Lunar Orbiter Takes a Meteorite Strike Right in the Camera

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 NAC on a bench in the clean room at Malin Space Science Systems. Credit: Courtesy of Malin Space Science Systems/ASU SESE

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.

As Robinson explained in a recent post on the LROC’s website:

“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.

LROC Narrow Angle Camera (NAC). Credit: ASU/LROC SESE

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.

Artist’s rendering of Lunar Reconnaissance Orbiter (LRO) in orbit. Credit: ASU/LROC

“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:

Further Reading: ASU/LROC

NASA Approves New Horizons Extended KBO Mission, Keeps Dawn at Ceres

New Horizons trajectory and the orbits of Pluto and 2014 MU69.
New Horizons trajectory and the orbits of Pluto and 2014 MU69.

In an ‘Independence Day’ gift to a slew of US planetary research scientists, NASA has granted approval to nine ongoing missions to continue for another two years this holiday weekend.

The biggest news is that NASA green lighted a mission extension for the New Horizons probe to fly deeper into the Kuiper Belt and decided to keep the Dawn probe at Ceres forever, rather than dispatching it to a record breaking third main belt asteroid.

And the exciting extension news comes just as the agency’s Juno probe is about to ignite a do or die July 4 fireworks display to achieve orbit at Jupiter – detailed here.

“Mission approved!” the researchers gleefully reported on the probes Facebook and Twitter social media pages.

“Our extended mission into the #KuiperBelt has been approved. Thanks to everyone for following along & hopefully the best is yet to come.

Dwarf planet Ceres is shown in this false-color renderings, which highlight differences in surface materials.  The image is centered on Ceres brightest spots at Occator crater. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Dwarf planet Ceres is shown in this false-color renderings, which highlight differences in surface materials. The image is centered on Ceres brightest spots at Occator crater. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

The New Horizons spacecraft will now continue on course in the Kuiper Belt towards an small object known as 2014 MU69, to carry out the most distant close encounter with a celestial object in human history.

“Here’s to continued success!”

The spacecraft will rendezvous with the ancient rock on New Year’s Day 2019.

Researchers say that 2014 MU69 is considered as one of the early building blocks of the solar system and as such will be invaluable to scientists studying the origin of our solar system how it evolved.

It was almost exactly one year ago on July 14, 2015 that New Horizons conducted Earth’s first ever up close flyby and science reconnaissance of Pluto – the most distant planet in our solar system and the last of the nine planets to be explored.

Pluto Explored at Last. The New Horizons mission team celebrates successful flyby of Pluto in the moments after closest approach at 7:49 a.m. EDT on July 14, 2015.   New Horizons Principal Investigator Alan Stern of Southwest Research Institute (SwRI), Boulder, CO., left, Johns Hopkins University Applied Physics Laboratory (APL) Director Ralph Semmel, center, and New Horizons Co-Investigator Will Grundy Lowell Observatory hold an enlarged print of an U.S. stamp with their suggested update after Pluto became the final planet in our solar system to be explored by an American space probe (crossing out the words ‘not yet’) - at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland.  Credit: Ken Kremer/kenkremer.com
Pluto Explored at Last. The New Horizons mission team celebrates successful flyby of Pluto in the moments after closest approach at 7:49 a.m. EDT on July 14, 2015. New Horizons Principal Investigator Alan Stern of Southwest Research Institute (SwRI), Boulder, CO., left, Johns Hopkins University Applied Physics Laboratory (APL) Director Ralph Semmel, center, and New Horizons Co-Investigator Will Grundy Lowell Observatory hold an enlarged print of an U.S. stamp with their suggested update after Pluto became the final planet in our solar system to be explored by an American space probe (crossing out the words ‘not yet’) – at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. Credit: Ken Kremer/kenkremer.com

The immense volume of data gathered continues to stream back to Earth every day.

“The New Horizons mission to Pluto exceeded our expectations and even today the data from the spacecraft continue to surprise,” said NASA’s Director of Planetary Science Jim Green at NASA HQ in Washington, D.C.

“We’re excited to continue onward into the dark depths of the outer solar system to a science target that wasn’t even discovered when the spacecraft launched.”

