Cosmic rays threaten future deep-space astronaut missions

Artist's rendition of the Lunar Reconnaissance Orbiter (LRO) at the moon. 

The CRaTER telescope is seen pointing out at the bottom right center of the LRO spacecraft.

Credit: Illustration by Chris Meaney/NASA

Crewed missions to Mars remain an essential goal for NASA, but scientists are only now beginning to understand and characterise the radiation hazards that could make such ventures risky, concludes a new paper by University of New Hampshire (UNH) scientists.

In a paper published online in the journal Space Weather, associate professor Nathan Schwadron of the UNH Institute for the Study of Earth, Oceans, and Space (EOS) and the department of physics says that due to a highly abnormal and extended lack of solar activity, the solar wind is exhibiting extremely low densities and magnetic field strengths, which causes dangerous levels of hazardous radiation to pervade the space environment.

"The behaviour of the sun has recently changed and is now in a state not observed for almost 100 years," says Schwadron, lead author of the paper and principal investigator for the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on NASA's Lunar Reconnaissance Orbiter (LRO).

He notes that throughout most of the space age, the sun's activity has shown a clockwork 11-year cycle, with approximately six- to eight-year lulls in activity (solar minimum) followed by two- to three-year periods when the sun is more active.

"However, starting in about 2006, we observed the longest solar minimum and weakest solar activity observed in the space age."

These conditions brought about the highest intensities of galactic cosmic rays seen since the beginning of the space age, which have created worsening radiation hazards that potentially threaten future deep-space astronaut missions.

"While these conditions are not necessarily a showstopper for long-duration missions to the moon, an asteroid, or even Mars, galactic cosmic ray radiation in particular remains a significant and worsening factor that limits mission durations," says Schwadron.

The study is the capstone article in the Space Weather CRaTER Special Issue, which provides comprehensive findings on space-based radiation as measured by the UNH-led detector.

The data provide critical information on the radiation hazards that will be faced by astronauts on extended missions to deep space such as those to Mars.

"These data are a fundamental reference for the radiation hazards in near Earth 'geospace' out to Mars and other regions of our sun's vast heliosphere," says Schwadron.

At the heart of CRaTER is material called "tissue equivalent plastic," a stand-in for human muscle capable of gauging radiation dosage. Ionizing radiation from galactic cosmic rays and solar energetic particles remains a significant challenge to long-duration crewed missions to deep space.

Human beings face a variety of consequences ranging from acute effects (radiation sickness) to long-term effects including cancer induction and damage to organs including the heart and brain.

The high radiation levels seen during the sun's last minimum cycle limits the allowable days for typical astronauts behind spacecraft shielding.

Given the trend of reducing solar output, the allowable days in space for astronauts is dropping and estimated to be 20 percent lower in the coming solar minimum cycle as compared to the last minimum cycle.

Journal Reference:
N. A. Schwadron, J. B. Blake, A. W. Case, C. J. Joyce, J. Kasper, J. Mazur, N. Petro, M. Quinn, J. A. Porter, C. W. Smith, S. Smith, H. E. Spence, L. W. Townsend, R. Turner, J. K. Wilson, C. Zeitlin. Does the worsening galactic cosmic radiation environment observed by CRaTER preclude future manned deep-space exploration? Space Weather, 2014; DOI: 10.1002/2014SW001084

ESA Rosetta - Lutetia's Lineaments: Dark side of asteroid hosts hidden crater

ESA's Rosetta spacecraft data. Tracing Lutetia’s grooves.

Credit: ESA /Rosetta /MPS for OSIRIS Team MPS /UPD /LAM /IAA /SSO /INTA /UPM /DASP /IDA

Grooves found on Lutetia, an asteroid encountered by ESA's Rosetta spacecraft, point to the existence of a large impact crater on the unseen side of the rocky world.

ESA's Rosetta spacecraft flew past Lutetia at a distance of 3168 km in July 2010, en route to its 2014 rendezvous with its target comet.

The spacecraft took images of the 100 km-wide asteroid for about two hours during the flyby, revealing numerous impact craters and hundreds of grooves all over the surface.

Impact craters are commonly seen on all Solar System worlds with solid surfaces, recording an intense history of collisions between bodies. However, grooves are much less prevalent.

To date, they have been discovered by visiting spacecraft only on the Martian moon Phobos and the asteroids Eros and Vesta.

