SpaceX FH : USSF-52 (X-37B OTV-7) : KSC LC-39A : 28/29 December 2023 01:07 UTC

[daveglo]

I think the key words in the press release are "expanding the envelope".  Think higher.  Boeing has already stated the service ceiling of 500 miles, but the other words about working with Boeing on this mission would seem to imply that number may grow.  Previous flights have maxed out at 260 miles.

Going to be fascinating to see how high this mission ends up going.  Spotters are going to be working hard on this one.

[bobthemonkey]

Has anyone run the numbers to see what a FH could be able to put into SSO with a dog leg from the East Coast?

Is there any benefit vs any of the available West Coast options?

[LouScheffer]

Of course the heat shield may be somewhat better than LEO only.  Also, if they are adventurous they could use aerobraking to circularize.  If so they could return from the more aggressive orbits in this group.

Why would you consider aerobraking 'adventurous' in this context? Other spacecraft have performed multi-pass aerobraking. Without heat shields. It seems that for this spacecraft it is a pretty straightforward way to lessen the loads on the heat shield for the final reentry.

It would be adventurous since, as a military asset, they would not use the well proven few-meters-per-second at a time aero-braking, with the overall process taking months to complete.  They would want to dive pretty deep into the atmosphere so they could bleed off speed in only a few passes.  This part of the aerobraking regime, especially with an aerodynamic vehicle, has little or no experience base I am aware of.

[Asteroza]

I think the key words in the press release are "expanding the envelope".  Think higher.  Boeing has already stated the service ceiling of 500 miles, but the other words about working with Boeing on this mission would seem to imply that number may grow.  Previous flights have maxed out at 260 miles.

Going to be fascinating to see how high this mission ends up going.  Spotters are going to be working hard on this one.

The emphasis of space domain awareness, plus the strange moon shadow on the fairing painting/patch, plus the original GTO tender, makes me wonder. There was all that talk about moon space domain awareness not too long ago. How hard would it be to shift to a lunar free return trajectory, or one of those weird low energy transfer orbits that could be done via the electric thruster?

[AstroWare]

Of course the heat shield may be somewhat better than LEO only.  Also, if they are adventurous they could use aerobraking to circularize.  If so they could return from the more aggressive orbits in this group.

Why would you consider aerobraking 'adventurous' in this context? Other spacecraft have performed multi-pass aerobraking. Without heat shields. It seems that for this spacecraft it is a pretty straightforward way to lessen the loads on the heat shield for the final reentry.

It would be adventurous since, as a military asset, they would not use the well proven few-meters-per-second at a time aero-braking, with the overall process taking months to complete.  They would want to dive pretty deep into the atmosphere so they could bleed off speed in only a few passes.  This part of the aerobraking regime, especially with an aerodynamic vehicle, has little or no experience base I am aware of.

I guess I don't understand why you think they would have to do deep atmosphere passes vs. multi month. A theoretical x-37 GEO mission would spend months or years in the *Mission* orbit. When it's done and leaves the mission orbit, and the mission is over.

It could take 6 mons to return, or hours. Doesn't really matter. The *mission* is over.

Would it be nice to have it back faster? Sure. But the refurb process on these has not been rapid. So really it's going to be years between launches. A few months isn't going to change that *drastically*

[Asteroza]

Of course the heat shield may be somewhat better than LEO only.  Also, if they are adventurous they could use aerobraking to circularize.  If so they could return from the more aggressive orbits in this group.

Why would you consider aerobraking 'adventurous' in this context? Other spacecraft have performed multi-pass aerobraking. Without heat shields. It seems that for this spacecraft it is a pretty straightforward way to lessen the loads on the heat shield for the final reentry.

It would be adventurous since, as a military asset, they would not use the well proven few-meters-per-second at a time aero-braking, with the overall process taking months to complete.  They would want to dive pretty deep into the atmosphere so they could bleed off speed in only a few passes.  This part of the aerobraking regime, especially with an aerodynamic vehicle, has little or no experience base I am aware of.

I guess I don't understand why you think they would have to do deep atmosphere passes vs. multi month. A theoretical x-37 GEO mission would spend years in the *Mission* orbit. When it's done and leaves the mission orbit, and the mission is over.

It could take 6 months to return, or hours. Doesn't really matter. The *mission* is over.

Would it be nice to have it back faster? Sure. But the refurb process on these has not been rapid. So really it's going to be years between launches. A few months isn't going to change that *drastically*

Deep passes would face a heat soak problem that probably can't be addressed by the existing radiator, so you either are committing to landing somewhat soon after a deep pass (skipping stone reentry), or stuck with light passes.

[Targeteer]

What ever the initial orbit, it will be the amateur satellite observers around the world who will answer all these questions.  Should we start a poll on how long after launch the payload(s) are spotted?

