Dawn probe to orbit asteroid Vesta

namloc1980

The Dawn spacecraft is due to enter orbit around the asteroid Vesta on July 16th next. It recently captured it's first image of the asteroid as it approached from a distance of 1.2 million km:



Vesta is the second most massive object in the asteroid belt after the dwarf planet Ceres. Dawn will actually enter orbit around Vesta and will stay for a year observing it before moving off and travelling onto Ceres by 2015.

Stargate

namloc1980 wrote: »

The Dawn spacecraft is due to enter orbit around the asteroid Vesta on July 16th next. It recently captured it's first image of the asteroid as it approached from a distance of 1.2 million km:



Vesta is the second most massive object in the asteroid belt after the dwarf planet Ceres. Dawn will actually enter orbit around Vesta and will stay for a year observing it before moving off and travelling onto Ceres by 2015.

Hard to believe namloc1980 it was discovered March 1807
We are finally getting a close look at it now

Stargate

stoneill

Cool -
Within the asteroid belt, the largest 4 objects, (Ceres and Vesta are the only two names I can remember) make up approx 50% of all the mass within the belt.
So basically the belt is mostly empty!

Zubeneschamali

I've spotted Ceres with binoculars, but not Vesta (yet).

Rubecula

If you can spot Vesta with Bino's I think it is getting a bit too close for comfort LOL:pac:

(Actually I dunno if it is possible to distinguish it through binos.)

Zubeneschamali

Rubecula wrote: »

(Actually I dunno if it is possible to distinguish it through binos.)

It is reportedly sometimes visible with the naked eye, never mind binoculars. In 2007 it made mag +5.4

namloc1980

Dawn is now slowly catching up with Vesta in it's orbit. Here's the latest image from about 265,000km, less than the distance between Earth and the Moon.



Link

Hal1

Each pixel in the image corresponds to roughly 16 miles (25 kilometers).

:eek:
That thing is huge. Just hope we don't need to send Bruce Willis up there yet :pac:.

namloc1980

Hal1 wrote: »

:eek:
That thing is huge. Just hope we don't need to send Bruce Willis up there yet :pac:.

Here is a side by side of Vesta and our Moon. For an asteroid it is very large!

namloc1980

Dawn captured this image 20th June from about 187,000km from Vesta. For scale comparison from a distance of 1km Vesta would be about the size of a regular sized garden shed.

dlofnep

Good stuff Can't wait til we get some detailed shots of Ceres in 2015.

RAID Ireland

http://dawn.jpl.nasa.gov/multimedia/dawn_vesta_image_062411.asp

namloc1980

Latest image from Dawn taken 1st July and it's a beauty!



That feature at the bottom looks incredible! It's a huge peak/mountain as a result of an impact aeons ago. It reaches well over 10km above the plain below - it makes Everest look like a mole-hill!

dlofnep

Latest pic

July 14, 2011 - PASADENA, Calif. -- 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).

Turtwig

NewScientist. wrote:

Land ho! After nearly four years of interplanetary travel, NASA's Dawn spacecraft is about to be captured into orbit around the giant asteroid Vesta. Meanwhile, a new paper argues that Vesta and Ceres, another huge asteroid set to be visited by Dawn, are the main stumbling blocks to predicting the long-term fate of the solar system.

At 530 kilometres across, Vesta is one of the biggest denizens of the asteroid belt, the junkyard of leftover planetary building blocks found between Mars and Jupiter.

Dawn is expected to enter orbit around it at 0500 GMT on Saturday (2200 PDT on Friday). Its cameras and spectrometers will study Vesta's topography and chemical composition. That could reveal clues about the era of early planet formation, since Vesta is thought to have finished growing long before Earth and the other planets.

Chaotic orbits

After a year in orbit, Dawn will head to Ceres, the solar system's biggest asteroid. While Vesta, like Earth, is divided internally into a metallic core and an outer rocky mantle and crust, Ceres seems to contain a lot of water ice. Scientists hope data collected by Dawn will help them understand how the two large asteroids ended up so different in composition.

Although Vesta and Ceres are tiny compared to Earth, they have a surprisingly large influence on our planet's orbit.

A study published this week says that because of chaotic interactions between Vesta and Ceres, astronomers will never be able to calculate Earth's trajectory more than 60 million years in the future, or rewind it more than 60 million years in the past.

Vesta and Ceres have frequent close passes with each other that change their orbits. The result is that their orbits are chaotic, changing in ways that are impossible to predict more than about 400,000 years into the future.

Event horizon

Gravitational tugs from Vesta and Ceres in turn affect the orbits of Earth and the other planets. The effect of these small tugs build up over time, making it impossible to calculate the positions of the planets more than 60 million years forwards or backwards in time.

