[meteorite-list] DoD To Engage Decaying Satellite

[Francis Graham]

  There is just something not right about the
assumptions in this press release; take it from an old
amateur rocket man.
  Hydrazine boils at 114 Celsius. If the tank
containing it re-enters, it is almost certain to heat
up and boil the material, overpressure the tank and
explode long before reaching the ground.
  If a fissure develops in the tank, and hydrazine is
exposed to the oxygen in the air, even in the
stratosphere, it will blow up at just above body
temperature, 37 Celsius.
  The chances of any hydrazine reaching the ground,
and spilling out after impact, is zero I would think.
It's not really a credible danger.
  There may be other perfectly valid reasons why the
DoD might want to destroy this satellite. Target
practice is one. And there may be perfectly good
reasons why they might not want souvenir hunters
picking over the wreckage if it lands. It's a
top-secret spy satellite, after all. Photos of the
wreckage could be used to understand surveillance
limitations and abilities. This is something the North
Koreans probably would like to know. These are very
good reasons for asking the public to stay clear.
  But hydrazine after re-entry? No, I don't think so.
  I realize I'm a bit controversial on this. So if any
of you folks want to point out why I could be wrong,
please do. But I think that hydrazine simply would not
survive re-entry.

Francis Graham




--- Ron Baalke <baalke at zagami.jpl.nasa.gov> wrote:

> 
> 
> Public Affairs
> U.S. Department of Defense
> Office of the Assistant Secretary of Defense
> Washington, D.C.
> 
> Media contact:
> +1 (703) 697-5131/697-5132
> 
> IMMEDIATE RELEASE: February 14, 2008
> 
> No. 0125-08
> 
> DoD To Engage Decaying Satellite
> 
> An uncontrollable U.S. experimental satellite which
> was launched in December
> 2006 is expected to reenter Earth's atmosphere
> between the end of February
> and early March. Because the satellite was never
> operational, analysis
> indicate that approximately 2,500 pounds (1134 kgs)
> of satellite mass will
> survive reentry, including 1,000 pounds (453 kgs) of
> propellant fuel
> (hydrazine), a hazardous material.
>  
> Although the chances of an impact in a populated
> area are small, the
> potential consequences would be of enough concern to
> consider mitigating
> actions. Therefore, the President has decided to
> take action to mitigate the
> risk to human lives by engaging the non-functioning
> satellite. Because our
> missile defense system is not designed to engage
> satellites, extraordinary
> measures have been taken to temporarily modify three
> sea-based tactical
> missiles and three ships to carry out the
> engagement.
>  
> Based on modeling and analysis, our officials have
> high confidence that the
> engagement will be successful. As for when this
> engagement will occur, we
> will determine the optimal time, location, and
> geometry for a successful
> engagement based on a number of factors. As the
> satellite's path continues
> to decay, there will be a window of opportunity
> between late February and
> early March to conduct this engagement. The decision
> to engage the satellite
> has to be made before a precise prediction of impact
> location is available.
>  
> Contact with hydrazine is hazardous. Direct contact
> with skin or eyes,
> ingestion or inhalations from hydrazine released
> from the tank upon impact
> could result in immediate danger. If this operation
> is successful, the
> hydrazine will then no longer pose a risk to humans.
>  
> The U.S. government has been and continues to track
> and monitor this
> satellite. Various government agencies are planning
> for the reentry of the
> satellite. In the event the engagement is not
> successful, all appropriate
> elements of the U.S. Government are working together
> to explore options to
> mitigate the danger to humans and to ensure that all
> parties are properly
> prepared to respond. In the unlikely event satellite
> pieces land in a
> populated area, people are strongly advised to avoid
> the impact area until
> trained hazardous materials (HAZMAT) teams are able
> to properly dispose of
> any remaining hydrazine.
> 
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