[Targeteer]

https://sattrackcam.blogspot.com/2023/11/boldly-going-where-no-spaceplane-has.html

[Star One]

I doubt this is the last vehicle to fly so it’s been on the ground for years so plenty of time to upgrade the heat shield for higher orbits. Plus that NASA experiment flying seeds, putting them long term at a higher orbit would be useful for future manned missions which is what that the press release indicates the experiment is for.

[LouScheffer]

I guess I don't understand why you think they would have to do deep atmosphere passes vs. multi month. A theoretical x-37 GEO mission would spend years in the *Mission* orbit. When it's done and leaves the mission orbit, and the mission is over.

It could take 6 months to return, or hours. Doesn't really matter. The *mission* is over.

Would it be nice to have it back faster? Sure. But the refurb process on these has not been rapid. So really it's going to be years between launches. A few months isn't going to change that *drastically*

A major point of a military space plane (with large maneuvering capability) is rapid response. So you want it to change orbits rapidly, not over the course of months.  Perhaps it has another task after returning from a higher orbit.  And in any case you can't relaunch it for another target until it returns.   Agreed it has not been refurbished fast *yet*, but it is not yet a mature system.

And if you want to get more speculative, perhaps it's returning from GEO (or elsewhere) with an interesting piece it collected.  (For failure analysis of our own satellites, of course.  It would be rude to collect parts from someone else's satellite.)  Then you want it down quickly for analysis on the ground.

[Jim]

A major point of a military space plane (with large maneuvering capability) is rapid response.

Not when it is placed on a Falcon Heavy.

[Jim]

I doubt this is the last vehicle to fly so it’s been on the ground for years so plenty of time to upgrade the heat shield for higher orbits. Plus that NASA experiment flying seeds, putting them long term at a higher orbit would be useful for future manned missions which is what that the press release indicates the experiment is for.

Not really.  It is the shape and not so much the tiles.

[Jim]

Deep passes would face a heat soak problem that probably can't be addressed by the existing radiator, so you either are committing to landing somewhat soon after a deep pass (skipping stone reentry), or stuck with light passes.

Not even heat soak.   Just operating for long periods without the radiators deployed will be an issue.    Also, the service module isn't going to ride along for any dip in the atmosphere. 

[Jim]

What about a dual payload and X-37 dropped off at a lower altitude.

[Bean Kenobi]

What about a dual payload and X-37 dropped off at a lower altitude.

In that case, fairing has to be expanded. Comparing with Falcon 9, if available mass is higher, volume isn't if fairing is the same.
This hypothesis requires the payloads to be stacked.

[Jim]

What about a dual payload and X-37 dropped off at a lower altitude.

In that case, fairing has to be expanded. Comparing with Falcon 9, if available mass is higher, volume isn't if fairing is the same.
This hypothesis requires the payloads to be stacked.

No,  there is room for more

[woods170]

What about a dual payload and X-37 dropped off at a lower altitude.

In that case, fairing has to be expanded. Comparing with Falcon 9, if available mass is higher, volume isn't if fairing is the same.
This hypothesis requires the payloads to be stacked.

No,  there is room for more

There is room alright. X-37B and its service module can be mounted at least another 1 meter higher up into the fairing compared to the time it flew on Falcon 9.

[Zed_Noir]

Deep passes would face a heat soak problem that probably can't be addressed by the existing radiator, so you either are committing to landing somewhat soon after a deep pass (skipping stone reentry), or stuck with light passes.

Not even heat soak.   Just operating for long periods without the radiators deployed will be an issue.    Also, the service module isn't going to ride along for any dip in the atmosphere.

Maybe the service module got some thermal protection on the windward side and deployable radiator array(s) on the leeward side for shallow dips in the atmosphere.

[LouScheffer]

Deep passes would face a heat soak problem that probably can't be addressed by the existing radiator, so you either are committing to landing somewhat soon after a deep pass (skipping stone reentry), or stuck with light passes.

Not even heat soak.   Just operating for long periods without the radiators deployed will be an issue.    Also, the service module isn't going to ride along for any dip in the atmosphere. 

These are reasonable concerns, but only if you did deep dips without designing for it.  Presumably, if they did this intentionally, they could close the doors just before the pass, and open them afterwards, so the radiators are only offline for a short time.  And the service module would be designed for dips.   It's quite strongly attached, and presumably could have at least some heat shielding on the exposed side - just enough for the dips, not re-entry level shielding.

I very much doubt they will try this, but if they if they did they would design for it, and I suspect could use much deeper dips than those used by unprotected spacecraft.

[LouScheffer]

A major point of a military space plane (with large maneuvering capability) is rapid response.

Not when it is placed on a Falcon Heavy.

Not sure of this logic.   If you want fast response, presumably you want an asset already in orbit with considerable maneuvering capability (and hence a huge fuel load).  So you'd launch it on a big rocket (which is not fast response) so it's on orbit when you need it.

I always thought (but of course cannot confirm) that this is how imaging satellites work.   They launch on a big (not rapid response) launcher so they can later get where they are needed, when they are needed.