The way in which grooves are formed on these bodies is still widely debated, but it likely involves impacts.

Shock waves from the impact travel through the interior of a small, porous body and fracture the surface to form the grooves.

"For Lutetia, by assuming that the grooves were formed in concentric patterns around their source impact crater, we identified 200 such features falling into distinct 'families', correlated with three different impact craters," describes Sebastien Besse, a research fellow at ESA's Technical Centre, ESTEC, in the Netherlands, and lead author of the paper published in Planetary and Space Science this month.

One of the groove systems on Lutetia is associated with the Massilia crater and another with the North Pole Crater Cluster, which comprises a number of superimposed craters. Both are on the asteroid's northern hemisphere.

This anaglyph 3D image of Lutetia can be viewed using stereoscopic glasses with red–green or red–blue filters. 

The two images making up this image were taken several minutes before Rosetta’s closest approach to the asteroid on 10 July 2010. 

The left-eye view was captured at 15:41:39 GMT from a distance of 4274 km from Lutetia’s surface and the right-eye view at 15:41:03 GMT from 4038 km (closest approach was at 15:45 GMT). 

Credit: ESA/H. Sierks (MPS, Göttingen, Germany)

But another group of grooves points to a crater not seen during Rosetta's brief flyby, in the asteroid's southern hemisphere.

Its implied presence has earned it the nickname 'Suspicio'. The grooves related to Suspicio cover a large area on the asteroid, suggesting it may span several tens of kilometres .

By comparison, Massilia, the largest known crater on Lutetia, is about 55 km wide, and the largest of the polar cluster is about 34 km across.

"These three major impacts seriously deformed Lutetia's surface," adds Sebastien.

Looking face on at the North Pole Crater Cluster (purple outline) on asteroid Lutetia, with Massilia crater to the lower left (red outline). 

Marked on the image are the concentric grooves or ‘lineaments’ associated with the large craters. 

The lineaments coloured blue infer the presence of a large crater, nicknamed Suspicio, on the unseen portion of Lutetia. 

Yellow denotes lineaments not associated with any of the craters discussed in this study. 

Credit: ESA /Rosetta /MPS for OSIRIS Team MPS /UPD /LAM /IAA /SSO /INTA /UPM /DASP /IDA

"As with grooves seen on other asteroids that may also be associated with impact events, this study provides new insights into the catastrophic history of these small bodies."

By observing how subsequent small craters lie over the grooves on Lutetia, the scientists determined the relative ages of the three larger cratering events.

Massilia is thought be the oldest of the three craters and the polar cluster the youngest, with Suspicio between.

The authors also looked at other, independent measurements of Lutetia, including ground-based observations with the Infrared Telescope Facility and space-based observations with ESA's Herschel and NASA's Spitzer.

The infra-red location of Suspicio crater on the unseen southern hemisphere of asteroid Lutetia (marked in blue). 

The hidden crater could be up to 45 km in diameter, the blue outlines correspond to diameter estimates of 15, 30 and 45 km, respectively. 

The crater is inferred based on the numerous grooves or ‘lineaments’ seen concentric to the crater in the northern hemisphere of the asteroid. 

There are no image data available for this side of the asteroid, as can be inferred from the blank shape model. 

Credit: ESA /Rosetta /MPS for OSIRIS Team MPS /UPD /LAM /IAA /SSO /INTA /UPM /DASP /IDA

The Infrared Telescope Facility suggested different compositions between the northern and southern hemisphere of the asteroid.

Sebastien and his colleagues propose that a large impact, presumably the one forming Suspicio, excavated enough material of a different composition to account for the observed differences.

"Our study ties together several independent analyses of Lutetia into one coherent story that is consistent with the presence of a large impact crater on the far side of the asteroid," says co-author Michael Küppers, from ESA's Space Astronomy Centre in Spain.

"Four years on and we are delighted still to be learning from just two hours' worth of data collected during the Lutetia flyby," says Matt Taylor, ESA's Rosetta project scientist.

"Rosetta is now in its main mission phase at its comet, where we are on the cusp of fantastic results. Rosetta is a true small bodies mission, two asteroids and one comet in single trip."

More information: S. Besse, M. Küppers, O.S. Barnouin, N. Thomas, J. Benkhoff, "Lutetia׳s lineaments," Planetary and Space Science, Volume 101, 15 October 2014, Pages 186-195, ISSN 0032-0633, dx.doi.org/10.1016/j.pss.2014.07.007

NASA's LRO mission: Musical space-weather reports

The Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on NASA's Lunar Reconnaissance Orbiter has six detectors to monitor the energetic charged particles from galactic cosmic rays and solar events. 

