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17 April 2007

In time the Rockies may crumble, Gibraltar may tumble, they're only made of clay / But our love is here to stay ( -- Ira Gershwin)

Comet Halley, photographed by the European Space Agency's Giotto probe.

Giotto was launched by an Ariane-1 by ESA on July 2 1985 (from French Guyana, I guess), and approached within 540 km +/- 40 km of the nucleus of Comet Halley on 13 March 1986.

The spacecraft carried 10 instruments including a multicolor camera, and returned data until shortly before closest approach, when the downlink was temporarily lost. Giotto was severely damaged by high-speed dust encounters during the flyby and was placed into hibernation shortly afterwards.

In April 1990, Giotto was reactivated. 3 of the instruments proved fully operational, 4 partially damaged but usable, and the remainder, including the camera, were unusable. On 2 July 1990, Giotto made a close encounter with Earth and was retargeted to a successful flyby of comet Grigg-Skjellerup on 10 July 1992.

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Jim Olson said...

I believe that would be Halley's Comet, as seen on the Bayeux Tapestry?

Tue Apr 17, 04:52:00 AM 2007

On the Nose! That's the Object!

Most astronomers are Very Impressed by Queen Mathilde's embroidery (the Bayeux Tapestry isn't really tapestry, but rather embroidery) of Comet Halley in the night skies over Normandy before the Battle of Hastings in 1066.

Here's the Closest Snapshot we have of it so far, from the European Space Agency's Giotto probe flyby in 1986. It was named Giotto because the Renaissance painter used his observation of Comet Halley as a model for the Star of Bethlehem.

But tracking backwards with an average period of 76.3 years almost completely rules out Comet Halley as a possible candidate for the Object in the skies at the season of Jesus' birth. The recent spectacular Comet McNaught, best seen over the Southern Hemisphere, was a long-period once-in-a-lifetime comet, and Jesus' Birthday Comet may have been one of those.

The USA forgot to send anything to welcome and photograph Comet Halley in 1986. Shame on NASA. What an embarrassment. Maybe NASA was being managed by AMTRAK.

But imagine what kind of mega-cool space hardware Earth will send when Comet Halley returns in 2061! Imagine how good and detailed the snapshots will be! We've just begun sending ambitious missions to actually bring back samples of Comet and planetoid/meteor/asteroid dust!

Comets are mostly ice objects, and we haven't really been able to see the ice solid in the center; a comet's Big Show is vapor and ionized gas boiled off by the Sun. The long tail always points away from the Sun because the Sun's radiation pushes the diffuse vapor/gas/plasma away.

Ever since New Hampshire's Old Man Of The Mountain fell off the top of its mountain into the parking lot below, I've panicked and been looking around for other stuff which is Always and Forever and Eternal and Dependable and Reliable. There's Math, of course, but I'm talking about Real Stuff in My Universe, stuff you can touch and punch and photograph and kick the tires and maybe travel to and land on and buy t-shirts and refrigerator magnets and snow globes. What's Forever? What won't ever slip off the mountain and slide into the parking lot?

This Object is the Most Reliable Eternal Thing I've found in our neighborhood so far. Just

* be careful crossing the street

* always wear your seatbelt, and

* eat fiber, dark chocolate, antioxidants and red wine

for the next 54 years, and Vleeptron GUARANTEES you'll see it again! Money Back Guarantee! (You MIGHT have to buy a ticket to the opposite hemisphere of Earth for a Really Good View. In '86, I flew to the Australian desert and had a GREAT time, we don't yet know if 2061 will be a spectacular or not-so-spectacular fly-by.)


Seth said...

And, don't forget to always wear a clean t-shirt!

Vleeptron Bob said...

well, Seth wasn't anonymous and he left a link ... which is his website that sells t-shirts.

Uhhh ... so I'll leave it here for a while, Seth respected Vleeptron's Only Rule. (I already deleted a Comment today that was an Anonymous Driveby finance scam.)

Look ... maybe somebody needs a t-shirt. I got a Halley's Comet t-shirt from Australia in '86. And a bush hat!

But I don't know how always wearing a clean t-shirt will keep you alive until 2061. Underwear maybe. Socks maybe. But a clean t-shirt?