Why Isn’t the Asteroid Belt a Planet?

Why Isn’t the Asteroid Belt a Planet?

It seems like there’s a strange gap in between Mars and Jupiter filled with rocky rubble. Why didn’t the asteroid belt form into a planet, like the rest of the Solar System?

Beyond the orbit of Mars lies the asteroid belt its a vast collection of rocks and ice, leftover from the formation of the solar system. It starts about 2 AU, ends around 4 AU. Objects in the asteroid belt range from tiny pebbles to Ceres at 950 km across.

Star Wars and other sci-fi has it all wrong. The objects here are hundreds of thousand of kilometers apart. There’d be absolutely no danger or tactical advantage to flying your spacecraft through it.

To begin with, there actually isn’t that much stuff in the asteroid belt. If you were to take the entire asteroid belt and form it into a single mass, it would only be about 4% of the mass of our Moon. Assuming a similar density, it would be smaller than Pluto’s moon Charon.

There’s a popular idea that perhaps there was a planet between Mars and Jupiter that exploded, or even collided with another planet. What if most of the debris was thrown out of the solar system, and the asteroid belt is what remains?

We know this isn’t the case for a few of reasons. First, any explosion or collision wouldn’t be powerful enough to throw material out of the Solar System. So if it were a former planet we’d actually see more debris.

Second, if all the asteroid belt bits came from a single planetary body, they would all be chemically similar. The chemical composition of Earth, Mars, Venus, etc are all unique because they formed in different regions of the solar system. Likewise, different asteroids have different chemical compositions, which means they must have formed in different regions of the asteroid belt.

Asteroids
Artist’s depiction of the asteroid belt between Mars and Jupiter. Credit: David Minton and Renu Malhotra

In fact, when we look at the chemical compositions of different asteroids we see that they can be grouped into different families, with each having a common origin. This gives us a clue as to why a planet didn’t form where the asteroid belt is.

If you arrange all the asteroids in order of their average distance from the Sun, you find they aren’t evenly distributed. Instead you find a bunch, then a gap, then a bunch more, then another gap, and so on. These gaps in the asteroid belt are known as Kirkwood gaps, and they occur at distances where an orbit would be in resonance with the orbit of Jupiter.

Jupiter’s gravity is so strong, that it makes asteroid orbits within the Kirkwood gaps unstable. It’s these gaps that prevented a single planetary body from forming in that region. So, because of Jupiter, asteroids formed into families of debris, rather than a single planetary body.

What do you think? What’s your favorite object in the asteroid belt. Tell us in the comments below.

Why the Asteroid Belt Doesn’t Threaten Spacecraft

Artist's impression of the asteroid belt. Image credit: NASA/JPL-Caltech

When you think of the asteroid belt, you probably imagine a region of rock and dust, with asteroids as far as the eye can see.  Such a visual has been popularized in movies, where spaceships must swerve left and right to avoid collisions.  But a similar view is often portrayed in more scientific imagery, such as the artistic rendering above.  Even the first episode of the new Cosmos series portrayed the belt as a dense collection of asteroids. But the reality is very different.  In reality the asteroid belt is less cluttered than often portrayed.  Just how much less might surprise you.

The Sloan digital sky survey (SDSS) has identified more than 100,000 asteroids in the solar system.  Not all of these lie within the asteroid belt, but there are about 80,000 asteroids in the belt larger than a kilometer.  Of course there are asteroids smaller than that, but they are more difficult to detect, so we aren’t exactly sure how many there are.

The pyramid-shaped zodiacal light cone is centered on the same path the sun and planets take across the sky called the ecliptic. This map shows the sky 90 minutes after sunset in early March facing west. Created with Stellarium
The pyramid-shaped zodiacal light cone is centered on the same path the sun and planets take across the sky called the ecliptic. This map shows the sky 90 minutes after sunset in early March facing west. Created with Stellarium

We have a pretty good idea, however, because the observations we have indicate that the size distribution of asteroids follows what is known as a power law distribution. For example, with a power law of 1, for every 100-meter wide asteroid there would be 10 with a diameter of 10 meters and 100 with a diameter of 1 meter. Based upon SDSS observations, asteroids seem to follow a power law of about 2, which means there are likely about 800 trillion asteroids larger than a meter within the belt. That’s a lot of rock. So much that sunlight scattering off the asteroid belt and other dust in the solar system is the source of zodiacal light.

