SpaceX ended January with and began February with two Starlink missions. These launches occurred two days apart from separate launch sites.
The first such mission — Starlink Group 2-6 — lifted off from Space Launch Complex 4 East (SLC-4E) at the Vandenberg Space Force Base in California, on Tuesday, Jan. 31 at 8:15 AM PST (16:15 UTC) after a delay from Monday “to allow additional time for pre-launch checkouts.” This will be followed by the Starlink Group 5-3 mission, launched from the historic Launch Complex 39A (LC-39A) at the Kennedy Space Center in Florida, on Thursday, Feb. 2 at 2:58 AM EST (07:58 UTC).
These two missions serve as the sixth and seventh Falcon 9 launches of the year, and the seventh and eighth overall launches for SpaceX in 2023. Both flights utilized flight-proven Falcon 9 boosters and feature booster recovery attempts.
Starlink Group 2-6 from Vandenberg used Falcon core B1071-7, which previously supported the launches of two missions for the United States National Reconnaissance Office (NROL-87 and NROL-85), SARah-1 for Airbus, SWOT for NASA and CNES, and two other Starlink flights. Following its launch on Tuesday morning, the first stage landed on the autonomous spaceport drone ship (ASDS) Of Course I Still Love You, stationed approximately 647 km downrange in the Pacific Ocean. The ship NRC Quest was also in position to retrieve the fairing halves for reuse.
Starlink Group 5-3 from Kennedy Space Center utilized Falcon booster B1069-5, which has launched the CRS-24, Starlink Group 4-23, Hotbird-13F, and OneWeb #15 missions. ASDS A Shortfall of Gravitas was on hand for first-stage recovery at an approximate downrange distance of 665 km within the Atlantic Ocean.
The launch from California — Group 2-6 — saw the deployment of 49 Starlink satellites into an orbit inclined 70 degrees with respect to the equator, at a final altitude of 570 km. The initial parking orbit was 327 km by 339 km, with Falcon 9 flying a south-southeastern trajectory.
The 570 km final orbit corresponds to the Starlink constellation’s “second shell”: an eventual grouping of 720 spacecraft spread across 36 planes, with 20 spacecraft per plane. Tuesday’s launch was only the third launch to target this second shell, as the Group 2-2, 2-3, and 2-5 missions have yet to launch. The first launch to Shell 2, Group 2-1, was deployed in September 2021.
Rendering of an ION Satellite Carrier vehicle in the midst of deploying CubeSats into low Earth orbit. (Credit: D-Orbit)
The Starlink satellites were not alone in the fairing for the Group 2-6 mission. An ION Satellite Carrier orbital transfer vehicle (SCV009 Eclectic Elena), developed and operated by the Italian company D-Orbit, served as a rideshare payload on Tuesday’s flight.
The ION Satellite Carrier platform features a customizable dispenser capable of hosting a combination of CubeSats of varying sizes. Throughout a mission, the vehicle can release its payloads individually, changing orbital parameters between one deployment event and the next. This adds a level of flexibility for missions that cannot be served by standard rideshare launches.
Following the launch of Starlink Group 2-6, SpaceX turned its attention to the East Coast for the launch of the Group 5-3 mission. This mission deployed a batch of Starlink satellites into an orbit with an inclination of 43 degrees. This means that Falcon 9 headed on a southeastern trajectory out of Florida — a common practice in the winter months as rougher seas to the north tend to complicate recovery efforts.
The satellites themselves are expected to be similar to the version 1.5 satellites that have been launched in the past few years.
A typical Starlink mission begins with the liftoff of Falcon 9 from its launchpad. The first stage’s nine Merlin 1D engines begin their ignition sequence at the T-3 second mark in the countdown, allowing them to achieve maximum thrust and pass final checks before committing to launch.
A previous mission, Starlink Group 4-37, lifts off from LC-39A in December 2022. (Credit: Julia Bergeron for NSF)
After liftoff, Falcon 9 climbs away from the launch site, pitching downrange as it maneuvers along its pre-programmed trajectory. Approximately 72 seconds into the flight, the vehicle passes through Max-Q — the point of maximum dynamic pressure, where mechanical stresses on the rocket are the greatest.
The nine first-stage engines continue to power Falcon 9 for the first two minutes and 27 seconds of the mission, until the time of main engine cutoff (MECO), at which point all nine engines shut down near-simultaneously. Stage separation normally occurs four seconds later, with the ignition of the second stage’s Merlin Vacuum engine coming about seven seconds after staging.
While the second stage continues onward to orbit with its payload, the first stage coasts upward to apogee — the highest point of its trajectory — before beginning its trip back to Earth. The booster refines its course toward the landing zone before attempting to softly touch down on the deck of one of SpaceX’s three drone ships. In this mission’s case, ASOG was the drone ship utilized.
Using a drone ship for booster recovery allows SpaceX to launch a more massive payload on Falcon 9 than it would be able to on a return-to-launch-site mission.
In the meantime, the second stage carries on with the primary mission. After stage separation and Merlin Vacuum engine ignition, the payload fairing halves are jettisoned, thereby exposing the satellites to space. Much akin to the Falcon 9 first stage, the fairing halves can be recovered and reused, using a system of thrusters and parachutes to make a controlled descent into the ocean where they will be picked up by a recovery vessel.
Second-stage engine cutoff (SECO-1) typically takes place just over eight and a half minutes into the flight. Other engine burns to modify the deployment orbit will follow if the mission requires it, such as on Group 2-6 which used a second burn before deploying SCV009 Eclectic Elena and the Starlink satellites.
The Starlink satellites are deployed into a low orbit so any faulty or non-functional spacecraft will quickly re-enter the atmosphere and be destroyed. Working satellites will raise themselves into a more stable orbit, where they will undergo checkouts before heading to their final operational orbits.
After spacecraft separation, the second stage will perform a deorbit burn for proper disposal, ensuring that reentry takes place over the ocean.
The Starship vehicle and Super Heavy booster, undergoing a Wet Dress Rehearsal fueling test at Starbase. (Credit: SpaceX)
With two successful launches, Falcon 9 reached a total of 200 orbital flights, with a launch success rate of 99%. These flights form part of a fast start to the year for SpaceX, which, according to CEO Elon Musk, is aiming for the ambitious goal of achieving up to 100 orbital launches in 2023. This would exceed its current record of 61 launches within a calendar year, set in 2022.
In addition to Falcon 9 and Falcon Heavy, SpaceX hopes to introduce Starship into its orbital catalog, starting this year with the first test flight of the full stack (the Starship vehicle and its Super Heavy booster). At this time, Starship is still undergoing readiness tests at the company’s Starbase testing and production facility in South Texas, with a launch date yet to be formally announced.
(Lead image: Falcon 9 lifts off from 39A – NSF Livestream)
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