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Space Rock – The movie

SCIENTISTS WORKING WITH the 70-metre-wide Deep Space Network antenna at Goldstone, California, have generated a short movie clip of asteroid 2005 YU55. The images used to generate the movie are the highest-resolution ever generated by radar of a near-Earth object.

Each of the six frames required 20 minutes of data collection by the Goldstone radar. At the time, 2005 YU55 was approximately 1.38 million kilometres away from Earth. Resolution is 4 metres per pixel.

“By animating a sequence of radar images, we can see more surface detail than is visible otherwise,” said radar astronomer Lance Benner, the principal investigator for the 2005 YU55 observations, from NASA’s Jet Propulsion Laboratory.

“The animation reveals a number of puzzling structures on the surface that we don’t yet understand. To date, we’ve seen less than one half of the surface, so we expect more surprises.”

No effect on Earth

The trajectory of asteroid 2005 YU55 is well understood. At the point of closest approach it was no closer than (324,600 kilometres, as measured from the centre of Earth.

The gravitational influence of the asteroid will have had no detectable effect on anything here on Earth, including our planet’s tides or tectonic plates.

Although 2005 YU55 is in an orbit that regularly brings it to the vicinity of Earth (and Venus and Mars), the 2011 encounter with Earth is the closest this space rock has come for at least the last 200 years.

The last time an asteroid as big came as close to Earth was in 1976, although astronomers did not know about the flyby at the time. The next known approach of an asteroid this large will be in 2028.

Adapted from information issued by NASA / JPL-Caltech.

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Mapping the Earth in 3D

Artist's impression of the TanDEM-X and TerraSAR-X satellites

An artist's impression of the TanDEM-X and TerraSAR-X satellites flying in formation in Earth orbit.

  • Dual radar satellites in Earth orbit
  • Will create detailed map of the planet
  • Second satellite due for launch 21 June

The German radar satellite TanDEM-X has passed a series of tests and is on track for a lift-off aboard a Russian Dnepr launcher from the Baikonur space centre in Kazakhstan on 21 June 2010.

Together with the almost identical TerraSAR-X satellite, which has been operational since 2007, TanDEM-X will generate a digital elevation model of the Earth’s landmasses in unprecedented quality over the course of three years.

TanDEM-X and TerraSAR-X will form a radar interferometer. The satellites will fly in close formation at a separation of only a few hundred metres, enabling simultaneous terrain images from different perspectives.

The two satellites will measure the complete land surface of the Earth (150 million square kilometres). For a 12-metre grid (street width), height information will be determined with an accuracy of less than two metres.

A TerraSAR-X radar image of the Eyjafjallajoekull volcano in Iceland.

A TerraSAR-X radar image of the Eyjafjallajoekull volcano in Iceland.

Extensive tests have been conducted to demonstrate  TanDEM-X ‘s suitability for operation in space. These included electromagnetic compatibility, thermal-vacuum tests including Sun simulation, vibration and acoustic tests.

A special feature during the test campaign was the so-called ‘Boom-Release Test’ simulating the shock the satellite will receive when it unfolds its antenna in space.

Radar satellites are play an important role in mapping the Earth, as they work day and night and are unaffected by weather and clouds.

The fields of application for the data range from an increased efficiency in the production of oil, gas or minerals, improved crisis mission planning, and prediction of the impacts of disaster situations.

But first and foremost, in many countries all over the world, cartographers will be able to obtain improved height information.

Adapted from information issued by ESA / EADS Astrium / Jürgen Dannenberg.