Astronomers will more precisely measure the positions of Vesta and Ceres with the Dawn spacecraft, but this will hardly matter for long-term predictions.

The chaotic interactions between Vesta and Ceres will quickly amplify even the tiniest of measurement errors, foiling any attempt to predict planet orbits beyond the 60-million year horizon, says the study's lead author Jacques Laskar of the Observatoire de Paris, France.

"[This] appears to be an absolute limit that will not be improved in the future," he says.

Journal reference: Astronomy and Astrophysics, DOI: 10.1051/0004-6361/201117504

Source.

Hal1 wrote: »

:eek:
That thing is huge. Just hope we don't need to send Bruce Willis up there yet :pac:.

And on that note...

Movie Physics Review. wrote:

A Texas-sized asteroid is headed toward Earth at 22,000 mph and the only way to save humanity is to to land a ragtag oil rig crew on its surface, drill an 800-foot-deep hole, plant a nuclear bomb on a convenient fault line, and split the asteroid in half, all of which has to be done in a mere 18 days. The crew is the usual lovable assortment of misfits and neurotics in a complete spectrum of shapes and sizes. They have no space flight experience and flunk their medical exams, but are supposedly the best people for the job thanks to their knowledge of oil well drilling. Of course, this knowledge cannot be conveyed to astronauts or NASA engineers.

One of the worst physics insults occurs after our plucky heroes are strapped into their shuttles and launched. They have to stop at the Mir space station and refuel. Evidently, one of the guys from the movie's accounting department pointed out that simulating apparent weightlessness would be expensive. In response, the moviemakers have the Russian on Mir throw a switch and create artificial gravity by rotating Mir. The station rotates fast enough to reach 1 g in less than 30 seconds, even though Mir's mass is about 124,340 kg.

The level of artificial gravity would be equal to the centripetal acceleration, which depends on the distance from the axis of rotation located in the center of Mir's main cylindrical-shaped section. As they walk around, the workers have their feet on one side of the axis of rotation and their heads on the other side. This means that their feet and heads would feel like they were being pulled in opposite directions. The artificial gravity level could not possibly seem constant unless they laid on the floor. Artificial gravity can only work in a gigantic space station where the height of a human is a small percentage of the radius of rotation. In such a situation astronauts would not feel the variation in artificial gravity between their heads and feet. Mir's highly variable artificial gravity would be disorienting and probably cause the workers to stumble and vomit.

If the rotation of Mir were set so that the inner wall of the main module had Earth-like artificial gravity (9.8 m/s2 centripetal acceleration), the outermost parts of Mir would experience about six times as much. This would be like attaching Mir to two freight train engines moving in opposite directions. Mir would be torn apart.

When our heroes land they find a hodgepodge of large, spike-like protrusions all over the asteroid. Evidently the spikes are supposed to make the place look scary. We would use the term silly. How could spikes possibly form? We're at a loss for an explanation or even an example of something like it somewhere else in the universe.

Our heroes have no problems walking or standing in an Earthlike way even though the gravity force would have been about a tenth of the gravity force on Earth. The low gravity cannot support an atmosphere and yet we see flames at the crash site of one of the space shuttles.

To get an idea of the asteroid's size, consider that Texas is 1,289,000 meters long from the eastern side to the western tip. Although the asteroid is misshapen, for convenience we'll assume it's spherical with a diameter of 1,289,000 meters. If it has the same density as Earth (5500 kg/m3), the asteroid would have a mass of about 6×1021 kg. A 243 meter (800 foot) deep hole seems awfully insignificant compared to the length of Texas.

We couldn't help thinking that a Texas-sized asteroid deserved a Texas-sized hole. This set our imaginations running about how to dig one. The answer hit us like a meteorite: bowling! Why not blast a hole in the asteroid with bowling balls? Each bowling ball's blast could come from its kinetic energy. With the asteroid headed toward Earth at 22,000 mph a space shuttle could head away from Earth at 22,000 mph straight toward the asteroid. This would give a closing speed of 44,000 mph or 19,678 m/s. A bowling ball rolled out the front of the shuttle would eventually strike the asteroid with so much kinetic energy that the ball would explode. We use the following equation to calculate the kinetic energy of each ball:

K = ½mv2

Where K is kinetic energy, m is mass, and v is the magnitude of velocity. If we assume each ball's mass is 8 kg, then the kinetic energy will be 1.5 billion joules, or the energy contained in 740 pounds of TNT. This would be a pretty big blast, but not enough for a Texas-sized hole. However, a space shuttle can carry a 29,545 kg payload, or in other words 3,693 bowling balls. Assuming that each ball blasted a 2-meter-deep hole, 3,693 bowling balls could create a hole 7,386 meters, or 24,350 ft, deep. Put another 3,190 on a second shuttle and the hole could be deepened to 45,385 ft (13,767.05 meters) or about 50 times deeper than the movie hole. This would still leave room on the second shuttle for a 9 megaton nuclear bomb (the biggest in the United States arsenal). Roll a ball every 4 seconds and the hole could be completed in 7.6 hours. Of course, this assumes that the balls land one after another in about the same place and that the explosion of one ball doesn't disrupt the others.

