Screenshot from ESA WebTV of the Euclid launch. It’s all in the tip before the rocket goes vertical
Mission Rundown: SpaceX Falcon 9 - Euclid
Written: July 1, 2023
ESA takes a deep space look
Euclid will launch on a SpaceX Falcon 9 rocket, no earlier than July, before starting its 1.5 million km journey to the Sun-Earth Lagrange point L2. In orbit, Euclid will map billions of galaxies out to 10 billion light years, across more than one third of the sky.
Lift Off took place on Saturday, July 1, 2023 at 11:12 EDT - 15:12 UTC from Space Launch Complex 40 at Cape Canaveral Space Force Station.
The Falcon 9 with booster B1080-2, the 243rd second stage built and surprisingly brand new fairings containing the Euclid satellite flew eastward after liftoff.
The Falcon 9 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.
B1080-2 will have made its 2nd flight after launching its next mission:
After separating from the second stage, the booster B1080-2 will land on the Autonomous Spaceport Drone Ship - A Shortfall Of Gravitas - and be returned safely to port.
Notam on Euclid’s flightpath directly from SLC-40 past Bahama èn route to Lagrange point two
After refurbishment of the booster, it will be designated as B1080-3. The 243rd produced second stage won't be safely deorbited after payload deployment.
The fairings are brand new, flying for the first time with only this mission flown together. Doug will recover them 817 km downrange.
The Euclid payload
ESA's Euclid mission is designed to map the large-scale structure of the Universe and help us understand these mysterious components: dark matter and dark energy.
Euclid aims to uncover the mysteries of the “dark” Universe. This ominous-sounding invisible part of the cosmos makes up more than 95% of the mass and energy in our Universe. For centuries, astronomers have aimed to learn more about the luminous sources of the cosmos: planets, stars, galaxies, gas. But these objects make up only a small fraction of what the Universe contains.
Scientists estimate that dark matter makes up 25% of the Universe and dark energy 70%. Dark matter and energy affect the motion and distribution of visible sources, but do not emit, absorb or reflect any light, and scientists do not know yet what these entities actually are. Understanding their nature is therefore one of the most compelling challenges of cosmology and fundamental physics today.
Euclid will create the largest, most accurate 3D map of the Universe ever. It will observe billions of galaxies out to 10 billion light-years, across more than a third of the sky. With this map, Euclid will reveal how the Universe has expanded and how its structure has evolved over cosmic history. And from this, we can learn more about the role of gravity and the nature of dark energy and dark matter.
ESA’s Euclid was fuelled inside an Astrotech facility near Cape Canaveral in Florida (USA) ahead of its launch on a SpaceX Falcon 9.
Photo of Euclid being fueled. Above the red toolbox there is a red Hydrazine tank and standing beside it is a gray Nitrogen tank. That's the space needed by 140 kg Hydrazine and 70 kg Nitrogen
The Euclid spacecraft is supplied with two types of propellant: hydrazine and gaseous nitrogen. Ten hydrazine thrusters will provide chemical propulsion to complete the journey to Sun-Earth Lagrange point L2, perform monthly maneuvers to stay in orbit, and dispose of the spacecraft at the end of the mission’s life.
140 kg of hydrazine are usually stored in one central 35-40 gallon titanium tank.
Fuelling the spacecraft is a delicate operation because the hydrazine fuel is highly toxic. The task had to be carried out by experts who each wore a self-contained atmospheric protective ensemble, or ‘scape’ suit.
To deliver images of the highest quality, the Euclid’s spacecraft must ensure a very precise and stable pointing. For accomplishing this, Euclid will use six cold gas micro-propulsion thrusters fed by nitrogen stored in four tanks at high pressure.
The stored 70 kg of nitrogen will ensure a mission lifetime of at least six years.
Graphic of the Euclid spacecraft overview (image credit: Euclid Consortium). It looks like a chair
The Euclid Spacecraft is composed of a Service Module (SVM) and a Payload Module (PLM). The Service Module comprises all the conventional spacecraft subsystems, the instruments' warm electronics units, the sun shield and the solar arrays.
In particular the Service Module provides the extremely challenging pointing accuracy required by the scientific objectives.
The Payload Module consists of a 1.2 m three-mirror Korsch type telescope and of two instruments, the visible imager and the near-infrared spectro-photometer, both covering a large common field-of-view enabling to survey more than 35% of the entire sky.
All sensor data are downlinked using K-band transmission and processed by a dedicated ground segment for science data processing. The Euclid data and catalogs will be made available to the public at the ESA Science Data Center.
The Sunshield, part of the SVM, protects the PLM from illumination by the sun and supports the photovoltaic assembly supplying electrical power to the spacecraft. The overall spacecraft envelope, compatible with the Soyuz ST and now the Falcon 9 fairing, fits within a diameter of 3.74 m and a height of 4.8 m.
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.
At 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 200 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. Other engine burns to modify or increase the speed will follow if the mission requires it, such as on this science mission which used a second burn before deploying the Euclid satellite in its heliocentric orbit behind the Earth.
The Euclid satellite are deployed into an orbit around Lagrange L2. The Euclid satellite will undergo final checkouts before reaching its final operational orbit.
After spacecraft separation, the second stage probably won’t perform a deorbit burn for proper disposal, ensuring that reentry takes place in the nearest available Ocean.
Propellant reserves after deployment will be depleted and the 243rd second stage will be thrusted out beyond Earth orbit into a graveyard orbit around the Sun.
The Falcon 9 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 Euclid 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 Euclid mission won't be utilizing this ‘push up’ fairing recovery program.
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