Falcon 9, Block 5, Crew-6, Liftoff

Transport & Tracking Layers 0-2 | Falcon 9 Block 5

Liftoff Time
(Subject to change)
September 2, 2023 — 14:25 UTC | 7:25 PDT
Mission Name
Transport & Tracking Layers 0-2 (0-2 meaning Tranche 0, Flight 2); SDA Tranche 0B in SpaceX’s nomenclature
Launch Provider
(What rocket company is launching it?)
(Who’s paying for this?)
Space Development Agency (SDA), a unit belonging to the United States Space Force (USSF)
Falcon 9 Block 5 B1063-13; 55.79 day turnaround
Launch Location
Space Launch Complex 4 East (SLC-4E),Vandenberg Space Force Base, California, USA
Payload mass
~5,000 kg (~11,000 lb)
Where are the satellites going?
950 km (~590 mi) circular low-Earth orbit (LEO) at 89.5 degrees inclination; initial: 950 km (~590 mi) x 81°
Will they be attempting to recover the first stage?
Where will the first stage land?
Back on land, on Landing Zone 4 (LZ-4), at ~300 m from the launch pad
Will they be attempting to recover the fairings?
The fairing halves will be recovered from the water ~526 km (~327 mi) downrange by GO Beyond
Are these fairings new?
How’s the weather looking?
This will be the:
– 252st Falcon 9 launch
– 184th Falcon 9 flight with a flight-proven booster
– 192nd re-flight of a booster
– 58th re-flight of a booster in 2023
– 222st booster landing
– 148th consecutive landing (a record)
– 62nd launch for SpaceX in 2023
– 50th SpaceX launch from SLC-4E
– 138th orbital launch attempt of 2023
Where to watch
Official Livestream

What’s This All Mean?

Transport & Tracking Layers 0-2’s patch (credit: SpaceX)

SpaceX is transporting a group of satellites for the Space Development Agency in the mission Transport & Tracking Layers 0-2. The company is using its Falcon 9 rocket in order to orbit 11 Transport Layer satellites. Additionally, another two fly toward the Tracking Layer. The vehicle is lifting off from Space Launch Complex 4 East (SLC-4E), at Vandenberg Space Force Base, in California, United States. This is the second of two flights aimed at placing spacecraft into the Tranche 0 for those layers. That is, Flight 2’s task is populating one of the two different orbital planes in this tranche for each layer. Both of them are at the same altitude of 950 km (~590 mi) and 89.5 degrees inclination. It is also worth noting that SpaceX calls this mission Space Development Agency’s second Tranche 0, or even SDA 0B.

What Is Transport & Tracking Layers 0-2?

A more correct name for the abbreviated version, Transport & Tracking Layers 0-2, is Transport and Tracking Layers, Tranche 0, Flight 2. It speaks of two components in a defense, low-Earth orbit (LEO) constellation, designated the Proliferated Warfighter Space Architecture (PWSA). Each of said components is considered a layer, of which the PWSA will consist in seven:

  • Transport
  • Tracking
  • Battle Management
  • Custody
  • Emerging Capabilities
  • Navigation
  • Support

As it becomes evident from the names, the different layers will carry out specific tasks. Additionally, these layers present subdivisions into a number of tranches, or groups. Each of them will have potentially increasing capabilities, as well as a growing number of satellites, and is expected to see launches every two years. Finally, tranches are populated with satellites by means of a number of launches (or flights), depending on the selected rocket and its cargo capacity. Tranche 0 represents a technology demonstration through a minimum viable product with enough performance to allow for testing, and exploration of the possibilities it offers. As such, it will feature two orbital planes with 14 satellites in each of them, at 950 km (~590 mi) altitude and 89.5 degrees inclination.

