A new study suggests that the moon's magnetic field from a dynamo in its liquid metallic core (inner red sphere) lasted 1 billion years longer than thought. (Image credit: Hernán Cañellas (provided by Benjamin Weiss))
Some fifty years ago, the Apollo Program sent the first astronauts to the Moon. In addition to the many science experiments they conducted on the surface, the Apollo astronauts brought back samples of lunar rock for analysis. The Soviet Luna program sent several robotic missions to the Moon around the same time that conducted sample-return missions. The examination of these rocks revealed a great deal about the composition of the Moon and led to new theories about the formation and evolution of the Earth-Moon system.
For example, analysis of the rocks revealed that the Earth and the Moon are similarly composed of silicate minerals and metals. This led to theories that the Moon’s interior is similarly divided into a silicate mantle and crust and a metallic core. However, many aspects of this theory, like the structure of the core (solid or molten?), have been debated for decades. According to new findings by a team of French scientists, it is now a scientific certainty that the Moon’s innermost region consists of a solid inner core surrounded by a molten outer core (just like Earth’s).
A team of UC San Diego students have created an experiment to test if beer can be brewed on the Moon. Credit: NASA
When human beings colonize other Solar bodies, how will they see to their basic needs? Already, research has been performed to determine where colonists would be able to procure water, how they might grow their own food, and where and how they might live. But what about the finer things in life, the things that make all the hard labor and sacrifice worth it? In case it’s not clear yet, I’m talking about beer!
If and when Lunar or Martian colonies become a reality, will the colonists be able to brew and enjoy their own beer? Or will imported beer be the only thing available to them? That’s the question a team of bioengineering students from the University of California San Diego sought to answer. As finalists who competed in the Lab2Moon competition being held by TeamIndus, they combined their love of beer with their love of space exploration.
As the only Indian team in the Google Lunar XPRIZE competition, TeamIndus has been working on a privately-funded spacecraft to send to the Moon. Once complete, TeamIndus hopes to conduct a soft landing on the surface of the Moon later this year. Their accomplishments so far include being one of the five teams selected to compete in the Milestone Prizes and successfully winning the $1 million Milestone Prize for their landing technology.
Johnny Koo, Jared Buchanan, Han Lu Ling, Neeki Ashari, Srivaths Kalyan, and Tavish Traut. Credit: Erik Jepsen/UC San Diego Publications
The Lab2Moon competition was held in order to see a youth experiment brought to the Moon aboard that spacecraft. And while their experiment did not take home the top prize, their final prototype will still be going into space. Thanks to Synergy Moon, who won an XPrize verified launch contract, the experiment will be launched aboard a rocket this December (the planned launch date is currently Dec. 28th, 2017).
For the sake of their experiment, the UC San Diego team – all undergraduates with the Jacobs School of Engineering – sought to test if yeast would be viable in a Lunar environment. As the key ingredient in the production of beer (and many other beneficial things), their experiment sought to determine if Lunar colonists will be capable of becoming their own brewmasters.
Their team name is “Original Gravity”, a delicious pun that alludes to both brewing and the Lunar conditions they are investigating. In the case of brewing, Original Gravity (OG) is the measure of sugars dissolved in the wort (the beer before it is fermented). In the case of the Moon, it refers to the fact that Lunar gravity is just 0.165 times that of Earth’s, which could affect the behavior of the microorganisms like yeast.
As Neeki Ashari, a fifth-year bioengineering student and the team’s PR & Operations Lead, said in a University press release:
“The idea started out with a few laughs amongst a group of friends. We all appreciate the craft of beer, and some of us own our own home-brewing kits. When we heard that there was an opportunity to design an experiment that would go up on India’s moonlander, we thought we could combine our hobby with the competition by focusing on the viability of yeast in outer space.”
With sponsorship from the Omega Yeast Labs, the team designed a unique brewing system. First, all the prep work that precedes the adding of yeast – for instance, combining malted barley and water to create wort – would take place on Earth. Second, the team plans to combine the “fermentation” and “carbonation” phases – which are usually done separately – into one phase.
