SES 14 / GOLD

Launch data:

Spacecraft data:

SES-14 is fueled in the S5 payload preparation facility. Credit: ESA/CNES/Arianespace

Description:

• SES 14 is a commercial communications satellite operated by Luxembourg-based telecommunications provider SES as part of its America & Atlantic fleet and it is the host of NASA′s GOLD instrument aiming to provide a critical understanding of Sun-Earth connections needed for improved insight into space weather phenomena. The satellite is the second spacecraft to employ the innovative Eurostar-3000EOR satellite platform built by Airbus Defence and Space; it is the 53rd SES satellite launched by Arianespace in a very successful business relationship of over three decades.

Mission details:

• Ariane flight VA241, using vehicle L5101, was launched from Kourou on Jan 25, 2018 carrying the SES-14 and Al Yah 3 communications satellites. The rocket appears to have flown on a wildly incorrect azimuth, heading southeast instead of east, and although the payloads were inserted into geotransfer orbit with a near-correct apogee and perigee, the orbital inclination was 20 degrees instead of 3 degrees.
  This will require the satellites to use a lot of extra propellant to reach their final geostationary locations.
• Arianespace has not yet explained the error but it is hard to see any way for this to happen other than a mission planning/preparation error in which the rocket was commanded to fly on an incorrect launch azimuth. In general accordance with the rules, with this launch falling at the low end of the ′orbit usable but not nominal′ range, the launch is given a 0.65 score.
  This gives the Ariane 5 overall a score of 96.8 percent over 97 launches; the Ariane 5 ECA model has 97.9 percent over 65 launches.
• JR March 2018: The investigation report confirms that a single wrong number was responsible for the incorrect orbit achieved by Ariane V241/L5101. The inertial reference system (IRS) was aligned at the usual 90 degrees azimuth, but for this mission - targeted at a slightly different transfer orbit than usual - 70 degrees should have been specified.
  Owners of the Al Yah 3 satellite requested that it have be deployed at 90 degrees to the flight direction. With the usual alignment, this involved a risk of the IRS going through a coordinate zero point which would cause potential loss of reference, so the alignment was to be offset; but, this offset was not applied in at least some of the places required.

External links:

• Satellite tracking (n2ya.com): Real time satellite tracking
• Arianespace: Ariane investigation report

Astrophilately covers:

Launch cancel Kourou

Headquarter cancel Paris. Credit covers: J.VdDr.

Launch cancel Goddard Space Flight Center.Credit: #402