But there is also a lot of volume within the asteroid belt. The belt can be said to occupy a region around the Sun from about 2.2 to 3.2 times the distance from the Earth to the Sun from the Sun (AU), with a thickness of about 1 AU. A bit of math puts that at about 50 trillion trillion cubic kilometers. So even though there are trillions of asteroids, each asteroid has billions of cubic kilometers of space on average. The asteroid belt is hardly something you would consider crowded. It should be emphasized that asteroids in the belt are not evenly distributed. They are clustered into families and groups. But even such clustering is not significant compared to the vast space it occupies.

An actual image from within the asteroid belt, taken from the NEAR probe as it was heading toward Eros (center). Credit: NASA
An actual image from within the asteroid belt, taken from the NEAR probe as it was heading toward Eros (center).
Credit: NASA

You can even do a very rough calculation to get an idea of just how empty the asteroid belt actually is. If we assumed that all the asteroids lay within a single plane, then on average there is 1 asteroid within an area roughly the size of Rhode Island. Within the entire United States there would be about 2000 asteroids, most of them only a meter across. The odds of seeing an asteroid along a cross-country road trip, much less hitting one, would be astoundingly small. So you can see why we don’t worry about space probes hitting an asteroid on their way to the outer solar system.  In fact, to get even close to an asteroid takes a great deal of effort.

Earth’s Water Story Gets A Plot Twist From Space Rock Search

Artist's conception of asteroids and a gas giant planet. Credit: Harvard-Smithsonian Center for Astrophysics

We at Universe Today have snow on our minds these days with all this Polar Vortex talk. From out the window, the snowflakes all look the same, but peer at flakes under a microscope and you can see all these different designs pop up. Turns out that our asteroid belt between Mars and Jupiter is also much more diverse than previously believed, all because astronomers took the time to do a detailed survey.

Here’s the interesting thing: the diversity, the team says, implies that Earth-like planets would be hard to find, which could be a blow for astronomers seeking an Earth 2.0 somewhere out in the universe if other research agrees.

To jump back a couple of steps, there’s a debate about how water arose on Earth. One theory is that back billions of years ago when the solar system was settling into its current state — a time when planetesimals were crashing into each other constantly and the larger planets possibly migrated between different orbits — comets and asteroids bearing water crashed into a proto-Earth.

Artist's conception of asteroids or comets bearing water to a proto-Earth. Credit: Harvard-Smithsonian Center for Astrophysics
Artist’s conception of asteroids or comets bearing water to a proto-Earth. Credit: Harvard-Smithsonian Center for Astrophysics

“If true, the stirring provided by migrating planets may have been essential to bringing those asteroids,” the astronomers stated in a press release. “This raises the question of whether an Earth-like exoplanet would also require a rain of asteroids to bring water and make it habitable. If so, then Earth-like worlds might be rarer than we thought.”

To take this example further, the researchers found that the asteroid belt comes from a mix of locations around the solar system. Well, a model the astronomers cite shows that Jupiter once migrated much closer to the sun, basically at the same distance as where Mars is now.

When Jupiter migrated, it disturbed everything in its wake and possibly removed as much as 99.9 per cent of the original asteroid population. And other planet migrations in general threw in rocks from everywhere into the asteroid belt. This means the origin of water in the belt could be more complicated than previously believed.

You can read more details of the survey in the journal Nature. Data was gathered from the Sloan Digital Sky Survey and the research was led by Francesca DeMeo, a Hubble postdoctoral fellow at the Harvard-Smithsonian Center for Astrophysics.

Source: Harvard-Smithsonian Center for Astrophysics

Comets Could Arise Closer To Earth, Study Suggests

Comet 'Bites the Dust' Around Dead Star
Comet 'Bites the Dust' Around Dead Star

There’s a potential “cometary graveyard” of inactive comets in our solar system wandering between Mars and Jupiter, a new Colombian research paper says. This contradicts a long-standing view that comets originate on the fringes of the solar system, in the Oort Cloud.

Mysteriously, however, 12 active comets have been seen in and around the asteroid belt. The astronomers theorize there must be a number of inactive comets in this region that flare up when a stray gravitational force from Jupiter nudges the comets so that they receive more energy from the Sun.

The researchers examined comets originating from the main asteroid belt between Mars and Jupiter, a spot where it is believed there are only asteroids (small bodies made up mostly of rock). Comets, by contrast, are a mixture of rocks and ice. The ice melts when the comet gets close to the sun, and can form spectacular tails visible from Earth. (Here’s more detail on the difference between a comet and an asteroid.)

