Posted on by Ken Kremer

Dawn Discovers Surprise 2nd Giant South Pole Impact Basin at Strikingly Dichotomous Vesta

Southern Hemisphere of Vesta; Rheasilvia and Older Basin. Colorized shaded-relief map showing identification of older 375-kilometer-wide impact basin beneath and overlapping with the more recent Rheasilvia impact structure at asteroid Vesta’s South Pole. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

[/caption]

Scientists leading NASA’s Dawn mission have discovered a 2nd giant impact basin at the south pole of the giant asteroid Vesta, which has been unveiled as a surprisingly “dichotomous” and alien world. Furthermore, the cosmic collisions that produced these two basins shuddered through the interior and created vast Vestan troughs, a Dawn scientist told Universe Today.

The newly discovered impact basin, nicknamed ‘Older Basin’, is actually significantly older in age compared to the initially discovered South Pole basin feature named ‘Rheasilvia’ – perhaps by more than a billion years. And that is just one of the many unexplained mysteries yet to be reconciled by the team as they begin to sift through the millions of bits of new data streaming back daily to Earth.

Scientists speculate that ‘Older Basin’ is on the order of 3.8 Billion years old, whereas ‘Rheasilvia’ might be as young as about 2.5 Billion years, but those are just tentative estimates at this time and subject to change. Measurements so far indicate Rheasilvia is composed of basaltic material.

Shaded-relief topographic map of Vesta southern hemisphere showing two large impact basins - Rheasilvia and Older Basin.
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

“We found many surprising things at Vesta, which is quite unique and the results have exceeded our expectations”, said Dr. Carol Raymond, Dawn deputy principal investigator, of NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

Researchers presented the latest findings from Dawn’s initial science mapping orbit at a news briefing at the annual meeting of the Geological Society of America in Minneapolis, Minn., on Oct. 13.

The team considers Vesta to be the smallest terrestrial planet.

Since achieving orbit in July, Dawn’s Framing Cameras (FC) have imaged most of Vesta at about 250 meter resolution and the Visible and Infrared mapping spectrometer(VIR) at about 700 meter resolution. The measurements were collected at the survey orbit altitude of 2700 km. Before Dawn, Vesta was just a fuzzy blob in humankind’s most powerful telescopes.

Vesta from Hubble (top) as a fuzzy blob and from Dawn in orbit (bottom) in crystal clear high resolution.
Credit: NASA/JPL-Caltech/ UCLA/MPS/DLR/IDA

“There is a global dichotomy on Vesta and a fundamental difference between the northern and southern hemispheres”, said Raymond. “The northern hemisphere is older and heavily cratered in contrast to the brighter southern hemisphere where the texture is more smooth and there are lots of sets of grooves. There is a massive mountain at the South Pole. One of the more surprising aspects is the set of deep equatorial troughs.”

“There is also a tremendous and surprising diversity of surface color and morphology. The south is consistent with basaltic lithology and the north with impacts. We are trying to make sense of the data and will integrate that with the high resolution observations we are now collecting.”

Indeed Vesta’s completely unique and striking dichotomy can be directly traced back to the basins which were formed by ancient cataclysmic impacts resulting in shockwaves that fundamentally altered the surface and caused the formation of the long troughs that ring Vesta at numerous latitudes.

“The troughs extend across 240 degrees of longitude,” said Debra Buczkowski, Dawn participating scientist, of the Applied Physics Laboratory at Johns Hopkins University, Laurel, Md. “Their formation can be tied back to the two basins at the South Pole.”

Asteroid Vesta and Equatorial Grooves
This full view of the giant asteroid Vesta was taken by NASA’s Dawn spacecraft, as part of a rotation characterization sequence on July 24, 2011, at a distance of 3,200 miles (5,200 kilometers). A rotation characterization sequence helps the scientists and engineers by giving an initial overview of the character of the surface as Vesta rotated underneath the spacecraft. This view of Vesta shows impact craters of various sizes and grooves parallel to the equator. The resolution of this image is about 500 meters per pixel. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

In an exclusive follow up interview with Universe Today, Raymond said “We believe that the troughs formed as a direct result of the impacts,” said “The two sets of troughs are associated with the two large basins [Rheasilvia and Older Basin].”

“The key piece of evidence presented was that the set of troughs in the northern hemisphere, that look older (more degraded) are circumferential to the older impact basin,” Raymond told me.

“The equatorial set are circumferential to Rheasilvia. That Rheasilvia’s age appears in places to be much younger is at odds with the age of the equatorial troughs. An explanation for that could be resurfacing by younger mass wasting features (landslides, slumps). We will be working on clarifying all these relationships in the coming months with the higher resolution HAMO (High Altitude Mapping Orbit) data.”

Dawn has gradually spiraled down closer to Vesta using her exotic ion thrusters and began the HAMO mapping campaign on Sept. 29.

Surface features are dated by crater counting methodology.

“Preliminary crater counting age dates for the equatorial trough region yields a very old age (3.8 Billion years). So there is a discrepancy between the apparent younger age for the Rheasilvia basin and the old age for the troughs. These could be reconciled if Rheasilvia is also 3.8 Billion years old but the surface has been modified by slumping or other processes,” Raymond elaborated.

Time will tell as further data is analyzed.

Dawn launch on September 27, 2007 by a Delta II Heavy rocket from Cape Canaveral Air Force Station, Florida. Credit: Ken Kremer

“Vesta is full of surprises, no more so than at the South Pole,” said Paul Schenk at the GSA briefing. Schenk is a Dawn participating scientist of the Lunar and Planetary Institute, Houston, Texas.

The ‘Rheasilvia’ basin was initially discovered in images of Vesta taken a decade ago by the Hubble Space Telescope which revealed it as a gaping hole in the southern hemisphere. But it wasn’t until Dawn entered orbit on July 16, 2011 after a nearly four year interplanetary journey that Earthlings got their first close up look at the mysterious polar feature and can now scrutinize it in detail to elucidate its true nature.

