[amsat-bb] Dnepr Upper Stage Apogee

[Burns Fisher]

Trevor, the link that Dan provided defines "orbital debris" as manmade.
 Thus I suspect the millions count does not include anything naturally
occurring.  It does seem to include flecks of paint and other material that
come off a spacecraft as a result of thermal stress or planned operations
(I assume explosive bolts and the like).

Dan, that is great info!  Thanks from me too.

73,

Burns W2BFJ


On Sun, Jul 6, 2014 at 5:19 AM, M5AKA <m5aka at yahoo.co.uk> wrote:

> Thanks for that Dan, can you just confirm that the millions of items of
> debris that NASA was referring to are naturally occurring chunks of rock ?
>
>
> As you mention Weapons Testing in space has produced thousands of debris
> pieces in orbits around 800 km and below.
>
> 73 Trevor M5AKA
>
>
>
> On Sunday, 6 July 2014, 8:03, Daniel Schultz <n8fgv at usa.net> wrote:
>
>
>
> >I noticed that after the last Dnepr launch, it's upper stage was raised
> >to an apogee of 1454 km, putting it in a 1454 km x 609 km orbit with a
> >97.9 degree inclination, in order to avoid collision with any of the 37
> >satellites it released.
>
> >There are, however, no legally binding requirements regarding debris
> mitigation.
>
>
> International agreement requires that objects in orbits lower than 2000 km
> must exit that region within 25 years after end of mission. Objects in
> orbits
> above 2000 km can remain there for longer than 25 years in a "disposal
> orbit",
> but only a few missions have the excess propulsion capacity to reach that
> orbit. Some US Government missions have disposed of upper stages to a
> higher
> orbit to avoid the need to issue a Notice to Airmen concerning the falling
> debris hazard. At least one polar orbiting weather satellite launch sent
> the
> upper stage on an Earth escape trajectory for disposal.
>
> It would seem that the Dnepr orbit is still too low to satisfy the
> international requirement.
>
> >In the case of amateur transponder satellites they can be assumed to have
> an
> >operation lifetime of 40+ years (think OSCAR-7), as I recall debris
> mitigation
> >suggests re-entry within 25 years of the end of mission. For amateur
> transponder
> >satellites this might imply 65 years in orbit.
>
> NASA is considering a revision to this policy to specify a total lifetime
> in
> LEO of no more than 30 years regardless of mission lifetime.
>
> Other interesting facts from Scott Hull's July 1 colloquium at NASA Goddard
> include:
>
> 1. There are about 22,000 objects larger than 10 centimeters in the NORAD
> database, an estimated 500,000 objects between 1 and 10 centimeters which
> are
> too small to track, and millions of objects less than one centimeter. The
> Chinese Fengyun 1C disintegration in 2007 produced about 2850 trackable
> pieces
> of debris. The new S-band space fence will be capable of tracking objects
> larger than 5 centimeters when it becomes operational in 2018.
>
> 2. There are about 4000 dead satellites on orbit, and about 1000 active
> satellites.
>
> 3. The debris population has peaks at 750, 900 and 1400 km. You would have
> to
> go to Saturn to find a worse debris environment than that of a 750 km Low
> Earth Orbit. Science missions can be difficult when you live in a
> minefield.
>
> 4. Most spacecraft disintegrations are caused by battery and pressure
> vessel
> explosions. Nickel hydrogen batteries are most susceptible to explosion but
> NiCd and lithium ion batteries can also explode. A lithium ion battery must
> NEVER be recharged after it has been fully drained. Rocket bodies left in
> GTO
> are subject to explosion when the perigee height dips low enough to begin
> atmospheric heating, which can cause remaining fuel in the tanks to
> explode.
> Modern mission design requires that batteries be disconnected from solar
> arrays and fully discharged and pressure tanks vented to space at the end
> of
> the satellite mission.
>
> 5. Space is still pretty big. We have been lucky so far. Statistics predict
> another eight or nine major collisions in the next 40 years with just the
> current population of debris.
>
> 6. The movie "Gravity" did have a science adviser, and they did get a few
> things right, namely that there were no loud sounds when the debris struck
> the
> shuttle, and objects with lower area to mass ratio arrived first.
> Nevertheless
> most NASA folks still consider the movie to be a comedy. If you have the
> DVD
> there is an additional 20 minute documentary video about orbital debris on
> the
> disk.
>
> For more information see http://orbitaldebris.jsc.nasa.gov/faqs.html#6
>
> 73, Dan Schultz N8FGV
>
>
>
>
>
>
>
>
>
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