This illustration shows three views of cometary activity. Top: The accepted view of comets, showing them coming from the outer solar system. Middle: The new proposal, saying some could come from the asteroid belt between Mars and Jupiter. Bottom: How the asteroid belt comets could have appeared during the early solar system's history. Credit: Ignacio Ferrin / University of Antioquia
This illustration shows three views of cometary activity. Top: The accepted view of comets, showing them coming from the outer solar system. Middle: The new proposal, saying some could come from the asteroid belt between Mars and Jupiter. Bottom: How the asteroid belt comets could have appeared during the early solar system’s history. Credit: Ignacio Ferrin / University of Antioquia

“Imagine all these asteroids going around the Sun for aeons, with no hint of activity,” stated Ignacio Ferrín, who led the research and is a part of the University of Antioquia in Colombia.

“We have found that some of these are not dead rocks after all, but are dormant comets that may yet come back to life if the energy that they receive from the Sun increases by a few per cent.”

The team believes this zone was far more active millions of years ago, but as the population got older they got more quiet.

“Twelve of those rocks are true comets that were rejuvenated after their minimum distance from the Sun was reduced a little,” the researchers stated.

“The little extra energy they received from the Sun was then sufficient to revive them from the graveyard.”

Check out more details of the research in the Monthly Notices of the Royal Astronomical Society. There is also a preprinted version available on Arxiv.

Source: Royal Astronomical Society

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.

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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

First Image Captured by NASAs Jupiter bound Juno; Earth – Moon Portrait

Earth & Moon Portrait - First Photo transmitted from Jupiter Bound Juno. This image of Earth (on the left) and the moon (on the right) was taken by NASA's Juno spacecraft on Aug. 26, 2011, when the spacecraft was about 6 million miles (9.66 million kilometers) away. It was taken by the spacecraft's onboard camera, JunoCam. Credit: NASA/JPL-Caltech

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NASA’s solar powered Jupiter bound Juno orbiter has captured her first image – a beautiful portrait of the Earth & Moon – since the probe blasted off from the home planet.

Juno lifted off 25 days ago at 12: 25 p.m. on August 5 from Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida. The spacecraft snapped the portrait with the onboard JunoCam camera on August 26 after journeying some 6 million miles (9.66 million km) from Earth and while traveling at a velocity of 77,600 miles per hour (124,900 kilometers per hour) relative to the sun.

“The image of the Earth Moon system is a rather unique perspective that we can get only by stepping outside of our home planet,” said Scott Bolton, Juno principal investigator, in an exclusive interview with Universe Today. Bolton is from the Southwest Research Institute in San Antonio.

“On our way to Jupiter, we’ve looked back at home and managed to take this amazing image.”

“Earth looking much like any other planet or star from a distance is glorious as this somewhat average looking “star” is home to all of humanity. Our companion, the moon, so beautiful and important to us, stands out even less.”

“We appear almost average and inconspicuous, yet all of our history originates here. It makes one wonder just how many other planets or solar systems might contain life like ours,” Bolton told me.

Juno casts a shadow back toward Earth and Space Shuttle Launch Pad 39A and the shuttle crawler way (at left) seconds after liftoff from adjacent Launch Pad 41 at Cape Canaveral, Florida. View from the VAB Roof. Credit: Ken Kremer

The Juno team commanded the probe to take the image as part of the checkout phase of the vehicles instruments and subsystems.

“The JunoCam instrument turn on and check out were planned activities. The instrument is working great and in fact, all the instruments that we’ve turned on thus far have been working great,” Bolton added.

So far the spacecraft is in excellent health and the team has completed the checkout of the Waves instrument and its two Flux Gate Magnetometer sensors and deployment of its V-shaped electric dipole antenna.

“We have a couple more instruments still to do,” Bolton noted.

The team reports that Juno also performed its first precession, or reorientation maneuver, using its thrusters and that the first trajectory control maneuver (TCM-1) was cancelled as unnecessary because of the extremely accurate targeting provided by the Atlas V rocket.

The portrait shot is actually not Juno’s last photo of her home.

The 8000 pound (3,600 kilogram) probe will fly by Earth once more on October 9, 2013 for a gravity assisted speed boost of 16,330 MPH (7.3 km/sec) to accelerate Juno past the asteroid belt on its long journey to the Jovian system.

Juno soars skyward to Jupiter on Aug. 5 from launch pad 41 at Cape Canaveral Air Force Station at 12:25 p.m. EDT. View from the VAB roof. Credit: Ken Kremer

JunoCam will collect new photos and the other science instruments will make measurements as Juno cartwheels past Earth during the slingshot to Jupiter.

