[meteorite-list] ESA Remembers the Night of the Comet (Giotto - Comet Halley)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 11 Mar 2011 15:48:58 -0800 (PST)
Message-ID: <201103112348.p2BNmwlV020623_at_zagami.jpl.nasa.gov>

11 March 2011

** Contact data are at the end. **

Text, images, and video:
http://www.esa.int/SPECIALS/Rosetta/SEMMA0YTVKG_0.html

ESA REMEMBERS THE NIGHT OF THE COMET

Twenty-five years ago, ESA made its mark in deep space. A small
spacecraft swept to within 600 km of Halley's comet. The Giotto probe
was nearly destroyed by the encounter, but what it saw changed our
picture of comets forever.

As debuts go, it doesn't get any better than Giotto. The spacecraft
was ESA's first deep-space mission. Built to a design that drew on the
Geos Earth-orbiting research satellites, it was fitted with shielding
to protect it from the 'sand-blasting' it was going to receive as it
sped through the comet's tail.

It was originally conceived as a joint mission with NASA, the Tempel-2
Rendezvous-Halley Intercept mission. When the US pulled out after
budget cuts, ESA took the bold decision to forge on, finding Japan and
Russia willing to contribute their own missions. Together, they sent a
flotilla, with the Russian missions serving as pathfinders to guide
Giotto to its dangerous encounter.

Scientists, controllers and engineers gathered at ESA's control center
in Darmstadt, Germany, on the night of 13-14 March 1986 to witness the
flyby.

"It was a once-in-a-lifetime event and it had a big impact on the
general public," says Giotto's former Deputy Project Scientist,
Gerhard Schwehm.

The scientific harvest from Giotto changed people's perception of
comets. By measuring its composition, Giotto confirmed Halley as a
primitive remnant of the Solar System, billions of years old. It
detected complex molecules locked in Halley's ices that could have
provided the chemical building blocks of life on Earth.

Yet the biggest triumph was the image of Halley itself. "It may sound
simple to say that but the picture was the best thing, the moment you
saw it...it was tremendous," remembers Gerhard.

Countless people have seen the ghostly shimmer of Halley's comet from
Earth. Records of it stretch back to China in 240 BC. It famously
appears on the Bayeux Tapestry, and the Italian artist Giotto di
Bondone used it to symbolize the star of Bethlehem in his masterpiece,
The Adoration of the Magi.

But none saw what his spacecraft namesake saw: the very heart of the
comet, the nucleus.

Just 10 x 15 km, it surprised everyone by being darker than coal,
reflecting just 4% of the light falling on its surface.

Instead of the whole surface boiling away, jets were localized in
specific areas.

Giotto nearly did not survive. As expected, the probe was pummeled.
Dust from the comet ripped into it at speeds of 68 km/s, eroding away
the shielding and the sensors, destroying the camera.

But Giotto itself lived on and was sent to meet a second comet,
Grigg-Skjellerup, in 1992.

Since Giotto's encounter, Halley has continued its journey, covering
about a third of its 76-year orbit. Although it will not return until
2061, there are other cometary targets.

"Giotto ignited the planetary science community in Europe -- we had
demonstrated that we could successfully lead demanding missions -- and
people started thinking about what else we could do," says Gerhard.

ESA's Rosetta is next. The spacecraft is en route to comet
Churyumov-Gerasimenko, for arrival in 2014. It will study the comet
and release a lander to analyze the surface material.

Recently, Rosetta flew by asteroid Lutetia and is now preparing to
hibernate for the rest of its cruise. Once at Churyumov-Gerasimenko,
Rosetta will follow the comet for months.

Where Giotto gave us the night of the comet, Rosetta promises the year
of the comet.

ESA PIO Source:
Markus Bauer
ESA Communication and Knowledge Department
+31 71 56 56799
markus.bauer at esa.int
Received on Fri 11 Mar 2011 06:48:58 PM PST