Inclination angles for LEO satellites

[Dave Michelson]

Hi, all.

I'm looking for the most common altitudes and inclination angles for LEO
satellites.

I found the distribution of altitudes easily enough. See

http://satjournal.tcom.ohiou.edu/issue6/current_debris2.html

What I need now is a similar result for inclination angles.

If you can help, I would be most appreciative.

[Rand Simberg]

On Mon, 11 Jun 2007 19:00:00 GMT, in a place far, far away, Dave

Post by Dave Michelson
Hi, all.
I'm looking for the most common altitudes and inclination angles for LEO
satellites.
I found the distribution of altitudes easily enough. See
http://satjournal.tcom.ohiou.edu/issue6/current_debris2.html
What I need now is a similar result for inclination angles.
If you can help, I would be most appreciative.

I don't have any data, but my guess is that sun-synch would dominate
(i.e., about 98 degrees, though exact inclination is of course a
function of altitude).

[Dave Michelson]

Post by Rand Simberg

Post by Dave Michelson
Hi, all.
I'm looking for the most common altitudes and inclination angles for LEO
satellites.
I found the distribution of altitudes easily enough. See
http://satjournal.tcom.ohiou.edu/issue6/current_debris2.html
What I need now is a similar result for inclination angles.
If you can help, I would be most appreciative.

I don't have any data, but my guess is that sun-synch would dominate
(i.e., about 98 degrees, though exact inclination is of course a
function of altitude).

I suspect you're right. Interestingly enough, the 600-800 km peak in the
altitude PDF corresponds to the "optimum" altitude for a satellite in a
98-degree sun synchronous orbit. Other peaks would correspond to the
large LEO comsat constellations such as Orbcomm, Iridium, and Globalstar.

If one had access to the NORAD TLE data base, I suppose that one could
easily run the numbers but I gather that it's been locked down. Or has
it?

--
Dave Michelson
***@ece.ubc.ca

[Rand Simberg]

On Mon, 11 Jun 2007 19:58:53 GMT, in a place far, far away, Dave

Post by Dave Michelson

Post by Rand Simberg

Post by Dave Michelson
Hi, all.
I'm looking for the most common altitudes and inclination angles for LEO
satellites.
I found the distribution of altitudes easily enough. See
http://satjournal.tcom.ohiou.edu/issue6/current_debris2.html
What I need now is a similar result for inclination angles.
If you can help, I would be most appreciative.

I don't have any data, but my guess is that sun-synch would dominate
(i.e., about 98 degrees, though exact inclination is of course a
function of altitude).

I suspect you're right. Interestingly enough, the 600-800 km peak in the
altitude PDF corresponds to the "optimum" altitude for a satellite in a
98-degree sun synchronous orbit. Other peaks would correspond to the
large LEO comsat constellations such as Orbcomm, Iridium, and Globalstar.

That's probably LEO, to first order.

Post by Dave Michelson
If one had access to the NORAD TLE data base, I suppose that one could
easily run the numbers but I gather that it's been locked down. Or has
it?

Are you looking for satellites currently in orbit, or historically?
Jonathan's Space Report might have a text file of all (unclassified)
launches that you could Perl out some results from.

[David Schneider]

Post by Rand Simberg
Are you looking for satellites currently in orbit, or historically?
Jonathan's Space Report might have a text file of all (unclassified)
launches that you could Perl out some results from.

Dr. Kelso's site probably has still has a fairly complete list of
TLE's. I used that site most when I was keeping up with stsplus, but I
still visit from time to time.

/dps

[snidely]

Post by David Schneider
Dr. Kelso's site probably has still has a fairly complete list of
TLE's. I used that site most when I was keeping up with stsplus, but I
still visit from time to time.

That would be <http://celestrak.com/NORAD/elements/>, wouldn't it?

/dps

[Dave Michelson]

Post by snidely

Post by David Schneider
Dr. Kelso's site probably has still has a fairly complete list of
TLE's. I used that site most when I was keeping up with stsplus, but I
still visit from time to time.

That would be <http://celestrak.com/NORAD/elements/>, wouldn't it?

Indeed it is. Thanks :-)

[t***@flash.net]

Post by Dave Michelson
If one had access to the NORAD TLE data base, I suppose that one could
easily run the numbers but I gather that it's been locked down. Or has
it?

"Supervised" is perhaps better than "locked down." You have to apply,
agree to the terms of usage (which are slightly weird but not
particularly oppressive), and get approved for access. After that,
it's very user-friendly, generally better than the NASA version that
preceded it.

If you're interested, go to http://www.space-track.org/perl/login.pl
and look at "Create a New Account".