Juno is on a 5 year and 1.7 Billion mile (2.8 Billion km) trek to the largest planet in our solar system. When she arrives at Jupiter on July 4, 2016, Juno will become the first polar orbiting spacecraft at the gas giant.

During a one year science mission – entailing 33 orbits lasting 11 days each – the probe will plunge to within about 3000 miles (5000 km) of the turbulent cloud tops and collect unprecedented new data that will unveil the hidden inner secrets of Jupiter’s genesis and evolution.

The goal is to find out more about the planets origins, interior structure and atmosphere, observe the aurora, map the intense magnetic field and investigate the existence of a solid planetary core.

“This is a remarkable sight people get to see all too rarely,” said Bolton in a NASA statement about the Earth-Moon photo. “This view of our planet shows how Earth looks from the outside, illustrating a special perspective of our role and place in the universe. We see a humbling yet beautiful view of ourselves.”

NASA’s Jet Propulsion Laboratory manages the Juno mission. The spacecraft was designed and built by Lockheed Martin Space Systems, Denver.

Juno and Booster Streak Across the Stars
NASA's Juno spacecraft and its spent Centaur upper rocket stage are captured in this telescope view as they move across the field of stars. The five-minute, timed exposure was acquired on Aug. 5 11:18pm Eastern time (Aug. 6 at 3:18 UTC) when Juno was at a distance of about 195,000 miles (314,000 kilometers) from Earth. The images were taken remotely by amateur astronomer Scott Ferguson using Global Rent-a-Scope's GRAS-016 Takahashi Widefield Refractor, which is located in Nerpio, Spain. Credit: Scott Ferguson
Juno Spacecraft Cruise Trajectory to Jupiter
This graphic shows Juno's trajectory, or flight path, from Earth to Jupiter. The spacecraft travels around the Sun, to a point beyond the orbit of Mars where it fires its main engine a couple of times. These deep space maneuvers set up the Earth flyby maneuver that occurs approximately two years after launch. The Earth flyby gives Juno the boost in velocity it needs to coast all the way to Jupiter. Juno arrives at Jupiter in July 2016. Credit: NASA/JPL-Caltech
View of Juno’s position on Aug. 24, 2011 nearly 6 million miles distant from Earth visualized by NASA’s Eyes on the Solar System website.

Read my continuing features about Juno
Juno Blasts off on Science Trek to Discover Jupiter’s Genesis
Juno Jupiter Orbiter poised at Launch Pad for Aug. 5 Blastoff
JUNO Orbiter Mated to Mightiest Atlas rocket for Aug. 5 Blastoff to Jupiter
Solar Powered Jupiter bound JUNO lands at Kennedy Space Center

Dawn Spirals Down Closer to Vesta’s South Pole Impact Basin

South Polar Region of Vesta - Enhanced View. NASA's Dawn spacecraft obtained this image centered on the south pole of Vesta with its framing camera on July 18, 2011. The image has been enhanced to bring out more surface details. It was taken from a distance of about 6,500 miles (10,500 kilometers) away from the protoplanet Vesta. The smallest detail visible is about 1.2 miles (2.0 km). Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA. Enhanced and annotated by Ken Kremer

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NASA’s Dawn Asteroid Orbiter is now spiraling down ever closer to the protoplanet Vesta – since arriving on July 16 – and capturing magnificent new high resolution images of the huge impact basin at the South Pole that dominates the surface. See enhanced image here.

The Dawn team just released a new image taken by the framing camera on July 18 as the orbiter flew from the day side to the night side at an altitude of 10,500 kilometers above Vesta, the second most massive body in the main Asteroid Belt between Mars and Jupiter.

NASA's Dawn spacecraft obtained this image centered on the south pole with its framing camera on July 18, 2011. It was taken from a distance of about 6,500 miles (10,500 kilometers) away from the protoplanet Vesta. The smallest detail visible is about 1.2 miles (2.0 km). Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

“I find this picture very dramatic !” exclaimed Dr. Marc Rayman, Dawn Chief Engineer from the NASA’s Jet Propulsion Laboratory in Pasadena, Calif., in an interview with Universe Today.

Dawn acquired this image after it had flown past the terminator and its orbit began taking it over the night side of Vesta.”

“After having this view, the spacecraft resumed gradually spiraling around its new home, heading for survey orbit where it will begin intensive observations of Vesta,” Rayman told me.

