SpaceX Falcon 9 Full Thrust - Formosat-5 - Launching August 24, 2017
Screenshot of SpaceX FT Formosat-5 with Tim Dodd hosting
Mission Rundown: SpaceX Falcon 9 FT - Formosat-5
Written: January 23, 2021
Fast track science satellite going up
SpaceX is launching a Falcon 9 Full Thrust carrying Formosat-5 satellite out of Vandenberg Air Force Base in California. They will be landing the first stage on their droneship "Just Read The Instructions" about 213 miles (343 km's) south of Vandenberg AFB and west of L.A. in the Pacific Ocean.
The 42-minute launch window opens on Thursday, August 24 at 11:51 a.m. PDT, or 18:51 UTC. The satellite will be deployed approximately 11 minutes after launch.
The Payload
Formosat-5 is an Earth observation satellite operated by the National Space Organization (NSPO) of Taiwan. It is NSPO's first indigenously developed remote sensing satellite.
The Remote Sensing Instrument (RSI) is the primary instrument aboard the spacecraft. It is composed of a Telescope and an Electrical Unit (EU). The Telescope consists of Optics, Structure Module (SM) and CMOS typed Focal Plane Assembly (FPA). The mission also incorporates a science payload, the Advanced Ionospheric Probe (AIP), for studies of ionospheric plasma physics.
The satellite is capable of returning images with a resolution of 2 meters (in black and white) or 4 meters in color, but only in weather-permitting conditions.
The satellite was flown from Taiwan to Los Angeles International Airport in the United States on 19 July 2017 via a China Airlines transport aircraft, and arrived at Vandenberg Air Force Base on 26 July. SpaceX launched Formosat-5 in a sun synchronous low earth orbit with an inclination of 98.2892° about 716 - 729 km above earth in a 99,25 minute orbit.
The last flight of B1038-1
This Falcon 9 booster is the last Full Thrust V1.2 rocket - Block 3 booster made in the third production set of 18 boosters in SpaceX main factory in Hawthorne, California. There is a small testset of 7 Block 4 made before the final production of the last Falcon 9 iteration of the fully reusable Block 5 begins.
The flight of this particular booster B1038-1 is as most SpaceX flights a testflight. It had a very light payload 475 kg going in a Sun Synchronous orbit, so it went almost straight up before the stage separation, and then it was the second stage’s job to go sideways from then on. That change in thrust direction was evident from the flight telemetry delivered.
The velocity dropped 300 km/h, and the second stage almost had to launch itself midair before it picked up any lateral velocity.
B1038-1 continued in a high parabolic arc before reaching its maximum peak and it started to fall back to earth with very little fuel left, because with 151 seconds of burn time spent, there is only 9 seconds full thrust left on all 9 Merlin 1D+ engines plus what isn't used because of down throttling during Max Q, going through the sound barrier and before MECO to lower the G force made by the higher thrust to weight ratio.
Now the re- entry burn uses 3 Merlin 1D+ engines in a 1 - 3 - 1 burn sequence each taking 4 - 29 - 2 seconds and they are throttled down, so the propellant consumption is reduced as the booster cuts its velocity by half at least - Well we don't see flight telemetry from the first stage all the time, but the next OTV-5 mission does give us that information.
It should be noted that B1038-1 is a Block 3 Full Trust booster and the following OTV-5 booster B1040-1 is a more powerful Block 4. Burntimes, speeds and altitudes may differ.
The landing burn does give us flight telemetry for just one Merlin 1D+ engine, and I left the figures in the Launch Debriefing above. 31 second burn time during the landing burn added with the 4 - 29 - 2 seconds entry burn time gives a total of 124 seconds burn time in one Merlin 1D+ engine and it’s assumed there is 9 second full thrust left for 9 Merlin 1D+ engines or 81 seconds for just one Merlin 1D+ engine.
The gap of -43 seconds must be covered by throttling down the Merlin 1D+ engines. 81 seconds over 124 seconds gives a ratio of 0,653 which must be close to the throttle down percentage on a Merlin 1D+ engine, which I on WikiPedia have read to be 70%. So that’s Block 3 in burn time numbers without having any idea about propellant weight, propellant consumption ratio, thrust to weight ratio aka. G forces, nor do I know how much propellant there is left in the booster.
As long it burns, there is fuel onboard. Personally I’m guessing 90 seconds burn time left with 3-4 seconds left as spare propellant.
During Apollo 13 “The movie” and probably also in real life Gene Krantz states:
“I don't care what it’s built to do. I care about what it can do.”
Wise words to live by. Now you know a little about what a Falcon 9 Block 3 can do.