This new global mosaic view of Pluto was created from the latest high-resolution images to be downlinked from NASA’s New Horizons spacecraft and released on Sept. 11, 2015. The images were taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers). This new mosaic was stitched from over two dozen raw images captured by the LORRI imager and colorized. Annotated with informal place names. Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Marco Di Lorenzo/Ken Kremer/kenkremer.com
This new global mosaic view of Pluto was created from the latest high-resolution images to be downlinked from NASA’s New Horizons spacecraft and released on Sept. 11, 2015. The images were taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers). This new mosaic was stitched from over two dozen raw images captured by the LORRI imager and colorized. Annotated with informal place names. Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Marco Di Lorenzo/Ken Kremer/kenkremer.com

While waiting for news on whether NASA would approve an extended mission, the New Horizons engineering and science team already ignited the main engine four times to carry out four course changes in October and November 2015, in order to preserve the option of the flyby past 2014 MU69 on Jan 1, 2019.

Green noted that mission extensions into fiscal years 2017 and 2018 are not final until Congress actually passes sufficient appropriation to fund NASA’s Planetary Science Division.

“Final decisions on mission extensions are contingent on the outcome of the annual budget process.”

Tough choices were made even tougher because the Obama Administration has cut funding for the Planetary Sciences Division – some of which was restored by a bipartisan majority in Congress for what many consider NASA’s ‘crown jewels.’

NASA’s Dawn asteroid orbiter just completed its primary mission at dwarf planet Ceres on June 30, just in time for the global celebration known as Asteroid Day.

“The mission exceeded all expectations originally set for its exploration of protoplanet Vesta and dwarf planet Ceres,” said NASA officials.

The Dawn science team had recently submitted a proposal to break out of orbit around the middle of this month in order to this conduct a flyby of the main belt asteroid Adeona.

Green declined to approve the Dawn proposal, citing additional valuable science to be gathered at Ceres.

The long-term monitoring of Ceres, particularly as it gets closer to perihelion – the part of its orbit with the shortest distance to the sun — has the potential to provide more significant science discoveries than a flyby of Adeona,” he said.

The funding required for a multi-year mission to Adeona would be difficult in these cost constrained times.

However the spacecraft is in excellent shape and the trio of science instruments are in excellent health.

Dawn arrived at Ceres on March 6, 2015 and has been conducting unprecedented investigation ever since.

Dawn is Earth’s first probe in human history to explore any dwarf planet, the first to explore Ceres up close and the first to orbit two celestial bodies.

The asteroid Vesta was Dawn’s first orbital target where it conducted extensive observations of the bizarre world for over a year in 2011 and 2012.

The mission is expected to last until at least later into 2016, and possibly longer, depending upon fuel reserves.

Due to expert engineering and handling by the Dawn mission team, the probe unexpectedly has hydrazine maneuvering fuel leftover.

Dawn will remain at its current altitude at the Low Altitude Mapping Orbit (LAMO) for the rest of its mission, and indefinitely afterward, even when no further communications are possible.

Green based his decision on the mission extensions on the biannual peer review scientific assessment by the Senior Review Panel.

Dawn was launched in September 2007.

The other mission extensions – contingent on available resources – are: the Mars Reconnaissance Orbiter (MRO), Mars Atmosphere and Volatile EvolutioN (MAVEN), the Opportunity and Curiosity Mars rovers, the Mars Odyssey orbiter, the Lunar Reconnaissance Orbiter (LRO), and NASA’s support for the European Space Agency’s Mars Express mission.

Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.

Ken Kremer

Scientists Identify the Source of the Moon’s Water

Over the course of the past few decades, our ongoing exploration the Solar System has revealed some surprising discoveries. For example, while we have yet to find life beyond our planet, we have discovered that the elements necessary for life (i.e organic molecules, volatile elements, and water) are a lot more plentiful than previously thought. In the 1960’s, it was theorized that water ice could exist on the Moon; and by the next decade, sample return missions and probes were confirming this.

Since that time, a great deal more water has been discovered, which has led to a debate within the scientific community as to where it all came from. Was it the result of in-situ production, or was it delivered to the surface by water-bearing comets, asteroids and meteorites? According to a recent study produced by a team of scientists from the UK, US and France, the majority of the Moon’s water appears to have come from meteorites that delivered water to Earth and the Moon billions of years ago.

For the sake of their study, which appeared recently in Nature Communications, the international research team examined the samples of lunar rock and soil that were returned by the Apollo missions. When these samples were originally examined upon their return to Earth, it was assumed that the trace of amounts of water they contained were the result of contamination from Earth’s atmosphere since the containers in which the Moon rocks were brought home weren’t airtight. The Moon, it was widely believed, was bone dry.