Dawn will reach the initial science survey orbit in early August, approximately 1700 miles above the battered surface. Vesta turns on its axis once very five hours and 20 minutes.

Vesta suffered an enormous cosmic collision eons ago that apparently created a gigantic impact basin in the southern hemisphere and blasted enormous quantities of soil, rocks and dust into space. Some 5% of all meteorites found on Earth originate from Vesta.

“The south pole region was declared to be a large impact basin after the Hubble Space Telescope (HST) data and images were obtained,” elaborated Prof. Chris Russell, Dawn Principal Investigator from UCLA.

“Now that we have higher resolution images we see that this region is unlike any other large impact on a small body but much of our experience here is on icy bodies of similar size,” Russell told me.

Dawn’s new images of Vesta taken at close range from just a few thousand miles away, now vastly exceed those taken by Hubble as it circled in Earth orbit hundreds of millions of miles away and may cause the science team to reevaluate some long held theories.

“The team is looking forward to obtaining higher resolution data over this region to look for confirmatory evidence for the impact hypothesis. They are not yet willing to vote for or against the HST interpretation. Needless to say the team got very excited by this image,” said Russell.

Dawn will orbit Vesta for one year before heading to its final destination, the Dwarf Planet Ceres.

Simulated View of Vesta from Dawn on July 23, 2011. Credit: NASA

Read my prior features about Dawn
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

Dawn Exceeds Wildest Expectations as First Ever Spacecraft to Orbit a Protoplanet – Vesta

Enhanced Image of Vesta Captured by Dawn on July 9, 2011. NASA's Dawn spacecraft entered orbit around Vesta on July 16, 2011. Dawn obtained the raw image of Vesta with its framing camera on July 9, 2011 - which has been enhanced and annotated. It was taken from a distance of about 26,000 miles (41,000 kilometers) away from the protoplanet Vesta. Each pixel in the image corresponds to roughly 2.4 miles (3.8 kilometers). Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA. Enhanced and annotated by Ken Kremer

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NASA’s super exciting Dawn mission to the Asteroid Belt marked a major milestone in human history by becoming the first ever spacecraft from Planet Earth to achieve orbit around a Protoplanet – Vesta – on July 16. Dawn was launched in September 2007 and was 117 million miles (188 million km) distant from Earth as it was captured by Asteroid Vesta.

Dawn’s achievements thus far have already exceeded the wildest expectations of the science and engineering teams, and the adventure has only just begun ! – so say Dawn’s Science Principal Investigator Prof. Chris Russell, Chief Engineer Dr. Marc Rayman (think Scotty !) and NASA’s Planetary Science Director Jim Green in exclusive new interviews with Universe Today.

As you read these words, Dawn is steadily unveiling new Vesta vistas never before seen by a human being – and in ever higher resolution. And it’s only made possible via the revolutionary and exotic ion propulsion thrusters propelling Dawn through space (think Star Trek !). That’s what NASA, science and space exploration are all about.

Dawn is in orbit, remains in good health and is continuing to perform all of its functions,” Marc Rayman of the Jet Propulsion Laboratory, Pasadena, Calif., told me. “Indeed, that is how we know it achieved orbit. The confirmation received in a routine communications session that it has continued thrusting is all we needed.”

Image of Vesta Captured by Dawn on July 9, 2011. NASA's Dawn spacecraft obtained this image with its framing camera on July 9, 2011. It was taken from a distance of about 26,000 miles (41,000 kilometers) away from the protoplanet Vesta. Each pixel in the image corresponds to roughly 2.4 miles (3.8 kilometers). Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Dawn entered orbit at about 9900 miles (16000 km) altitude after a nearly 4 year journey of 1.73 billion miles.

Over the next few weeks, the spacecrafts primary task is to gradually spiral down to its initial science operations orbit, approximately 1700 miles above the pock marked surface.

Vesta is the second most massive object in the main Asteroid Belt between Mars and Jupiter. Dawn is the first probe to orbit an object in the Asteroid Belt.

I asked Principal Investigator Chris Russell from UCLA for a status update on Dawn and to describe what the team can conclude from the images and data collected thus far.

“The Dawn team is really, really excited right now,” Russell replied.

“This is what we have been planning now for over a decade and to finally be in orbit around our first ‘protoplanet’ is fantastic.”

“The images exceed my wildest dreams. The terrain both shows the stress on the Vestan surface exerted by 4.5 billion years of collisions while preserving evidence [it seems] of what may be internal processes. The result is a complex surface that is very interesting and should be very scientifically productive.”

