SpaceX Falcon 9 Block 5 - Starlink L28 - Launching May 26, 2021
Screenshot from SpaceX Webcast of the launch of Starlink L28
Mission Rundown: SpaceX Falcon 9 B5 - Starlink L28
Written: July 27, 2021
Filling Starlink Shell 1 almost to the Brim
SpaceX will launch 60 Starlink satellites on their Falcon 9 rocket. It’s launching Wednesday May 26, 2021 at 14:59 EDT - 18:59 UTC, from Space Launch Complex 40 (SLC-40) at Cape Canaveral Space Force Station, Florida
Starlink L28 is the last operational launch of SpaceX’s Starlink communication satellite constellation in Shell 1 – which aims to deliver a fast, low-latency broadband internet service to rural locations where access has been unreliable, expensive, or completely unavailable. This is the 28th operative flight of Starlink satellites.
After boosting the second stage along with its payload towards orbit, the first stage will perform an entry burn to slow the vehicle down in preparation for atmospheric reentry. The booster will then land 634 km downrange aboard SpaceX’s autonomous spaceport drone ship. Starlink V1.0 L28 first stage booster B1063-2 is set to again land on JRTI - ‘Just Read The Instructions’ around eight and a half minutes after liftoff.
SpaceX will also attempt to catch or recover both fairing halves with Go Searcher and Go Navigator having recently joined fairing recovery operations. L28 is their job today.
Shelia Bordelon only recovered seven sets of Starlink fairings from the ocean.
B1063-2 made its second flight after launching the Sentinel-6 - “Michael Freilich” radar altimeter satellite in November 2020 from Vandenberg, California. After performing a return to launch site landing at LZ-4, this booster was moved across the country for this week’s Starlink V1.0 L28 launch from Space Launch Complex 40 - SLC-40 located at Cape Canaveral Space Force Station, Florida.
B1063-2 did perform a static fire test at 19:05 EDT May 25, 2021 after six month waiting for a west coast launch out of Vandenberg. SpaceX has since Starlink V1.0 L08 omitted this safety precaution fifteen times so far. It is not required to perform a static fire test inhouse missions like Starlink, that was not to save money and time before the launch.
SpaceX is the first entity ever that recovers and reflyes 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 fairings are a used pair from six different missions. The active fairing half flew on four Starlink missions L0, L05, L12 and L17 prior to the v1.0 L28 mission. The passive other half flew on a single Starlink Mission L21 as well as the Transporter-1 mission.
Both fairings survived the landing. Active fairings are equipped with four pushrods to separate the two fairings.
Fairings have evenly spaced venting ports that have been redesigned a number of times by having first ten, then eight and now having their venting ports built as close pairs along the fairing edge. This prevents saltwater from the ocean from flooding and sinking the fairing, and makes refurbishment toward the next flight easier.
Check out the recovery marks on cauth fairings and salvaged fairings.
The Payload
SpaceX plans to offer service in North America by the end of 2020 and estimates that once complete, its venture will make $30-50 billion annually. The funds from which will, in turn, be used to finance its ambitious Mars program.
To achieve initial coverage, SpaceX plans to form a net of 12,000 satellites, which will operate in conjunction with ground stations, akin to a mesh network.
Furthermore, the company recently filed for FCC permission on an additional 30,000 spacecraft, which, if granted, could see the constellation amount to a lucrative 42,000. This would octuple the number of operational satellites in earth orbit, further raising concerns about the constellations' effect on the night sky and earth-based astronomy.
For more information on Starlink, watch the Real Engineering video listed below.
Each Starlink satellite is a compact design that weighs 260 kg. SpaceX developed them to be a flat-panel design to fit as many satellites as possible within the Falcon 9’s 5.2 meter wide payload fairing. 60 satellites fit into a dispenser affixed to the second stage. The entire Starlink payload weighs around 15,600 kg. That’s near the limit that a Falcon 9 can lift into LEO and still have enough propellant for landing.
For such small satellites, each one comes loaded with high-tech communications technology. There are six antennas, four high-powered phased-array and two parabolic ones that all support high-speed data throughput. Starlink also features a SpaceX built and designed star track navigation system to enable precision placement of broadband throughput.
Four inter-satellite laser links (ISLLs) allow high-speed communication between Starlink satellites. SpaceX placed two ISLLs on the front and rear of the satellite to talk with Starlink satellites in the same orbital plane. They remain fixed in position. Two ISLLs on the satellite’s sides track other Starlink satellites in different orbital planes. This means they have to move to track the other satellites.