This process makes for a system that is much easier to design, eliminates the need for releasing accumulated CO² (which can be a hazard) and also prevents the possibility of over-pressurization if anything in the system fails. Last, the testing of fermentation will not rely on density measurements that rely on gravity (as brewers do on Earth), using pressure to determine sugar content instead.
As Han Ling, a fifth-year bioengineering undergraduate student and the team’s leader, explained, “Converting the pressure buildup to fermentation progress is straightforward, as long as volume and original gravity – specific gravity before fermentation, hence our name – are known prior to the experiment.” Measuring roughly as wide as a soda can, their system is able to ferment yeast and worst to create beer, even under Lunar conditions.
In addition to being the first-ever experiment to brew beer in space, their experiment will also be the first to craft beer using such a small apparatus. A Srivaths Kaylan, a fourth-year nano-engineering major and the team’s mechanical lead, indicated:
“Our canister is designed based on actual fermenters. It contains three compartments—the top will be filled with the unfermented beer, and the second will contain the yeast. When the rover lands on the moon with our experiment, a valve will open between the two compartments, allowing the two to mix. When the yeast has done it’s job, a second valve opens and the yeast sink to the bottom and separate from the now fermented beer.”
Team Original Gravity’s revolutionary brewing system. Credit: jacobsschool.ucsd.edu
Looking to the future, Ashari and the team hope to see their experiment adapted for use on other planets – like Mars! Other proposed experiments that were entered in the competition included methods for photosynthesis to producing electricity in a Lunar environment. Beyond making beer, understanding how yeast will behave in a Lunar environment is also important in the development of pharmaceuticals and yeast-containing foods, such as bread.
It certainly is interesting to think about what kind of beers could be produced in an extra-terrestrial environment, isn’t it? Will future generations of brewers have the option of using locally-grown barley, wheat, hops, and yeast cultures to craft their beer? Will the use of Lunar or Martian water have an effect on the taste of the beer?
And then there’s the matter of names and styles. Will Lunar brewers create a Dark Side of the Moon Stout? Will the people of Mars specialize in Red Ales? Like I said, interesting!
The first image from the surface of the Moon via Luna 9, Feb. 3-4, 1966. (Credit: Roscosmos)
On this date half a century ago the Soviet Luna 9 spacecraft made humanity’s first-ever soft landing on the surface of the Moon. Launched from Baikonur on Jan. 31, 1966, Luna 9 lander touched down within Oceanus Procellarum — somewhere in the neighborhood of 7.08°N, 64.37°E* — at 18:44:52 UTC on Feb. 3. The fourth successful mission in the USSR’s long-running Luna series, Luna 9 sent us our first views of the Moon’s surface from the surface and, perhaps even more importantly, confirmed that a landing by spacecraft was indeed possible.
The entire Luna 9 lander was made up of two main parts: a 1,439-kg flight/descent stage which contained retro-rockets and orientation engines, navigation systems, and various fuel tanks, and a 99-kg (218-lb) pressurized “automatic lunar station” that contained all the science and imaging instruments along with batteries, heaters, and a radio transmitter.
When a probe on the descent stage detected contact with the lunar surface, the spherical station — encased in an inflated airbag — was jettisoned to soft-land a safe distance away — after a bit of bouncing, of course; the lander hit the Moon’s surface at about 22 km/hr (13 mph)!
The Luna 9 lunar station lander. (NSSDC)
Once the airbag cushions deflated Luna 9, like a shiny metal flower, opened its four “petals,” extended its radio antennas and began taking panoramic television camera images of its surroundings, at the time lit by a very low Sun on the lunar horizon. Received on Earth early on Feb. 4, 1966, they were the first pictures taken from the surface of the Moon and in fact the first images acquired from the surface of another world.
Other missions, both Soviet and American, had captured close-up images of the Moon in previous years but Luna 9 was the first to soft-land (i.e., not crash land) and operate from the surface. The spacecraft continued transmitting image data to Earth until its batteries ran out on the night of Feb. 6, 1966. A total of four panoramas were acquired by Luna 9 over the course of three days, as well as data on radiation levels on the Moon’s surface (not to mention the valuable knowledge that a spacecraft wouldn’t just completely sink into the lunar regolith!)