Surely Bob's bowling buddies would have even more appeal than a bunch of oil rig workers. Think of the possible misfits. Imagine a scene where NASA guys try to bowl and throw gutter balls as Bob's boys guffaw. Only Bob's boys could put that special spin and accuracy on the ball needed for proper blasting. The NASA guys would have to tear out Bob's lanes and redesign them for installation on the space shuttles, but that would add to the drama. Once in space, one of of Bob's boys could get space psychosis, think he was playing basketball, and waste a few bowling balls. Bob could reason that his mass was just enough to compensate for the missing bowling balls and become a hero by not letting go of the last bowling ball as he hurled it down the lane. He would fly kamikaze-style into the hole and successfully blast the last few feet of depth.

Unfortunately, Bob's bowling buddies would be subject to the same physical limitations as the oil drillers. By our calculations the asteroid was about 10 hrs away from Earth when the drillers landed on it. Allowing 8 hours to drill, the bomb could not have been detonated any more than 2 hours before the asteroid was supposed to impact. Given this detonation time, the asteroid halves need a separation velocity of 4,738 mph (2,119 m/s) to miss Earth by the 400 miles stated in the movie. Each asteroid half would acquire 6.7 × 1027 joules of kinetic energy when it reached the required velocity. The biggest nuclear bomb ever built was constructed in Russia and had a 100-megaton yield. To give the asteroid halves the required kinetic energy would require 64 billion of them. This assumes that no energy is needed to create the split and that about 50% of the bombs' blast energy goes into the kinetic energy of the asteroid halves. It also neglects the gravitational attraction force between the two asteroid halves, which would tend to slow their separation velocity.

Even if the bomb did split the asteroid, the halves would not translate outward as depicted in the movie. They would rotate as they moved apart since the bomb was located near the asteroid's center of mass. The force created by the bomb would create a torque or twisting action on each asteroid half. To visualize this effect, imagine splitting a peeled orange by pulling it apart on one side. The gap at the front of the orange would widen faster than the gap at the back, giving each half a slight rotational motion. For the asteroid halves, this rotational motion would add to the total kinetic energy requirement, meaning we would need an even bigger bomb.

According to the movie the asteroid starts rotating on three axes as it passes the Moon. Yet miraculously, the asteroid is lined up perfectly with Earth when the bomb detonates. What's more, the asteroid splits exactly in half, and the parts have no rotational motion.

Okay, let's assume that everything falls perfectly into place, and the core of the asteroid just happens to be a fissionable material which is exploded by the nuclear bomb. Even if the halves fly apart and miss Earth by 400 miles exactly as depicted, it's still going to be a tragedy. The gravitational force created by the asteroid halves as they pass Earth will be about 100 times higher than the gravitational force from the Moon, which causes tidal actions on Earth. Since most of Earth's population lives in coastal areas, most of the world's population will be destroyed in the resulting tidal surge. Sometimes there's just no way to have a happy ending.

Phil Plaits review included for good measure.

Beeker

Dawn now in orbit around Vesta, heres the lattest pic

2 stroke

Why are we only being showed one side of this?

Captain Chaos

2 stroke wrote: »

Why are we only being showed one side of this?

What do you mean one side. Look at all the photos, the outline is different in every one of them at Vesta rotates. The probe has only gone into orbit now.

Do you think there is an alien base on the "back" of it or something?

Rubecula

It is very round. Almost a dwarf planet. Well that is my impression. Great stuff.

2 stroke

looks to me as if we are only seeing about 75% of it so far.

dlofnep

2 stroke wrote: »

looks to me as if we are only seeing about 75% of it so far.

What's your point? It has only published a handful of photos, and will continue to do so until July 2012.

namloc1980

2 stroke wrote: »

looks to me as if we are only seeing about 75% of it so far.

Dawn is approaching Vesta from under it's South Polar region. If you were flying over Earth's South Pole you wouldn't expect to see the North Pole. Same thing here. Once it's in orbit we'll get full surface coverage.

