Arianespace Launches Inquiry into Ariane 5 Anomaly

Arianespace has established an independent commission to investigate an anomaly that occurred during the Ariane 5 launch of two commercial communications satellites last night.  The satellites were placed into the wrong orbits, but their operators expect to be able to get them to their intended destinations anyway.

The two satellites, SES-14 and Al Yah 3, are fine other than being in the wrong orbits.

The Ariane 5 rocket was supposed to place them into an intermediate Geostationary Transfer Orbit (GTO) on their way to their final destinations in Geostationary Orbit (GEO) above the equator.  The satellites have their own propulsion systems to take them from GTO to GEO and both satellite operators indicated today that they will be able to get to GEO nonetheless, but it will take longer.

SES S.A. of Luxembourg said that SES-14 is in good health and the delay in reaching GEO will be about four weeks.  Orbital ATK, which built Al Yah 3 for the UAE’s Yahsat, similarly reported that Al Yah 3 is OK and they will execute a revised flight plan to get it to its intended location, but did not say how long it will take.

NASA has an earth science instrument, GOLD, aboard SES-14 as a hosted payload and NASA tweeted today that it has been advised by SES that there will be “minimal impact” on the satellite and “we expect no effect on the quality of GOLD’s observations & data”.

SES has informed us there is minimal impact on the SES-14 satellite carrying #NASAGOLD after the Jan. 25 launch anomaly. As the satellite is in good health, we expect no effect on the quality of GOLD’s observations & data. Full details at https://t.co/hG1FDKcP4G.

— NASA Sun & Space (@NASASun) January 26, 2018

Arianespace has established an independent commission to investigate what happened, led by the European Space Agency’s (ESA’s) Inspector General.  In the meantime it said its launch schedule will continue as planned.

Flight VA241’s two satellite payloads – SES-14 and Al Yah 3 – are in orbit and operating nominally, despite a trajectory deviation experienced during the launch. Upcoming launch campaigns currently underway at the Guiana Space Centre (CSG) are proceeding as scheduled.

— Stéphane Israël (@arianespaceceo) January 26, 2018

Astrophysicist Jonathan McDowell, editor of Jonathan’s Space Report, tweeted (@planet 4589) the orbits where the satellites should have been versus where they are based on the Two Line Elements (TLEs) issued by DOD’s Joint Space Operations Center through the publicly available Space-Track.org.

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

— Jonathan McDowell (@planet4589) January 26, 2018

His initial analysis is that a software error may have been at fault.  The altitude of the orbits is close to what was intended, but not their angles to the equator (inclinations).

Too early to tell, but this smells to me like a software/input data error could be the culprit – it’s hard to make the hardware fail in such a way as to get the right heights but the wrong inclination

— Jonathan McDowell (@planet4589) January 26, 2018

The independent inquiry will make a final determination as to what went wrong.

Ariane 5 has an impressive record, with 82 successes in a row since a failure in December 2002. The satellites were placed into orbit, even if it was the wrong one, and are expected to ultimately reach their destinations, so some record-keepers may count the launch as a success, but any anomaly is serious.   Commercial satellites like SES-14 and Al Yah 3 are often insured and comparatively easy to replace, but Ariane also launches government satellites, which typically are not insured and can be quite expensive.  Ariane 5 will launch NASA’s $8 billion James Webb Space Telescope in 2019, for example, as part of a cooperative agreement between NASA and ESA.