Quote from: LouScheffer on 11/09/2023 07:58 pmOf 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.
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.
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.
Quote from: AstroWare on 11/09/2023 08:36 pmQuote from: LouScheffer on 11/09/2023 07:58 pmOf 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.
Quote from: LouScheffer on 11/09/2023 10:35 pmQuote from: AstroWare on 11/09/2023 08:36 pmQuote from: LouScheffer on 11/09/2023 07:58 pmOf 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*
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.
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.
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.
What about a dual payload and X-37 dropped off at a lower altitude.
Quote from: Jim on 11/10/2023 01:04 pmWhat 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.
Quote from: Bean Kenobi on 11/10/2023 02:29 pmQuote from: Jim on 11/10/2023 01:04 pmWhat 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
Quote from: Asteroza on 11/10/2023 01:35 amDeep 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.
Quote from: LouScheffer on 11/10/2023 12:31 pmA major point of a military space plane (with large maneuvering capability) is rapid response.Not when it is placed on a Falcon Heavy.