Credit: NASA/GSFC

The latest tool for checking space weather is an internet radio station fed by data from NASA's Lunar Reconnaissance Orbiter (LRO).

The radio station essentially operates in real time, receiving measurements of how much radiation the spacecraft is experiencing and converting those into a constant stream of music.

The radiation levels determine which instrument is featured, the musical key being used and the pitches played.

"Our minds love music, so this offers a pleasurable way to interface with the data," said the leader of the music project, Marty Quinn of the University of New Hampshire, Durham.

"It also provides accessibility for people with visual impairments." The radiation levels are determined by LRO's Cosmic Ray Telescope for the Effects of Radiation (CRaTER).

Equipped with six detectors, CRaTER monitors the energetic charged particles from galactic cosmic rays and solar events. The instrument makes two kinds of crucial measurements.

One type studies the interaction of radiation in space with a material that is like human tissue; this is helping scientists assess the effects that exposure would have on people and organisms.

The other type looks at radiation hitting the moon and the products generated by that interaction, which provides a way to explore the composition of the regolith on the moon.

"CRaTER has discovered wide-ranging and fundamental aspects of such radiation," said Nathan Schwadron, the principal investigator for CRaTER.

"For example, we have discovered that tissue-equivalent plastics and other lightweight materials can provide even more effective protection than standard shielding, such as aluminum."

Each detector on CRaTER reports the number of particles registered every second.

These counts are relayed to CRaTER Live Radio, where software converts the numbers into pitches in a four-octave scale. Six pitches are played every second, one for each detector.

Higher, tinkly pitches indicate less activity, whereas lower, somber-sounding pitches indicate more activity.

The software selects the primary instrument and a musical key based on recent activity. At the lowest radiation levels, the main instrument will be a piano, playing pitches from one of the major scales.

But as the peak radiation level climbs, one of the minor scales will be selected instead, and the piano will be replaced by one of seven other instruments.

Volcanic eruption: Stromboli Lava Flow on Sciara del Fuoco

The activity at Stromboli has lately increased, over the holidays. Since 23 December small lava overflows occurred from the eastern crater area and produced lava flows with varying length on the upper part of the Sciara del Fuoco (360deg view).

Yesterday afternoon and evening, it looked as if the lava flow had increased and extended on a good portion of the Sciara where lava blocks detaching from the flow rolling down created a dense incandescent stream.

It is still unclear whether the flows come from a new vent at the eastern crater terrace or whether they are overflows of lava from an existing vent.

The seismic activity has increased and in addition to the tremor, explosion and rockfall, signals are elevated as well.

Such lava (over-)flows from the crater are usually relatively short-lived, but come often in phases.

All news about: Stromboli volcano

Mars Impact Crater and Ejecta - Image

This enhanced-colour image shows an impact crater and its ejecta and scientists claim it shows some of the best exposures of ancient bedrock on Mars. 

The different colours in this image each represent a different type of rock.

NASA Mars HiRISE Image: Gully Monitoring on Crater Slopes in Terra Sirenum

These crater gullies lie on the northern wall of an unnamed 9-kilometer diameter southern hemisphere crater in Terra Sirenum. The image was acquired during early winter in the southern hemisphere, so the crater wall is in shadow.

These gullies were first imaged by HiRISE in 2006. Since that time the possible role of seasonal frost in gully formation along with the association of polygonal terrain with these and other gullies has garnered considerable interest.

As a result, these gullies have become one of several locations being monitored by HiRISE throughout multiple Mars years. Over a dozen images of these gullies have been acquired to date throughout different Mars seasons.

In this image, frost (likely water-ice) is once again forming on these southern hemisphere mid-latitude crater slopes.  

The subimage shows gullies on the shadowed polar-facing slope. The large dynamic range of the HiRISE camera allows one to see into the shadows dimly lit by sunlight scattered by the surface and the atmosphere.

These gullies are thinly veiled with frost and range in width from several meters to tens of meters and in length from a couple kilometers or so. Dark regions within the gullies are warmer areas where frost likely evaporated or melted exposing the darker underlying surface.