Transport Layer

This will be the backbone of the mentioned architecture, the PWSA, as Transport Layer designates the group of spacecraft charged with data-relaying activities. In other words, inside this constellation they will provide communications services. Populating Tranche 0 of this layer, there will be 20 spacecraft — 10 manufactured by Lockheed Martin and another 10, by York Space Systems. These contractors were awarded by the SDA with USD 187.5M, and USD 94M respectively back in 2020.

In each of these groups of 10, some of the satellites will be provided with four optical (laser) cross-links — group A — while the remaining ones, with two cross-links and two downlinks — group B. This is how satellites are able to communicate among peers in the same layer (even if they are built by different companies), with satellites in other layers, as well as with defense systems on the surface: land, sea, or even air.

Tracking Layer

On the other hand, the Tracking Layer will operate quite differently. In this case, the satellites in it will remain vigilant for possible detection of ballistic missiles, and, especially, of hypersonic glide missiles, heading toward the US. These follow much lower trajectories, and can maneuver, which prevents the DoD’s satellites sitting in geostationary orbit (GEO) from responding in time.

In order to do their job, these spacecraft will have a wide field-of-view (WFOV) overhead persistent infrared (OPIR) sensor. Once a missile is targeted by it, the satellite will relay the information of its location and its trajectory through a secure path. The spacecraft will use its optical cross-links, to talk to the Transport Layer. In turn, this one will talk to whichever asset is needed, e.g. an interceptor.

Back in 2020, the SDA bought the first eight satellites for this layer: four contracted to L3Harris, for USD 193.50M; another four, to a SpaceX-Leidos team, for USD 149M. As a matter of fact, this was the first U.S. military announcement of a satellite order from SpaceX. The former developed a new bus in-house, while SpaceX based its satellites on the Starlink bus. In this flight, the remaining two satellites built by the latter flew to space. L3Harris ones will fly on a launch for the Missiles Defense Agency (MDA), due to production delays.

Space Development Agency

This agency’s creation was in 2019 with the goal of leveraging from the commercial side of the space market, and all of the innovation taking place there regarding small satellites. The idea is to make use of this, and apply this new model to military systems. In particular, it is of priority to the SDA, and to the Pentagon before it, to deploy a constellation of infrared sensors in LEO. Potential adversaries like Russia and China have already at least tested hypersonic missiles. This is why it is important to the US to have an adequate defense system.

This is a departure from traditional procurement in military space, because of the use of the two-year spiral growth. That is, every two years another batch of satellites should be put in orbit. These will also, most likely, be provided by different vendors. In this way, it is possible to shorten the time needed to give warfighters a useful tool. By contrast, the DoD would take a decade to loft a spacecraft, as it would aim to provide “the perfect” solution. Additionally, sending up satellites more often means a new technological development can be put into practice much earlier.

The SDA aims at having global, operational coverage through these two layers by 2025, when Tranche 1 is orbited. This will be a proliferated constellation, meaning it is difficult for an enemy to take it down, due to its size. On the other hand, the SDA’s Tracking Layer will feed the MDA’s Hypersonic and Ballistic Tracking Space Sensor (HBTSS). Particularly, this will operate medium field-of-view (MFOV) infrared satellites. These, because of their narrower field of view, which will feed a ground-based interceptor.

Launch Campaign, Delays, Future

At the end of 2020, SpaceX was awarded a launch contract for USD 150.4M to carry out the launches related to Transport & Tracking Layers, Tranche 0.

It turned out that Flight 1 of Tranche 0 comprises eight satellites from the Transport Layer, and another two from the Tracking Layer. This first flight was expected back in September 2022, but a number of delays took place. Many of them were related to the shortage in microelectronic components, and other supply chain issues, stemming from the pandemic. Subsequently, the SDA planned to launch before the end of March, though out of caution, it was postponed to the very first days of April 2023. The latest flight for this constellation, the present one, was scheduled for June but it slipped.

Contracts have already been awarded to Lockheed Martin (USD 700M), Northrop Grumman (USD 692M), and York Space Systems (USD 382M) to build each 42 satellites for Tranche 1 in the Transport Layer, expected for 2025. Similarly, for the Tracking Layer, Tranche 1: L3Harris (USD 700M), will build 14 satellites, as well as Northrop Grumman (USD 617M).

