Screenshot from SpaceX Webcast of the Starlink Grp. 2-6 launch. Sunshine here? It’s gorgeous
Mission Rundown: SpaceX Falcon 9 - Starlink Grp 2-6
Written: January 31, 2023
Starlight in your blue eyes
SpaceX’s Starlink Group 2-6 mission will launch 49 Starlink satellites atop a Falcon 9 rocket. The Falcon 9 will lift off from Space Launch Complex 4 East (SLC-4E), at the Vandenberg Space Force Base, in California, United States.
Starlink Group 2-6 will mark the 69th operational Starlink mission, boosting the total number of Starlink satellites launched to 3,822, of which ~3,530 will still be in orbit around the Earth once launched.
Starlink Group 2-6 will mark the third launch to the second Starlink shell.
The booster supporting the Starlink Group 2-6 mission is B1071-7; as the name implies, the booster has supported six previous flights.
B1071-7 will have made its seventh flight after launching its next mission:
On successful landing, its designation will change to B1071-8 awaiting its next mission.
Following stage separation, the Falcon 9 will conduct a reentry burn lasting 20 seconds and a 22 second landing burn. These two burns aim to land the booster softly on SpaceX’s autonomous spaceport drone ship Of Course I Still Love You.
NOTAM regarding flight path and recovery area 647 km downrange. Blue/green dots are so close
The used fairings, which have flown four and two times before, will be retrieved by NRC Quest in the Pacific Ocean close to OCISLY. The fairings are now programmed to return towards the drone ship using the RCS gas thrusters and parachutes.
The days of ballistic falling fairings are over. It's a boost ‘blow’ back with Nitrogen gas.
The mission payload
Starlink is SpaceX’s internet communication satellite constellation. The low-Earth orbit constellation delivers fast, low-latency internet service to locations where ground-based internet is unreliable, unavailable, or expensive. The first phase of the constellation consists of five orbital shells.
Starlink is currently available in certain regions, allowing anyone in approved regions to order or preorder. After 28 launches SpaceX achieved near-global coverage, but version 1 of the constellation will not be complete until all five shells are filled.
Once Starlink generations 1 and 2 are complete, the venture is expected to profit $30-50 billion annually. This profit will largely finance SpaceX’s ambitious Starship program, as well as Mars Base Alpha.
Each Starlink v1.5 satellite has a compact design and a mass of 307 kg. SpaceX developed a flat-panel design, allowing them to fit as many satellites as possible into the Falcon 9’s 5.2 meter wide payload fairing.
Due to this flat design, SpaceX is able to fit up to 60 Starlink satellites and the payload dispenser into the second stage, while still being able to recover the first stage. This is near the recoverable payload capacity of the Falcon 9 to LEO, around 16 tonnes.
As small as each Starlink satellite is, each one is packed with high-tech communication and cost-saving technology. Each Starlink satellite is equipped with four phased array antennas, for high bandwidth and low-latency communication, and two parabolic antennas. The satellites also include a star tracker, which provides the satellite with attitude data, ensuring precision in broadband communication.
Each Starlink v1.5 satellite is also equipped with an inter-satellite laser communication system. This allows each satellite to communicate directly with other satellites, not having to go through ground stations. This reduces the number of ground stations needed, allowing coverage of the entire Earth’s surface, including the poles.
The Starlink satellites are also equipped with an autonomous collision avoidance system, which utilizes the US Department of Defense (DOD) debris tracking database to autonomously avoid collisions with other spacecraft and space junk.
Each satellite has a single solar panel, which simplifies the manufacturing process. To cut costs, Starlink’s propulsion system, an ion thruster, uses krypton as fuel, instead of xenon. While the specific impulse (ISP) of krypton is significantly lower than xenon’s, it is far cheaper, which further decreases the satellite’s manufacturing cost.
Each Starlink satellite is equipped with the first Hall-effect krypton-powered ion thruster. This thruster is used for both ensuring the correct orbital position, as well as for orbit raising and orbit lowering.
