[meteorite-list] Re: NEAR Bounces to Historic Landing on Asteroid Eros

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 09:41:10 2004
Message-ID: <200102142347.PAA16230_at_zagami.jpl.nasa.gov>

> (from this post):
>
> > They also have a better picture of what happened in the moments
> > after the landing: What they originally thought was the spacecraft
> > bouncing may have been little more than short hop or "jiggle" on
> > the surface; the thrusters were still firing when the craft hit the
> > surface, but cut off on impact; and NEAR Shoemaker came down
> > only about 650 feet (200 meters) from the projected landing site.
>
> Not to beat a dead horse, but isn't this getting
> a bit Clinton-esque with the language? The spacecraft
> bounced, just as some of us said it would. Calling
> it a short hop or "jiggle" is just playing with
> semantics. Did NEAR leave the surface of Eros for
> any length of time subsequent to initial contact?

As mentioned at the press conference, there was always the
possibility of a small bounce. There was never a possbility
of the spacecraft bouncing off the asteroid, as someone
had suggested earlier. The spacecraft had a slight lateral
movement, so may have just dragged itself a little on the
surface, which I think was the reference to the "jiggle".

>It most certainly did not
> just hit, sink in, and "fall over" as some at NASA
> suggested it would.

The spacecraft had no choice but to fall over. It
wasn't designed to be lander and had no landing legs.
The spacecraft did fall over into
a tripod position, sitting on the spacecraft body and
two of the solar arrays, with the high gain antenna
pointed at Earth. This was exactly the landing
orientation the navigators were shooting for, though
most people thought it unlikely it would be achieved and
that the spacecraft would survive.
 
> That's not to take away from the incredible achievement
> of successfully landing on a highly irregular asteroid
> using a spacecraft that was never designed to land.

True. It was a high risk landing.

> The fact that communication with the spacecraft was/is
> still possible following touch down is even more amazing.
> The orbital engineers who designed the deorbit and landing
> trajectory have every reason to be proud of their
> unprecedented achievement. Congratulations!
 
Even though the mission has been extended 10 days, I wish
they would keep the mission going as ong as the spacecraft is alive.
As long as we're getting a signal from the spacecraft, this acts
as a beacon, and we can really nail down the rotation rate of
the asteroid.

Ron Baalke
Received on Wed 14 Feb 2001 06:47:07 PM PST