Dawn - Mission to Vesta and Ceres
Dawn – one mission, two heavenly bodies
NASA’s Dawn spacecraft was launched on 27 September 2007. On 16 July 2011, it arrived at the asteroid Vesta, which it explored until 5 September 2012. The spacecraft then departed for the dwarf planet Ceres, where it will arrive on 6 March 2015. The Dawn mission is the first to successively study two celestial bodies from orbit.
An encounter with Ceres
The NASA Dawn spacecraft will arrive at the dwarf planet Ceres on 6 March 2015. Once there, it will record the surface with the German-developed Framing Camera. This image was acquired from a distance of 237,000 kilometres from the dwarf planet.
Two Faces of Ceres
These two views of Ceres were acquired by NASA's Dawn spacecraft on Feb. 12, 2015, from a distance of about 52,000 miles (83,000 kilometers) as the dwarf planet rotated. The images, which were taken about 10 hours apart, have been magnified from their original size. The Dawn spacecraft is due to arrive at Ceres on March 6, 2015.
Ceres half in shadow
These images of dwarf planet Ceres were acquired on 25 February 2015, at a distance of 40,000 kilometres, by the German-built Framing Camera on board NASA's Dawn spacecraft. The image resolution is 3.7 kilometres per pixel.
View of Ceres
This image of the dwarf planet Ceres was acquired on 1 March 2015, by the German-built Framing Camera on board NASA’s Dawn spacecraft, from a distance of 49,000 kilometres. The image resolution is 4.6 kilometres per pixel. This is the last image acquired before Dawn entered orbit around Ceres. During this manoeuvre, no further imaging was possible because Dawn could not point its instruments towards the surface of the dwarf planet.
A new side of Ceres
This image shows a side of dwarf planet Ceres not previously imaged by NASA’s Dawn spacecraft. Cere’s surface is covered with several bright spots and impressive craters - some of which feature a central mountain. The picture was taken by the camera system on board Dawn on 4 February 2015 from a distance of 145 000 kilometers.
Bright patches on Ceres
There are several unusually bright patches on the surface of Ceres. The brightest of these is in the middle of a large impact crater and is clearly visible in this image. It is also obvious that there is another, slightly less bright region, apparently in the same impact basin. The German-built Framing Camera on board NASA’s Dawn spacecraft acquired this image on 19 February 2015, from nearly 46,000 kilometres away.
White spots on Ceres
The white spots in a crater on Ceres can be seen at the top of this image, which was acquired by the Dawn orbiter on 15 April 2015.
Chain of mountains in Urvara crater
This image was acquired by the Framing Camera on board the Dawn spacecraft on 19 August 2015. From an altitude of 1470 kilometres, the interior of Urvara Crater is visible. A mountain range can be seen in the lower left corner of the image, and the crater rim can be observed to the right of the image.
Rocks and craters on Ceres
This image of the dwarf planet Ceres was acquired on 19 August 2015 by the Dawn spacecraft from a distance of 1470 kilometres. It shows a six-kilometre high, pyramid-shaped mountain in the southern hemisphere between the craters Kirnis, Rongo and Yalode. Note the bright stripes on its steep slopes. The image resolution is 140 metres per pixel.
Gaue crater on Ceres
This image of Gaue crater on the dwarf planet Ceres was acquired on 18 August 2015. The 84-kilometre diameter crater partially overlaps an older crater. The image was acquired by the Dawn Framing Camera from a distance of 1470 kilometres from the surface .
Ceres – a surface covered in craters
This mosaic shows the surface of the dwarf planet Ceres and is composed of images acquired by the German-built Framing Camera on board NASA's Dawn mission on 19 February 2015. The distance between the camera and Ceres was 46,000 kilometres and the image resolution is four kilometres per pixel.
Huge troughs on Vesta – a result of mega impacts at the south pole
As NASA’s Dawn spacecraft sent the first images of Vesta back to Earth in July 2011, scientists immediately noticed numerous troughs, as if carved with a gigantic plough. This image shows two troughs in the Divalia Fossa system, running parallel to the lower edge of the image. The majority of these troughs extend along the equator, but a second group – inclined with respect to the equator – have been identified in the northern hemisphere. These parallel trenches are usually several hundred kilometres long, up to 15 kilometres wide and more than one kilometre in depth. They are the result of two large asteroid impacts at the South Pole, demonstrating that impact events that occurred hundreds of kilometres apart caused shocks throughout Vesta and altered its surface.