At the end of the satellite’s life, this thruster is used to deorbit the satellite.
Starlink’s second shell will host 720 satellites in a 70° 570 km orbit. These satellites will significantly increase the global coverage area to around 94% of the Earth. SpaceX will put 20 satellites in each of the 36 planes in the shell.
This shell is currently hosting 151 Starlink V1.5 satellites including this third launch.
The ION SCV0009 payload
The Italian company D-Orbit’s ION Satellite Carrier ‘Eclectic Elena’ features customizable 64U satellite dispensers.
D-Orbit has signed a hosted payload contract with Ensign-Bickford Aerospace & Defense Company (EBAD) for the in-orbit demonstration (IOD) of its NEA® 8’’ Payload Release Ring. Available in 8”, 15” and 24” diameters, EBAD’s separation system will be connected to a satellite simulator, which will be integrated within ION Satellite Carrier.
After being deployed from the Falcon second stage, the satellite carrier can release small satellites individually and change orbital parameters between deployments.
As the name implies, this will be D-Orbit’s 9th launch of this spacecraft, having previously launched eight others on Vega rockets and the Falcon 9.
Per webcast and press release we learn that the payloads onboard ION SCV009 is from:
- HPS, Germany
ADEO-N3, an autonomous braking sail developed by Munich-based space company HPS designed to help deorbit satellites in LEO (up to 900 km) faster than with natural orbital decay. ADEO can be used on satellites with flight altitudes below 900 kilometers. D-Orbit has already performed a successful deployment of ADEO’s smallest variant in December 2022. The smallest version of the ADEO family, ADEO-N3 weighs less than one kilogram, with dimensions of only 10 x 10 x 10 centimeters (1U) and a sail area of 5.0 m2.
- EBAD Ensign-Bickford Aerospace & Defense Company, USA
NEA® Payload Release Ring (PRR) by Ensign-Bickford Aerospace & Defense Company (EBAD) for the deployment of payloads/spacecraft from a launch vehicle or Orbital Transfer Vehicle (OTV).
Available in 8”, 15”, and 24” diameters, the NEA® Payload Release Ring consists of four NEA® release mechanisms, two ring halves, and separation springs with corresponding holders. The ring will be used to release a spacecraft simulator from ION.
- EPFL, Switzerland
Bunny, an onboard computer developed in-house by the students of the Spacecraft Team of the Swiss Institute École Polytechnique Fédérale de Lausanne (EPFL). This experiment is part of the CHESS project, which aims at launching a constellation of two CubeSats to analyze the Earth’s atmosphere chemical composition and its evolution over time and test a proof-of-concept for low-cost probes to investigate extraterrestrial atmospheres in future planetary missions.
- Stardust.me, New Zealand
SD-1, a memorial payload by StardustMe consisting of a batch of aluminum machined capsules, each carrying a gram of human cremated ashes, contained in an additive manufactured frame and enclosure. The assembly, permanently fixed to the main core of ION, will eventually re-enter the atmosphere with the host vehicle during decommissioning, providing an ultimate form of space burial. D-Orbit's mission control is now conducting the launch and early orbit phase (LEOP) in preparation for the operational phase.
The rocket launch
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.
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.
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 rocket vehicle
The Falcon 9 Block 5 is SpaceX’s partially reusable two-stage medium-lift launch vehicle. The vehicle consists of a reusable first stage, an expendable second stage, and, when in payload configuration, a pair of reusable fairing halves.
The Falcon 9 first stage contains 9 Merlin 1D+ sea level engines. Each engine uses an open gas generator cycle and runs on RP-1 and liquid oxygen (LOx). Each engine produces 845 kN of thrust at sea level, with a specific impulse (ISP) of 285 seconds, and 934 kN in a vacuum with an ISP of 313 seconds. Due to the powerful nature of the engine, and the large amount of them, the Falcon 9 first stage is able to lose an engine right off the pad, or up to two later in flight, and be able to successfully place the payload into orbit.