“The South Pole [Rheasilvia] basin is a roughly circular, impact structure and a deep depression dominated by a large central mound,” said Schenk. “It shows sharp scarps, smooth areas, landslide deposits, debris flows. It’s about 475 km in diameter and one of the deepest (ca. 20 -25 km) impact craters in the solar system.”

The central peak is an enormous mountain, about 22 km high and 180 km across- one of the biggest in the solar system. “It’s comparable in some ways to Olympus Mons on Mars,” Schenk stated.

“We were quite surprised to see a second basin in the mapping data outside of Rheasilvia. This was unexpected. It’s called ‘Older Basin’ for now.”

‘Older Basin’ is about 375 km in diameter. They overlap at the place where Rheasilvia has a missing rim.

“These basins are interesting because we believe Vesta is the source of a large number of meteorites, the HED meteorites that have a spread of ages,” Schenk explained.

Images showing key components of Rheasilvia impact basin on Vesta in high resolution ,referred to Shaded-relief topographic map. Credit: NASA/JPL-Caltech/ UCLA/MPS/DLR/IDA

Multiple large impacts over time may explain the source of the HED (Howardite, Eucrite and Diogenite) meteorites.

“We did expect large impacts on Vesta, likely associated with the late heavy bombardment recognized in the lunar impact record,” Raymond told Universe Today. “The surprising element is that the two apparently largest impacts – keeping in mind that other larger impact basins may be lurking under the regolith – are overlapping.”

Dawn’s VIR spectrometer has detected pyroxene bands covering Vesta’s surface, which is indicative of typical basaltic material, said Federico Tosi, a VIR team member of the Italian Space Agency, Rome. “Vesta has diverse rock types on its surface.”

“VIR measured surface temperatures from 220K to 270 K at the 5 micron wavelength. The illuminated areas are warmer.”

So far there is no clear indication of olivine which would be a marker for seeing Vesta’s mantle, Tossi elaborated.

The VIR spectrometer combines images, spectral information and temperature that will allow researchers to evaluate the nature, composition and evolutionary forces that shaped Vesta’s surface.

The team is absolutely thrilled to see a complicated geologic record that’s been preserved for study with lots of apparent surface layering and surprisingly strong and complex structural features with a large range of color and brightness.

Stay tuned for a year of Vestan delights !

Asteroid Vesta from Dawn
South Pole Rheasilvia basin is at lower right. NASA's Dawn spacecraft obtained this image of the giant asteroid Vesta with its framing camera on July 24, 2011 from a distance of about 3,200 miles (5,200 kilometers). Dawn entered orbit around Vesta on July 16, and will spend a year orbiting the body.
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Read Ken’s continuing features about Dawn and Vesta starting here:
Amazing New View of the Mt. Everest of Vesta
Dramatic 3 D Imagery Showcases Vesta’s Pockmarked, Mountainous and Groovy Terrain
Rheasilvia – Super Mysterious South Pole Basin at Vesta
Space Spectacular — Rotation Movies of Vesta
3 D Alien Snowman Graces Vesta
NASA Unveils Thrilling First Full Frame Images of Vesta from Dawn
Dawn Spirals Down Closer to Vesta’s South Pole Impact Basin
First Ever Vesta Vistas from Orbit – in 2D and 3D
Dawn Exceeds Wildest Expectations as First Ever Spacecraft to Orbit a Protoplanet – Vesta

Posted on by Nancy Atkinson

Human Mission to an Asteroid: Getting There With the New Space Launch System

The new SLS on the launchpad. Credit: NASA

[/caption]

With NASA’s announcement of its new, mammoth Space Launch System (SLS), preparations can begin in earnest for the first human mission to an asteroid. The SLS will take the Orion Multipurpose Crew Vehicle (MPCV) on the first human forays into deep space, out of the Earth/Moon system. “We are definitely excited about it,” Laurence Price, Lockheed Martin’s Orion deputy program manager told Universe Today during a briefing last week. “It is very good to get this baselined and be able to move forward.”

Lockheed Martin has been working on the Orion MPCV, which was originally part of the Constellation program to return to the Moon. But NASA has now been given a presidential directive to land astronauts on an asteroid by 2025, a mission that some say represents the most ambitious and audacious plan yet for the space agency. Orion will likely be re-worked and updated for potential “stepping stone” missions that will take humans to possible destinations such as lunar orbit, the Lagrange points, asteroids, and potentially the moons of Mars. The ultimate destination on this path is to send humans to the Red Planet.

Stepping stone destinations on the way to Mars. Credit: Lockheed Martin.

Billed as the biggest rocket ever built, the first incarnation of NASA’s SLS heavy-lift booster — which was unveiled on Sept. 14, 2011 — will stand over 30 stories tall, have a mass of 2.5 million kg (5.5 million pounds) and use a liquid hydrogen and liquid oxygen propulsion system, with 5 space shuttle main engines and an improved J-2X engine for the upper stage. (NASA just tested one of those engines). The SLS will have an initial lift capacity of 70 metric tons (mT), or about 69,853 kg (154,000 pounds) of payload into low Earth orbit. For reference, that’s more than double the lift capacity of any current launch vehicle, and it is estimated to be able to generate 10% more thrust than the Saturn 5 rockets produced at liftoff, the launchers that sent the Apollo missions to the Moon.

Later, to send the Orion and a service module out into space, the SLS would add two more RD-25D/E engines on the first stage, and the “evolved” architecture would be able to lift 130 metric tons, or 129,727 kg (286,000 pounds) of mass to low Earth orbit. This would increase the mass of the stack to 2.6 million kg (6.5 million pounds) and it would stand as tall as a 40-story building. This configuration would enable thrust of 4.2 million kg (9.2 million pounds), 20% more than the Saturn 5.

But Lockheed Martin is still in the initial stages of learning about the capabilities and timelines of the new launch system so they can produce the best version of Orion to pair with the SLS.

“While there are some challenges,” Price said, “we have been looking at various configurations of the architecture over the past year, so a lot of work has already been going on. So, any of the initial challenges, we have already worked toward mitigating.”