The topography of Vesta’s south pole
From stereo images obtained with Dawn’s framing camera, scientists were able to produce a global shape model of asteroid Vesta. With diameters between 458 and 578 kilometres, Vesta is not a spherical body, so its surface topography is referenced to the theoretical surface of a three-axial ellipsoidal body with semi-major axes of 289 kilometres, 280 kilometres, and 229 kilometres, respectively. On Earth, we reference all topography to the spherical ‘surface’ of our global ocean level. The image shows the elevation of surface structures above or below this ellipsoidal body with a horizontal resolution of about 750 metres per pixel. The terrain model of Vesta’s southern hemisphere shows a remarkable circular structure with a diameter of about 500 kilometres, its rim rising above the interior of the structure for more than 15 kilometres. From low-resolution images of the Hubble Space Telescope it was known that a big depression existed at Vesta’s south pole, and was suspected to be a big impact basin. Dawn scientists are investigating the processes that formed this structure.
Perspective view of a part of the edge of the south pole basin on Vesta
A visitor from Earth would encounter a dramatic landscape at Vesta's south pole: cliffs several kilometres high, deep trenches and craters which have formed the southern tip of this fascinating protoplanet in the asteroid belt, and a mountain massif up to 15 kilometres high. For the scientists working on the Dawn mission, it is not yet clear how this wild landscape was formed – collisions with other asteroids contributed, but also the internal processes that played a role during the asteroid’s early formation phases. This diagonal view was derived from a global digital elevation model of the asteroid created from stereo image data obtained with the German Framing Camera on board NASA's Dawn space probe at an altitude of 2420 kilometres above Vesta's surface. The images, which were acquired during Dawn's observation orbit, have a resolution of about 250 metres per pixel.
Craters and grooves
NASA's Dawn spacecraft acquired this image of the surface of Vesta with its Framing Camera, using the clear filter, on 11 August 2011. The image has a resolution of about 260 metres per pixel.
NASA's Dawn spacecraft acquired this image of the surface of Vesta with the Framing Camera, using the clear filter, on 12 August 2011. The image has a resolution of about 260 metres per pixel.
Mosaic of Vesta's equatorial region
The image shows a mosaic of Vesta’s equatorial region (30°N to 30°S). The mosaic is composed of observations taken through the panchromatic filter and obtained on 24 July 2011 as part of a rotation characterisation sequence (RC3); it has a scale of about 400 metres per pixel and shows impact craters of different sizes, grooves parallel to the equator and dark features within some of the craters. The mosaic is in equidistant map projection, based on a digital terrain model from RC3a/OPNAV18/RC2 and Lambertian photometrically corrected.
Vesta's equatorial region in false colours
NASA's Dawn spacecraft acquired this false-colour image with its Framing Camera on 25 July 2011. The red–green tones show an increase in luminosity in the visible continuum, while the green tones show its relative decrease in the near infrared caused by iron-containing minerals.
Up and down on Vesta's crater-strewn surface
NASA's Dawn spacecraft obtained this image with the Framing Camera on 11 August 2011 using the clear filter. The image has a resolution of about 260 metres per pixel.
Anaglyphs of the 'Snowman Crater'
This anaglyph image shows the topography of a set of three craters on Vesta that, due to their unusual arrangement, have informally been nicknamed 'Snowman' by the camera's team members. The image data was acquired using the Framing Camera on board NASA's Dawn spacecraft on 6 August 2011. The image has a resolution of about 260 metres per pixel. If you would like to view this image in 3D, you must use red-green (or red-blue) glasses (left: red; right: green [blue]).
Scarp in the south polar region
NASA's Dawn spacecraft acquired this image with its Framing Camera, using the clear filter, on 12 August 2011. The image has a resolution of about 260 metres per pixel.
