from the LROC images it is now certain that the American flags are still standing and casting shadows at all of the sites, except Apollo 11. Astronaut Buzz Aldrin reported that the flag was blown over by the exhaust from the ascent engine during liftoff of Apollo 11, and Robinson said that from the images of the Apollo 11 landing site, it looks like he was correct.
Caption: Enlargement of area surrounding Apollo 11 landing site. Credit: NASA/GSFC/Arizona State University
Robinson added that the most convincing way to see that the flags are still there, is to view a time series of LROC images taken at different times of day, and watch the shadow circle the flag (see movie below; the flag is just above the LM descent stage).