NASA Researchers Estimate Ice Content of Crater at Moon's South Pole

Elevation (left) and shaded relief (right) image of Shackleton, a 21-km-diameter (12.5-mile-diameter) permanently shadowed crater adjacent to the lunar south pole. 

The structure of the crater's interior was revealed by a digital elevation model constructed from over 5 million elevation measurements from the Lunar Orbiter Laser Altimeter. 

Credit: NASA/Zuber, M.T. et al., Nature, 2012

NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft has returned data that indicate ice may make up as much as 22 percent of the surface material in a crater located on the moon's south pole.

The team of NASA and university scientists using laser light from LRO's laser altimeter examined the floor of Shackleton crater.

They found the crater's floor is brighter than those of other nearby craters, which is consistent with the presence of small amounts of ice.

This information will help researchers understand crater formation and study other uncharted areas of the moon. The findings are published in Thursday's edition of the journal Nature.

"The brightness measurements have been puzzling us since two summers ago," said Gregory Neumann of NASA's Goddard Space Flight Center in Greenbelt, Md., a co-author on the paper.

"While the distribution of brightness was not exactly what we had expected, practically every measurement related to ice and other volatile compounds on the moon is surprising, given the cosmically cold temperatures inside its polar craters."

The spacecraft mapped Shackleton crater with unprecedented detail, using a laser to illuminate the crater's interior and measure its albedo or natural reflectance. The laser light measures to a depth comparable to its wavelength, or about a micron.

That represents a millionth of a meter, or less than one ten-thousandth of an inch. The team also used the instrument to map the relief of the crater's terrain based on the time it took for laser light to bounce back from the moon's surface. The longer it took, the lower the terrain's elevation.

NASA HiRISE Image: A Wild Assortment of Jumbled Rocks

This image covers a region of Mars near Nili Fossae that contains some of the best exposures of ancient bedrock on Mars.

The enhanced-colour subimage shows part of the ejecta from an impact crater.

The impact broke up already diverse rocks types and mixed them together to create this wild jumble of colours, each representing a different type of rock.

NASA MARS HiRISE website

You can also visit the NASA MARS HiRise 3D site Anaglyph

ESA Space Image: Lava crater in Mauritania, Sahara

The Sahara remains amazing. An old lava crater in Mauritania.

ESA ISS Image: Manicouagan impact crater, Quebec

From warm Pacific to the cold plains of Canada in 30 minutes. Manicouagan impact crater, Quebec.

Andre Kuipers looks down on the Manicougan impact crater in Canada from his vantage point onboard the International Space Station.

Credit: ESA/NASA

MARS HiRISE Image: Very Fresh Impact Crater Superposing a Wrinkle Ridge in Hesperia Planum

The ridge captured in this HiRISE image is called a wrinkle ridge.

This wrinkle ridge is located in Hesperia Planum, a region of over two million square kilometers (over 770,000 square miles) in the southern highlands of Mars.

It is located northwest of the Hellas basin and adjacent to Tyrrhena Patera and contains abundant orthogonal and intersecting wrinkle ridges.

Wrinkle ridges are long, winding topographic highs and are often characterized by a broad arch with superposed narrow asymmetric ridges. These features have also been identified on the Moon, Mercury, and Venus.

Their origin is attributed to horizontal compression or shortening of the crust due to faulting and folding. They commonly have asymmetrical cross sectional profiles and an offset in elevation on either side of the ridge.

Superposing or located on top of the wrinkle ridge, is a very fresh impact crater. We can tell that this crater is fresh because of its relatively sharp or crisp rim and unmodified shape.

If you look closely, you can see faint rays of relatively fine material, boulders, and smaller secondary craters radiating from the crater and superposing the wrinkle ridge and older surrounding craters.

Meteor impact crater in Canada

Meteor impact crater in Canada

Credit: ESA/NASA

Messenger Mercury: Collision With Giant Asteroid May Have Caused Spin Change

Updated NASA Messenger probe images obtained on September 29, 2011, shows a large crater with a floor partially covered by large numbers of Coalesced Hollows.

Mercury may have a lot in common with Earth, but close-up images and data captured by NASA'S MESSENGER probe this year show it's still a bit of a planetary weirdo. REUTERS/NASA/Handout

A new study suggests that Mercury's strange spin may have been caused by collision with a giant asteroid, which may have also caused Caloris Basin, Mercury's largest impact crater.

"Mercury once had a spin rate synchronous with the sun, like the moon with the Earth," said study co-author Alexandre Correia, a planetary scientist at the University of Aveiro in Portugal.

