SpaceX F9 - NROL-85 - SLC-4E

[Grendal]

Launch Date: April 17
Launch Window: 6:13am PDT (9:13am EDT, 13:13 UTC)
Launch site: SLC-4E, Vandenberg Space Force Base
Core Booster Recovery: RTLS
Booster: B1071-2
Fairings: Reused - TBD
Mass: None of your business - It's a secret!
Orbit: LEO

Classified mission awarded to SpaceX in February 2019. A SpaceX Falcon 9 rocket will launch a classified payload for the National Reconnaissance Office, the U.S. government’s spy satellite agency. The mission is designated NROL-85. The first stage will return to Landing Zone 4 at Vandenberg.

This will be SpaceX's 14th orbital launch of the year.

First reused booster for an NROL launch.

 

[Grendal]

An opportunity moment for California residents who want to watch a launch happen.

Launch window time added.

 

[Electroman]

RTLS !!!

>>Mass: None of your business - It's a secret!

Well, since it is RTLS and LEO, we can get an idea on the upper bound on the mass

 

[Grendal]

Static fire test of Falcon 9 complete – targeting Friday, April 15 for launch of the NROL-85 mission from Vandenberg in California. The Falcon 9 first stage supporting this mission previously launched NROL-87 in February.
https://twitter.com/SpaceX/status/1511393752312520706/photo/1

https://twitter.com/x/status/1511393752312520706

 

[Electroman]

NROL-87 was launched ahead of NROL-85 ?

 

[bush174]

It would be a nice trip down there to come watch.

 

[Grendal]

NROL-87 was launched ahead of NROL-85 ?

It happens.

 

[Grendal]

 

[Grendal]

 

[ecarfan]

SpaceX tweet from an hour and half ago:

Due to excessive upper level winds forecasted for Saturday, we are now targeting no earlier than Sunday, April 17 for Falcon 9’s launch of NROL-85 from Vandenberg Space Force Base

 

[JohnnyEnglish]

Just like clockwork. Love the precision. RTLS always feels a bit more special.

 

[MyJoule]

Nice launch and landing. I like it when John is the host of the web cast, we seem to get more information when he hosts...I guess it's because he's an integration guy

 

[HVM]

https://twitter.com/x/status/1515682228172296196

 

[ecarfan]

Because of the low clouds, the view from the booster just before landing did not show the ground. It was kind of weird to see the booster descending in the final seconds without being able to see the LZ. But of course the software knew exactly where it was all the time.

 

[HVM]

https://twitter.com/x/status/1515683849371594754

 

[Electroman]

Are there transmitters and sensors on the ground on the landing zone that sends signals to the rocket and directs & guides it so precisely ?

I don't think there is, but if I were to design a landing system my first intuition would be to design one like that, not too dissimilar from automated guided landing systems for airplanes in major airports. But of course the technology used by SpaceX even removed that 'crutch' and lands completely on its own using GPS I guess.

Of course guidance is one thing, but the precise firing of rockets with the right amount of power and cut-off at the correct moment (with a precision to less than half a second maybe?) is equally key for a safe soft landing.

This is not Science. This is Magic.

 

[ecarfan]

It’s physics (“magic” is just another form of delusion). The fact that SpaceX can land boosters so reliably and precisely is because some humans have learned that science, properly done, is a powerful tool for understanding the universe, and the knowledge gained can be employed to accomplish useful objectives.

It is my understanding that the booster’s onboard avionics and guidance system controls the cold gas thrusters, grid fins, and engines to guide it to the landing site‘s GPS coordinates. But I don’t work for SpaceX so I could be wrong…

 

[HVM]

There's no transmission from ground. F9 uses inertial guidance system and GNSS (GPS in this case) for the position and radar for the altitude near landing.

 

[HVM]

https://twitter.com/x/status/1515798858328018945

 

[HVM]

https://twitter.com/x/status/1515717961172008968