SpaceX launches Starlink 4-15 mission booster fleet

SpaceX is launched its twentieth Falcon 9 rocket of the year with a batch of Starlink satellites to Low Earth Orbit (LEO) on the Starlink Group 4-15 mission. Liftoff occurred from Space Launch Complex 40 (SLC-40) at Cape Canaveral Space Force Station (CCSFS) in Florida.

The Falcon 9 rocket performed its traditional 35-minute-long automated launch countdown sequence prior to liftoff. Main Engine Cut-Off – or MECO – occurred about two and a half minutes into flight with stage separation and MVac ignition occurring shortly after. The fairing halves separated approximately 5 seconds after MVac ignition.

The first stage for this mission then performed its usual trip back to Earth via a set of entry and landing burns. It soft landed on SpaceX’s Autonomous Spaceport Drone Ship (ASDS) “Just Read The Instructions” stationed approximately 626km downrange in the north Atlantic Ocean. The fairing halves also came back to Earth via a set of thrusters that orient them for reentry and a parachute that slows them down to a soft splashdown in the ocean. Recovery from the ocean will be performed by SpaceX’s multi-purpose recovery vessel Bob.

booster B1049 is now set to be expended on the Nilesat 301 mission, with the O3b mPOWER missions having been re-planned in such a way that the first stage won’t have to be expended to meet customer requirements. On the other hand, booster B1060 is set to be temporarily retired once it reaches 15 flights later this year; this is understood to be for a deep-dive examination of its systems and components to better understand how to refurbish and reuse boosters up to 20 flights.

Apparently, this is not meant to be a complete overhaul but rather just a study into what it takes to efficiently and cheaply refurbish and keep using Falcon 9 boosters beyond the 15-flight mark. After this, the booster will return to the fleet with aims to fly it up to the 20-flight mark by next year.

With boosters going out of commission and demand at all-time high at SpaceX for launching their own Starlink satellites and new customers coming in like One Web, it was necessary to introduce another booster in the fleet to meet schedules. Although this could have been done on a customer mission, apparently SpaceX had already assigned boosters to customer missions well into the year, so the only possibility was to introduce the booster in one of their own missions.

Another particular rarity of this booster is the lack of the usual F9 logo, and the SpaceX 4-15 only on one side of its fuselage, which led observers to initially think it was destined to be a Falcon Heavy side booster. While its first flight is going to be as a Falcon 9 booster, it is indeed true that currently this booster is being targeted for flight as a Falcon Heavy side booster on its seventh flight.

The second stage’s first burn, the orbital insertion burn, lasted approximately 6 minutes after which the second stage and the Starlink satellites 4-15 mission. were in an elliptical Low Earth Orbit (LEO). About 30 minutes later, the second stage made a second burn to inject the satellites into the 305 by 318-kilometer 53.2° inclination target orbit. The satellites will then separate about an hour after launch.

The second stage will perform a third and final burn for deorbit and disposal over the Indian Ocean west of Australia. The Starlink satellites will then raise their orbit to an approximate 350km circular orbit for checkouts and phasing. Those that pass the checks will then raise their orbit to the 540km operational altitude.

This mission was the 46th dedicated Starlink mission by SpaceX and it is launching 53 Starlink satellites into shell four of Starlink’s first generation constellation. This will make up a total of 2600 satellites launched into LEO by SpaceX. Of these, 248 of them have reentered and 1749 are in their operational orbit

Source:This news is originally published by nasaspaceflight