Four months later, on June 2, 1966, NASA’s Surveyor 1 would become the first U.S. spacecraft to soft-land on the Moon. Surveyor 1 would send back science data and 11,240 photos over the course of a month in operation but, in terms of the space “race,” Luna 9 will always be remembered as first place winner.
*Or is it 7.14°N/60.36°W? Even today it’s still not precisely known where Luna 9 landed, but researchers at Arizona State University are actively searching through Lunar Reconnaissance Orbiter Camera pictures in an attempt to spot the “lost” spacecraft and/or evidence of its historic landing. Read more about that here.
Moon halo by Rob Sparks. Taken in Tuscon, Arizona with a Canon 6D, Rokinon 14mm f/2.8 lens.
Have you ever looked up on a clear night and noticed there’s a complete ring around the Moon? In fact, if you look closely, the ring can have a rainbow appearance, with bright spots on either side, or above and below. What’s going on with the Moon and the atmosphere to cause this effect?
This ring surrounding the Moon is caused by the refraction of Moonlight (which is really reflected sunlight, of course) through ice crystals suspended in the upper atmosphere between 5-10 km in altitude. It doesn’t have to be winter, since the cold temperatures at high altitudes are below freezing any time of the year. Generally they’re seen with cirrus clouds; the thin, wispy clouds at high altitude.
The ice crystals themselves have a very consistent hexagonal shape, which means that any light passing through them will always refract light – or bend – at the same angle.
Path of rays in a hexagonal prism” by donalbein – Own work. Licensed under CC BY-SA 2.5 via Commons.Moonlight passes through one facet of the ice crystal, and is then refracted back out at exactly the angle of 22-degrees.
Of course, the atmosphere is filled with an incomprehensible number of crystals, all refracting moonlight off in different directions. But at any moment, a huge number happen to be in just the right position to be refracting light towards your eyes. You just aren’t in a position to see all the other refracted light. In fact, everyone sees their own private halo, because you’re only seeing the crystals that happen to be aligning the light for your specific location. Someone a few meters beside you is seeing their own private version of the halo – just like a rainbow.
A halo rings the bright moon and planet Jupiter (left of moon) Credit: Bob King
The size of the ring is most commonly 22-degrees. This is about the same size as your open hand on your outstretched arm. The Moon itself, for comparison, is the size of your smallest nail when you hold out your hand.
The 22-degree size corresponds to the refraction angle of moonlight.
We see a rainbow because the different colors are refracted at slightly different angles. This is exactly what happens with a rainbow. The moonlight is broken up into its separate colors because they all refract at different angles, and so you see the colors split up like a rainbow.
Lunar halo with rainbow. Photo credit: Gustav Sanchez.Moon dogs (or “mock moons”) are seen as bright spots that can appear on either side of the Moon, when the Moon is closer to the horizon, and at its fullest. These are located on either side of the lunar ring, parallel to the horizon.
In certain conditions, especially in the Arctic, where the ice crystals can be close to the surface, you can get a moon pillar. The light from the Moon reflects off the ice crystals near the surface, creating a glow near the horizon. This is a Sun pillar (not a moon pillar), but it’s the same general idea. Photo credit: Mary Spicer.
Want to see more? Here’s a great lunar halo photo from NASA’s APOD. And here’s more info from Earth and Sky.
On Wednesday morning October 8, Earth's shadow will nibble away at the moon for this year's second total lunar eclipse. Credit: Bob King
Ready for Wednesday’s morning lunar eclipse? Some people – and I envy them at times – treat an eclipse more casually. They enjoy the show with no desire to set up a telescope or take a photo. For those of us can’t part with our cameras, here’s a little guide to help you get better pictures.
From Philadelphia and other eastern U.S. cities the partial phases of the eclipse will take place with the moon well up in the western sky. By the start of totality, the moon will have dropped to within about 6º of the horizon as shown here. Source: Stellarium
If you’re also into photography and would like to grab a few shots, here are a few tips on what equipment you’ll need and camera settings. This eclipse offers unique opportunities especially for the eastern half of the country because the eclipsed moon will be low in the western sky near the start of and during morning twilight.
