SpaceX Falcon 9 Block 5 - Starlink L15 - Launching November 24/25, 2020
Screenshot from SpaceX Webcast of the launch of Starlink L15
Mission Rundown: SpaceX Falcon 9 B5 - Starlink L15
Written: July 23, 2021
100 launches and 66 landings of Falcon 9
SpaceX will launch 60 Starlink satellites on their Falcon 9 rocket Saturday at 21:13 EDT on November 24, 2020 - 02:13 UTC November 25, 2020 at Space Launch Complex 40 - SLC-40 from Cape Canaveral Air Force Station, Florida. Starlink L15 is the latest operational launch of SpaceX’s Starlink communication satellite constellation.
SpaceX’s near-global satellite constellation – Starlink aims to deliver a fast, low-latency broadband internet service to locations where access has previously been unreliable, expensive, or completely unavailable. This is the sixteenth flight of Starlink “L0 - L15”.
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 633 km downrange aboard SpaceX’s autonomous spaceport drone ship. Starlink V1.0 L15 first stage booster B1049-7 is set to again land on ‘Of Course I Still Love You’ around eight minutes after liftoff.
SpaceX will also attempt to recover both fairing halves with their humorously named fairing catcher vessels: ‘GO Ms. Tree‘ and ‘GO Ms. Chief.’
B1049 first flew with the Telstar 18V/Apstar-5C satellite on September 10, 2018. After launching Starlink V1.0 L15 the booster’s designation changed to B1049-7.
Like most Falcon 9 missions, B1049 performed a static fire test, being held down at the launch pad and igniting its nine Merlin 1D engines for a few seconds to make sure all was in working order. The test was originally scheduled for approximately 01:30 EST (06:30 UTC) on 20 November, although the firing was aborted due to high winds at the launch pad. The test proceeded successfully at approximately 16:00 EST (21:00 UTC) on November 21, clearing the Falcon 9 for flight.
It is not required to test inhouse missions like Starlink, that was not to save money and time before the launch. SpaceX has omitted this safety precaution four times.
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 re-flown odd couple from three different missions, A Type 3.1 flown on Starlink L06 + Amos-17 and Type 3.1 fairing flown on Starlink L07. They have been rebuilt by moving their venting ports in pairs near the fairing edge.
Type 2.1 is a lifeboat sized fairing - 34 x 17 feet with 8 evenly spaced ventilation ports, a heat resistant thermal steel tip and no acoustic tiles inside the fairings. By relocating the ventilation ports 2 and 3 to port 1 and 4 the type number changes to 3.1.
Type 2.2 is a lifeboat sized fairing - 34 x 17 feet with 8 evenly spaced ventilation ports, a heat resistant thermal steel tip, a lowered square protrusion and acoustic tiles inside the fairing. By relocating the ventilation ports in pairs the type number changes to 3.2.
Check out these recovery marks on caught 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 sixteen launches of one testbed Starlink mission and fifthteen operational Starlink missions V0.9 L0 - V1.0 L15 brings the total number of launched operational Starlink satellites to 893. How many that still work’s, or are in orbit, are in this very old article.
The sum of Starlink batches: 60 60 60 60 60 60 60 58 57 58 60 60 60 60 60 = 893
On board the Starlink L15 flight were 60 of SpaceX’s Starlink internet satellites, which will now join the 833 v1.0 satellites already on 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 887 operational Starlink V1.0 satellites.
Spreading the wings of individual Starlink satellites in their orbit tracks - Graphic by Ben Craddock
The fleet of test satellites V0.9 which formed the v1.0 design are also currently in the process of being deorbited for destructive reentries. The Tintin B satellite, one of two Tintin test satellites launched in 2018, reentered on August 8. Tintin A’s orbit is also decaying and is expected to re-enter Earth’s atmosphere in the near future.
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. 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.
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.
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, totalling 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 L07 mission (launched on June 4), all Starlink satellites that will launch on subsequent missions “L08 - L15” 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 34 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 gateway locations were added in Arizona, Georgia, Kansas and Alabama.
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.
Starlink is currently in an employee beta, but a public 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 by the middle of 2021.