NASA's Dawn spacecraft, illustrated in this artist's concept, is propelled by ion engines to Protoplanets Vesta and Ceres. Credit: NASA/JPL

“The team is looking at our low resolution images and trying to make preliminary assessments but the final answers await the higher resolution data that is still to come.”

Russell praised the team and described how well the spacecraft was operating.

“The flight team has been great on this project and deserves a lot of credit for getting us to Vesta EARLY and giving us much more observation time than we had planned,” Russell told me.

“And they have kept the spacecraft healthy and the instruments safe. Now we are ready to work in earnest on our science observations.”

Dawn will remain in orbit at Vesta for one year. Then it will fire its ion thrusters and head for the Dwarf Planet Ceres – the largest object in the Asteroid Belt. Dawn will then achieve another major milestone and become the first spacecraft ever to orbit two celestial objects.

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

Jim Green, Director of Planetary Science for the Science Mission Directorate (SMD) at NASA HQ in Washington, DC, summed up his feelings about Dawn in this way;

“Getting Dawn into orbit is an amazing achievement,” Green told me.

“Instead of the ‘fire the thrusters full blast’ we just sort of slid into orbit letting gravity grab the spacecraft with a light tug. This gives us great confidence that the big challenge down the road of getting into orbit around Ceres can also be accomplished just as easily.”

Sharper new images from Vesta will be published by NASA in the next day or so.

“We did take a few navigation images in this last sequence and when they get through processing they should be put on the web this week,” Russell informed. “These images are from a similar angle to the last set and with somewhat better resolution and will not reveal much new.”

However, since Dawn is now orbiting Vesta our upcoming view of the protoplanet will be quite different from what we’ve seen in the approach images thus far.

“We will be changing views in the future as the spacecraft begins to climb into its science orbit,” stated Russell.

“This may reveal new features on the surface as well as giving us better resolution. So stay tuned.”

Marc Rayman explained how and why Dawn’s trajectory is changing from equatorial to polar:

“Now that we are close enough to Vesta for its gravity to cause a significant curvature in the trajectory, our view is beginning to change,” said Rayman. “That will be evident in the pictures taken now and in the near future, as the spacecraft arcs north over the dark side and then orbits back to the south over the illuminated side.”

“The sun is over the southern hemisphere right now,” added Russell. “When we leave we are hoping to see it shine in the north.”

Dawn is an international mission with significant participation from Germany and Italy. The navigation images were taken by Dawn’s framing cameras which were built in Germany.

Exploring Vesta is like studying a fossil from the distant past that will immeasurably increase our knowledge of the beginnings of our solar system and how it evolved over time.

Dawn Infographic Poster - click to enlarge. Credit: NASA

Vesta suffered a cosmic collision at the south pole in the distant past that Dawn can now study at close range.

“For now we are viewing a fantastic asteroid, seeing it up close as we zero in on its southern hemisphere, looking at the huge central peak, and wondering how it got there,” explained Jim Green

“We know Vesta was nearly spherical at one time. Then a collision in its southern hemisphere occurred blowing off an enormous amount of material where a central peak now remains.”

That intriguing peak is now obvious in the latest Dawn images from Vesta. But what does it mean and reveal ?

“We wonder what is that peak? replied Green. “Is it part of the core exposed?

“Was it formed as a result of the impact or did it arise from volcanic action?”

“The Dawn team hopes to answer these questions. I can’t wait!” Green told me.

As a result of that ancient south pole collision, about 5% of all the meteorites found on Earth actually originate from Vesta.

Keep your eyes glued to Dawn as mysterious Vesta’s alluring secrets are unveiled.

Dawn Trajectory and Current Location in orbit at Vesta on July 18, 2011. Credit: NASA/JPL

Read my prior features about Dawn
Dawn Closing in on Asteroid Vesta as Views Exceed Hubble
Revolutionary Dawn Closing in on Asteroid Vesta with Opened Eyes

Dawn Closing in on Asteroid Vesta as Views Exceed Hubble

Hubble and Dawn Views of Vesta. These views of the protoplanet Vesta were obtained by NASA's Dawn spacecraft and NASA's Hubble Space Telescope. The image from Dawn, on the left, is a little more than twice as sharp as the image from Hubble, on the right. The image from Hubble, which is in orbit around the Earth, was obtained on May 14, 2007, when Vesta was 109 million miles (176 million kilometers) away from Earth. Dawn's image was taken on June 20, 2011, when Dawn was about 117,000 miles (189,000 kilometers) away from Vesta. The framing cameras were developed and built under the leadership of the Max Planck Institute for Solar System Research in Katlenburg-Lindau, Germany. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/PSI and NASA/ESA/STScI/UMd

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A new world in our Solar System is about to be unveiled for the first time – the mysterious protoplanet Vesta, which is the second most massive object in the main Asteroid Belt between Mars and Jupiter.

