spaceSpace and Physics

We Now Know What Caused A Rocket To Enter The Wrong Orbit Last Month, And It's Kind Of Embarrassing


Jonathan O'Callaghan

Senior Staff Writer

An Ariane 5 rocket launched into the wrong orbit on January 25. Arianespace

Engineers say they’ve worked out what caused their Ariane 5 rocket to run into problems last month, namely that it had been given the wrong coordinates, causing it to enter the wrong orbit.

On January 25, an Ariane 5 rocket suffered an anomaly while taking two satellites into orbit, the SES-14 and Al Yah-3, along with a NASA Earth-observation instrument called GOLD (Global-scale Observations of the Limb and Disk).


The usually highly dependable rocket accidentally deployed the satellites into an incorrect orbit. Fortunately, they were later able to get back on track and head towards their planned geostationary orbits 35,000 kilometers (22,000 miles) above Earth.

In a statement released on February 23, European company Arianespace – which operates the rocket – said it had identified the cause of the anomaly. They said that an “incorrect value” had been used on the rocket, placing it an orbital inclination of 20 degrees, rather than the planned 3 degrees.

“The cause of the trajectory deviation, therefore, was due to a bad specification of one of the launcher mission parameters that was not detected during the standard quality checks carried out during the Ariane 5 launches’ preparation chain,” they said.

They added they would “increase the robustness of the control of certain data used in preparation of the mission,” and, “strengthen the process of developing and verifying the documents required for launcher preparation.”


The next launch of the Ariane 5 is expected around March 21, when it will take two communications satellites into orbit – one for Japan and one owned by UK company Avanti Communications. Now that the cause of the previous error has been identified, that launch should be fine to go ahead.

Ensuring the Ariane 5 is up to speed will be of particular interest NASA and the rest of the astronomy community, as the agency’s James Webb Space Telescope (JWST) – over budget and significantly delayed – is scheduled to launch on an Ariane 5 by March 2019 at the earliest.

Fortunately, the Ariane 5 had 82 consecutive launches in a row prior to this January 25 flight without any problems. Now that the issue has been identified, this reliable launcher should be able to get back on track as it faces growing competition.


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