What Is Falcon 9 Block 5?

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.

First Stage

The Falcon 9 first stage contains nine 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 the flight, and be able to successfully place the payload into orbit.

The Merlin engines are ignited by triethylaluminum and triethylborane (TEA-TEB), which instantly 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.

Second Stage

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.

SpaceX is currently flying two different versions of the MVacD engine’s nozzle. The standard nozzle design is used on high-performance missions. The other nozzle is a significantly shorter version of the standard, decreasing both performance and material usage; with this nozzle, the MVacD engine produces 10% less thrust in space. This nozzle is only used on lower-performance missions, as it decreases the amount of material needed by 75%. This means that SpaceX can launch over three times as many missions with the same amount of Niobium as with the longer design.

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.

falcon 9 block 5, launch
Falcon 9 Block 5 launching on the Starlink V1.0 L27 mission (Credit: SpaceX)

Falcon 9 Booster

The booster supporting Transport & Tracking Layers 0-2 mission is B1063-13. As the name implies, the booster had supported 12 previous missions; its designation will change to B1063-14 upon successful landing.

Previous B1063’s missionsLaunch Date (UTC)Turnaround Time (Days)
Sentinel-6November 21, 2020 17:17N/A
Starlink V1.0 L28May 26, 2021 18:59186.07
DARTNovember 24, 2021 06:21181.47
Starlink Group 4-11February 25, 2022 17:1262.45
Starlink Group 4-13May 13, 2022 22:07108.20
Starlink Group 3-1July 11, 2022 01:3958.15
Starlink Group 3-4August 31, 2022 05:4051.17
Starlink Group 4-31October 28, 2022 01:1457.82
Starlink Group 2-5February 17, 2023 19:12112.75
Transporter-7April 15, 2023 6:48 UTC56.48
Iridium-9 and OneWeb 19May 20, 2023 13:1635.27
Starlink Group 5-13July 7, 20203 19:2948.26

Following stage separation, the Falcon 9 will conduct three burns. These burns will aim to softly touch down the booster on SpaceX’s Landing Zone 4 (LZ-4).

falcon 9 booster, landing, drone ship
Falcon 9 landing on Of Course I Still Love You after launching Bob and Doug (Credit: SpaceX)

Falcon 9 Fairings

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.

Both fairing halves are equipped with cold gas thrusters and a parafoil which are used to softly touch down the fairing half in the ocean. SpaceX used 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 Transport & Tracking Layers 0-2 mission, SpaceX will presumably attempt to recover the fairing halves from the water with its recovery vessel GO Beyond.

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.

00:38:00SpaceX Launch Director verifies go for propellant load
00:35:00RP-1 (rocket grade kerosene) loading begins
00:35:001st stage LOX (liquid oxygen) loading begins
00:16:002nd stage LOX loading begins
00:07:00Falcon 9 begins engine chill prior to launch
00:01:00Command flight computer to begin final prelaunch checks
00:01:00Propellant tank pressurization to flight pressure begins
00:00:45SpaceX Launch Director verifies go for launch
00:00:03Engine controller commands engine ignition sequence to start
00:00:00Falcon 9 liftoff

Launch And Landing

All Times Approximate

00:01:12Max Q (moment of peak mechanical stress on the rocket)
00:02:181st stage main engine cutoff (MECO)
00:02:211st and 2nd stages separate
00:02:292nd stage engine starts (SES-1)
00:02:35Boostback burn start
00:03:06Fairing deployment
00:03:29Boostback burn end
00:06:021st stage entry burn start
00:06:191st stage entry burn complete
00:07:151st stage landing burn start
00:07:311st stage landing

Because of the nature of this mission, the complete timeline after liftoff is not available.

Adapted rocket section’s original author, Trevor Sesnic.

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