However, a giant asteroid may have collided with planet causing it to rotate three times on its axis for every two orbits it completes around the sun.

According to the study, computer models suggest that a giant impact from an asteroid knocked the planet it into its current strange configuration.

The space rock would have been at least 43 miles wide and 550 trillion metric tons in mass, or 1/600,000 the mass of Mercury, Correia said.

Evidence of the collision could include Mercury's largest impact crater, the Caloris Basin as it matches the predicted size, age and location of the impact.

Such an impact might also explain certain hollows seen on Mercury's surface, the researchers said.

Scientists had long assumed that Mercury was tidally locked with the sun, however, radar observations revealed that the planet led a far stranger life, rotating three times on its axis for every two orbits it completes around the sun.

NASA's Dawn: Reaches Lowest Orbit Above Vesta

This image of the giant asteroid Vesta was obtained by NASA's Dawn spacecraft in the evening Nov. 27 PST (early morning Nov. 28, UTC), as it was spiraling down from its high altitude mapping orbit to low altitude mapping orbit. Full frame image available at NASA/JPL-Caltech.

NASA's Dawn spacecraft has successfully maneuvered into its closest orbit around the giant asteroid Vesta, beginning a new phase of science observations.

The spacecraft is now circling Vesta at an altitude averaging about 130 miles (210 kilometers) in the phase of the mission known as low altitude mapping orbit.

"Dawn has performed some complicated and beautiful choreography in order to reach this lowest orbit," said Marc Rayman, Dawn chief engineer and mission manager based at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We are in an excellent position to learn much more about the secrets of Vesta's surface and interior."

HiRISE: Gullies and Lobate Material in a Crater in the Nereidum Montes

This image includes a crater that has been heavily influenced by later geologic processes.

First of all, terrain-altering or -burying processes have eliminated much of the pattern of ejecta that surrounds fresh craters.

The crater also appears fairly flat-floored with short walls (not very deep) for its size, indicating material has filled it in.

These modifying effects may be due to deposition and activity of ice-rich or other mantling sediments deposited at some point in the past.

Finally, the crater clearly exhibits gullies starting on its northern wall and extending to its center.

The arc-shaped ridge inside the southern edge of the crater, partially buried by the filling material, is particularly curious - it could be a wind-caused or other accumulation of crater-fill material.

One of the rationales for acquiring an image of this location is to investigate the relationship between these features; HiRISE's full resolution can provide better details of the terrain.

NASA Messenger: Mercury Dominici crater

This NASA Messenger Satellite colour image shows the Dominici Crater on the planet Mercury.

Picture: AFP/NASA

Strange Hollows Discovered on Mercury

Hollows inside the Raditladi impact basin. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.

NASA's MESSENGER spacecraft has discovered strange hollows on the surface of Mercury. Images taken from orbit reveal thousands of peculiar depressions at a variety of longitudes and latitudes, ranging in size from 60 feet to over a mile across and 60 to 120 feet deep. No one knows how they got there.

"These hollows were a major surprise," says David Blewett, science team member from the Johns Hopkins University Applied Physics Laboratory.

"We've been thinking of Mercury as a relic - a place that's really not changing much anymore, except by impact cratering. But the hollows appear to be younger than the craters in which they are found, and that means Mercury's surface is still evolving in a surprising way."

Mars Reconnaissance Orbiter spotted similar depressions in the carbon dioxide ice at Mars' south pole, giving that surface a "swiss cheese" appearance. But on Mercury they're found in rock and often have bright interiors and halos.

"We've never seen anything quite like this on a rocky surface."

If you could stand in one of these "sleepy" hollows on Mercury's surface, you'd find yourself, like Ichabod Crane, in a quiet, still, haunting place, with a black sky above your head.

"There's essentially no atmosphere on Mercury," explains Blewett. "And with no atmosphere, wind doesn't blow and rain doesn't fall. So the hollows weren't carved by wind or water. Other forces must be at work."

As the planet closest to the Sun, Mercury is exposed to fierce heat and extreme space weather. Blewett believes these factors play a role.

A key clue, he says, is that many of the hollows are associated with central mounds or mountains inside Mercury's impact craters.

These so-called "peak rings" are thought to be made of material forced up from the depths by the impact that formed the crater. Excavated material could be unstable when it finds itself suddenly exposed at Mercury's surface.

