Re: Graveyard Orbit

From: BahlsD@aol.com
Date: Mon Jun 04 2001 - 21:21:36 PDT

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    Here is a link to the NASA Safety Standard 1740.14 - "Guidelines and 
    Assessment Procedures for Limiting Orbital Debris."
    
        http://www.orbitaldebris.jsc.nasa.gov/mitigate/nss1740/nss1740.html
    
    This document addresses guidelines and procedures for end of life spacecraft 
    disposal including planning for orbit decay or transferring to disposal 
    orbits.  Section 6 - Post-Mission Disposal of Space Structures, is the 
    operative section.  To quote from the document:
    
    "In general, the post-mission disposal options are (1) direct retrieval and 
    deorbit, (2) maneuver to an orbit for which atmospheric drag will remove the 
    structure within 25 years, and (3) maneuver to one of a set of disposal 
    regions in which the structures will not interfere with future space 
    operations."
    
    Option 1 is not widely used (yet).
    
    Option 2 is typically used for spacecraft in orbits with altitude less than 
    about 2000 km.  At the end of life, perigee of the orbit is lowered to a 
    point where (based on the mass and area characteristics of the satellite and 
    some curves supplied by NASA) it is assumed the satellite orbit will decay 
    and the satellite reenter within 25 years.
    
    Option 3 is generally used for orbits higher than 2000 km.  There are 
    generally three disposal regions.  1 - Low-altitude storage region (altitude 
    2500 km to 19,900 km), 2 High-altitude storage region (altitude 20,500 to 
    35,288 km) and 3 - Super-GEO storage region (altitude > 36,088 km).  At the 
    end of life the satellite is maneuvered into one of these regions.  At end of 
    life GEO satellites are typically boosted to higher altitudes to be out of 
    the way of future spacecraft being launched to GEO. 
    
    Figure 6-1 of the standard lays out these regions.
    
    Cheers,
    Daryl Bahls
        
    
    In a message dated 6/4/01 8:11:21 PM Pacific Daylight Time, 
    rickmcf@sympatico.ca writes:
    
    >  > Jonathan T Wojack wrote:
    >  >
    >  > > Does anyone know precisely what a "graveyard orbit" is like?  i.e., 
    what
    >  > > are the orbit parameters?
    >  >
    >  > The "graveyard orbit" is rather poorly defined. It is a higher than
    >  > geostationary orbit but the difference in semimajor axis (ie. period ie.
    >  > mean motion M) depends on the amount of propellants avaliable for final
    >  > orbit adjustments. See for example:
    >  
    >  I've been puzzled by this question for a while, and was hoping someone 
    would
    >  address it in this thread.
    >  
    >  Why higher?
    >  
    >  It would seem more sensible to me to move decommissioned geostationary
    >  satelites into a lower orbit.  I assume there's a good reason for chosing a
    >  higher orbit - anyone lnow what it is?
    >  
    >  Thanks.
    
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