Global photo mosaic of Vesta
The first global map of the asteroid Vesta generated from images acquired with the Framing Camera. In July and August 2011, Dawn orbited the third largest object in the asteroid belt initially in a 'mapping orbit' at an altitude of about 2400 kilometres above its surface. In doing so, the camera acquired hundreds of images with a spatial resolution of about 250 metres per pixel. What is referred to as ‘simple cylindrical projection’ was selected for the representation of this global map. In this map projection the south pole is not a point but is extended as a line the length of the equator. Thus, the south pole covers the entire lower edge of the image and all characteristics of this region are represented in distortion. The spatial resolution of the photo is 750 metres per pixel.
Pseudo-true colour image of the three 'Snowman' craters
Three impact craters of different sizes, arranged in the shape of a snowman, make up one of the most striking features on Vesta. In this view the three 'snowballs' are upside down, so that the shadows make the features easily recognisable. North is to the lower right in the image, which has a resolution of 70 metres per pixel. The image is composed of many individual photographs taken during the high-altitude mapping orbit, at about 680 kilometres above Vesta's surface. The largest of the three craters, Marcia, has a diameter of 60 kilometres. The central crater, which is about 50 kilometres in diameter, is named Calpurnia, and the lower crater, named Minucia, has a diameter of about 22 kilometres. Marcia and Calpurnia are possibly the result of an impact by doublet asteroids, whereas Minucia was formed by a later impact. To derive the colour information, images acquired by the German camera system on the Dawn spacecraft in two near-infrared channels (917 nanometres and 749 nanometres) and an ultraviolet channel (438 nanometres) were combined to create what is referred to as a pseudo-true colour image. The true colours of the surface of Vesta appear somewhat different, but the subtle changes in material properties across the craters and impact ejecta can be detected. In both Marcia and Calpurnia, landslides can be seen; also, dark material has been exposed below the rim of Marcia.
The topographical map reveals a double impact at Vesta’s south pole
Observations with the Hubble Space Telescope hinted that the south pole of the approximately 500-kilometre asteroid Vesta was somewhat flattened. With the images acquired by the Dawn spacecraft, it became obvious that there is a huge impact basin, with a diameter of 500 kilometres. It has been named Rheasilvia, after one of the Vestal Virgins of ancient Rome. DLR has computed topographical maps of asteroid’s surface from stereoscopic image data; these reveal the extent of this cosmic collision (red and white – elevated areas; green and blue – low regions). The impact left a 500-kilometre wide and, in some places, more than 10-kilometre deep basin surrounded by a ring of elevated rock. In the centre of Rheasilvia is a more than 20-kilometre high central peak. What surprised the researchers was the discovery of a second, older basin with a diameter of 400 kilometres, which was named Veneneia. In the right-hand image, dashed lines indicate the outlines of Rheasilvia and Veneneia. The centres of the basins are each marked with an ‘X’.
The Rheasilvia impact basin on Vesta's south pole
This false colour topographic map of Vesta's south pole shows parts of the 500-kilometre Rheasilvia impact basin in shades of blue. In the centre of the structure is a striking 20-kilometre high mountain shown in green, yellow and red tones. The global surface topographic model of Vesta was generated by DLR scientists using thousands of individual images through stereo photogrammetry.
Landslides in Marcia crater
Marcia is a 58-kilometre diameter crater near Vesta's equator. The topography of the crater is a bit unusual, as it does not have the typical bowl shape, like that of a crater on the Moon. This is likely the result of mass movements in the interior of the crater. Material from Marcia's right edge slid to its interior, forming a shallower slope. The image shows details up to a size of 70 metres.
Overview of the asteroid Vesta
Scientists from the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) have created an atlas of Vesta from about 10,000 individual images of the asteroid. The camera orbited the asteroid on board NASA’s Dawn spacecraft.
South pole of Vesta
This image shows the south polar region of asteroid Vesta. The map was created by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR).
Colour-coded map of Vesta
The camera on board the Dawn spacecraft imaged the asteroid Vesta from an altitude of 210 kilometres. Planetary researchers at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) processed this data to create maps and elevation models. This map employs colour-coding to depict the high and low points of the south polar region.
Unnamed mountain on Vesta
Towering 22 kilometres, almost three times the height of Mount Everest, a still-unnamed mountain rises in the centre of a 450 kilometre-wide impact basin at the south pole of the asteroid Vesta.
