[meteorite-list] NASA Spacecraft En Route to Pluto PreparesforJupiter Encounter

From: Gerald Flaherty <grf2_at_meteoritecentral.com>
Date: Thu, 18 Jan 2007 19:35:58 -0500
Message-ID: <00f601c73b61$ca0f1100$6402a8c0_at_Dell>

Doh!!
Jerry Flaherty
----- Original Message -----
From: "Sterling K. Webb" <sterling_k_webb at sbcglobal.net>
To: "Rob McCafferty" <rob_mccafferty at yahoo.com>; "Ron Baalke"
<baalke at zagami.jpl.nasa.gov>; <meteorite-list at meteoritecentral.com>
Sent: Thursday, January 18, 2007 6:46 PM
Subject: Re: [meteorite-list] NASA Spacecraft En Route to Pluto
PreparesforJupiter Encounter


> Hi, Rob,
>
> I see Ron just posted the explanation to you and
> the List, but if you like colored line diagrams galore
> and equations with delta's in them, take a look at:
> http://en.wikipedia.org/wiki/Gravitational_slingshot
>
> Gotta love those little delta's. Sir Isaac would be
> de-lighted.
>
> The article also explains the "powered slingshot"
> when you do a engine burn at closest approach, which
> adds the energy of the burn to the energy provided by
> the planet, and to the energy the fuel picked up while
> falling in. It all goes to the spacecraft, because after
> you burn the fuel, it gets "left behind."
>
> The powered slingshot is why the Earth is a hopeless
> candidate for spaceports of the future. You want to go
> somewhere else in the solar system? Depart from the
> Moon!
>
> It's got gentle escape velocity, no bothersome draggy
> atmosphere, then you drop like a rock in a circumterrestial
> orbit that skims the edge of that unhealthy Earth atmosphere.
> and do your big burn there. Hello, Mars, Venus, wherever
> you want to go!
>
> I'll be selling lunar condos in the lobby afterward, and
> LunaPort construction bonds, too...
>
>
> Sterling K. Webb
> ----------------------------------------------------------------
> ----- Original Message -----
> From: "Rob McCafferty" <rob_mccafferty at yahoo.com>
> To: "Ron Baalke" <baalke at zagami.jpl.nasa.gov>;
> <meteorite-list at meteoritecentral.com>
> Sent: Thursday, January 18, 2007 4:33 PM
> Subject: Re: [meteorite-list] NASA Spacecraft En Route to Pluto Prepares
> forJupiter Encounter
>
>
> Jupiter's
>> gravity will
>> accelerate New Horizons away from the sun by an
>> additional 9,000
>> miles per hour, pushing it past 52,000 mph and
>> hurling it toward a
>> pass through the Pluto system in July 2015.
>>
>
> Could someone clarify something which ahs been
> bothering me for years about this gravity assist
> technique?
>
> Why does the spacecraft come out of the gravity well
> going faster than it went in without thrust?
>
> You remember the conservation of energy stuff from
> school? GravPotential to Kinetic to GravPotential. A
> ball rolling down a hill can only roll up the other
> side to a height as high as it was released from.
>
> Why does this not apply to spacecraft?
> It's climbing out of the suns gravity well so it ought
> to be slowing down all the way. When you drop into
> Jupiters gravity well I can see that you're going to
> speed up but on the way out surely it'll lose all that
> speed and at the end of the encounter should be no
> faster than it went in at. In fact, slower because
> it's now further up the hill of the suns gravity well.
>
> Please, will someone tell me what I'm missing. It
> bothers me tremendously that I have a BSc in physics
> and studied both astronomy and astrophysics subsids
> and I don't get it.
> It's the same with asteroids getting ejected into
> orbits further out. How? How?
>
> Sir Isaac would not be amused
>
> Rob McC
>
>
>
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Received on Thu 18 Jan 2007 07:35:58 PM PST