There are several differences between SLS and Constellation, Price said, with SLS having potentially a liquid booster with solid strap-ons instead of a solid first stage. “But we’ve been flying in space for 50 years and all the analytical tools to predict the environments, flight trajectories and flight conditions are all fairly straightforward, and we’re working to close on it. The launch vehicle design change is not a big perturbation on our ability to continue to mature the vehicle.”

In factoring the capability of how much mass the SLS can launch to deep space, Lockheed Martin can begin to work on how they would manifest the various parts of the mission.

“For example, would we launch the two spacecraft together on one rocket,” said Josh Hopkins from Lockheed Martin, in an interview with Universe Today, “and like Apollo, go to deep space quickly, or would we do what Constellation was planning, where you’d launch the larger pieces on the heavy lift vehicle and launch the crew separately on a second launch and connect them in Earth orbit?”

Hopkins is the Principal Investigator for Advanced Human Exploration Missions at Lockheed Martin, and leads a team of engineers who develop plans and concepts for a variety of future human exploration missions, including visits to asteroids.

The Orion casule in an Acoustic Chamber for testing at Lockheed Martin. Credit: Lockheed Martin

“If the two are launched separately,” Hopkins continued, “then you’d have to allocate a few days in orbit to have the two hook up, or one scrubbed launch could ruin the attempt. So those are the top level kinds of things we are looking forward to finding out from NASA. At the detailed level, we’re working on things like what the flight environments will be like, how much load will the spacecraft see. What we’ve inferred from the studies we’ve been doing is that we think that Orion is already designed to a pretty rigorous set of acoustics, dynamic pressure and G-loads during ascent.”

“We already know a lot about this vehicle, its environment, load conditions and trajectory,” Price said, “so we are accommodating the unique capability of the launch vehicle into the design of the Orion MPCV. We are already converging on how this vehicle will fly, and as soon as possible, we will transition to flying our test flights on early versions of the SLS.”

Lockheed Martin is targeting late 2013 or early 2014 for their first flight test of the Orion MPCV and they have reserved a Delta 4 Heavy for an unpiloted launch from Kennedy Space Center, but they are still evaluating what launcher would be best.

“We are identifying what the best test booster will be,” Price said, “and are trying to maximize the benefit to both programs, the launch system maturation and our spacecraft.”

An artist's concept shows the Orion Multipurpose Crew Vehicle and future destinations for human exploration beyond Earth orbit: the moon, an asteroid and Mars. Credit: NASA

As far as actually sending humans to an asteroid, there are many details to be worked out, and NASA and Lockheed Martin must allow for all the unknowns of flying humans in deep space, including a very important one of making sure humans can endure the radiation environment in space.

Hopkins said the robotic spacecraft that have flown to asteroids and Mars have tested the environment of deep space. “So, we have elegant models of how to design systems to withstand radiation shielding,” he said, “even though we don’t know the effect of deep space radiation on people, and what the environments around small asteroids actually like.” Hopkins added that redundant systems for keeping humans safe are an integral part of Orion’s design, but NASA might also first send a robotic scout mission to visit an asteroid.

Yes, there’s much to be worked out to actually send humans to an asteroid. But one initial item of importance is knowing the timing of when SLS will be ready to do a human deep space mission, as that would determine what asteroids we’d be able to go to.

And finding an asteroid that is just right is going to be a challenge, too. We’ll discuss that in the next in our series of articles on a human asteroid mission.

Previous articles in this series:

Human Mission to an Asteroid: Why Should NASA Go?

Human Mission to an Asteroid: The Orion MPCV

Posted on by Ken Kremer

Dramatic 3 D Imagery Showcases Vesta’s Pockmarked, Mountainous and Groovy Terrain

3 D Anaglyph of Craters at Rheasilvia - the South Polar Region of Vesta. This 3-D image shows the topography, craters and grooves of Vesta’s south polar region obtained by the framing camera instrument aboard NASA’s Dawn spacecraft on Aug. 23 and 28, 2011. The image has a resolution of about 260 meters per pixel.

[/caption]

Try not to plummet off a steep crater cliff or be buried under a landslide while gazing at the irresistibly alluring curves of beautiful Rheasilvia – the mythical mother of Romulus and Remus – whose found a new home at the South Pole of the giant Asteroid Vesta.

3 D is undoubtedly the best way to maximize your pleasure. So whip out your cool red-cyan anaglyph glasses to enhance your viewing experience of Rheasilvia, the Snowman and more – and maximize your enjoyment of this new 3 D collection showcasing the heavily cratered, pockmarked, mountainous and groovy terrain replete at Vesta.

3D Details of Wave-Like Terrain in the South Pole of Vesta
This image was obtained by NASA’s Dawn spacecraft from an orbit of about 1,700 miles (2,700 kilometers) above the surface of the giant asteroid Vesta. Topography in the area surrounding Vesta's south pole area shows impact craters, ridges and grooves. These images in 3D provide scientists with a realistic impression of the solid surface of the celestial body.
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Can you find the location of the 3 D image above in the 2 D South Pole image below?

Scientists and mortals have been fascinated by the enormous impact crater Rheasilvia and central mountain unveiled in detail by NASA’s Dawn Asteroid Orbiter recently arrived at Vesta, the 2nd most massive object in the main asteroid belt. Ceres is the largest object and will be Dawn’s next orbital target in 2015 after departing Vesta in 2012.

3D - A Big Mountain at Asteroid Vesta’s South Pole
Scientists were fascinated by this enormous mound inside a big circular depression at the south pole- dubbed Rheasilvia. This stereo image was recorded from an altitude of about 1,700 miles (2,700 kilometers) above the surface and shows the structure of the mountain, displayed in the right half of this 3D image. The base of the mountain has a diameter of about 125 miles (200 kilometers), and its altitude above the surroundings is about 9 miles (15 kilometers). The vicinity of the peak of the mountain shows landslides that occurred when material from the flanks of the mountain were slipping down. Also visible are tectonic structures from tension in Vesta's crust. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

“Vesta is the smallest terrestrial planet in our Solar System”, said Chris Russell in an interview with Universe Today. “We do not have a good analog to Vesta anywhere else in the Solar System.”

