SpaceX launches second Starlink mission of the week

by Danny Lentz

Two days after scrubbing a previous attempt shortly before launch, and still less than a week after the previous Starlink flight, SpaceX launched its third batch of Starlink satellites this month into orbit at 11:31 EDT (15:31 UTC) on Saturday, 24 October.  The v1.0 L14 mission — the 14th launch of operational satellites and 15th Starlink flight overall — was launched from pad SLC-40 at Cape Canaveral Air Force Station.

The weather forecast showed a 60% chance of favorable weather, with the primary concern being the Cumulus Cloud Rule.  There was a moderate risk of bad weather in the recovery zone approximately 633 km northeast of the pad where the drone ship Just Read the Instructions (JRTI) was waiting to recover the first stage of the rocket.

Initially scheduled for Thursday, 22 October, the mission was delayed at T-13 minutes.  SpaceX announced on Twitter they were delaying the launch “to allow additional time for mission assurance work”.  CEO Elon Musk later tweeted that it was “Just a small-seeming issue with loss of upper stage camera.  Probably nothing serious, but standing down to re-examine whole vehicle just in case.”

The payload for this flight was a batch of 60 satellites for SpaceX’s Starlink satellite constellation that will provide high speed internet service.  With each satellite having a mass of about 260 kg, the full payload stack massed nearly 16 metric tons.  According to pre-launch data released on Celestrak, the targeted deployment orbit was approximately 260 x 270 km.

The Falcon 9 launch vehicle for this mission was booster 1060.3, which launched the GPS III SV03 and the Starlink 11 operational flight earlier this year.  The vehicle performed a successful static fire test Wednesday, 21 October to verify that it was ready for flight.  This was the 19th Falcon 9 launch this year (including the suborbital In-Flight Abort Test), and the 13th Starlink mission of the year.

Falcon 9 launches on Starlin flight 15. (Credit: Stephen Marr for NSF/L2).

One reason for this volley of consecutive Starlink flights is that SpaceX has been busy diagnosing an engine issue that showed up during a launch attempt of another Falcon 9 carrying the GPS III SV04 payload for the Department of Defense at the beginning of the month.

Two engines from that vehicle were removed and sent back to the SpaceX facility in McGregor, Texas, for a closer look.  Subsequent investigation showed the problem may also affect a small number of engines on the vehicles for two upcoming NASA flights.

NASA Associate Administrator for human spaceflight Kathy Lueders tweeted Wednesday that one engine was being replaced on each of the boosters for the Sentinel 6 Michael Freilich and Crew-1 flights.  If all goes well with the repairs, SpaceX aims to launch those three missions and also the NROL-108 payload for DoD over the next month.

Starlink beta testing begins:

As SpaceX nears the beginning of wider beta testing and the subsequent start of service in the northern U.S. and southern Canada, SpaceX recently qualified to participate in the first round of Federal Communication Commission’s (FCC’s) Rural Digital Opportunity Fund (RDOF) Auction, which will disburse $16 billion to internet providers over the next decade for connecting locations that do not currently have access to speedy internet connections at reasonable prices.

The auction will take place on 29 October and allows bidders to choose different performance tiers for their service based on speed and latency that will be taken into account when ranking the bids.  Some competitors, especially Viasat, were very vocal in trying to restrict SpaceX bidding low levels of performance, much lower than their network should be capable of.  It is not yet publicly known which performance tiers SpaceX was approved to bid.

Moreover, following reports of Starlink being used to provide internet to the Hoh Tribe Reservation in rural Washington State, there was an announcement this week from the 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.

In addition to its uses for connecting rural households and disaster response, other recent agreements highlight more uses for Starlink and technologies derived from the program.  On Tuesday, 20 October, Microsoft’s Azure Space division announced a partnership with SpaceX that will leverage Starlink to provide high speed, low latency internet connections to their new Azure Mobile Datacenter offering.

Microsoft is serving as a subcontractor to SpaceX on another Starlink related project.  Earlier in October, SpaceX was awarded a contract from the DoD’s Space Development Agency to produce four missile tracking satellites based on the Starlink satellite bus for the agency’s Tranche 0 Tracking Layer program.

The Tranche 0 constellation is designed to prove the utility of deploying higher numbers of lower cost satellites than the military has traditionally used.  Based on recent documents related to the request for proposals to launch those satellites, it appears they are significantly larger than the normal Starlinks.

Outside the U.S. and constellation growth:

SpaceX has continued to build out their network of ground stations that will connect the Starlink satellites to the internet.  Recent filings for Starlink gateways in California, Texas, and North Carolina bring the current total to 42 locations in the United States.

In addition, there has been progress on Starlink developments in other countries.

SpaceX’s TIBRO subsidiary has been used to handle their international business, with branches being set up in various countries around the globe.  Recently, some of these local subsidiaries have begun changing their names from TIBRO to Starlink as SpaceX nears the initiation of their service.

A filing in Alaska lists 13 international affiliates under the TIBRO and Starlink names.

Graphic by Ben Craddock for NASASpaceflight shows the Starlink satellites spreading into their orbital planes. Satellites from Launch 8 onward are still moving into position.

In Australia, filings for four ground stations have been made, along with two in New Zealand and a couple more in France.  In Canada, SpaceX received approval for a BITS (Basic International Telecommunications Services) license they applied for earlier in the year, with a notification letter posted on 15 October.

Other countries with SpaceX affiliates are Austria, Chile, Colombia, Japan, Mexico, The Netherlands, Norway, South Africa, and the United Kingdom.