The blue areas show locations on the Moon's south pole where water ice is likely to exist (NASA/GSFC)
The blue areas show locations on the Moon’s south pole where water ice is likely to exist. Credit: NASA/GSFC

However, a 2008 study revealed that the samples of volcanic glass beads contained water molecules (46 parts per million), as well as various volatile elements (chlorine, fluoride and sulfur) that could not have been the result of contamination. This was followed up by the deployment of the Lunar Reconnaissance Orbiter (LRO) and the Lunar Crater Observation and Sensing Satellite (LCROSS) in 2009, which discovered abundant supplies of water around the southern polar region,

However, that which was discovered on the surface paled in comparison the water that was discovered beneath it. Evidence of water in the interior was first revealed by the ISRO’s Chandrayaan-1 lunar orbiter – which carried the NASA’s Moon Mineralogy Mapper (M3) and delivered it to the surface. Analysis of this and other data has showed that water in the Moon’s interior is up to a million times more abundant than what’s on the surface.

The presence of so much water beneath the surface has begged the question, where did it all come from? Whereas water that exists on the Moon’s surface in lunar regolith appears to be the result of interaction with solar wind, this cannot account for the abundant sources deep underground. A previous study suggested that it came from Earth, as the leading theory for the Moon’s formation is that a large Mars-sized body impacted our nascent planet about 4.5 billion years ago, and the resulting debris formed the Moon. The similarity between water isotopes on both bodies seems to support that theory.

Near-infrared image of the Moon's surface by NASA's Moon Mineralogy Mapper on the Indian Space Research Organization's Chandrayaan-1 mission Image credit: ISRO/NASA/JPL-Caltech/Brown Univ./USGS
Near-infrared image of the Moon’s surface by NASA’s Moon Mineralogy Mapper on the Indian Space Research Organization’s Chandrayaan-1 mission. Credit: ISRO/NASA/JPL-Caltech/Brown Univ./USGS

However, according to Dr. David A. Kring, a member of the research team that was led by Jessica Barnes from Open University, this explanation can only account for about a quarter of the water inside the moon. This, apparently, is due to the fact that most of the water would not have survived the processes involved in the formation of the Moon, and keep the same ratio of hydrogen isotopes.

Instead, Kring and his colleagues examined the possibility that water-bearing meteorites delivered water to both (hence the similar isotopes) after the Moon had formed. As Dr. Kring told Universe Today via email:

“The current study utilized analyses of lunar samples that had been collected by the Apollo astronauts, because those samples provide the best measure of the water inside the Moon. We compared those analyses with analyses of meteoritic samples from asteroids and spacecraft analyses of comets.”

By comparing the ratios of hydrogen to deuterium (aka. “heavy hydrogen”) from the Apollo samples and known comets, they determined that a combination of primitive meteorites (carbonaceous chondrite-type) were responsible for the majority of water to be found in the Moon’s interior today. In addition, they concluded that these types of comets played an important role when it comes to the origins of water in the inner Solar System.

These images produced by the Lyman Alpha Mapping Project (LAMP) aboard NASA's Lunar Reconnaissance Orbiter reveal features at the Moon's northern and southern poles in the regions that lie in perpetual darkness. They show regions that are consistent with having large surface porosities — indicating "fluffy" soils — while the reddening is consistent with the presence of water frost on the surface. Credit: Southwest Research Institute
Images produced by the Lyman Alpha Mapping Project (LAMP) aboard NASA’s Lunar Reconnaissance Orbiter reveal features at the Moon’s northern and southern poles, as well as the presence of water frost. Credit: NASA/SwRI

For some time, scientists have argued that the abundance of water on Earth may be due in part to impacts from comets, trans-Neptunian objects or water-rich meteoroids. Here too, this was based on the fact that the ratio of the hydrogen isotopes (deuterium and protium) in asteroids like 67P/Churyumov-Gerasimenko revealed a similar percentage of impurities to carbon-rich chondrites that were found in the Earth’s coeans.

But how much of Earth’s water was delivered, how much was produced indigenously, and whether or not the Moon was formed with its water already there, have remained the subject of much scholarly debate. Thank to this latest study, we may now have a better idea of how and when meteorites delivered water to both bodies, thus giving us a better understanding of the origins of water in the inner Solar System.

Some meteoritic samples of asteroids contain up to 20% water,” said Kring. “That reservoir of material – that is asteroids – are closer to the Earth-Moon system and, logically, have always been a good candidate source for the water in the Earth-Moon system. The current study shows that to be true. That water was apparently delivered 4.5 to 4.3 billion years ago.

The existence of water on the Moon has always been a source of excitement, particularly to those who hope to see a lunar base established there someday. By knowing the source of that water, we can also come to know more about the history of the Solar System and how it came to be. It will also come in handy when it comes time to search for other sources of water, which will always be a factor when trying to establishing outposts and even colonies throughout the Solar System.

Further Reading: Nature Communications