And the best is yet to come. In a few days, Dawn begins snapping images from a much lower altitude at the HAMO mapping orbit of ca. 685 km vs the initial survey orbit of ca, 2700 km. where most of these images were taken.

Can you find the location of the 3 D South Pole images above in the 2 D South Pole image below?

Topography of Densely Cratered Deformed Terrain
This 3 D anaglyph image shows the topography of Vesta's densely cratered terrain obtained by the framing camera instrument aboard NASA's Dawn spacecraft on August 6, 2011. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Anaglyph of the ‘Snowman' Crater. This anaglyph image shows the topography of Vesta's three craters, informally named the "Snowman," obtained by the framing camera instrument aboard Dawn on August 6, 2011. The camera has a resolution of about 260 meters per pixel. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Vesta's Ancient, Cratered Surface in 3D
This image of the giant asteroid Vesta obtained by NASA's Dawn spacecraft shows the surface of the asteroid from an orbit of about 1,700 miles (2,700 kilometers) above the surface. Numerous impact craters illustrate the asteroid's violent youth. By counting craters on distinct geological surfaces scientists can deduce relative ages of the asteroid's surface. This 3D view provides scientists the opportunity to learn more about the morphology of craters on asteroids and physical properties of the material at Vesta's surface.. Image resolution is about 260 meters per pixel. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Viewing the South Pole of Vesta and Rheasilvia Impact Basin
This image obtained by Dawns framing camera shows the south pole of the giant asteroid Vesta. Scientists are discussing whether the Rheasilvia circular structure that covers most of this image originated by a collision with another asteroid, or by internal processes early in the asteroid's history. Images in higher resolution from Dawn's next lowered orbit might help answer that question. The image was recorded from a distance of about 1,700 miles (2,700 kilometers). The image resolution is about 260 meters per pixel. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Rhea Silvia, torso from the amphitheatre at Cartagena in Spain that was rediscovered in 1988. Rhea Silvia was the mother of Romulus and Remus, the mythical founders of Rome. Source: Wikipedia

Read Ken’s continuing features about Dawn and Vesta

Rheasilvia – Super Mysterious South Pole Basin at Vesta
Space Spectacular — Rotation Movies of Vesta
3 D Alien Snowman Graces Vesta
NASA Unveils Thrilling First Full Frame Images of Vesta from Dawn
Dawn Spirals Down Closer to Vesta’s South Pole Impact Basin
First Ever Vesta Vistas from Orbit – in 2D and 3D
Dawn Exceeds Wildest Expectations as First Ever Spacecraft to Orbit a Protoplanet – Vesta
Dawn Closing in on Asteroid Vesta as Views Exceed Hubble
Dawn Begins Approach to Asteroid Vesta and Snaps First Images
Revolutionary Dawn Closing in on Asteroid Vesta with Opened Eyes

Posted on by Ray Sanders

Finding NEEMO: NASA’s Underwater Simulations Focus on Human Asteroid Mission

NEEMO engineering crew diver simulates anchoring to an asteroid surface. Image credit: NASA

[/caption]
The sight of NASA mission specialists performing mission training underwater has been fairly common over the years. On October 15th, NASA astronaut and former ISS crew member Shannon Walker will lead a different kind of underwater training mission. Walker will be leading the 15th expedition of NASA Extreme Environment Mission Operations (NEEMO), and interestingly, the crew includes Steve Squyres, head of the Mars Rover Exploration Project.

What makes NEEMO different from the other NASA underwater training simulations we’ve seen in the past?

Think asteroid.

With manned exploration of an asteroid on NASA’s roadmap, new technologies and procedures need to be created in order to ensure astronaut safety and achieve mission science goals. The NEEMO program at NASA will be putting experts to the task of developing solutions to the new challenges presented with near-Earth asteroid exploration. During NEEMO 15, NASA will test new tools, techniques and communication technologies.

Before now, NASA hasn’t given much thought to the operations necessary for a manned mission to an asteroid. With the nearly non-existent surface gravity of an asteroid, astronauts won’t be able to walk on the surface. One idea being tested is for the astronauts to anchor themselves to the asteroid. One difficulty with using anchors is that not all asteroids are made of the same materials – some asteroids are mostly metal, others are loose rubble and some are a mix of rock, metal and dust. Underwater testing on the ocean floor provides an environment that is perfectly suited for the NEEMO 15 mission, allowing NASA to simulate an environment with weak gravity and diverse materials.

Artist's concept of anchoring to the surface of an asteroid. Image credit: NASA

There are three main goals for the NEEMO 15 mission. First NASA will test methods for anchoring to the surface of the asteroid. Moving on the surface of an asteroid will require a method of connecting multiple anchors. The second major goal of the mission is to determine the best way to connect the anchor system. The third major goal will explore methods of collecting samples on the surface of an asteroid.

In addition to mission leader Shannon Walker, and Steve Squyres, the crew of NEEMO 15 includes astronaut Takuya Onishi (Japan Aerospace Exploration Agency) and David Saint-Jacques (Canadian Space Agency). Also joining the astronauts on the NEEMO 15 crew are: James Talacek and Nate Bender (University of North Carolina). Squyres is principal investigator for the Mars Exploration Rover (Spirit and Opportunity) mission, while Talacek and Bender are professional aquanauts.

Serving as support crew, NASA astronauts Stan Love, Richard Arnold and Mike Gernhardt, will participate in the NEEMO mission from the DeepWorker submersible, which they will pilot. NASA is using the DeepWorker submarine as an underwater stand-in for the Space Exploration Vehicle (SEV) which NASA has been testing separately in the “Desert RATS” field trial mission.

