Mars puts asteroid probe on course

Dawn completes Swing-By-Man ver on the Red Planet

NASA spacecraft DAWN at Mars © DLR
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After a 17-month spaceflight, the Dawn asteroid spacecraft approached Mars tonight to about 565 kilometers. The goal of the so-called swing-by maneuver was to pick up speed and get Dawn on track for the asteroid Vesta, which is due to arrive in August 2011.

The researchers are also testing the German camera system aboard the probe, which was developed under the direction of the Max Planck Institute for Solar System Research (MPS) in Katlenburg-Lindau in Lower Saxony on this close flyby on the Red Planet. The scientists hope for impressive pictures of the red planet. The images will then be compared with the HRSC stereo camera operated by the German Aerospace Center (DLR) on board the ESA spacecraft Mars Express.

Dress rehearsal in space

"The almost simultaneous observations of the same area on Mars serve to check the performance characteristics of the Dawn and Mars Express camera systems, " explains Stefano Mottola from the DLR Institute for Planetary Research in Berlin.

And Holger Sierks, head of the project team at the MPS, adds: "The distant stars that the camera system otherwise picks up during its travel have only a few pixels in size on the pictures." That was the situation that the camera had with the Arrival at the asteroid Vesta expected, not comparable. The flyby on Mars alone offers a similar motif to the camera system. "This way, we can take pictures of a large body that would otherwise be impossible, " says Sierks.

Data transfer takes a week

About three hours before DAWN reached the shortest distance to Mars at 1.27 am Central European Time (CET), the camera system went into operation. It stays on for about a week. The scientists from the MPS want to use this time to extensively test the device and prepare it for its future tasks. For example, they want to examine exactly how the optics of the camera system react to stray light. The fact that impressive images of Mars can occur during the tests is a welcome by-product. display

"We hope the camera system will deliver lots of pictures of the red planet, " says Sierks. However, scientists have to be patient for a while before they can view the images. Only after about a week will DAWN have transmitted all data to Earth.

The NASA mission DAWN has been on the road to a region beyond Mars since September 2007, which scientists call an asteroid belt. Two of the many asteroids orbiting the Sun in an orbit between Mars and Jupiter to give the region its name will accompany the probe for several months each: in August 2011, DAWN will become the Vesta asteroid and in February 2015 the Ceres asteroid to reach.

View into an early development phase of the solar system

Asteroids allow researchers to take a look at the early stages of the evolution of the solar system. For the minor planets were trapped between the gravitational force of Jupiter and the Sun about 4.5 billion years ago, so they could not evolve into larger planets. In the asteroids, a state is thus preserved that can no longer be observed in our part of the solar system.

Mars gravity gets the asteroid probe going

Researchers speak of a Mars Gravity Assist (MGA) during the flyby on Mars. On the one hand, it serves to increase the flight speed of the probe with the gravitational effect of Mars and to extend the radius of the spiral - shaped trajectory of Dawn around the sun, so that the spacecraft gradually in the coming months in the direction of Asteroid main Görs between Mars and Jupiter. Vesta is about two and a half times as far from the sun as the earth (150 million kilometers).

Another important goal of the MGA maneuver is to change the angle of the Dawn orbital plane around the sun. The orbit of Vesta is tilted by more than seven degrees relative to the ecliptic, the plane of the earth's orbit around the Sun Dawn is now steered by the Mars flyby into the orbital plane of the asteroid.

(Max Planck Institute for Solar System Research / German Aerospace Center (DLR), 18.02.2009 - DLO)