In the Midwest at the start of the hour-long totality, the red moon will be about 20º (two fists) above the western horizon. From the East Coast the moon slips into total eclipse only a half hour before sunrise 6-7º high. So if you live in the eastern half of the country, find a site with a good view to the west.
Seen from Denver, total eclipse begins with the moon 30º high (three fists). All of totality and all partial phases of the eclipse will be visible from western Midwest west to Hawaii and Alaska. Source: Stellarium
A low moon means easier framing with a pleasing foreground like a grove of fall trees, a church or distant line of mountain peaks. And the lower it drops, the longer the telephoto lens you can use to enlarge the moon relative to the foreground. When the moon is high in the sky it’s more difficult to find a suitable foreground.
Sometimes it’s nice to have a foreground object to add character to your eclipse photos. Last April’s totally eclipsed moon joins the old Central High School clock tower in downtown Duluth, Minn. Mars at upper right. Details: 80mm lens, f/5, 1.6-second exposure at ISO 400 on a tripod. Credit: Bob King
As the scene brightens during twilight, balancing the light of the dim moon, your photos will get even more interesting. Textures and details in foreground objects will stand out instead of appearing as silhouettes.
Use the table below to plan when to watch depending on your time zone. The blanks mean the moon will have set by the time of the event.
Eclipse Events EDT CDT MDT PDT
Penumbra first visible
4:45 a.m.
3:45 a.m.
2:45 a.m.
1:45 a.m.
Partial eclipse begins
5:15 a.m.
4:15 a.m.
3:15 a.m.
2:15 a.m.
Total eclipse begins
6:25 a.m.
5:25 a.m.
4:25 a.m.
3:25 a.m.
Mid-eclipse
6:55 a.m.
5:55 a.m.
4:55 a.m.
3:55 a.m.
Total eclipse ends
7:24 a.m.
6:24 a.m.
5:24 a.m.
4:24 a.m.
Partial eclipse ends
———
7:34 a.m.
6:34 a.m.
5:34 a.m.
Penumbra last visible
———
———
7:05 a.m.
6:05 a.m.
Exposures and lens settings
Partial phase during the April 14-15 eclipse this year. Details: Telescope (=1300mm telephoto lens) at f/11, 1/250 second at ISO 400. Credit: Bob King
The full moon and even the partially eclipsed moon (up to about half) are so bright you can shoot a handheld photo without resorting to a tripod. Exposures at ISO 400 are in the neighborhood of f/8 at 1/250-1/500 second. Only thing is, all you’ll get is the moon surrounded by blackness. These exposures are so brief almost nothing will show in your foreground except for possibly moonlit clouds. That’s usually fine for the early partial phases.
Once the moon is more than half smothered by shadow, open up your lens to a wider setting – f/2.8 to f/4 – or increase the exposure. Let the back of the camera be your guide. If the images look too bright, dial back. If too dim, increase exposure or open the lens to a wider aperture.
To capture the encroaching shadow during partial phases you’ll need to overexpose the sunlit part of the moon. Details: f/11, 2-second exposure at ISO 400. Credit: Bob King
While you can continue to shoot the partially eclipsed moon at f/8 from 1/30-1/125 second, you’ll miss the best part – the portion filling up with Earth’s red shadow. To capture that, break out the tripod, open the lens all the way up – f/2.8-f/4 – and expose at ISO 400 between 1/4 and 1 second.
You can also shoot at ISO 800 and cut those times in half, important if you’re using a longish telephoto lens. Remember, Earth’s rotation means the moon’s on the move and will show trailing if you expose longer than a few seconds. On the other hand, this won’t be a problem if you’re shooting with a wide angle lens though they have their limits, too.
The moon completely immersed in Earth’s umbra during totality. Details: f/11, 6-second exposure, ISO 400. To prevent trailing I used a motorized mount to track the moon. Credit : Bob King
During totality, expose anywhere from 1/2 to 5 seconds at f/2.8-4.5 at ISO 400. Let’s say you want to include both scenic foreground and stars in the picture using a wide angle or standard lens. Dial up the ISO to 800, open your lens wide and expose between 6-10 seconds. On the 6-second end you’ll catch only the brightest stars, but the moon won’t show trailing; on the longer end you’ll get lots more stars with some overexposure of the eclipsed moon.