If you’d like to learn more about NASA’s NEEMO field test mission, visit: http://www.nasa.gov/neemo

You can view information on the NEEMO 15 crew at: http://www.nasa.gov/mission_pages/NEEMO/NEEMO15/crew.html, and follow the mission on Twitter and Facebook

Source: NASA NEEMO Press Release

Posted on by Ken Kremer

Rheasilvia – Super Mysterious South Pole Basin at Vesta is Named after Romulus and Remus Roman Mother

A False-Color Topography of Vesta's South Pole. This false-color map of the giant asteroid Vesta was created from stereo images obtained by the framing camera aboard NASA’s Dawn spacecraft. The image shows the elevation of surface structures with a horizontal resolution of about 750 meters per pixel. The terrain model of Vesta's southern hemisphere shows a big circular structure with a diameter of about 300 miles (500 kilometers), its rim rising above the interior of the structure for more than 9 miles (15 kilometers.) Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Video caption: Rheasilvia Impact Basin and Vesta shape model. This false-color shape model video of the giant asteroid Vesta was created from images taken by the framing camera aboard NASA’s Dawn spacecraft. Rheasilvia – South Pole Impact Basin – shown at bottom (left) and head on (at right). Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

‘Rheasilvia’ – that’s the brand new name given to the humongous and ever more mysterious South Pole basin feature being scrutinized in detail by Dawn, according to the missions top scientists in a Universe Today exclusive. Dawn is NASA’s newly arrived science orbiter unveiling the giant asteroid Vesta – a marvelously intriguing body unlike any other in our Solar System.

What is Rheasilvia? An impact basin? A crater remnant? Tectonic action? A leftover from internal processes? Or something completely different? That’s the hotly debated central question consuming loads of attention and sparking significant speculation amongst Dawn’s happily puzzled international science team. There is nothing closely analogous to Vesta and Rhea Silvia – and thats a planetary scientists dream come true.

“Rheasilvia – One thing that we all agree on is that the large crater should be named ‘Rheasilvia’ after the mother of Romulus and Remus, the mythical mother of the Vestals,” said Prof. Chris Russell, Dawns lead scientist, in an exclusive interview with Universe Today. Russell, from UCLA, is the scientific Principal Investigator for Dawn.

“Since we have never seen any crater just like this one it is difficult for us to decide exactly what did happen,” Russell told me. “The name ‘Rheasilvia’ has been approved by the IAU and the science team is using it.”

Craters on Vesta are being named after the Vestal Virgins—the priestesses of the Roman goddess Vesta. Other features will be named for festivals and towns of that era. Romulus and Remus were the mythical founders of Rome.
[/caption]

‘Rheasilvia’ has the science team in a quandary, rather puzzled and reevaluating and debating long held theories as they collect reams of new data from Dawn’s three science instruments – provided by the US, Germany and Italy. That’s the scientific method in progress and it will take time to reach a consensus.

Prior to Dawn’s orbital insertion in July 2011, the best views of Vesta were captured by the Hubble Space Telescope and clearly showed it wasn’t round. Scientists interpreted the data as showing that Vesta’s southern hemisphere lacked a South Pole! And, that it had been blasted away eons ago by a gargantuan cosmic collision that excavated huge amounts of material that nearly utterly destroyed the asteroid.

The ancient collision left behind a colossal 300 mile (500 km) diameter and circular gaping hole in the southern hemisphere – nearly as wide as the entire asteroid (530 km) and leaving behind an as yet unexplained and enormous central mountain peak, measuring some 9 miles (15 km) high and over 125 miles (200 km) in diameter. The mountain has one of the highest elevations in the entire solar system.

“We are trying to understand the high scarps that we see and the scarps that should be there and aren’t,” Russell explained. “We are trying to understand the landslides we think we see and why the land slid. We see grooves in the floor of the basin and want to interpret them.

“And the hill in the center of the crater remains as mysterious today as when we first arrived.”

Viewing the South Pole of Vesta and Rheasilvia Impact Basin
This image obtained by Dawns framing camera and shows the south pole of the giant asteroid Vesta. Scientists are discussing whether the Rheasilvia circular structure that covers most of this image originated by a collision with another asteroid, or by internal processes early in the asteroid's history. Images in higher resolution from Dawn's lowered orbit might help answer that question. The image was recorded from a distance of about 1,700 miles (2,700 kilometers). The image resolution is about 260 meters per pixel. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Another top Dawn scientist described Rheasilvia in this way:

“I would say that the floor of the impact feature contains chaotic terrain with multiple sets of intersecting grooves, sometimes fairly straight and often curvy, said Carol Raymond to Universe Today. Raymond is Dawn’s Deputy Principal Investigator from NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

“The crater rim is not well-expressed”, Raymond told me. “We see strong color variations across Vesta, and the south pole impact basin appears to have a distinct spectral signature.

“The analysis is still ongoing,” Russell said.


“The south is distinctly different than the north. The north has a varied spectrum and the south has a distinct spectral feature but it has little variation.” Time will tell as additional high resolution measurements are collected from the forthcoming science campaign at lower orbits.

Russell further informed that the team is rushing to pull all the currently available data together in time for a science conference and public briefing in mid-October.

“We have set ourselves a target to gather everything we know about the south pole impact feature and expect to have a press release from what ever we conclude at the GSA (Geological Society of America) meeting on October 12. “We will tell the public what the options are.”

“We do not have a good analog to Vesta anywhere else in the Solar System and we’ll be studying it very intently.”

Impressive South Pole MountainTop at Rheasilvia Crater on Vesta
This mountain, which measures about 125 miles (200 kilometers) in diameter at its base, is one of the highest elevations on all known bodies with solid surfaces in the solar system. The image has been recorded with the framing camera aboard NASA's Dawn spacecraft from a distance of about 1,700 miles (2,700 kilometers). The image resolution is about 260 meters per pixel. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Right now Dawn is using its ion propulsion system to spiral down four times closer to Vesta, as it descends from the initlal survey orbit(about 2700 km, 1700 mi) to the new science orbit, elegantly named HAMO – or High Altitude Mapping Orbit (about 685 km.)