Starlink Orbit Plans
The twenty-nine launches of one testbed Starlink mission and twenty-eight operational Starlink missions V0.9 L0 - V1.0 L28 brings the number of launched Starlink satellites to 1665. How many that still work’s, or are in orbit, are mentioned in this old article.
All Starlink payload batches in launch order: L1 L2 L3 etc. including launch L28.
5 x 60 = 300 293 300 300 300 52 60 60 = 1665 Starlink V1.0 satellites launched
On board the Starlink L28 flight were 60 of SpaceX’s Starlink internet satellites, which will now join the 1605 v1.0 satellites already in orbit. Of the v1.0 satellites that have been launched prior to this launch, six have either destructively reentered, as designed, or after encountering issues after launch, leaving 1659 operational Starlink V1.0 satellites.
Spreading the wings of individual Starlink satellites in their orbit tracks - Graphic by Ben Craddock
Of the 60 v0.9 satellites launched in 2019, 46 have reentered by now to date, 6 are still under some control with the remaining 8 either actively deorbiting or naturally decaying. The Tintin and v0.9 satellites will not be in the operational Starlink satellite constellation. These pre-satellites lack the communications payload needed for full operation.
SpaceX will assign 18-20 Satellite Vehicles to each of three adjacent orbital planes. Orbital planes are to satellites as tracks are to trains – they are orbits parallel to each other designed to maximize area coverage while minimizing the number of satellites required.
Since early-December 2020, SpaceX has been altering the spacing of the satellites already on orbit. It appears the company is arranging many of the planes to have 18 active satellites instead of 20, which would fill some small gaps and free up some satellites to act as spares. There will eventually be 72 planes of 22 satellites each in the initial shell of the Starlink constellation.
Look for an Animation by Ben Craddock for NASASpaceflight showing the movements of Starlink satellites into their orbital planes since August 1, 2020. The satellites from each launch split into three groups that each formed a plane.
Just a little peak in the current Starlink orbit mesh, it’s still a work in progress - small gabs does it
SpaceX plans to begin offering Starlink service to Canada and the northern United States later this year. Near global coverage is expected to start next year. Pricing has not been made public, but it has been hinted that speeds up to one gigabit may be possible.
Having now filled 18 evenly spaced planes in the constellation, SpaceX should be attaining continuous coverage in the northern U.S. and southern Canada areas where they intend to launch the Starlink service. SpaceX are now working on filling up to 72 evenly spaced planes in the constellation.
Starlink Phase 1 Orbital Shells
The first orbital shell of Starlink satellites will consist of 1,584 satellites in a 53° 550 km low-Earth orbit. This is the shell that SpaceX is currently filling, and it is expected that this shell will be complete by June 2021. Once complete, the first shell will provide coverage between roughly 52° and -52° latitude (~80% of the Earth’s surface), and will not feature laser links until replacement satellites will launch after 2021.
Completed - 1659 launched operational Starlink V1.0 are now using a few months to reach operational orbits in 72 planes with 18 - 22 Satellite Vehicles in each plus spares. Some SV are not equipped with the same communication equipment - Laser links or sun shades, so they will be replaced with a number of extra Starlink missions to Shell 1.
The second currently approved orbital shell will consist of 1,600 satellites in a 53.8° 1,100 km low-Earth orbit. However, in April of 2020, SpaceX submitted a request to the FCC to change this shell from the aforementioned orbit to a 570 km 53.2° LEO with 1,440 satellites. This updated orbital configuration would slightly increase coverage area and would drastically increase the bandwidth of the constellation. After the first shell’s completion and once approval is granted for this change it is expected that SpaceX will fill this shell alongside the 4th shell next.
The third shell of Starlink phase 1 that is currently approved will host 400 satellites in a 70° 1,325 km orbit. Included in the FCC request submitted in 2020, SpaceX wants to change this shell to host 720 satellites in a 70° 570 km orbit. These satellites would significantly increase the coverage area, which would make the Starlink constellation cover around 94% of the globe.
For the fourth shell, SpaceX currently is permitted to launch 374 satellites into a 74° 1,130 km orbit. However, SpaceX has also requested that this shell gets changed. Shell 4 has been moved to a 97.6° 560 km orbit that will contain 336 satellites. SpaceX deployed 10 laser link test satellites into this orbit on their Transporter-1 mission to test satellites in a polar orbit.
The fifth shell of phase 1 currently allots for 450 satellites in a 81° 1,275 km orbit. However, just like shells 2, 3, and 4 SpaceX has requested to move this shell to another 97.6° 560 km low-Earth polar orbit with 172 satellites. It is unclear why this shell covers the same orbital plane as shell 4.
