GPS, satellite failures, and space junk

[Roger[_6_]]

Now that we have lost LORAN and are scheduled to lose most other
ground based navigation aids, I wonder what the thoughts are now that
the unthinkable happened this past week.

Two large communications? satellites collided at very high speed
creating a debris cloud about 200 X 300 miles and spreading. This
increases the chances of other Low Earth Orbit (LEO) collisions by at
least an order of magnitude. Technically there should be two debris
clouds diverging and spreading out like a shotgun blast even if the
collision had been at a shallow angle, which it wasn't.

As one astronaut said, the greatest danger in the flight going back to
the moon or mars is getting through the cloud of junk surrounding the
earth (paraphrased).

I wonder what this has done to the risk for our GPS constellation?

Roger (K8RI)

[Don Poitras]

Roger > wrote:
> Now that we have lost LORAN and are scheduled to lose most other
> ground based navigation aids, I wonder what the thoughts are now that
> the unthinkable happened this past week.

> Two large communications? satellites collided at very high speed
> creating a debris cloud about 200 X 300 miles and spreading. This
> increases the chances of other Low Earth Orbit (LEO) collisions by at
> least an order of magnitude. Technically there should be two debris
> clouds diverging and spreading out like a shotgun blast even if the
> collision had been at a shallow angle, which it wasn't.

> As one astronaut said, the greatest danger in the flight going back to
> the moon or mars is getting through the cloud of junk surrounding the
> earth (paraphrased).

> I wonder what this has done to the risk for our GPS constellation?

> Roger (K8RI)

Was it somehow kept secret? I can't find any such news report. The last
one I remember was a year ago when the russian satellite hit an Irridium (sp?).
I think that was a fairly low orbit. GPS is way up at 20,000 km.

--
Don Poitras

[Martin X. Moleski, SJ]

On Sat, 17 Apr 2010 23:50:45 +0000 (UTC), (Don Poitras) wrote in >:

>Was it somehow kept secret? I can't find any such news report. The last
>one I remember was a year ago when the russian satellite hit an Irridium (sp?).

That's the only one I could find.

February 2009:

http://www.cbsnews.com/stories/2009/02/11/tech/main4792976.shtml

>I think that was a fairly low orbit. GPS is way up at 20,000 km.

The article above said ~491 miles up.

It's a big sky--but strange things do happen.

Marty
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[Ron Wanttaja[_2_]]

Martin X. Moleski, SJ wrote:
> On Sat, 17 Apr 2010 23:50:45 +0000 (UTC), (Don Poitras) wrote in >:
>
>> Was it somehow kept secret? I can't find any such news report. The last
>> one I remember was a year ago when the russian satellite hit an Irridium (sp?).
>
> That's the only one I could find.
>
> February 2009:
>
> http://www.cbsnews.com/stories/2009/02/11/tech/main4792976.shtml
>
>> I think that was a fairly low orbit. GPS is way up at 20,000 km.
>
> The article above said ~491 miles up.
>
> It's a big sky--but strange things do happen.

The Iridium and the Russian S/C were significantly lower than GPS...on
the order of 10,000 miles or more. Strange things do happen, but it
would take some incredible stretches of luck for a bit from the
collision to not only make it up high enough but to try pass through
space coinciding with the location of a GPS satellite. Now, after a
year, it's even less likely (any debris would have been in elliptical
orbit with a low perigee).

And what might have happened if we'd been incredibly unlucky? A single
GPS satellite might have failed. The system doesn't depend on single
satellites....

Ron Wanttaja

[Roger[_6_]]

On Sat, 17 Apr 2010 23:50:45 +0000 (UTC), (Don
Poitras) wrote:

>Roger > wrote:
>> Now that we have lost LORAN and are scheduled to lose most other
>> ground based navigation aids, I wonder what the thoughts are now that
>> the unthinkable happened this past week.
>
>> Two large communications? satellites collided at very high speed
>> creating a debris cloud about 200 X 300 miles and spreading. This
>> increases the chances of other Low Earth Orbit (LEO) collisions by at
>> least an order of magnitude. Technically there should be two debris
>> clouds diverging and spreading out like a shotgun blast even if the
>> collision had been at a shallow angle, which it wasn't.
>
>> As one astronaut said, the greatest danger in the flight going back to
>> the moon or mars is getting through the cloud of junk surrounding the
>> earth (paraphrased).
>
>> I wonder what this has done to the risk for our GPS constellation?
>
>> Roger (K8RI)
>
>Was it somehow kept secret? I can't find any such news report. The last
>one I remember was a year ago when the russian satellite hit an Irridium (sp?).
>I think that was a fairly low orbit. GPS is way up at 20,000 km.

The way it was reported it sounded like the collision had just
happened, but these are the satellites to which they referred.

At such low orbits and with solar storms increasing, (2 in the last
several weeks) it's unlikely much of the debris, or at least the
smaller pieces, will stay in orbit long. Each solar storm impact on
the atmosphere causes it to expand substantially which creates a
slight increase in drag that has a much more noticeable affect on the
less massive pieces.


Roger (K8RI)

[Mxsmanic]

Roger writes:

> I wonder what this has done to the risk for our GPS constellation?

The collision was last year. GPS satellites are in orbits thousands of miles
higher than those of the Iridium and Kosmos satellites that collided.

The major risk of GPS is not satellite loss, but spoofing and jamming and
temporary signal loss due to natural phenomena.

It amazes me that the President was stupid enough to approve the
decommissioning of LORAN, since it worked well and provided a viable back-up
system to GPS.

Many people are rushing headlong towards a GPS-only navigation system that
will be crippled if anything happens to GPS (and sooner or later, something
will).

The current situation with volcanic ash in Europe stopping airline flights is
a good example of what happens when you have no contingency plans at all. GPS
for aviation is moving in that same direction.