“Our current plan is to begin HAMO on Sept. 29, but we will not finalize that plan until next week,” Dr. Marc Rayman told Universe Today. Rayman, of NASA’s JPL, is Dawn’s Chief Engineer.

“Dawn’s mean altitude today (Sept. 20) is around 680 km (420 miles),” said Rayman .

“Dawn successfully completed the majority of the planned ion thrusting needed to reach its new science orbit and navigators are now measuring its orbital parameters precisely so they can design a final maneuver to ensure the spacecraft is in just the orbit needed to begin its intensive mapping observations next week.”

Watch for lots more stories upcoming on Vesta and the Dawn mission

Read Ken’s continuing features about Dawn
Space Spectacular — Rotation Movies of Vesta
3 D Alien Snowman Graces Vesta
NASA Unveils Thrilling First Full Frame Images of Vesta from Dawn
Dawn Spirals Down Closer to Vesta’s South Pole Impact Basin
First Ever Vesta Vistas from Orbit – in 2D and 3D
Dawn Exceeds Wildest Expectations as First Ever Spacecraft to Orbit a Protoplanet – Vesta
Dawn Closing in on Asteroid Vesta as Views Exceed Hubble
Dawn Begins Approach to Asteroid Vesta and Snaps First Images
Revolutionary Dawn Closing in on Asteroid Vesta with Opened Eyes

Posted on by Tammy Plotner

Did Asteroid Baptistina Kill The Dinosaurs? Think Other WISE…

It's long been thought that a giant asteroid, which broke up long ago in the main asteroid belt between Mars and Jupiter, eventually made its way to Earth and led to the extinction of the dinosaurs. New studies say that the dinosaurs may have been facing extinction before the asteroid strike, and that mammals were already on the rise. Image credit: NASA/JPL-Caltech

[/caption]

Once upon a time, about 65 million years ago, scientists hypothesize a sizable asteroid crashed into Earth and contributed to the extinction of the dinosaurs. The evidence is a 150-kilometer-wide crater located just off the Yucatan peninsula and legend has it the 10-kilometer-wide asteroid was a fragment of a larger parent – Baptistina. Now, thanks to observations by NASA’s Wide-field Infrared Survey Explorer (WISE), we just might have to re-think that theory.

While there’s almost absolutely no doubt an asteroid crash was responsible for a cataclysmic climate change, science has never been particularly sure of what asteroid caused it. A visible-light study done by terrestrial telescopes in 2007 pointed a finger at a huge asteroid known as Baptistina. The conjecture was that about 160 million years ago, it collided with another main belt asteroid and sent pieces flying. Even though it was plausible, the theory was quickly challenged and now infra-red evidence from WISE may finally lay this family of asteroids to rest.

“As a result of the WISE science team’s investigation, the demise of the dinosaurs remains in the cold case files,” said Lindley Johnson, program executive for the Near Earth Object (NEO) Observation Program at NASA Headquarters in Washington. “The original calculations with visible light estimated the size and reflectivity of the Baptistina family members, leading to estimates of their age, but we now know those estimates were off. With infrared light, WISE was able to get a more accurate estimate, which throws the timing of the Baptistina theory into question.”

For over a year, WISE took an infra-red survey of the entire sky and asteroid-hunting portion of the mission, called NEOWISE, cataloged 157,000 members – discovering an additional 33,000 new ones. By utilizing the more accurate infra-red data, the team examined 1,056 members of the Baptistina family and discovered its break-up was closer to 80 million years ago – less than half the time previously suggested. By better knowing their size and reflectivity, researchers are able to calculate how long it would take for Baptistina members to reach their current position. The results show that in order for this particular asteroid to have caused an extinction level event, that it would have had to have impacted Earth much sooner… like about 15 million years.

“This doesn’t give the remnants from the collision very much time to move into a resonance spot, and get flung down to Earth 65 million years ago,” said Amy Mainzer, a study co-author and the principal investigator of NEOWISE at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena. Calif. “This process is thought to normally take many tens of millions of years.”

Like bouncing a super ball off the walls, resonance spots can jettison asteroids out of the main belt. This means a dinosaur-killing Baptistina event isn’t likely, but other asteroid families in NEOWISE study show similar reflective properties and one day we may be able to locate a responsible party.

“We are working on creating an asteroid family tree of sorts,” said Joseph Masiero, the lead author of the study. “We are starting to refine our picture of how the asteroids in the main belt smashed together and mixed up.”

Original Story Source: JPL/NASA News.

Posted on by Ken Kremer

Space Spectacular — Rotation Movies of Vesta

Viewing the South Pole of Vesta. This image obtained by Dawns framing camera and shows the south pole of the giant asteroid Vesta. Scientists are discussing whether the circular structure that covers most of this image originated by a collision with another asteroid, or by internal processes early in the asteroid's history. Images in higher resolution from Dawn's lowered orbit might help answer that question. The image was recorded from a distance of about 1,700 miles (2,700 kilometers). The image resolution is about 260 meters per pixel. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Take us into orbit Mr. Sulu!

The Dawn science team has released two spectacular rotation movies of the entire globe of the giant asteroid Vesta. The flyover videos give the distinct impression that you are standing on the bridge of the Starship Enterprise and gazing at the view screen as the ship enters orbit about a new planet for the first time and are about to begin an exciting new journey of exploration and discovery of the body you’re looking at below.

Thanks to NASA, DLR, ASI and Dawn’s international science and engineering team, we can all join the away team on the expedition to unveil Vesta’s alluring secrets.

Click the start button and watch protoplanet Vesta’s striking surface moving beneath from the perspective of Dawn flying above – in the initial survey orbit at an altitude of 2700 kilometers (1700 miles). Vesta is the second most massive object in the main asteroid belt and Dawn’s first scientific conquest.

Another video below was compiled from images taken earlier on July 24, 2011 from a higher altitude after Dawn first achieved orbit about Vesta and revealed that the northern and southern hemispheres are totally different.

