RE: LAGEOS reentry

From: David Tiller (
Date: Tue Aug 31 2010 - 15:05:36 UTC

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    Is it really made of DU?
    According to the wikipedia and NASA's sites, LAGEOS-1 is a 60cm golf ball that weighs between 405 and 411kg. Wikipedia claims that it's a aluminum-covered brass ball, not DU. 
    Given those parameters, LAGEOS-1 has a volume of 113,097 cm^3. That makes the average density of 3.6 g/cm^3. Uranium is 18.9 g/cm^3, brass is between 8.4 and 8.73 g/cm^3, and aluminum is 2.7 g/cm^3. It sounds like a solid sphere of aluminum with a brass coating to me. A 60cm ball of uranium would mass in at 2138 kg, more than 5 times its actual mass.
    This paper claims the Stella satellite has a DU core, but doesn't mention LAGEOS having one:
    There's also a reference to a Starlette sat having a DU core but an overall mass of only 47kg and diameter of 48cm.
    Has anyone come across better documentation as to its construction?
    David Tiller
    Lead Consultant/Architect | CapTech Ventures
    -----Original Message-----
    From: on behalf of George Roberts
    Sent: Tue 8/31/2010 10:31 AM
    To: Derek C Breit; 'JAY RESPLER'; 'SeeSat-L'
    Subject: Re: LAGEOS reentry
    > Ummmm... Don't they mean the Uranium will decay in 8 million years, and 
    > are
    > not referring to the satellite??
    Depleted Uranium has already decayed so it's not radioactive.  It's very 
    dense.  Makes lead feel light in comparison.  It's very popular in the 
    military as it makes bullets that go through steel and such.  It's also 
    The lower the density of a satellite (such as a balloon) the faster it will 
    decay.  An inflatible satellite will decay faster than a rock.  A satellite 
    with solar panels will usually decay faster than one without.  Also the 
    higher the orbit, the longer it will take to decay.  This altitude 
    relationship isn't linear - it's probably exponential.  This is because 
    there is much less atmosphere when you go another few hundred miles higher. 
    So 2X the orbital altitude and you might increase the lifetime by 100X.
    Combine high density with high orbit and you have a satellite that will 
    decay in 8 million years.  Very quick in astronomical terms but a bit slow 
    in artificial satellite terms.
    Unless you were joking?  Was that a joke and I just ruined it?  You don't 
    have to answer.
    - George Roberts
    From: "Derek C Breit" <>
    Sent: Tuesday, August 31, 2010 9:22 AM
    To: "'JAY RESPLER'" <>; "'SeeSat-L'" 
    Subject: RE: LAGEOS reentry
    > Derek
    > -----Original Message-----
    > From:
    > [] On Behalf
    > Sent: Tuesday, August 31, 2010 1:08 AM
    > To: SeeSat-L
    > Subject: Re: LAGEOS reentry
    >  On 8/30/2010 5:08 PM, Dale Ireland wrote:
    >> Any speculation on what the reentry would be like or look like for an
    >> object like this? Uranium has a pretty high melting point of over 1100
    >> C. 2ft sphere weighing over 1000lbs. Dale
    > We'll have to watch for it in 8.4 million years.
    >>> -----Original Message-----
    >>> On 8/27/2010 5:01 PM, Dale Ireland wrote:
    >>>> Has anyone seen the LAGEOS 1?
    >> It is 5000km out and only 2ft across with corner reflectors. Made of
    >> depleted Uranium it weighs half a ton and will not decay for 8.4
    >> million years.
    >> I saw it back in Oct. 1994.
    >> Mag 11.0
    >> --
    >> Jay Respler
    > -- 
    > Jay Respler
    > 732-431-1464
    > --
    >              Freehold, New Jersey
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