[robert casey]

Post by Dave Michelson
inclination angles.

Unless a satellite needed a specific inclination for its application,
the inclination would likely be that of the launch site. Cape Canaveral
is around 27 degrees, and Russia's launch site is something like 51
degrees. Odds are you'll find a clumping at these two values.

[Chris Jones]

Post by Dave Michelson
inclination angles.

Unless a satellite needed a specific inclination for its application, the

Which it usually does.

inclination would likely be that of the launch site. Cape Canaveral is around
27 degrees, and Russia's launch site is something like 51 degrees. Odds are

Actually, Baikonur is closer to 48 degrees, and Plesetsk (which at
various times is either the most common or 2nd most common Russian
launch site) is close to 63 degrees. Neither uses those as
inclinations, as a rule, as payload considerations and where the launch
stages fall dictate other than due easterly launch azimuths, as they do
for launches from KSC and Vandenberg, the two most popular US launch
sites (and really, every other launch site).

you'll find a clumping at these two values.

[Allen Thomson]

Post by Dave Michelson
What I need now is a similar result for inclination angles.

Would p.5 of http://www.spaceelevator.com/docs/800Carroll.pdf help?

[Dave Michelson]

Post by Allen Thomson

Post by Dave Michelson
What I need now is a similar result for inclination angles.

Would p.5 of http://www.spaceelevator.com/docs/800Carroll.pdf help?

Thanks, that's very helpful!

I presume 'other' is mostly ESA. If so, I had no idea they had put up
so many satellites into near equatorial LEO.

[Rand Simberg]

On Wed, 13 Jun 2007 16:44:06 GMT, in a place far, far away, Dave

Post by Dave Michelson

Post by Allen Thomson

Post by Dave Michelson
What I need now is a similar result for inclination angles.

Would p.5 of http://www.spaceelevator.com/docs/800Carroll.pdf help?

Thanks, that's very helpful!
I presume 'other' is mostly ESA. If so, I had no idea they had put up
so many satellites into near equatorial LEO.

Well, they're the only ones who can (except Sea Launch). Not sure
that's a good enough reason to do it, though. I wonder why? It
doesn't seem like a very useful orbit.

[Dave Michelson]

Post by Rand Simberg

Post by Dave Michelson

Post by Allen Thomson

Post by Dave Michelson
What I need now is a similar result for inclination angles.

Would p.5 of http://www.spaceelevator.com/docs/800Carroll.pdf help?

Thanks, that's very helpful!
I presume 'other' is mostly ESA. If so, I had no idea they had put up
so many satellites into near equatorial LEO.

Well, they're the only ones who can (except Sea Launch). Not sure
that's a good enough reason to do it, though. I wonder why? It
doesn't seem like a very useful orbit.

Agreed!

(Of course, the ordinate in the graph is radar cross section so we don't
really know exactly what the objects are except that they're man-made.)

[Dave Michelson]

Post by Dave Michelson

Post by Rand Simberg

Post by Dave Michelson

Post by Allen Thomson

Post by Dave Michelson
What I need now is a similar result for inclination angles.

Would p.5 of http://www.spaceelevator.com/docs/800Carroll.pdf help?

Thanks, that's very helpful!
I presume 'other' is mostly ESA. If so, I had no idea they had put up
so many satellites into near equatorial LEO.

Well, they're the only ones who can (except Sea Launch). Not sure
that's a good enough reason to do it, though. I wonder why? It
doesn't seem like a very useful orbit.

Agreed!
(Of course, the ordinate in the graph is radar cross section so we don't
really know exactly what the objects are except that they're man-made.)

I found some very nice scatter plots showing the number of objects with
mass > 1 mg or diameter > 1 cm over altitudes between 100 and 100000 km
(log scale) and inclination angles between 0 and 165 degrees in a
journal article,

C. Pardini and L. Anselmo, "Assessing the Risk of Orbital Debris
Impact," Space Debris. Dordrecht: 1999. Vol. 1, Iss. 1; p. 59-80.

There's no evidence of a spike in equatorial LEO as seen in the figure
on page 5 of Carroll.

[t***@flash.net]

Post by Dave Michelson
C. Pardini and L. Anselmo, "Assessing the Risk of Orbital Debris
Impact," Space Debris. Dordrecht: 1999. Vol. 1, Iss. 1; p. 59-80.
There's no evidence of a spike in equatorial LEO as seen in the figure
on page 5 of Carroll.

That might be an artifact of the time the article was written and the
fact that US coverage of low-inclination LEO orbits hasn't been, at
least historically speaking, all that good.