The array of images in the videos was snapped by Dawn’s framing camera which was provided by the German Aerospace Center (DLR). The team then created a shape model from the images, according to Dr. Carol Raymond, Dawn’s Deputy Principal Investigator from NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

The shape model will aid in studying Vesta’s strikingly diverse features of mountains, ridges, valley’s, scarps, cliffs, grooves, craters, even a ‘snowman’ and much more.

Notice that not all of Vesta is illuminated – because it’s northern winter at the asteroid. Vesta has seasons like Earth and the northern polar region in now in perpetual darkness. Data is collected over the day side and radioed back to Earth over the night side.

“On Vesta right now, the southern hemisphere is facing the sun, so everywhere between about 52 degrees north latitude and the north pole is in a long night,” says Dr. Rayman, Dawn’s Chief Engineer from JPL. “That ten percent of the surface is presently impossible to see. Because Dawn will stay in orbit around Vesta as together they travel around the sun, in 2012 it will be able to see some of this hidden scenery as the seasons advance.”

Another movie highlight is a thorough look at the gigantic south pole impact basin. The circular feature is several hundred miles wide and may have been created by a cosmic collision eons ago that excavated massive quantities of material and basically left Vesta lacking a south pole.

[/caption]

The massive feature was discovered in images taken by the Hubble Space Telescope several years ago and mission scientists have been eager to study it up close in a way that’s only possible from orbit. Dawn’s three science instruments will investigate the south pole depression in detail by collecting high resolution images and spectra which may reveal the interior composition of Vesta.

Dawn entered the survey orbit on Aug. 11 and completed seven revolutions of 69 hours each on Sept. 1. It transmitted more than 2,800 pictures from the DLR framing camera covering the entire illuminated surface and also collected over three million visible and infrared spectra from the VIR spectrometer – provided by ASI, the Italian Space Agency. This results exceeded the mission objectives.

The Dawn spacecraft is now spiraling down closer using its ion propulsion system to the next mapping orbit – known as HAMO – four times closer than the survey orbit and only some 680 km (420 miles) above the surface.

Read Ken’s continuing features about Dawn
3 D Alien Snowman Graces Vesta
NASA Unveils Thrilling First Full Frame Images of Vesta from Dawn
Dawn Spirals Down Closer to Vesta’s South Pole Impact Basin
First Ever Vesta Vistas from Orbit – in 2D and 3D
Dawn Exceeds Wildest Expectations as First Ever Spacecraft to Orbit a Protoplanet – Vesta
Dawn Closing in on Asteroid Vesta as Views Exceed Hubble
Dawn Begins Approach to Asteroid Vesta and Snaps First Images
Revolutionary Dawn Closing in on Asteroid Vesta with Opened Eyes

Posted on by Nancy Atkinson

Human Mission to an Asteroid: Asteroid Field Testing

How will we work and set up a base camp on an asteroid? NASA is currently doing some field work to test technologies that could be used on future human missions to asteroids. The Desert Research And Technology Studies (D-R.A.T.S) crew is back in action, testing communication scenarios for near-Earth asteroids, and 2 new instruments from Goddard Spaceflight Center, the ExPED and VAPoR. The video shows more info.

The crew will be doing live webcasts the next few days. You can watch below, or at this link. Times of the webcast vary, so watch the side chat window for updates.
Continue reading “Human Mission to an Asteroid: Asteroid Field Testing”

Posted on by Nancy Atkinson

Human Mission to an Asteroid: The Orion MPCV

The Orion casule in an Acoustic Chamber for testing at Lockheed Martin. Credit: Lockheed Martin

Back in 2007, when the Constellation program to return to the Moon was still the program of record for NASA, a group from Lockheed Martin began investigating how they might be able to use the Orion lunar capsule to send humans on a mission to an asteroid. Originally, this plan — called Plymouth Rock — was just a study to see how an asteroid mission with Orion could possibly serve as a complement to the baseline of Constellation’s lunar mission plans.

Now, it has turned into much more.

The Orion MPCV being built and tested at Lockheed Martin in Boulder, Colorado. Credit: John O'Connor, NASATech.net. Click for super-large, pan-able image.

Thanks to John O’Connor from NASATech.net, we are able to show you some views of the Orion MPCV inside Lockheed Martin’s facilities in Boulder, Colorado. If you click on the images, you’ll be taken to the NASATech website and extremely large versions of the images that you can pan around and see incredible details of the MPCV and the building.

After canceling Constellation in February of 2010, two months later President Obama outlined sending astronauts to a nearby asteroid by 2025 and going to Mars by the mid-2030’s.

In May of 2011, NASA confirmed that the centerpiece of those missions will be the Orion – now called the Orion MultiPurpose Crew Vehicle. The repurposed Orion lunar vehicle would now be going to an asteroid, just like Josh Hopkins and his team from Lockheed Martin envisioned in their Plymouth Rock study.

Hopkins is the Principal Investigator for Advanced Human Exploration Missions, a team of engineers who develop plans and concepts for a variety of future human exploration missions.

“Normally when you take a spacecraft or a piece of hardware that has been designed for one job and you try to figure out how to use it for a different job, you discover there are all these details that don’t work out quite right,” Hopkins told Universe Today. “But we were pleasantly surprised that when we took this lunar version of Orion and applied it to an asteroid mission, it is a really flexible and capable vehicle and a lot of the requirements for the lunar mission match pretty well with the asteroid mission.”

Concept drawing of the Plymouth Rock mission to an asteroid. Credit: Lockheed Martin.

The Plymouth Rock design called for using two specially modified Orion spacecraft docked nose to nose in order to provide enough living space, propulsion, and life-support for two astronauts heading to an asteroid. But NASA has said the MPCV will be used primarily for launch and entry while a larger habitation module would be docked to the MPCV to enable a crew of 4 to travel to deep space.

Shuttle astronaut Tom Jones was impressed with the Plymouth Rock concept, but knows a larger companion vehicle will be needed for a trip to an asteroid. “Plymouth Rock is the minimalist approach to do an asteroid mission,” he said. “That’s one way to solve the redundancy problem in the short-term.”

