Screenshot from SpaceX Webcast of the Inmarsat I-6 F2 launch. Didn’t we do this five days ago?
Mission Rundown: SpaceX Falcon 9 - Inmarsat I-6 F2
Written: February 19, 2023
Double decker bus going up
Space Exploration Technologies, Inc. - SpaceX is launching a communications satellite to Geostationary Earth Orbit (GEO) for Inmarsat, a satellite communications company.
This satellite, I-6 F2, is the second of two I-6 series of satellites, and is the twin of I-6 F1 which flew on a Japanese H-IIA rocket in 2021. This satellite will operate in both the L-band and Ka-band. It is part of Inmarsat’s network of the future, ORCHESTRA, which will provide seamless, high-capacity, low-latency connectivity for global mobility.
The flight is on board a Falcon 9 Block 5 rocket, the third flight for the booster B1077-3 is launched from SLC-40 on February 17, 2023 at 22:59 EST.
Notam of flight path + landing area of B1077-3 from Cape Canaveral SLC-40 665 km downrange
After boosting the second stage along with its payload towards orbit, the first stage will freefall in a parabolic curve before it performs a 19 second re-entry burn meant to slow the vehicle down before the atmospheric reentry. The booster will then perform a 23 second landing burn and softly land aboard SpaceX’s autonomous spaceport drone ship.
It landed on the drone ship Just Read The Instruction, 665 km east of the launch site, roughly eight and half minutes after liftoff.
B1077-3 will have made its third flight after launching its next mission:
Booster B1077-3 didn’t perform or complete a static fire test before this flight.
SpaceX is the first entity ever that recovers and reflies its fairings. The recovery vessel Bob - named after Astronaut Bob Behnken - will salvage the fairing halves.
The Inmarsat I-6 F2 payload
Inmarsat is a UK-based company which since the 1970s has launched and operated a set of geostationary communications satellites at a range of longitudes. These satellites provide various services for marine and airborne traffic.
The satellite network covers the majority of the globe, apart from very high latitudes, i.e. coverage is complete from 82° South to 82° North. Antarctica is out of coverage.
Inmarsat is now a private company, but owes its roots to the International Maritime Satellite Organization (INMARSAT for short). INMARSAT was created through the United Nations. It was superseded in 1999 by the International Mobile Satellite Organization (IMSO), and at this time the operational part of the old organization was transferred to Inmarsat Ltd, based in London.
Inmarsat provides support for, amongst other services:
voice telephone calls
low bandwidth communications on the Global Broadband Area Network (BGAN) via General Packet Radio Service (GPRS)
faster Internet access via Global Xpress (up to 50 Mbit/s)
FleetBroadband, a maritime service based on BGAN technology
SwiftBroadband, an aeronautical service also based on BGAN technology
Telephone devices supported by Inmarsat are all allocated a number with country code 870. Prior to December 2008, each global region had its own individual country code.
It also has a software-defined radio that can switch between L-band and Ka-band modes depending on the demand and availability of the spectrum. This will allow the satellite to offer full routing flexibility over more than 8,000 channels and dynamic power allocation of more than 200 spot beams in the L-band.
The satellite weighs 5,470 kg and is built on the Airbus Eurostar-3000 EOR satellite bus. It utilizes the Fakel SPT140D propulsion unit and has two 21 kW deployable solar arrays.
One of the last tasks at the AirbusSpace facility in Toulouse is to load Inmarsat I-6 F2 with over 1,000 kg of Xenon gas, a non-combustible liquid air propellant which will power the satellite’s all-electric Hall-effect propulsion system for orbit raising
Flight MH-370
On March 8, 2014, Malaysian Airlines flight MH-370 disappeared during a flight from Kuala Lumpur to Beijing. Military radar systems of several countries tracked the flight for a period of time after communications from the aircraft ceased.
However, once the military radars could no longer track the aircraft, all information as to its subsequent fate appeared to be lost.
MH-370 had on board a “Classic Aero” satellite data unit fitted, which continued to function for several more hours. Inmarsat data systems in London recorded a number of “pings” - short handshake messages - between this unit and an Inmarsat satellite over the Indian Ocean Region (64° East).
Inmarsat specialists looked at the encoded information in relation to these pings. This allowed them to conclude that the aircraft turned to the South and continued to fly onward for another 7 hours.
Inmarsat’s role in tracking the fate of flight MH-370. (Credit: BBC)
Because the satellite was flying in a “figure of 8” formation above the point on the equator at 64° East, very subtle differences in timing and frequency of these messages could be recorded. Analysis of these differences were used to prove that the aircraft was last airborne over the Southern Indian Ocean, near Australia.
I wrote something about my thoughts on this in the Inmarsat-5 F4 mission rundown.
The Falcon 9 launch
The now familiar Falcon 9 countdown sequence began at T-38 minutes when the Launch Director verified that the vehicle was ‘go for’ propellant loading. Three minutes later, at T-35 minutes, SpaceX began loading subcooled RP-1 onto both the first and second stages, as well as super-chilled liquid oxygen (LOX) onto the first stage.
Around T-20 minutes, a large cloud vented from the strong back, signifying the second stage was fully fueled with RP-1 and the Transporter-Erector was being readied for Stage 2 LOX loading, which began at T-16 minutes.
At T-7 minutes, the Falcon 9 ran small amounts of liquid oxygen through the nine Merlin 1D# engines on the first stage. Known as engine chill, this process cools the engines slowly, ensuring they do not crack from thermal shock when super-chilled LOX flows through them at engine ignition.
At T-1 minute, Falcon 9 entered startup and began tank pressurization for flight. At this time, the Falcon 9 was in command of its countdown.
Forty-five seconds before launch, the Launch Director verified that all systems were ‘go for’ launch. Manual aborts could be called by the launch operators up until T-10 seconds, after which technical aborts are only handled by the vehicle flight computers.
At T-3 seconds, the booster’s flight computer commanded the ignition of the first stage’s nine Merlin 1D engines. The engines on the first stage ignite in pairs to reduce startup transients and loads on the vehicle.
Once Falcon 9 ensured all systems were nominal, it commanded the hydraulic clamps at the base of the vehicle to release, letting the rocket lift off from the pad.
B1077 burned for approximately two minutes and 31 seconds before it commanded the shutdown of all nine of its engines. The stages then separated, and the second stage ignited its single vacuum-optimized Merlin engine, in an event known as SES-1.
At T+3:23, the fairing halves deployed from the second stage, exposing the Inmarsat I-6 F2 payload to the vacuum of space.
The second stage continued burning until approximately T+8:09 when it then shut down the MVac engine. Booster B1077-3 then landed atop JRTI, becoming B1077-4. This marked SpaceX’s 99th consecutive successful landing.
After an 18-minute long coast, the second stage ignited again for 63 seconds before shutting down. Five minutes later, the Inmarsat I-6 satellite was deployed, marking SpaceX’s 182nd consecutive successful launch.
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 Inmarsat I-6 F2, SpaceX will attempt to recover the fairing halves from the water with their recovery vessel Bob.
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. It’s not clear whether or not the cold gas nitrogen thrusters are capable of doing a boost back ‘push’ so the fairings stop their forward momentum mid flight.
No comments:
Post a Comment