Of course, you can go to even higher ISOs and shorten exposure times considerably. But in all but the newest, high-end cameras that comes at the price of increased graininess and less color saturation.
Wide scene from April’s total eclipse with Spica below the moon and Mars to the right. Details: 24mm lens at f/2.8, 8-second exposure at ISO 800. The moon was deliberately overexposed to show it in a field of stars. You can vary the exposure to your taste but the shorter it is, the fewer stars. Longer exposures will show trailing. Credit: Bob King
Where parts of the eclipse happen in twilight, even mobile phones may suffice. There should be enough light to capture a pretty scene with the moon just emerging from total eclipse and during the ensuing partial phases.
The partial lunar eclipse of June 4, 2012, pre-dawn at moonset, from home in southern Alberta. This is a single exposure with the Canon 60Da and 18-200mm Sigma lens at 115mm and at f/5.6 for 0.4 sec at ISO 160. Copyright: Alan Dyer
If you’re clouded out or on the wrong side of the planet for the eclipse, you can catch live webcasts from the following sites:
Astrobotic's model rover explores a mine on Earth to train for lunar lava tunnels (Video screenshot)
Ever since (and most likely long before) the first tantalizing glimpses of a lunar lava tube and skylight were captured by Japan’s Kaguya spacecraft in 2009, scientists have been dreaming of ways to explore inside these geological treasures. Not only would they provide valuable information on the movement of ancient lunar lava flows, but they could also be great places for future human explorers to set up camp and be well-protected from dangerous solar and cosmic radiation.
But before human eyes will ever peer into the darkness of a lava tube on the Moon, robotic rovers will roll along their silent floors — at least, they will if Google Lunar XPRIZE competitor Astrobotic has anything to say about it.
Last month, engineer and Astrobotic CEO Dr. Red Whitttaker talked to NASA about why they want to explore a Moon cave and the history and progress of their project. Check it out below:
“Something so unique about the lava tubes is that they are the one destination that combines the trifecta of science, exploration, and resources.”
– Dr. William “Red” Whittaker, CEO Astrobotic Technology, Inc.
The international Google Lunar XPRIZE aims to create a new “Apollo” moment for a new generation by driving continuous lunar exploration with $40 million in incentive-based prizes. In order to win, a private company must land safely on the surface of the Moon, travel 500 meters above, below, or on the lunar surface, and send back two “Mooncasts” to Earth… all by Dec. 31, 2015.
Astrobotic Technology Inc. is a Pittsburgh-based company that delivers affordable space robotics technology and planetary missions. Spun out of Carnegie Mellon University’s Robotics Institute in 2008, Astrobotic is pioneering affordable planetary access that promises to spark a new era of exploration, science, tourism, resource utilization and mining. (Source)
The central peak of Bullialdus crater (Credit: NASA/GSFC/Arizona State University)
Scientists have detected magmatic water — water that originates from deep within the Moon’s interior — on the surface of the Moon. These findings represent the first such remote detection of this type of lunar water, and were arrived at using data from NASA’s Moon Mineralogy Mapper (M3) carried aboard India’s Chandrayaan-1 lunar orbiter.
The discovery represents an exciting contribution to the rapidly changing understanding of lunar water according to Rachel Klima, a planetary geologist at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., and lead author of the paper, “Remote detection of magmatic water in Bullialdus Crater on the Moon” published in the August 25 issue of the journal Nature Geoscience.
Chandrayaan-1, India’s first mission to the Moon, entered lunar orbit on Nov. 8, 2008
“For many years, researchers believed that the rocks from the Moon were ‘bone dry’ and that any water detected in the Apollo samples had to be contamination from Earth,” said Klima, a member of the NASA Lunar Science Institute’s (NLSI) Scientific and Exploration Potential of the Lunar Poles team. “About five years ago, new laboratory techniques used to investigate lunar samples revealed that the interior of the Moon is not as dry as we previously thought. Around the same time, data from orbital spacecraft detected water on the lunar surface, which is thought to be a thin layer formed from solar wind hitting the lunar surface.”