NASA’s Dawn Asteroid orbiter has entered its final approach phase to Vesta and for the first time is snapping images that finally exceed those taken several years ago by the iconic Hubble Space Telescope.

“The Dawn science campaign at Vesta will unveil a mysterious world, an object that can tell us much about the earliest formation of the planets and the solar system,” said Jim Adams, Deputy Director, Planetary Science Directorate at NASA HQ at a briefing for reporters.

Vesta holds a record of the earliest history of the solar system. The protoplanet failed to form into a full planet due to its close proximity to Jupiter.

Check out this amazing NASA approach video showing Vesta growing in Dawn’s eyes. The compilation of navigation images from Dawn’s framing camera spans about seven weeks from May 3 to June 20 was released at the NASA press briefing by the Dawn science team.

Dawn’s Approach to Vesta – Video

Best View from Hubble – Video

Be sure to notice that Vesta’s south pole is missing due to a cataclysmic event eons ago that created a massive impact crater – soon to be unveiled in astounding clarity. Some of that colossal debris sped toward Earth and survived the terror of atmospheric entry. Planetary Scientists believe that about 5% of all known meteorites originated from Vesta, based on spectral evidence.

After a journey of four years and 1.7 billion miles, NASA’s revolutionary Dawn spacecraft thrusting via exotic ion propulsion is now less than 95,000 miles distant from Vesta, shaping its path through space to match the asteroid.

The internationally funded probe should be captured into orbit on July 16 at an initial altitude of 9,900 miles when Vesta is some 117 million miles from Earth.

After adjustments to lower Dawn to an initial reconnaissance orbit of approximately 1,700 miles, the science campaign is set to kick off in August with the collection of global color images and spectral data including compositional data in different wavelengths of reflected light.

Dawn Approaching Vesta
Dawn obtained this image on June 20, 2011. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/PSI and NASA/ESA/STScI/UMd

Dawn will spend a year investigating Vesta. It will probe the protoplanet using its three onboard science instruments – provided by Germany, Italy and the US – and provide researchers with the first bird’s eye images, global maps and detailed scientific measurements to elucidate the chemical composition and internal structure of a giant asteroid.

“Navigation images from Dawn’s framing camera have given us intriguing hints of Vesta, but we’re looking forward to the heart of Vesta operations, when we begin officially collecting science data,” said Christopher Russell, Dawn principal investigator, at the University of California, Los Angeles (UCLA). “We can’t wait for Dawn to peel back the layers of time and reveal the early history of our solar system.”

Because Dawn is now so close to Vesta, the frequency of imaging will be increased to twice a week to achieve the required navigational accuracy to successfully enter orbit., according to Marc Rayman, Dawn Chief Engineer at the Jet Propulsion Laboratory (JPL) in Pasadena, Calif.

“By the beginning of August, it will see Vesta with more than 100 times the clarity that Hubble could ever obtain,” says Rayman.

Vesta in Spectrometer View
On June 8, 2011, the visible and infrared mapping spectrometer aboard NASA's Dawn spacecraft captured the instrument's first images of Vesta that are larger than a few pixels, from a distance of about 218,000 miles (351,000 kilometers). The image was taken for calibration purposes. An image obtained in the visible part of the light spectrum appears on the left. An image obtained in the infrared spectrum, at around 3 microns in wavelength, appears on the right. The spatial resolution of this image is about 60 miles (90 kilometers) per pixel. Credit: NASA/JPL-Caltech/UCLA/ASI/INAF

Dawn will gradually edge down closer to altitudes of 420 miles and 120 miles to obtain ever higher resolution orbital images and spectal data before spiraling back out and eventually setting sail for Ceres, the largest asteroid of them all.

Dawn will be the first spacecraft to orbit two celestial bodies, only made possible via the ion propulsion system. With a wingspan of 65 feet, it’s the largest planetary mission NASA has ever launched.

“We’ve packed our year at Vesta chock-full of science observations to help us unravel the mysteries of Vesta,” said Carol Raymond, Dawn’s deputy principal investigator at JPL.

