Launch News Ariane 5 (VA241) : SES-14 (with NASA GOLD payload) & Al Yah-3 : Jan. 25, 2018

[Thunder Chicken]

Apparently the satellites were put into a 20 degree inclination orbit instead of a 3-degree inclination, but orbital apogee/perigee are about correct.

[ame="https://twitter.com/planet4589/status/956942816655040513"]Jonathan McDowell on Twitter: "TLEs are out - the Ariane objects are in 230 x 43160 km x 20 degree
geotransfer instead of the intended 250 x 45000 x 3 deg, so inclination totally off but height pretty much fine"[/ame]

Maybe somebody typed the wrong inclination into the *.ini file? :lol:

Seriously, that's a lot of angle to correct and will probably affect mission lifetime, but it's better than a complete loss.

---------- Post added at 04:24 PM ---------- Previous post was at 04:15 PM ----------

I am seeing some discussion on other forums talking about the possibility of coding for the wrong launch complex. Apparently ELA-2 and ELA-3 are rotated approximately 20-degrees from each other, and the target inclination required a 2-degree dog leg from Korou. Very early and I have no idea how likely that would be, but interesting.

 

[boogabooga]

The angle wouldn't be so bad since they go high and slow (20 degrees still better than Cape Canaveral), but the argument of perigee is way off as well.

 

[Urwumpe]

ELA-2 and ELA-3 also have practically the same latitude, so it has no effect on inclination.

Would the Ariane 5 have launched at the wrong azimuth, we would have seen a range safety case...explosion.

 

[Zeehond]

ELA-2 and ELA-3 also have practically the same latitude, so it has no effect on inclination.

Would the Ariane 5 have launched at the wrong azimuth, we would have seen a range safety case...explosion.

The Ariane 5 did launch at the wrong azimuth. That is why they lost telemetry (because the tracking stations were pointed in the wrong direction) and why the inclination of the orbit is wrong. See this picture from a map a few minutes into the flight, the x denoting the actual position of the rocket and the green circle the intended position:

Why range safety didn't do anything about it while the rocket was almost heading to Brazil, I don't know.

 

[Urwumpe]

Why range safety didn't do anything about it while the rocket was almost heading to Brazil, I don't know.

That is really strange - it was way outside the corridor and that to the south, not to the north. It should have been stopped for preventing damage.

 

[Andy44]

That is really strange - it was way outside the corridor and that to the south, not to the north. It should have been stopped for preventing damage.

So that means two potential problems to be resolved: the anomaly itself and the RSO's response to it.

 

[Urwumpe]

So that means two potential problems to be resolved: the anomaly itself and the RSO's response to it.

Exactly. Thats pretty odd in combination.

 

[Notebook]

RSO..."its a very expensive rocket, and things may get better...sometime soon."

N.

 

[Thunder Chicken]

ELA-2 and ELA-3 also have practically the same latitude, so it has no effect on inclination.

Would the Ariane 5 have launched at the wrong azimuth, we would have seen a range safety case...explosion.

What about the roll coming off the pad? If the pads are rotated 20-degrees off, would that not affect inclination? I honestly don't know what guidance information is used to control the rocket inclination.

Also, maybe the anomaly was only with the 2nd stage? But then that would be some serious dV to change inclination by 17 degrees and still get to the proper perigee/apogee.

 

[Notebook]

When did the telemetry fail?

N.

 

[Urwumpe]

What about the roll coming off the pad? If the pads are rotated 20-degrees off, would that not affect inclination? I honestly don't know what guidance information is used to control the rocket inclination.

Also, maybe the anomaly was only with the 2nd stage? But then that would be some serious dV to change inclination by 17 degrees and still get to the proper perigee/apogee.

It was already off during first stage. I thought it is impossible, but I guess I must admit I was wrong and I lacked imagination.

But the 20° could then make sense and maybe it could also explain the RSO response, if the 20° error was introduced already during alignment of the inertial navigation platform. If it was calibrated for the other pad instead of using the correct alignment data, almost all telemetry would look right, you would only notice the error by ground radar.

 

[Notebook]

So, vehicle position is just down to telemetry?

N.

 

[Urwumpe]

So, vehicle position is just down to telemetry?

N.

At least for the flight controllers. Not sure what the RSO did see. Maybe he saw a problem and was not able to communicate this to the flight controllers.

The flight controllers should only see telemetry. So, the vehicle position reported should be ALMOST as expected.

 

[Thunder Chicken]

Is vehicle guidance only based on inertial sensing of acceleration and integration from a known starting position and orientation? If you take a rocket and turn it 20 degrees on the pad and launch it, will the inclination be off by 20 degrees? Is there really no control for a target inclination other than pad orientation and programed rotations?

 

[Urwumpe]

If you take a rocket and turn it 20 degrees on the pad and launch it, will the inclination be off by 20 degrees?

As close as CSG is to the equator: Approximately yes.

 

[Thunder Chicken]

I really hope they sort this out before trying to put JWST up.

 

[Linguofreak]

I really hope they sort this out before trying to put JWST up.

Keep in mind that the type's last 82 launches have been successful. Still, I would at least think they'd include a compass or a sun tracker or something to sanity check the guidance system.

 

[GLS]

Keep in mind that the type's last 82 launches have been successful. Still, I would at least think they'd include a compass or a sun tracker or something to sanity check the guidance system.

Clearly they used humans....

 

[boogabooga]

I rewatched the live broadcast.

The broadcast announcer kept on talking as if the mission were proceeding successfully, despite signs to the contrary. (The shot of a poor engineer wiping away tears should have been a dead giveaway). The animation- which continued unphased- was obviously pre-recorded and not tied to the telemetry. Perhaps Ariane Space needs to look into a more tactful way of interrupting the broadcast when it needs to.

 

[Thunder Chicken]

I rewatched the live broadcast.

The broadcast announcer kept on talking as if the mission were proceeding successfully, despite signs to the contrary. (The shot of a poor engineer wiping away tears should have been a dead giveaway). The animation- which continued unphased- was obviously pre-recorded and not tied to the telemetry. Perhaps Ariane Space needs to look into a more tactful way of interrupting the broadcast when it needs to.

Where did you see this?