To date, SpaceX has launched 773 of the v1.0 satellites, with a half dozen of those being deorbited already and another dozen or so, mainly from the early launches, suffering impairments to their functionality.  Only 14 of the 60 test satellites from the v0.9 launch remain in orbit.  Of the remainder, about six seem to still be under some control, but none of those are close to reentry.

That leaves about 750-760 fully operational satellites, nearly 200 of which from the last five flights are still moving into their positions within the constellation.  With another 60 launching on this flight, SpaceX will have more than 800 operational satellites on orbit, significant progress towards the 1,400-1,500 satellites that will comprise the initial deployment.

With satellites from the last mission, which launched this past Sunday, likely to fill the last gap in a group of 36 evenly spaced orbital planes, progress should now begin on the next set of 36 planes that will be needed to bring reliable service down to equatorial latitudes.

As an occasional satellite has had a failure or fallen behind its launch group during initial operations, a few gaps have appeared in the early planes.  Recently some of these holes have begun to be filled by satellites from other launches.  Starlink-1029 from the L1 group spent some time at low altitudes and then eventually plugged a hole in one of the L6 planes.  An L4 hole was plugged by an L7 sat (Starlink-1406), and it appears — based on orbital tracking — that two L10 sats (Starlink-1642 and Starlink-1643) are on their way to plug two holes in an L2 plane.

Satellites being deployed during the Starlink v1.0 L13 mission

After completing the initial orbital shell of the constellation, SpaceX can turn their attention to deploying new orbital planes at higher inclinations that will provide service to higher latitudes and polar regions.

SpaceX submitted a modification in April that would lower the altitude of this next group of satellites and allow users to communicate with satellites closer to the horizon than had previously been approved.  The filings related to this change request have grown increasingly frequent and contentious, with other satellite operators arguing that the modification is significant enough that the SpaceX constellation should be moved to a later processing round rather than keep its existing position in the round from 2016.

Its position in the earlier processing round puts SpaceX on par with competitors such as OneWeb and Telesat when sharing communications frequencies for service in the United States, and gives them higher priority than constellations filed later, such as Amazon’s Project Kuiper.  This has led to recent presentations to the FCC from SpaceX and its competitors as both sides argue their case, with both Gwynne Shotwell and Elon Musk participating in such calls during the last week.


For launch, the final stages of preparation commenced at the T-38 minute mark, when the Launch Director determined the vehicle was ready for propellant loading.  When the “go” is given, chilled RP-1 kerosene fuel flowed into both stages of the Falcon 9 launch vehicle at 35 minutes to liftoff, along with liquid oxygen (LOX) loading into the first stage.  LOX loading onto Falcon 9’s second stage started at T-16 minutes.

At T-7 minutes prior to liftoff, the liquid oxygen pre-valves on the nine Merlin-1D first stage engines opened, allowing LOX to flow through the engine plumbing and thermally condition the turbopumps for ignition. This process is known as “engine chill,” and is used to prevent thermal shock that could damage the engines upon startup.

At T-1 minute, the Falcon 9’s onboard flight computers ran through final checks of the vehicle’s systems and finalized tank pressurization before flight.  The launch director gave a final “go” for launch at T-45 seconds.

The engine ignition sequence for the nine Merlin-1D engines on the first stage started at T-3 seconds, with liftoff taking place at T-0 following a quick final check by the onboard computers to verify all systems are operating nominally.

Falcon 9’s flight profile for today’s mission. (Credit: SpaceX)

After lifting off from SLC-40, the Falcon 9 pitched downrange as it accelerated towards orbital velocity.  At around a minute and 12 seconds into the flight, the vehicle passed through the region of maximum aerodynamic pressure, or “Max-Q.”  During this portion of flight, the mechanical stresses on the rocket and payload were at their highest.

The nine Merlin-1D engines on Falcon 9’s first stage continued to burn until around T+2 minutes and 32 seconds, at which point they shut down in an event known as MECO, or Main Engine Cutoff.  Stage separation occurred shortly afterward, with second stage Merlin Vacuum engine ignition taking place at the T+2 minute 43 second mark.  Upon engine startup, the second stage continued to carry all 60 satellites to a low Earth orbit, with an inclination of 53 degrees.

The 5-meter payload fairing housing the satellites during the initial phases of launch separated at 3 minutes and 20 seconds into the flight.  The fairing halves fell back to Earth and descended under parafoils, landing about 45 minutes after launch to be recovered.

While Falcon 9’s second stage and payload continued towards orbit, the first stage performed an entry burn, which ended at 6 minutes and 40 seconds into the flight, in order to slow its descent and refine its trajectory to the droneship.  A final landing burn began shortly before the booster touched down on the deck of JRTI, approximately 8 minutes and 23 seconds after liftoff and about 633 km downrange from the launch site.

The Merlin Vacuum engine on Falcon 9’s second stage shut down for the first time at 8 minutes and 48 seconds into the flight in an event known as SECO-1, or Second Engine Cutoff.  After coasting for more than half an hour, the second stage reignites at the T+44:13 mark for a two second burn to raise the perigee into a more circular orbit.

Just over an hour into flight, the group of Starlink satellites floated away from the second stage when the tension rods holding them together were released at T+01:03:10.

The second stage is expected to light its engine one more time for a deorbit burn, splashing down in the ocean west or south of Australia on its second orbit.

Lead image: Booster 1060 launches on the 15th flight of Starlink. Credit: Stephen Marr for NSF/L2.

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