The crater Haulani on Ceres
The crater Haulani is about 34 kilometres in diameter, about the size of the Nördlinger Ries in the Swabian Alb. It does not seem to be very old yet, because the edge is still sharp. The blue tones in the contrast-enhanced image are also indicative of this. Landslides show that erosion has begun its setting work.
Ahuna Mons on Ceres
Ahuna Mons on Ceres, with crater-free (therefore geologically young) slopes, rises some 5000 metres above the surroundings, which are otherwise pockmarked by craters. Is it a cryovolcano that spews out ice as well as lava? Researchers think it is possible.
The Occator crater on dwarf planet Ceres shows currently unexplained bright patches dotted across the inner surface. This true colour image reveals more recent bluish material. The images were acquired from a distance of 1470 kilometres, and have a resolution of 140 metres per pixel.
Occator region on the dwarf planet Ceres
Planetary researchers from the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) used camera images acquired by the Dawn orbiter at a distance of 4400 kilometres from Ceres to produce this map. It shows the striking Occator crater and the unusually bright spots on its interior.
Cracks and bright spots in the Occator crater
The complex structures of the Occator crater on dwarf planet Ceres are clearly visible in the close-up images acquired from a distance of just 385 kilometres: in addition to mysterious bright spots on the inside of the crater, a large, light-coloured bulge can be seen next to innumerable cracks and fractures.
Crater with a rare filling
At the centre of the 90 kilometre-wide impact structure Occator is the largest occurrence of the strange white deposits on Ceres. These are principally carbonates, salts and carbonic acid. The blue false colours also indicate the existence of bright deposits associated with sulphuric salts, popularly known as plaster.
Ceres – an icy dwarf
According to Dawn’s recordings, the largest body in the Main Asteroid Belt could be constructed as follows: A core dominated by hydrated silicates, above it a thick mantle of water ice with silicate components and on the exterior a crust made up of light rocks and frozen volatile components, mainly water ice.
Measurements with the spectrometers on the Dawn probe confirm that the howardite, eucrite and diogenite types of meteorite come from the asteroid Vesta. In the laboratory, analyses with polarised light can now be used to precisely determine the mineral content.
Dawn’s ion propulsion system
If only rocketry pioneers Wernher von Braun and Sergei Korolev had lived to see this! The NASA Dawn mission reached its target not with a conventional rocket engine, but with a propulsion system that slowly but constantly accelerated the probe using a concentrated jet of ionised inert gas (xenon).
Occator crater on Ceres
With a diameter of 92 kilometres, Occator crater is larger than Tycho crater on the Moon – which appears like a bright back when seen with the naked eye. Its steep walls stand tall at over 2000 metres, higher than the North face of the Eiger in the Bernese Alps. The origin and nature of the bright spots in its interior is still not clear.
Dawn spacecraft with a nebula in the background
About four and a half billion years ago, the Main Belt asteroids formed from a disk of dust and ice particles over the course of only about 10 million years. They include Ceres (right), the largest dwarf planet in the main asteroid belt – with a diameter of nearly 1000 kilometres, and Vesta (to the left of the Dawn spacecraft), the third largest body. The representations of the two asteroids are based on images acquired by the Hubble Space Telescope, artistically modified in accordance with scientific criteria. The background image is also based on realistic assumptions and was created by the planetary researcher William Hartmann from the Planetary Science Institute in Tucson (Arizona).
NASA's Dawn spacecraft was launched on 27 September 2007, and has been in space for more than 11 years exploring the asteroid Vesta and the dwarf planet Ceres.
Dawn – one mission, two heavenly bodiesNASA’s Dawn spacecraft was launched on 27 September 2007. On 16 July 2011, it arrived at the asteroid Vesta, which it explored until 5 September 2012. The spacecraft then departed for the dwarf planet Ceres, where it will arrive on 6 March 2015. The Dawn mission is the first to successively study two celestial bodies from orbit.
An encounter with CeresThe NASA Dawn spacecraft will arrive at the dwarf planet Ceres on 6 March 2015. Once there, it will record the surface with the German-developed Framing Camera. This image was acquired from a distance of 237,000 kilometres from the dwarf planet.