But even developing an in-space habitat could be a matter of repackaging things we already have. “The hab module could be derived directly from what we’ve done for space station, or it could be a commercial inflatable like from Bigelow, so that might be tried out by a commercial station or hotel in the next 10 years, so that would be demonstrated technology,” Jones said.

The Orion MPCV along with some of the people on the team that is developing and testing the capsule at the Lockheed Martin facility in Boulder, Colorado. Credit: John O'Connor, NASATech.net. Click for large, pan-able image.

“Basically the tradeoff between a larger in-space habitat module versus the dual Orion approach is that by having a separate habitat you have more living space, more storage space, and there is the potential that it would be better for performing spacewalks,” said Hopkins. “But then you have to invest the costs for developing that system.”

Hopkins added that when he and his team initially conceived the Plymouth Rock mission, they were trying to figure out how to do an asteroid mission for as little as possible. Using two Orions was cheaper than developing a module specific to an asteroid mission.

“For Plymouth Rock, we had spelled out the need to basically increase the amount of food, water, oxygen and storage in the spacecraft, and some of that is accomplished by the fact of having two spacecraft,” Hopkins said.

For now, NASA hasn’t yet changed many of the requirements for the MPCV from what they previously were for the lunar vehicle, and as the mission design evolves, so might the MPCV. But so far, the lunar design seems to be working, and Hopkins said there are several design features already in Orion that make it very capable as a deep space vehicle.

For lunar missions, Orion was designed for basically 21 days with a crew on board going from Earth to the Moon and back and having a roughly have a six month “loiter period” while the crew was down on the lunar surface. That scenario would work for an asteroid mission, as a crewed flight to an asteroid would likely be about a six-month roundtrip journey, depending on the destination.

“So in things like reliability, leak rate of atmosphere in the cabin, and protection from radiation and micrometeorites, Orion is already designed for 6-7 month missions for the hardware,” Hopkins explained. “It is just not designed to have people for that long of time period.”

Orion has solar arrays rather than fuel cells like Apollo, which enable longer missions. Another big selling point is that the MPCV is designed to be 10 times safer during ascent and entry than its predecessor, the space shuttle.

“The reentry speeds are just a little bit faster for an asteroid mission than a lunar mission,” Hopkins said, “but current the thermal protection system we have should be able to handle it.”

At look inside the hatch of the Orion capsule at the Michoud Assembly Facility near New Orleans. Credit: John O'Connor, NASATech.net. Click for large, pan-able image.

Inside the MPCV is 9 cubic meters of habitable volume. “That is not total pressurized volume of the structure, but the space that’s left after computers, seats, supplies are all accounted for,” said Hopkins. “That’s about twice the size of a modern passenger van, like a Toyota Sienna.”

One big challenge is to figure out how use every nook and cranny to package a lot of supplies in a small amount of space, as the Orion could serve as a storeroom of sorts. “We think it’s possible,” Hopkins said. “We’ve done initial calculations that we can pack a reasonable amount of volume but it would be a pretty tight fit and we also have to think about the secondary things that need to be included, so that’s work that is ongoing.”

Logistically, the Orion MPCV could even support doing an EVA from the hatch on the capsule.

“We have a hatch that is big enough that an astronaut in a space suit can get out,” Hopkins said, “and the internal systems in the spacecraft are designed to tolerate the cabin being depressurized. We don’t rely on air circulation to carry the heat away from the electronics – they have their own cold plates to take the heat away. The knobs are designed to be manipulated with spacesuit gloves on, not just bare hands. A lot of those features just worked out to be pretty applicable to the asteroid mission because it was designed for a similar set of mission requirements.”

Lockheed Martin’s Space Operations Simulation Center in Colorado can simulates the MPCV docking with an asteroid. Credit: John O'Connor, NASATech.net. Click for large, pan-able image.

Hopkins knows the requirements and capabilities the Orion, as well as the in-space habitat will likely change over time, depending on the destination and the timeline. “If the plan is to go to the moons of mars or distant asteroids relatively soon, say in the late 2020’s or early 2030s, you might go ahead and build a relatively large, capable in space habitat, because you will definitely need it for those more distant missions. But if the idea were to go to the easiest asteroids to get to and do that relatively soon, then you might stick with a smaller simpler habitat module, or perhaps even the twin Orion approach.”

When the MPCV does return from a mission to an asteroid, it will likely land in the Pacific Ocean. NASA has begun some at NASA’s Langley Research Center to certify the vehicle for water landings. Engineers have dropped a 22,000-pound MPCV mockup into the basin. The test item is similar in size and shape to MPCV, but is more rigid so it can withstand multiple drops. Each test has a different drop velocity to represent the MPCV’s possible entry conditions during water landings.

So while these tests are happening and while Hopkins and his team from Lockheed Martin are working on and testing the Orion MPCV, NASA is still trying to decide on a heavy-lift launch system capable of bringing humans beyond low Earth orbit and they have not named anyone to lead the design of a human mission to an asteroid. The NASA website doesn’t even have any official information about a human asteroid mission; it only mentions “beyond low Earth orbit” as the next stop for humans.

“We’re talking about something that is going to happen in 2025 so we haven’t even decided on a spacecraft yet,” said Michael Braukus from NASA’s Exploration Systems Mission Directorate via a phone call. “We’re planning on the asteroid mission happening; it’s just that we haven’t designated a person to be responsible for the asteroid mission itself. We have the Orion MPCV under construction and we are awaiting on the decision of a space launch system, which will be the rocket that will carry it to deep space, and we’re progressing down the road, but haven’t reached a point yet where we have actually assigned someone to start developing the mission.”

So, that appears to be NASA’s current biggest hurdle to a human asteroid mission: deciding on the Space Launch System.

Previous article in this series: Human Mission to an Asteroid: Why Should NASA Go?

You can follow Universe Today senior editor Nancy Atkinson on Twitter: @Nancy_A. Follow Universe Today for the latest space and astronomy news on Twitter @universetoday and on Facebook.