Starlink 18 | Falcon 9 Block 5

Lift Off Time
February 04, 2021 – 06:19:24 UTC | 01:19:24 EST
Mission Name
Starlink v1.0 L18 (Starlink RF Mission 1-1): the 18th Starlink mission
Launch Provider
(What rocket company launched it?)
(Who paid for this?)
Falcon 9 Block 5 B1060-5; 27 day turn around
Launch Location
Space Launch Complex 40 (SLC-40), Cape Canaveral Space Force Station, Florida
Payload mass
15,600 kg (~34,000 lbs) (60 x 260 kg, plus dispenser)
Where did the satellites go?
550 km circular Low-Earth Orbit (LEO)
Did they recover the first stage?
Where did the first stage land?
B1060-5 successfully landed 633 km downrange on Of Course I Still Love You

Tug: Lauren Floss; Support: GO Quest
Did they recover the fairings?
One half was successfully recovered from the water and the other was destroyed
Were the fairings new?
No, one fairing half flew on the SAOCOM-1B mission and the other flew on the GPS III SV03 mission; 158 day and 219 day turn around time, respectively
This was the:
– Fastest turn around of a booster, at 27 days (Previous record: 38 days)
– 9th Falcon 9 mission with no static fire
– 107th Falcon 9 launch
– 53rd re-flight of a booster
– 6th 5th flight of a booster
– 4th re-flight of a booster in 2021
– 74th booster landing
– 24th consecutive landing (New record for SpaceX)
– 43rd landing attempt on OCISLY
– 4th launch for SpaceX in 2021
– 1st SpaceX launch on February 4
– 64th SpaceX launch from SLC-40
– 10th orbital launch attempt of 2021
Where to watch
Official replay

How did it go?

SpaceX successfully launched 60 Starlink satellites atop its Falcon 9 Block 5 on their Starlink V1.0 L18 mission. The Falcon 9 lifted off from Space Launch Complex 40 (SLC-40), Cape Canaveral Space Force Station, in Florida. Starlink 18 marked the 17th operational Starlink mission, boosting the total number of Starlink satellites launched to 1,085.

This mission also marked the fastest turn around time of a booster to date at 27 days, which is a significant decrease from the previous record, at 38 days. This rapid turn around time has brought the average turn around time of a booster in 2021 to only 47.5 days.

Another interesting note was the different landing burn for this mission. Instead of only using the single E9 engine for the landing burn, Falcon 9 conducted a 1-3-1 landing burn, igniting E9, then E1 and E5, then shutting down E1 and E5. A 1-3-1 landing burn is more difficult, but more efficient. After landing, Musk noted the landing was a “tough one,” citing rough seas and wind. However, despite these conditions, B1051 softly touched down in the center of Of Course I Still Love You.

Starlink is SpaceX’s internet communication satellite constellation. The Low-Earth orbit constellation will deliver fast, low-latency internet service to locations where ground-based internet is unreliable, unavailable, or expensive. 

Starlink is currently in limited public beta, but a wider release beta is expected to start in under 3 months. As of now, only higher latitudes are covered (between 44 and 52 degrees according to one source). However, SpaceX only needs 24 launches for global coverage. Given SpaceX’s current Starlink production and launch rate, Starlink will have global coverage, excluding the poles, by the middle of 2021.

Once Starlink is 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 V1.0 satellite has a compact design and a mass of 260 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 Falcon 9’s payload capacity to LEO, at around 17 tonnes. 

Starlink satellites and dispenser.
A stack of 60 Starlink satellites prior to be encapsulated into Falcon 9’s payload fairing. (Credit: SpaceX)

For how small each Starlink satellite is, each one is packed with high-tech communication and cost-saving technology. Each Starlink satellite is equipped with 4 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. 

The Starlink satellites are also equipped with an autonomous collision avoidance system, which utilizes the DOD’s debris tracking database to autonomously avoid collisions with other spacecraft and space junk. 

Currently, the Starlink satellites being launched into polar orbit have a laser communication system on board. This system is currently in version 0.9, however SpaceX is expecting all new Starlink satellites to be equipped with it by next year.

To decrease costs, each satellite only has a single solar panel, which simplifies the manufacturing process. To further 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.

Ion Power

Each Starlink satellite is equipped with the first Hall-effect krypton powered ion thruster. This just means that Krypton is accelerated by an electric field, rather than through a chemical reaction, as in liquid fueled rocket engines. This thruster is used both for ensuring the correct orbital position, but is also used for orbit raising and orbit lowering. At the end of the satellite’s life, this thruster is used to deorbit the satellite.

