NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/sci/space/18066

Text File | 1992-12-22 | 3.1 KB | 62 lines

Newsgroups: sci.space
Path: sparky!uunet!wupost!eclnews!wucs1!gene
From: [e-mail] (_Floor_)
Subject: Re: Acceleration
Message-ID: <[e-mail]>
Sender: [e-mail] (News Administrator)
Nntp-Posting-Host: wucs1
Organization: The K-Zoo Crew
References: <[e-mail]>
Distribution: sci
Date: Tue, 22 Dec 1992 22:04:05 GMT
Lines: 48

In article <[e-mail]> [e-mail] (John Roberts) writes:
] That applies to things that are somewhat resiliant (like humans with their
] limbs not locked), because if deformation continues throughout the period
] of acceleration, then the entire body is not really subjected to the full
] acceleration. (For another example, putting rubber feet or a springy internal
] suspension in a piece of equipment can greatly reduce the maximum shock if
] you drop it.)

Hmmm...you think maybe rigidity has something to do with this?
If something is rigid, it is much more likely to break than something
flimsy, which will bend.  Electronics certainly canot be built in
a manner that will bend. Any flexing of the probe would have to
be somehow accounted for in the design.

] But other than that, and factors such as prolonged stress on human hydraulic
] systems, the greater problem can be with rapid changes in acceleration, which
] are of course associated with short bursts of acceleration. (I believe the
] usual term for the time derivative of acceleration is "jerk".) These rapid
] changes can cause very high internal stresses that are not found with slow,
] steady increases in acceleration.
]
] Just as an example, compare your body lying in a bed with a downward
] acceleration of one gravity, or being clamped in a device that repeatedly
] shakes your body back and forth, with a maximum acceleration of half a gravity.
] Which do you think would be likely to place more stress on your body, and
] which would be quicker to cause discomfort? :-)
]
] John Roberts

You're joking me if you think the Galileo probe will experience constant
deceleration. There's going to be buffeting worse than we could imagine,
I imagine (:-). Especially at speeds many times that of sound (which I'm
sure will be different for the Jovian atmosphere)! So you're point is
very applicable. Experiencing this jolting for milliseconds (as per
a dropping watch) may not cause any damage. But if you dangled the watch
from the ceiling and proceeded to place a jackhammer at its face,
slamming into its face for a couple of minutes, liklihood is that
the watch will no longer function! Ditto for an atmospheric probe.
That thing is going to get one whale of a beating. You've helped me
emphasize my point even more! Thanks :-)


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