Huygens begins its final journey into the unknown

from Science and Education (55 articles)

A-

A+

Page: 1 2 3 4

Eminent Dutch scientist Christiaan Huygens (1629-1695) discovered Titan in 1655, and was the first to deduce that Saturn was surrounded by a ring. He also invented the pendulum clock, the first accurate time-keeping device. Painting by Vaillant, courtesy

Image Gallery ( 13 images )

3 January 2005 Global cooperation will see yet another frontier breached in the next week as the European Space Agency's Huygens probe makes its descent towards the surface of Saturn's largest and most mysterious moon, Titan. The European Space Agency's Huygens probe was successfully released by NASA's Cassini orbiter on Christmas Day and is now on a controlled collision course toward Titan, where on 14 January it will make a descent through one of the most intriguing atmospheres in the solar system to an unknown surface. This will be the first man-made object to explore in-situ this unique environment, whose chemistry is assumed to be very similar to that of the early Earth just before life began, 3.8 billion years ago.

A few minutes after separation, Cassini turned back to Earth and relayed back information about the separation. This signal then took 1 hour and 8 minutes to cross the 1.2 billion kilometres separating the Cassini spacecraft and Earth. "Today's release is another successful milestone in the Cassini/Huygens odyssey", said Dr David Southwood, ESA's director of science programmes. "This was an amicable separation after seven years of living together. Our thanks to our partners at NASA for the lift. Each spacecraft will now continue on its own but we expect they'll keep in touch to complete this amazing mission. Now all our hopes and expectations are focused on getting the first in-situ data from a new world we've been dreaming of exploring for decades".

Final stage of a seven year odyssey

The Cassini/Huygens mission, jointly developed by NASA, ESA and the Italian space agency (ASI), began on 15 October 1997, when the composite spacecraft were launched from Cape Canaveral, Florida, atop a Titan 4B/Centaur vehicle.

Together, the two probes weighed 5548 kg at launch and became the largest space mission ever sent to the outer planets. To gain sufficient velocity to reach Saturn, they had to conduct four gravity-assist manoeuvres by flying twice by Venus, once by the Earth and once by Jupiter. On 1 July 2004, Cassini/Huygens eventually became the first spacecraft to enter an orbit around Saturn.

On 17 December, while on its third orbit around the ringed planet, the Cassini orbiter performed a manoeuvre to enter a controlled collision trajectory towards Titan.

A fine-tuning of the trajectory took place on 22 December to place Huygens on its nominal entry trajectory. While Huygens will remain on this trajectory till it plunges into Titan's atmosphere on 14 January, the orbiter performed a deflection manoeuvre on 28 December to avoid crashing onto the moon. The Christmas Day separation was achieved by the firing of pyrotechnic devices. Under the action of push-off springs, ramps and rollers, the probe was released at a relative velocity of about 0.3 m/s with a spin rate of 7 rpm.

Telemetry data confirming the separation were collected by NASA's Deep Space Network stations in Madrid, Spain and Goldstone, California, when the telemetry playback signal from Cassini eventually reached the Earth.

The Huygens probe is now dormant and will remain so throughout its 20-day coast phase to Titan. Four days before its release, a triply-redundant timer was programmed in order to wake-up the probe's systems shortly before arrival on Titan.

...continued

Page: 1 2 3 4