Unexpected detail in first-ever Venus south pole images
13 April 2006
ESA's Venus Express has
returned the first-ever images of the hothouse planet’s
south pole from a distance of 206 452 kilometres, showing
surprisingly clear structures and unexpected detail. The images
were taken 12 April during the spacecraft’s initial capture
orbit after successful arrival on 11 April 2006.
Scientists are especially intrigued by the dark vortex shown almost directly over the south pole, a previously suspected but until now unconfirmed structure that corresponds to a similar cloud structure over the north pole. “Just one day after arrival, we are already experiencing the hot, dynamic environment of Venus,” said Dr Hakan Svedhem, Venus Express project scientist. “We will see much more detail at an unprecedented level as we get over 100 times better resolution as we get closer to Venus, and we expect to see these spiral structures evolve very quickly.”
initial, low-quality images were taken from an extreme distance
of 206 452 kms from the planet, yet caught scientists’
attention, particularly with the surprisingly clear structures
and unexpected details shown in the VIRTIS spectrometer
half is itself a composite of images taken via wavelength filters
and chiefly shows sunlight reflected from the tops of clouds,
down to a height of about 65 km above the planet’s surface.
The more spectacular night half, shown in reddish false colour, was taken via an IR filter at a wavelength of 1.7 microns, and chiefly shows dynamic spiral cloud structures in the lower atmosphere, around 55 km altitude. The darker regions correspond to thicker cloud cover, while the brighter regions correspond to thinner cloud cover, allowing hot thermal radiation from lower down to be imaged.
Express fired its main engine to enter Venus orbit on 11 April
2006 and is now in the first 9-day capture orbit taking it to
apocentre (maximum height) at 350 000 kilometres below the south
pole. It will swing back up to pass pericentre (minimum height)
at an altitude of 250 kilometres over the planet’s north
In addition to VMC and VIRTIS, the spacecraft’s MAG (Venus Express Magnetometer) has been switched on for initial verification and is operating nominally. Together with the ASPERA (Analyser of Space Plasma and Energetic Atoms), the two instruments are expected to gather information about the unperturbed solar wind and the atmospheric escape processes on Venus, a planet with no magnetic protection.
A series of further engine and thruster burns are planned to gradually reduce the apocentre during the following 16 orbital loops around the planet and the spacecraft is due to attain its final 24-hour polar orbit on 7 May, ranging from 66 000 to 250 kilometres above Venus.
Source / Credit: ESA
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