Screenshot from SpaceX Webcast of the Intelsat 40e launch. It takes forever to get ready...
Mission Rundown: SpaceX Falcon 9 - Intelsat 40e
Written: April 7, 2023
Piggybacking into Space
SpaceX will launch the Intelsat 40e satellite for the communication company Intelsat, which will host a NASA payload with instruments to measure tropospheric emissions: monitoring of pollution (TEMPO) spacecraft package.
This will mark SpaceX’s 23rd launch of 2023–averaging a launch every 4.2 days.
Lift Off took place on Friday, April 7, 2023 at 00:30 EDT - 04:30 UTC from Space Launch Complex 40 at Cape Canaveral Space Force Station.
Booster B1076-4 didn't perform a static fire test of the engines. This has been omitted many times due to Falcon 9’s increasing reliability. Only after engine swabs and issues with the importance of the payload does a static fire test become necessary.
B1076-4 will have made its fourth flight after launching its next mission:
After separating from the second stage, the booster B1076-4 will land on the autonomous SpacePort Drone Ship - A Shortfall Of Gravitas.
Notam of Intelsat 40e flightpath. Blue dot is ASOG. Green dot is Doug’s fairing recovery area
After refurbishment of the booster, it will be designated as B1076-5. The second stage will after payload deployment be deorbited in the South - North Indian/Pacific Ocean south of Cape Town - Australia - east of Hawaii a couple of hours after the launch.
The fairings are both reused, flying for the second and eighth time with no known previous missions flown together. Doug will recover them 872 km downrange.
The mission payload
The Intelsat 40e (IS-40e) is a high-throughput geostationary communications satellite built by Maxar Technologies and operated by Intelsat.
The satellite will provide Intelsat customers across North and Central America with flexible coverage. The satellite has a lifetime of 15 years, made possible by two large deployable dollar arrays and batteries.
The spacecraft is powered by four SPT-100 plasma thrusters, which will allow the spacecraft to raise its orbit from GTO.
Intelsat 40e is based on Space System Loral’s SSL-1300 satellite bus. Having been used on a large number of other satellites, including most of Intelsat’s satellites, this bus is the basic satellite platform that provides stability and reliability to the instruments and gives the satellite 45 C-band transponders and 20 Ku-band its fixpoints.
The C-band transponders allow for mobile backhaul services, which allow mobile network operations to extend their coverage in remote and rural areas.
The Ku-band transponders, on the other hand, offer high-speed connectivity. The satellite will also host NASA’s TEMPO mission.
The Tropospheric Emissions: Monitoring of Pollution (TEMPO) spacecraft is a UV-visible spectrometer that will measure air quality across North America.
The TEMPO payload was built by Ball Aerospace in collaboration with NASA and the Smithsonian Astrophysical Observatory.
TEMPO is a UV-visible spectrometer built by Ball Aerospace along with NASA and the Smithsonian Astrophysical Observatory that will measure atmospheric pollution formed by ozone, nitrogen oxide, sulfur dioxide and other key pollutants over North America.
The instrument, about the size of a dishwasher, will allow the first hourly measurements of pollution across the continent during the daytime, allowing researchers to quickly and better understand changes in air quality.
Additionally, the data collected by this spacecraft will be used to improve air quality forecasts, which will help reduce exposure to harmful pollutants.
TEMPO will constantly be pointed toward the Earth, using light-collecting mirror scans for a constant east-to-west field of regard. The spacecraft measures reflected sunlight from the Earth’s surface and atmosphere.
TEMPO is the second of a three-instrument constellation designed to monitor air pollution on an hourly basis.
The first, the Geostationary Environment Monitoring Spectrometer (GEMS) is a sister instrument to TEMPO and is mounted onto the Korean Aerospace Research Institute GEO-KOMPSAT-2B satellite which was launched on an Ariane 5 rocket in Feb. 2020 and allows measurements to be taken over Asia.
The final instrument of the constellation will be mounted onto the Sentinel-4 satellite. It is currently expected to be launched in 2024 and will provide coverage to Europe and Northern Africa.
The rocket launch
A typical Starlink mission begins with the countdown that has a traditional 35-minute long propellant load sequence which begins with RP-1 (a refined form of kerosene) loading on both stages and liquid oxygen (LOX) loading on the first stage only.
Loading of RP-1 on the second stage wraps up first at the T-20 minute mark followed by the usual “T-20 minute vent” as the oxygen purging begins on the pipelines of the Falcon 9 Transporter/Erector (T/E) that supplies fluids and power to the vehicle. LOX load on the second stage begins about four minutes after that at T-16 minutes.
Engine chill commences at the T-7 minute mark with a small flow of LOX going into the turbopumps on all nine Merlin engines on the first stage. RP-1 loading on the booster then wraps up about a minute later at the T-6 minute mark.
LOX load on the first and second stages ends at around the T-3 minute and T-2 minute mark respectively, and the rocket takes control of the countdown at the T-1 minute mark.
Engine ignition is commanded at T-3 seconds allowing them to achieve maximum thrust and pass final checks before committing to launch and if engine checks look correct, the ground clamps release the rocket for liftoff at the expected T0 time.
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 30 seconds of the mission, until the time of main engine cutoff (MECO), at which point all nine engines shut down nearly simultaneously.
Stage separation normally occurs 3-4 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.
Two or three burns are required to secure the safe return and landing of a Falcon 9 booster depending on the chosen landing site. A boost back burn nullifies the horizontal speed from about 7000 km/h plus to a 1000 km/h negative if a return to launch site is chosen.
Normally a free fall trajectory is chosen which requires a re-entry burn designed to break the speed into the denser atmosphere. The Merlin 1D# engines start in a 1-3-1 sequence with the center engine 9 starting 4 seconds before lighting up engine 1 and 5 in a burn lasting 14-16 seconds ending with a 2 second center engine solo burn.
The re-entry burn last 20-22 seconds and the booster is now falling and steering through the denser atmosphere with the 6x8 feet grid fins. A last landing burn performed by the Merlin 1D# center engine is timed to the last millisecond securing the aiming and breaking of the boosters speed. The booster landing has now been performed over 180 times.
Using a drone ship for booster recovery allows SpaceX to launch more mass in a payload on Falcon 9 than it would be able to launch 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) takes place just over eight and a half minutes into the flight. A second transfer burn was performed before deploying Intelsat 40e.
After spacecraft separation, the second stage will perform a deorbit burn for proper disposal, ensuring that reentry takes place in the south Pacific or Indian 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 Falcon 9 can put some or many payloads in different orbits on 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 mission extension package it has a gray strip, which helps keep the RP-1 warm in sunlight, 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.
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.
Comparison of Type 1 and 2 with measurements based on pixels - Type 2 are 5-6 inches thicker
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 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. On this Intelsat 40e mission, SpaceX will attempt to recover the fairing halves from the water with the recovery vessel Doug.
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.
The ‘Push Up’ maneuver wasn’t used on this Intelsat 40e mission.