“This surficial water unfortunately did not give us any information about the magmatic water that exists deeper within the lunar crust and mantle, but we were able to identify the rock types in and around Bullialdus crater,” said co-author Justin Hagerty, of the U.S. Geological Survey. “Such studies can help us understand how the surficial water originated and where it might exist in the lunar mantle.”
LRO image of the 60-km Bullialdus crater (NASA/GSFC/Arizona State University)
M3 (pronounced “M-cube”) fully imaged the large impact crater Bullialdus in 2009. “It’s within 25 degrees latitude of the equator and so not in a favorable location for the solar wind to produce significant surface water,” Klima explained. “The rocks in the central peak of the crater are of a type called norite that usually crystallizes when magma ascends but gets trapped underground instead of erupting at the surface as lava. Bullialdus crater is not the only location where this rock type is found, but the exposure of these rocks combined with a generally low regional water abundance enabled us to quantify the amount of internal water in these rocks.”
After examining the M3 data, Klima and her colleagues found that the crater has significantly more hydroxyl — a molecule consisting of one oxygen atom and one hydrogen atom — compared to its surroundings. “The hydroxyl absorption features were consistent with hydroxyl bound to magmatic minerals that were excavated from depth by the impact that formed Bullialdus crater,” Klima writes.
The internal magmatic water provides information about the Moon’s volcanic processes and internal composition, Klima said. “Understanding this internal composition helps us address questions about how the Moon formed, and how magmatic processes changed as it cooled. There have been some measurements of internal water in lunar samples, but until now this form of native lunar water has not been detected from orbit.”
“This impressive research confirms earlier lab analyses of Apollo samples, and will help broaden our understanding of how this water originated and where it might exist in the lunar mantle.”
The blue areas show locations on the Moon's south pole where water ice is likely to exist (NASA/GSFC)
The Moon might seem like a poor place to hunt for water, but in fact there’s a decent amount of the stuff dispersed throughout the lunar soil — and even more of it existing as ice deposits in the dark recesses of polar craters. While the LCROSS mission crashed a rocket stage into one of these craters in October 2009 and confirmed evidence of water in the resulting plume of debris, there haven’t been any definitive maps made of water deposits across a large area on the Moon — until now.
Over the course of several years, NASA’s Lunar Reconnaissance Orbiter scanned the Moon’s south pole using its Lunar Exploration Neutron Detector (LEND) to measure how much hydrogen is trapped within the lunar soil. Areas exhibiting suppressed neutron activity — shown above in blue — indicate where hydrogen atoms are concentrated most, strongly suggesting the presence of water molecules… aka H2O.
The incredibly-sensitive LEND instrument measures the flux of neutrons from the Moon, which are produced by the continuous cosmic ray bombardment of the lunar surface. Even a fraction of hydrogen as small as 100 ppm can make a measurable change in neutron distribution from the surface of worlds with negligible atmospheres, and the hydrogen content can be related to the presence of water.
No other neutron instrument with LEND’s imaging capability has ever been flown in space.
Watch the video below for more details as to how LRO and LEND obtained these results:
“While previous lunar missions have observed indications of hydrogen at the Moon’s south pole, the LEND measurements for the first time pinpoint where hydrogen, and thus water, is likely to exist.”
What’s so important about finding water on the Moon? Well besides helping answer the question of where water on Earth and within the inner Solar System originated, it could also be used by future lunar exploration missions to produce fuel for rockets, drinking water, and breathable air. Read more here.
In the ultimate example of science imitating art, engineers working with NASA’s Lunar Reconnaissance Orbiter recently beamed an image of the Mona Lisa to the LRO and back via laser beam in order to measure the rate of transmission between the spacecraft and Earth. This allowed them to then calibrate their software to correct for any discrepancies between the image sent and the one received, resulting in a picture-perfect result.
Leonardo would definitely have approved.
From NASA’s Goddard Space Flight Center:
As part of the first demonstration of laser communication with a satellite at the moon, scientists with NASA’s Lunar Reconnaissance Orbiter (LRO) beamed an image of the Mona Lisa to the spacecraft from Earth.