“This is an unprecedented opportunity to spend a year at a body that we know almost nothing about,” added Raymond. “We are very interested in the south pole because the impact exposed the deep interior of Vesta. We’ll be able to look at features down to tens of meters so we can decipher the geologic history of Vesta.”

Possible Piece of Vesta
Scientists believe a large number of the meteorites that are found on Earth originate from the protoplanet Vesta. A cataclysmic impact at the south pole of Vesta, the second most massive object in the main asteroid belt, created an enormous crater and excavated a great deal of debris. Some of that debris ended up as other asteroids and some of it likely ended up on Earth. Image Credit: NASA/JPL-Caltech
Dawn Trajectory and Current Location on June 29, 2011. Credt: NASA/JPL
Dawn launch on September 27, 2007 by a Delta II rocket from Cape Canaveral Air Force Station, Florida. Credit: Ken Kremer

Read my prior feature about Dawn here

Dawn Begins Approach to Asteroid Vesta and Snaps First Images

Dawn's First Glimpse of Vesta – Processed. This image, processed to show the true size of the giant asteroid Vesta, shows Vesta in front of a spectacular background of stars. It was obtained by the framing camera aboard NASA's Dawn spacecraft on May 3, 2011, from a distance of about 1.2 million kilometers (750,000 miles). Since Vesta is so bright that it outshines its starry background, Dawn team members commanded a long exposure time to make the stars visible. They corrected the resulting exaggerated size of Vesta by superimposing a short exposure image of the target asteroid, showing its true size. Vesta is the small, bright pearl in the middle of the image. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

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NASA’s revolutionary Dawn Asteroid Orbiter has begun the final approach phase to the giant asteroid Vesta and snapped its first science image. The image was taken on May 3, when Dawn was approximately 1.21 million kilometers (752,000 miles) distant from Vesta using the science imager known as the Framing Camera.

Besides the pure delight of seeing Vesta up close for the first time, the images play a crucial role in navigating Dawn precisely through space and successfully achieve orbit around the protoplanet that nearly formed into a full fledged planet.

Vesta is the second most massive object in the Asteroid Belt and is 530 kilometers (330 miles) in diameter.

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

Dawn should be captured into orbit about Vesta around July 16 as the engineering team works to maneuver the spacecraft to match the asteroids path around the sun using the exotic ion thrusters. Using the background stars in the framing camera images, they will be able to determine Dawn’s location in space relative to the stars in order to precisely navigate the spacecrafts trajectory towards Vesta.

“After plying the seas of space for more than a billion miles, the Dawn team finally spotted its target,” said Carol Raymond, Dawn’s deputy principal investigator at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “This first image hints of detailed portraits to come from Dawn’s upcoming visit.”

The best images of Vesta to date were taken by the Hubble Space Telescope. Jim Adams, Deputy Director of Planetary Science, told me that the images from Dawn’s Framing Camera will exceed those from Hubble in a few weeks.

Dawn will initially enter a highly elliptical polar orbit around Vesta and start collecting science data in August from an altitude of approximately 1,700 miles (2,700 kilometers). The orbit will be lowered in stages to collect high resolution data as Dawn spends about a year collecting data from its three science instruments.

Dawn's First Glimpse of Vesta -- Unprocessed
This image shows the first, unprocessed image obtained by NASA's Dawn spacecraft of the giant asteroid Vesta in front of a background of stars. It was obtained by Dawn's framing camera on May 3, 2011, from a distance of about 1.2 million kilometers (750,000 miles). Vesta is inside the white glow at the center of the image. The giant asteroid reflects so much sunlight that its size is dramatically exaggerated at this exposure. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Thereafter Dawn will be targeted to Ceres, the largest object in the Asteroid Belt which it will reach in 2015.

Dawn is an international mission.

The framing cameras have been developed and built under the leadership of the Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany, with significant contributions by the German Aerospace Center (DLR) Institute of Planetary Research, Berlin, and in coordination with the Institute of Computer and Communication Network Engineering, Braunschweig. The framing camera project is funded by the Max Planck Society, DLR, and NASA.

The Visible and Infrared mapping camera was provided by the Italian Space Agency. The Gamma Ray Detector was supplied by Los Alamos National Labotatory.

Read more about Dawn in my prior story:
Revolutionary Dawn Closing in on Asteroid Vesta with Opened Eyes

Dawn spacecraft under construction in cleanroom. Picture shows close up view of two science instrument; the twin Framing Cameras at top (white rectangles) and VIR Spectrometer at right. Credit: Ken Kremer