Falcon 9 launches Koreasat 6A
Launch
This launch was carried out by a Falcon 9 rocket, lifting off from Launch Complex 39A at Kennedy Space Center at 12:22pm EDT. The nine Merlin engines at the base of the rocket powered it through the thickest parts of the atmosphere until it reached separation at T+02:26.
Falcon 9 carrying Koreasat-6A. Credit: John Kraus
After separation, the first stage ignited 3 of its engines at T+02:33 for a 60 second duration boostback burn to put it in a trajectory towards the launch site; due to the low mass of the satellite, this first stage had enough propellant to come back and land at LZ-1 (Landing Zone 1). After the stage completed its boostback burn, it conducted a brief coast phase in which it used its cold gas thrusters to flip itself and position correctly for the entry burn, which occurred at T+06:39 lasting 17 seconds; this burn was made to protect the first stage from the high heating of reentry, and it was also conducted using 3 engines.
Lastly, the first stage ignited its center Merlin engine for the landing burn at T+ 07:47 and successfully landed at LZ-1 at T+08:08, as the second stage completed its first burn, reaching 26.945 km/h. Then, a brief coast phase followed until SES-2 occurred, at T+28:21 and lasting 57 seconds; this last burn brought the second stage in the target orbit and at a speed of 34.954 km, and a few minutes later, at T+34:40, payload separation occurred. This was an important launch and landing, because this first stage booster is the first to have reached 23 launches and landings! B1061 and B1062 previously launched 23 times, but they were expended during the Hera mission and failed the landing on ASOG, respectively. This pushes again the boundaries of rocket reusability!
B1067 during landing burn. Credit: John Kraus
Koreasat-A right after deployment. Credit: SpaceX
Koreasat family
The Koreasat satellites are communications satellites for South Korea and the greater East Asiatic region, operated by KT (Korea Telecom) SAT. All these satellites orbit in a GEO (Geostationary Earth Orbit), at such a distance that their orbital period matches the Earth’s, allowing for them to stay over a precise location. Most of these satellites are stationed at 116°E, but some are stationed over 113°E (Koreasat 5 and 5A) and one at 75°E (Koreasat 8). The first satellite of this family, Koreasat 1, launched onboard a Delta II on August 5th, 1995, but ended up in a shorter than planned orbit; in the end it managed to reach its operational orbit, but this shortened its lifespan by more than half. The shorter orbit was the result of a failure in the separation of 1 SRB of the rocket, causing a decrease in performance. However, all following 8 satellites were a complete success.
Koreasat 6A
Koreasat 6A will replace the Koreasat 6 satellite, launched in space onboard an Ariane 5 on December 29th, 2010, with a life expectancy of 15 years. Koreasat 6A was built by Thales Alenia Space (a joint venture between Thales, 67%, and Leonardo, 33%) following the signing of a contract in September 2022. Koreasat 6A will be placed in a GTO (Geostationary Transfer Orbit) and then it will reach its operational orbit, GEO, at 116°E. This satellite will supply South Korea with both FSS (Fixed Satellite Service) and BSS (Broadcasting Satellite Service), allowing for a wide range of uses; for these purposes, it features 6 BSS transponders and 20 FSS transponders. It’s been realized on the satellite bus (which provide services to the satellites such as power and propulsion, usually used for GEO satellites) Spacebus’ 4000B2 platform, which is the latest version, developed by Thales Alenia Space. Additionally, Koreasat 6A will feature a SBAS payload (Satellite-Based Augmentation System) to allow better performance of the KASS (Korea Augmentation Satellite System) navigation system for South Korea; this system has been developed since 2016 for GNSS (Global Navigation Satellite Services) and is used especially for GPS and aviation positioning. Thanks to the futuristic system KASS, the GPS positioning error in South Korea will pass from the current 15-33 m to as low as 1-1.6 m in real time, also with the addition of this system on the satellite. The Korean Aerospace Research Institute, or Kari (the nation’s space agency) thinks that KASS’ applications in the future will also include public transport, security, defense and science. Overall, the satellite has a mass of 3500 kg and a life expectancy of 15 years; after launch, the satellite separated at T+34:40, ready to begin its journey.
References
https://www.spacex.com/launches/mission/?missionI=koreasat-6a
What is Broadband Satellite Service (BSS)? - SatNow
What is Fixed Satellite Service (FSS)? - SatNow
https://www.euspa.europa.eu/eu-space-programme/egnos/what-sbas