"Certain minerals, for example those that contain sulfur and other volatiles, would be easily vaporized by the onslaught of heat, solar wind, and micrometeoroids that Mercury experiences on a daily basis," he says.

"Perhaps sulphur is vapourising, leaving just the other minerals, and therefore weakening the rock and making it spongier. Then the rock would crumble and erode more readily, forming these depressions."

Chicxlub Impact Crater: Princeton model shows fallout of a giant meteorite strike

The Princeton model shows (at left) that the structure of the Earth's surface at the time of the meteorite impact that caused the Chicxulub crater in Mexico would have placed the Deccan Traps in India far west of the crater's antipodal point, instead of directly opposite of the impact. 

Correspondingly, the model shows (at right) that the meteorite struck far east of the antipodal point for the Deccan Traps, which are remnants of large volcanoes thought to have contributed to the mass extinction event at the end of the Cretaceous period. 

The model also revealed that the Chicxulub impact, when the Earth's surface and shape are considered, would have likely been too small to cause the Deccan Traps. (Images by Conor Myhrvold)

Seeking to better understand the level of death and destruction that would result from a large meteorite striking the Earth, Princeton University researchers have developed a new model that can not only more accurately simulate the seismic fallout of such an impact, but also help reveal new information about the surface and interior of planets based on past collisions.

Princeton researchers created the first model to take into account Earth's elliptical shape, surface features and ocean depths in simulations of how seismic waves generated by a meteorite collision would spread across and within the planet.

Current projections rely on models of a featureless spherical world with nothing to disrupt the meteorite's impact, the researchers report in the October issue of Geophysical Journal International.

The researchers, based in the laboratory of Jeroen Tromp, the Blair Professor of Geology in Princeton's Department of Geosciences, simulated the meteorite strike that caused the Chicxulub crater in Mexico, an impact 2 million times more powerful than a hydrogen bomb that many scientists believe triggered the mass extinction of the dinosaurs 65 million years ago.

The team's rendering of the planet showed that the impact's seismic waves would be scattered and unfocused, resulting in less severe ground displacement, tsunamis, and seismic and volcanic activity than previously theorised.

The Princeton simulations also could help researchers gain insight into the unseen surface and interior details of other planets and moons, the authors reported.

The simulations can pinpoint the strength of the meteorite's antipodal focus - the area of the globe opposite of the crater where the energy from the initial collision comes together like a second, smaller impact.

The researchers found this point is determined by how the features and composition of the smitten orb direct and absorb the seismic waves.

Scientists could identify the planet or moon's characteristics by comparing a crater to the remnants of the antipodal point and calculating how the impact waves spread.

Lead author Matthias Meschede of the University of Munich developed the model at Princeton through the University's Visiting Student Research Collaborators program with co-authors Conor Myhrvold, who earned his bachelor's degree from Princeton in 2011, and Tromp, who also is director of Princeton's Institute for Computational Science and Engineering and a professor of applied and computational mathematics. Meschede describes the findings as follows:

DLR Vesta: an asteroid full of surprises

South pole centred colour coded digital terrain model of the 'basin'

The latest 3D images, which show the whole asteroid, make something very clear – Vesta holds quite a number of challenges for the scientists on the Dawn team.

"For example, we can see a very large impact crater in the south polar region, the likes of which we have never seen before," emphasises Jaumann.

The shape and structure of the crater differ from every other impact crater in the Solar System.

"We are unable to find similar craters on other bodies, and cannot yet explain exactly what has caused it."

Another critical question faced by the planetary scientists is whether or not there has been volcanism on Vesta.

The numerous impact craters are not making this easy for scientists. "Any evidence of volcanic activity has been covered by impact ejecta and our current challenge is to find traces of volcanic deposits," explains Jaumann.

Dark material associated with craters that appears in some of the 3D images might provide the scientists with information on potential volcanic activity. But it could also be the remnants of the impacting body, in which case, the search for signs of volcanism must continue.

More information on Vesta at DLR Portal - Vesta - an asteroid full of surprises

The Moon: Crater Petavius

The Moon’s Crater Petavius seen to the lower right of the photograph is almost 200 kilometres wide and over three kilometres deep, with a central peak reaching nearly two kilometres from the crater floor.

The Moon’s many craters have been formed by meteorites, asteroids and comets which have crashed into the lunar surface over billions of years.

Picture: George Tarsoudis