Ion Drive with Krypton gas
Innovative ion propulsion technology keeps these satellites in the correct position while on orbit. They use ion Hall-effect thrusters to achieve their working orbit. Each Starlink satellite incorporates an autonomous collision avoidance system. It uses the Department of Defence’s debris tracking data to avoid colliding with space debris or other satellites.
Starlink’s low altitude also allows SpaceX to easily deorbit malfunctioning satellites, even if their engines fail. Although 100 km is commonly described as the upper limit of Earth’s atmosphere, there is no “hard barrier”. Even at 550 km altitude, there is still a slight amount of atmospheric drag pulling the satellites down. Each satellite’s onboard ion Hall-effect thruster engine is powerful enough to keep it in orbit, but if the engine fails, it will fall back to Earth within about a year. Read about the Hall-effect thruster engine here.
The miniscule atmospheric drag in low Earth orbit will help ensure that dead satellites don’t stay in orbit for long. This will help reduce the amount of space debris in orbit, which is rapidly becoming a major concern.
Starlink Satellite Constellation
Constellations use multiple satellites working in conjunction for a common purpose. SpaceX plans eventually to form a network of about 12,000 satellites. They will operate roughly 4,400 satellites using Ku- and Ka-band radio spectrum, and almost another 7,500 satellites in the V-band.
To achieve initial coverage, Starlink will use 72 orbital planes, angled at 53 degrees from the Earth’s equator at an altitude of 550 km. They will put 22 satellites into each of these orbital planes, totaling 1,584 satellites. They will communicate with other Starlink satellites and with ground stations, akin to a mesh network.
In late 2019, the company asked the American Federal Communications Commission (FCC) for permission to launch an additional 30,000 satellites into orbits ranging from 328 km to 580 km in altitude. If the FCC okays the request, the constellation could grow to 42,000 satellites. This would increase the number of operational satellites in Earth orbit by at least a factor of 20 from pre-2019 levels.
The constellation’s large numbers are raising concerns regarding their effect on the night sky and Earth-based astronomy. However, Elon Musk stated that he is confident that SpaceX can mitigate light pollution issues and is working with industry experts to minimize the potential for any impact. Future Starlink satellites will use a sunshade that is a patio-like umbrella to reduce light reflectivity.
This batch of 60 Starlink satellites should be "VisorSat" fitted with the new sunshade to help reduce the brightness of the satellites as seen from the ground. These visors will deploy shortly after spacecraft separation during Saturday’s launch.
As was the case with a single Starlink satellite on the V1.0 L7 mission (launched on June 4), all Starlink satellites that will launch on subsequent missions “L8 - L28” going forward will feature a sun shade or visor, which will assist in blocking sunlight from reflecting off the majority of the spacecraft body while in orbit and reducing its overall albedo/intrinsic brightness as observed from the ground.
Starlink ground antennas
Prototypes of the Starlink user terminal antenna have been spotted alongside the other antennas at Starlink gateway locations in Boca Chica, Texas and Merrillan, Wisconsin. These user terminals will be crucial to the success of the Starlink network.
SpaceX board member Steve Jurvetson recently tweeted that the company’s board had an opportunity to try out the user terminals at the company headquarters in Hawthorne. The devices use a Power over Ethernet (PoE) cable for their power and data connection. The antenna connects to a SpaceX branded router with Wi-Fi (802.a/b/g/n/ac, transmitting at 2.4 & 5GHz). SpaceX is producing the antenna assemblies in-house while outsourcing production of the more common router component.
SpaceX continues to make progress setting up its network of gateways for the Starlink system. New gateways are being added in the Northwest and North Central U.S. with locations in Northern California, Idaho, Minnesota, Montana, Washington, and Wyoming. In the Southeastern U.S., previously filed gateways in Tennessee and Florida were removed while new locations were added in Georgia and Alabama.
More locations were recently added in Arizona and Kansas. This brings the number of U.S. Ka-band gateway locations to 34. Emergency crews in Malden, Washington got a disk.
Beta Starlink is being tested now by the Hoh tribe and Ector County Independent School District in Texas that they have initiated a program to provide free connectivity with Starlink to some local students and their families beginning next year.
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 by the middle of 2021.
SpaceX is currently offering a beta version of the Starlink internet service, jokingly named the “Better Than Nothing Beta”. Users pay $500 for the Starlink terminal and router and then $99 per month for the service.
Invitations to participate in the beta were sent out to people who signed up through the official Starlink website and live in parts of the northern United States, southern Canada, and very recently the United Kingdom.
The results so far have been very promising, with SpaceX reporting speeds of 100mbps with 20-40ms latency, well below geostationary satellite latency. Many users have reported speed tests even higher than 100mbps.