[David M. Palmer]

Post by Rand Simberg
On Wed, 13 Jun 2007 16:44:06 GMT, in a place far, far away, Dave

Post by Dave Michelson

Post by Allen Thomson

Post by Dave Michelson
What I need now is a similar result for inclination angles.

Would p.5 of http://www.spaceelevator.com/docs/800Carroll.pdf help?

Thanks, that's very helpful!
I presume 'other' is mostly ESA. If so, I had no idea they had put up
so many satellites into near equatorial LEO.

Well, they're the only ones who can (except Sea Launch). Not sure
that's a good enough reason to do it, though. I wonder why? It
doesn't seem like a very useful orbit.

If you want to put the most stuff in orbit from an equatorial launch
site, such as French Guyana, an equatorial orbit is optimum.

And there are reasons why equatorial orbits are better for some things.
a) It passes over your ground station more often and for longer each
time, assuming your ground station is equatorial
b) It never passes through the South Atlantic Anomaly high-radiation
zone.

These are sufficiently important for some missions that the gamma ray
burst astronomical satellite mission HETE was launched into an
equatorial orbit by a Pegasus XL (air launched, so you don't need a
fixed launch pad).

For the later GRB mission Swift, we bought an extra solid rocket motor
to strap to the Delta in order to bring the (Cape Kennedy-launched)
orbital inclination from 28 degrees down to 23.

[th]

Post by Dave Michelson

Post by Allen Thomson

Post by Dave Michelson
What I need now is a similar result for inclination angles.

Would p.5 of http://www.spaceelevator.com/docs/800Carroll.pdf help?

Thanks, that's very helpful!
I presume 'other' is mostly ESA. If so, I had no idea they had put up
so many satellites into near equatorial LEO.

ESA has not launched to equatorial LEO, most ESA LEO are polar. Couldn't
this be remainders of telecom GTO launches?

[Rand Simberg]

On Fri, 15 Jun 2007 16:25:07 GMT, in a place far, far away, th

Post by th

Post by Dave Michelson

Post by Allen Thomson

Post by Dave Michelson
What I need now is a similar result for inclination angles.

Would p.5 of http://www.spaceelevator.com/docs/800Carroll.pdf help?

Thanks, that's very helpful!
I presume 'other' is mostly ESA. If so, I had no idea they had put up
so many satellites into near equatorial LEO.

ESA has not launched to equatorial LEO, most ESA LEO are polar. Couldn't
this be remainders of telecom GTO launches?

Could be, though those would presumably be in GTO, rather than LEO.
Are they circular LEO, or do they have a high apogee?

[th]

Post by Rand Simberg
On Fri, 15 Jun 2007 16:25:07 GMT, in a place far, far away, th

Post by th

Post by Dave Michelson

Post by Allen Thomson

Post by Dave Michelson
What I need now is a similar result for inclination angles.

Would p.5 of http://www.spaceelevator.com/docs/800Carroll.pdf help?

Thanks, that's very helpful!
I presume 'other' is mostly ESA. If so, I had no idea they had put up
so many satellites into near equatorial LEO.

ESA has not launched to equatorial LEO, most ESA LEO are polar. Couldn't
this be remainders of telecom GTO launches?

Could be, though those would presumably be in GTO, rather than LEO.
Are they circular LEO, or do they have a high apogee?

GEO launcher stages normally remain in GTO but this orbit frequently
visits the low altitudes and might be included in the statistics.

[Rand Simberg]

On Fri, 15 Jun 2007 19:01:37 GMT, in a place far, far away, th

Post by th

Post by Rand Simberg
On Fri, 15 Jun 2007 16:25:07 GMT, in a place far, far away, th

Post by th

Post by Dave Michelson

Post by Allen Thomson

Post by Dave Michelson
What I need now is a similar result for inclination angles.

Would p.5 of http://www.spaceelevator.com/docs/800Carroll.pdf help?

Thanks, that's very helpful!
I presume 'other' is mostly ESA. If so, I had no idea they had put up
so many satellites into near equatorial LEO.

ESA has not launched to equatorial LEO, most ESA LEO are polar. Couldn't
this be remainders of telecom GTO launches?

Could be, though those would presumably be in GTO, rather than LEO.
Are they circular LEO, or do they have a high apogee?

GEO launcher stages normally remain in GTO but this orbit frequently
visits the low altitudes and might be included in the statistics.

Yes, that's what I'm asking. GTO has LEO perigee, but a much higher
(generally GEO altitude) apogee. Is that what's being counted here?
If so, that makes the most sense. But I wouldn't call them LEO
satellites.