A satellite constellation is a group of satellites that work in conjunction for a common purpose. Currently, SpaceX plans to form a network of roughly 12,000 satellites; however, in 2019 SpaceX filed an application with the Federal Communication Commission (FCC) for permission to launch and operate an additional 30,000 satellites. These additional satellites would be placed in orbits ranging from 328 km to 580 km, which would further decrease latency, and increase the bandwidth. To put this number of satellites into perspective, this is roughly 20 times more satellites than were launched before 2019. 

Of the initial 12,000 satellites, 4,400 would operate on the Ku and Ka bands, with the other 7,600 operating on the V-Band. 

To achieve initial coverage, SpaceX will use 72 orbital planes, in a 53 degree 550 km circular orbit. The Starlink satellites will then communicate with other Starlink satellites and ground stations, to form a mesh network. 

Due to the vast number of Starlink satellites, many astronomers are concerned about their effect on the night sky. However, SpaceX is working with the astronomy community and implementing changes to the satellites to make them harder to see from the ground and less obtrusive to the night sky. SpaceX has changed how the satellites raise their orbits and, starting on Starlink V1.0 L9, added a sunshade to reduce light reflectivity. These changes have already significantly decreased the effect of Starlink on the night sky.

What is Falcon 9 Block 5?

The Falcon 9 Block 5 is SpaceX’s partially reusable two-stage medium-lift launch vehicle. Block 5 is the final iteration of the Falcon 9; the goal is to apply all the lessons learned from 56 previous Falcon 9 pre-Block 5 flights into a human-rated reusable rocket. The Falcon 9 contains 3 main components: a reusable first stage, an expendable second stage, and a reusable fairing.

Falcon 9
Falcon 9 Block 5 launching on the GPS Block III SV03 mission (Credit: SpaceX)

Block 5 updates:

SpaceX introduced a lot of changes on Block 5, allowing it to become the crew-launching reusable rocket that we know today. To start, the Composite Overwrapped Pressure Vessels (COPVs) had to undergo a complete redesign. NASA mandated the COPV redesign, as it had been the cause of both of the Falcon 9 failures: AMOS-6 and CRS-7.

Alongside with certification for human spaceflight, Block 5 came with a number of other major changes. To increase the amount of flight each booster could handle, and decrease the turnaround time, SpaceX reinforced the landing legs, upgraded the grid fins, and added a carbon fiber interstage. They also added heat-resistant external paint and upgraded the engines. For more information about the changes in Block 5, and the other Blocks of the Falcon 9, check out this video by the Everyday Astronaut:

Falcon 9 comparison
Tim Dodd explains the differences between the Falcon 9 versions. (Click image to watch) (Credit: Andrew Taylor)

Falcon 9 Booster B1060

The booster that supported this mission is B1060. This booster had already flown four times. Its maiden flight was on the GPS III SV 03 mission, which launched on June 30, 2020. The second flight of this booster was on the Starlink V1.0 L11, which launched on September 3, 2020. Its third and fourth flight was on Starlink V1.0 L14 and on the Türksat-5A mission, launching on October 24, 2020 and January 8, 2021 respectively. As Starlink 18 was the boosters 5th flight, its designation changed to B1060-5. 

Following stage separation, the Falcon 9 conducted 2 burns. These burns will softly touched down the booster on Of Course I Still Love You.

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

Fairing Reuse

SpaceX is the first entity ever that recovers and reflies its fairings. The recovery vessels, Go Ms. Tree and Go Ms. Chief, and attempted to recover the Starlink 18 fairing halves from the water. 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 parafoils to help them glide down to a soft landing for recovery. 

Hr/Min/Sec              Event

– 00:38:00                 SpaceX Launch Director verifies go for propellant load.
– 00:35:00                 RP-1 (rocket grade kerosene) loading underway.
– 00:35:00                 1st stage LOX (liquid oxygen) loading underway
– 00:16:00                 2nd stage LOX loading underway
– 00:07:00                 Falcon 9 begins engine chill prior to launch
– 00:01:00                 Command flight computer to begin final prelaunch checks
– 00:01:00                 Propellant tank pressurization to flight pressure begins
– 00:00:45                 SpaceX Launch Director verifies go for launch
– 00:00:03                 Engine controller commands engine ignition sequence to start
– 00:00:00                 Falcon 9 Liftoff

Launch, Landing, and Satellite Deployment*

Hr/Min/Sec              Event

00:01:12                   Max Q (moment of peak mechanical stress on the rocket)
00:02:33                   1st stage main engine cutoff (MECO)
00:02:36                   1st and 2nd stages separate
00:02:44                   2nd stage engine starts (SES-1)
00:03:10                   Fairing deployment
00:06:41                   1st stage entry burn complete
00:08:25                   1st stage landing
00:08:50                   2nd stage engine cutoff (SECO-1)
00:45:55                   2nd stage engine starts (SES-2)
00:45:56                   2nd stage engine cutoff (SECO-2)
01:04:52                   Starlink 18 payload deploy

* All times are approximate

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