# Is is possible to launch a satellite to a strange orbit?

1. Sep 17, 2007

### Alex Nesh

Is it possible to launch the satellite into orbit with inclination less than of latitude of the launch site? Can you please explain to me using some formulas.

2. Sep 17, 2007

### Alex Nesh

For instance is is possible to launch a space vehicle from Baikonur (47 degrees north) and place the satellite into orbit with inclination of 28 degrees . But only during the boost phase.

3. Sep 17, 2007

### mgb_phys

Any orbit is possible with enough fuel - I don't know if it's practical!
Presumably geostationary orbits are 0 inclination ( it's been a few years since spherical trig) and they are launched from everywhere.
Similairly GLONASS must be in range of inclinations and presumably they are all launcedh from Baikonur.

4. Sep 17, 2007

### Astronuc

Staff Emeritus
One can put a satellite in any orbit, from equatorial to polar, and do it during boost phase provided one supplies sufficient fuel, as mgb_phys indicated.

Normally, one tries to minimize fuel in order to minimize cost, at least commercial (for-profit) entities do. Military institutions and governments are not so constrained.

5. Nov 9, 2010

### alexjbuck

Assuming you use a standard "launch":

No.

Think of it this way. If you were to start at 67 degrees north latitude and just teleport the spacecraft up 200km and get it moving instantly due east at circular orbit velocity (roughly 8km/s for LEO) then it would have an inclination of 67 degrees. The instant we "play" this scenario, gravity will pull the spacecraft towards the earth, which happens to be "down" in the sense of latitudes, aka the spacecraft will start to descend in latutude, passing through the equator and eventually reaching the opposite side of the orbit at 67 degrees south latitude.

If instead the initial velocity was anything other than due east, the spacecraft either will continue to head north (if the vector is pointed north east-ish) or will just have come from a more northern latitude (if the vector is pointed south east-ish).

Of course spacecraft don't just teleport up to orbit BUT the launch phase is fast with respect to the orbit period. This means we can imagine the spacecraft simply being displaced E/W and N/S from the launch site, and not just in an Up/Down sense.

So to get a lower inclination the spacecraft needs to be heading due east while at a lower inclination. Launching from 67 degrees north latitude, the only way to get to a more southern latitude is to head south. Now, if the launch azimuth is southerly, the inclination will actually be greater than 67 degrees (when the s/c comes back around after one complete orbit it passes over the launch site heading south! That means it was just further north, thus at a higher inclination).

Thus the only way to get a lower inclination orbit is to first boost south and then TURN and boost east. Now this isn't really a practical launch, and in essence is simply moving to a more southern launch site then launching from there.

I suppose you could boost west but you'd be working against the earths rotation at that point (~2-300 m/s at northerly latitudes).

All of that being said, you can always transfer into any other orbit once in orbit. To change your inclination you need to be at a node (a point where the orbit plane crosses the equator, aka the satellite is over the equator, 0 degrees latitude). You can draw this out, with the inclined orbit heading diagonally lower left to upper right (or vice versa...) and the equitorial orbit heading left to right. The velocity vectors of those two orbits are aligned with the orbit paths so you can use trig (law of cosines works well) to figure out the deltaV vector to change a velocity of ~8km/s at 67 degrees above the horizontal to a vector of ~8km/s at 0 degrees above the horizontal.

But thats not during the boost phase. So the answer to your question is no.

6. Nov 9, 2010

### alexjbuck

As one who has seen the inner workings of a military comm spacecraft program in development, this is ALWAYS a constraint. The engineers are always trying to trim the cost and use less fuel.

The absolute cost is just a function of the complexity of the task, independent of commercial/military.