The Merlin engines are ignited by triethylaluminum and triethylborane (TEA-TEB), which instantaneously burst into flames when mixed in the presence of oxygen. During static fire and launch the TEA-TEB is provided by the ground service equipment. However, as the Falcon 9 first stage is able to propulsively land, three of the Merlin engines (E1, E5, and E9) contain TEA-TEB canisters to relight for the boost back, reentry, and landing burns.
The Falcon 9 second stage is the only expendable part of the Falcon 9. It contains a singular MVacD engine that produces 992 kN of thrust and an ISP of 348 seconds. The second stage is capable of doing several burns, allowing the Falcon 9 to put payloads in several different orbits.
For missions with many burns and/or long coasts between burns, the second stage is able to be equipped with a mission extension package. When the second stage has this package it has a gray strip, which helps keep the RP-1 warm, an increased number of composite-overwrapped pressure vessels (COPVs) for pressurization control, and additional TEA-TEB.
SpaceX is the first entity ever that recovers and reflies its fairings. After being jettisoned, the two fairing halves will use cold gas thrusters to orientate themselves as they descend through the atmosphere. Once at a lower altitude, they will deploy drogue chutes and parafoils to help them glide down to a soft landing for recovery.
Comparison of Type 1 and 2 with measurements based on pixels - Type 2 are 5-6 inches thicker
The Falcon 9’s fairing consists of two dissimilar reusable halves. The first half (the half that faces away from the transport erector) is called the active half, and houses the pneumatics for the separation system. The other fairing half is called the passive half. As the name implies, this half plays a purely passive role in the fairing separation process, as it relies on the pneumatics from the active half.
SpaceX will attempt to recover the Starlink Group 2-6 fairing halves from the water with their recovery vessel NRC Quest.
In 2021, SpaceX started flying a new version of the Falcon 9 fairing. The new “upgraded” version has vents only at the top of each fairing half, by the gap between the halves, whereas the old version had vents placed spread equidistantly around the base of the fairing. Moving the vents decreases the chance of water getting into the fairing, making the chance of a successful scoop significantly higher.
SpaceX used boats with giant suspended nets to attempt to catch the fairing halves, however, at the end of 2020 this program was canceled due to safety risks and a low success rate.
There are three known types of 34 x 17 foot fairings used by SpaceX to protect payload during ascent through the atmosphere. The first type had 10 evenly spaced ventilation ports in a circle on the bottom part of the fairings. This type was not aerodynamic enough to carry a parachute and ACS - Attitude Control System.
The aerodynamic balance during descent must have made them prone to stalling, or they burned up too easily. ACS gas tanks, flight orientation computers and ACS thrusters must have helped with these problems during development of type 2 fairings.
The second type is a slightly thicker fairing with only 8 evenly spaced ventilation ports in a circle on the bottom part of the fairings. The ventilation ports release the pressurized Nitrox gas during ascent, but let seawater in which makes it harder to refurbish the fairings after recovery from the ocean.
In 2021, SpaceX started flying a new “upgraded” version of the Falcon 9 fairing. The third type has 8 ventilation ports in pair’s near the edge of the fairings.
Some old type 2 fairings have been rebuilt and reused in Starlink launches. That have been a test program to develop the type 3 fairings to prevent saltwater from the ocean from flooding and sinking the fairing, and makes refurbishment toward the next flight easier.
Lately it’s apparent that the fairings are actively being aiming for the droneship in order to speed up the recovery process and cut corners of the time table. The fairing is actively breaking its speed and turning back before deploying its parachute at the last moment.
Another solution is a ‘vertical’ boost lifting the fairings apogee so the ballistic trajectory is changed aiming for a landing nearer the droneship. It’s equivalent to raising the angle on a water hose giving the water stream an higher arc but giving it a shorter reach.
It’s not clear whether or not the cold gas nitrogen thrusters alone are capable of doing a ‘boost back’ or a ‘push up’ so the fairings can alter their forward momentum mid-flight.