The iconic image traveled nearly 240,000 miles in digital form from the Next Generation Satellite Laser Ranging (NGSLR) Station at NASA’s Goddard Space Flight Center in Greenbelt, MD, to the Lunar Orbiter Laser Altimeter (LOLA) instrument on the spacecraft. By transmitting the image piggyback on laser pulses that are routinely sent to track LOLA’s position, the team achieved simultaneous laser communication and tracking.
“This test, and the data obtained from it, sets the stage for future high data-rate laser communications demonstrations that will be an essential feature of NASA’s next Moon mission: the Lunar Atmosphere and Dust Environment Explorer.“
When the Moon was receiving its highest number of impacts, so was Earth. Credit: Dan Durda
Some questions about our own planet are best answered by looking someplace else entirely… in the case of impact craters and when, how and how often they were formed, that someplace can be found shining down on us nearly every night: our own companion in space, the Moon.
By studying lunar impact craters both young and old scientists can piece together the physical processes that took place during the violent moments of their creation, as well as determine how often Earth — a considerably bigger target — was experiencing similar events (and likely in much larger numbers as well.)
With no substantial atmosphere, no weather and no tectonic activity, the surface of the Moon is a veritable time capsule for events taking place in our region of the Solar System. While our constantly-evolving Earth tends to hide its past, the Moon gives up its secrets much more readily… which is why present and future lunar missions are so important to science.
Take the crater Linné, for example. A young, pristine lunar crater, the 2.2-km-wide Linné was formed less than 10 million years ago… much longer than humans have walked the Earth, yes, but very recently on lunar geologic terms.
It was once thought that the circular Linné (as well as other craters) is bowl-shaped, thus setting a precedent for the morphology of craters on the Moon and on Earth. But laser-mapping observations by NASA’s Lunar Reconnaissance Orbiter (at right) determined in early 2012 that that’s not the case; Linné is actually more of a truncated inverted cone, with a flattened interior floor surrounded by sloping walls that rise up over half a kilometer to its rim.
On our planet the erosive processes of wind, water, and earth soon distort the shapes of craters like Linné, wearing them down, filling them in and eventually hiding them from plain sight completely. But in the Moon’s airless environment where the only weathering comes from more impacts they retain their shape for much longer lengths of time, looking brand-new for many millions of years. By studying young craters in greater detail scientists are now able to better figure out just what happens when large objects strike the surface of worlds — events that can and do occur quite regularly in the Solar System, and which may have even allowed life to gain a foothold on Earth.
Most of the craters visible on the Moon today — Linné excluded, of course — are thought to have formed within a narrow period of time between 3.8 and 3.9 billion years ago. This period, called the Late Heavy Bombardment, saw a high rate of impact events throughout the inner Solar System, not only on the Moon but also on Mars, Mercury, presumably Venus and Earth as well. In fact, since at 4 times its diameter the Earth is a much larger target than the Moon, it stands to reason that Earth was impacted many more times than the Moon as well. Such large amounts of impacts introduced material from the outer Solar System to the early Earth as well as melted areas of the surface, releasing compounds like water that had been locked up in the crust… and even creating the sorts of environments where life could have begun to develop and thrive.
(It’s been suggested that there was even a longer period of heavy impact rates nicknamed the “late late heavy bombardment” that lingered up until about 2.5 billion years ago. Read more here.)
In the video below lunar geologist David Kring discusses the importance of impacts on the evolution of the Moon, Earth and eventually life as we know it today:
“Impact cratering in Earth’s past has affected not only the geologic but the biologic evolution of our planet, and we were able to deduce that in part by the lessons we learned by studying the Moon… and you just have to wonder what other things we can learn by going back to the Moon and studying that planetary body further.”
It’s these sorts of connections that make lunar exploration so valuable. Keys to our planet’s past are literally sitting on the surface of the Moon, a mere 385,000 km away, waiting for us to just scoop them up and bring them back. While the hunt for a biological history on Mars or resource-mining an asteroid are definitely important goals in their own right, only the Moon holds such direct references to Earth. It’s like an orbiting index to the ongoing story of our planet — all we have to do is make the connections.
Learn more about lunar research at the LPI site here, and see the latest news and images from LRO here.