Vargulf

Closer look

namloc1980

Dawn is now in it's science orbit around Vesta and even at this stage it is revealing a very interesting world indeed!

Below is a beautiful movie of Vesta's rotation compiled from Dawn images:

https://www.youtube.com/watch?v=MQZq2xQdUO4

Some really interesting features including those long linear features around the equator. Exciting times ahead!!

Streets_of Rage 2 Come_On

*Thread bump*

It's been taking a bit of a battering the last few years this, high energy particle radiation has messed up it's systems twice, but nothing turning it off and on again can't fix, lol. Set for Ceres Orbit in April, bit later than planned because of the shutdowns.

http: // www .nasa.gov/jpl/dawn/operating-normally-after-safe-mode-triggered/#.VBmcfPldWSo


It's taking pics of Ceres now to.

The Dawn spacecraft has delivered a glimpse of Ceres, the largest body in the main asteroid belt, in a new image taken 740,000 miles (1.2 million kilometers) from the dwarf planet. This is Dawn's best image yet of Ceres as the spacecraft makes its way toward this unexplored world.

http: // www .jpl.nasa.gov/news/news.php?release=2014-414&rn=news.xml&rst=4395

MeteoritesEire

http://www.jpl.nasa.gov/news/news.php?release=2015-023

As NASA's Dawn spacecraft closes in on Ceres, new images show the dwarf planet at 27 pixels across, about three times better than the calibration images taken in early December. These are the first in a series of images that will be taken for navigation purposes during the approach to Ceres.

Over the next several weeks, Dawn will deliver increasingly better and better images of the dwarf planet, leading up to the spacecraft's capture into orbit around Ceres on March 6. The images will continue to improve as the spacecraft spirals closer to the surface during its 16-month study of the dwarf planet.

"We know so little about dwarf planet Ceres. Now, Dawn is ready to change that," said Marc Rayman, Dawn's chief engineer and mission director, based at NASA's Jet Propulsion Laboratory in Pasadena, California.

The best images of Ceres so far were taken by NASA's Hubble Space Telescope in 2003 and 2004. This most recent images from Dawn, taken January 13, 2015, at about 80 percent of Hubble resolution, are not quite as sharp. But Dawn's images will surpass Hubble's resolution at the next imaging opportunity, which will be at the end of January.

"Already, the [latest] images hint at first surface structures such as craters," said Andreas Nathues, lead investigator for the framing camera team at the Max Planck Institute for Solar System Research, Gottingen, Germany.

Ceres is the largest body in the main asteroid belt, which lies between Mars and Jupiter. It has an average diameter of 590 miles (950 kilometers), and is thought to contain a large amount of ice. Some scientists think it's possible that the surface conceals an ocean.

Dawn's arrival at Ceres will mark the first time a spacecraft has ever visited a dwarf planet.

"The team is very excited to examine the surface of Ceres in never-before-seen detail," said Chris Russell, principal investigator for the Dawn mission, based at the University of California, Los Angeles. "We look forward to the surprises this mysterious world may bring."

The spacecraft has already delivered more than 30,000 images and many insights about Vesta, the second most massive body in the asteroid belt. Dawn orbited Vesta, which has an average diameter of 326 miles (525 kilometers), from 2011 to 2012. Thanks to its ion propulsion system, Dawn is the first spacecraft ever targeted to orbit two deep-space destinations.

JPL manages the Dawn mission for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. The University of California at Los Angeles (UCLA) is responsible for overall Dawn mission science. Orbital Sciences Corp. in Dulles, Virginia, designed and built the spacecraft. The Dawn framing cameras were developed and built under the leadership of the Max Planck Institute for Solar System Research, Gottingen, Germany, with significant contributions by 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/JPL. The Italian Space Agency and the Italian National Astrophysical Institute are international partners on the mission team.

More information about Dawn is online at http://dawn.jpl.nasa.gov.

Maximus Alexander

Why is nobody talking about this??



I'm so excited! First real look at a new world! When was the last time that happened? I wonder what the bright dot is gonna be?

Kidchameleon

Same potential for an ocean as Europa. Cant wait for the closeups

nokia69

Kidchameleon wrote: »

Same potential for an ocean as Europa. Cant wait for the closeups

are Vista and Ceres just ice

Europa has liquid water under the surface because it close to Jupiter

Kidchameleon

nokia69 wrote: »

are Vista and Ceres just ice

Europa has liquid water under the surface because it close to Jupiter

http://www.space.com/24366-dwarf-planet-ceres-water-ice-volcanoes.html

ElizKenny

www .jpl.nasa.gov/news/news.php?feature=4475