
What We Know The X-37B Was Up To During Its 780 Days In Space - tomohawk
https://www.thedrive.com/the-war-zone/30699/here-what-we-know-the-shadowy-x-37b-was-up-to-during-its-record-720-days-in-space
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walrus01
> We also know that the previous OTV-4 mission involved the test of Aerojet
> Rocketdyne's XR-5A Hall-effect thruster, a type of electric propulsion
> system that offers greater efficiency for satellites and spacecraft
> maneuvering in orbit. This was officially in support of the Advanced
> Extremely High Frequency (AEHF) satellite program, but the technology could
> be valuable for other space-based systems, as you can read about more here.
> In August 2018, during OTV-5, the X-37B modified its orbit using an
> unspecified onboard propulsion system.

If I had to guess, they're experimenting with novel, relatively untested ion
and hall effect type thruster systems that have very low thrust in newtons or
kilonewtons, but very high specific impulse. Before putting things like that
on billion dollar geostationary military communications satellites (or LEO/MEO
radar imaging satellites, or billion dollar NRO satellites), they'd want to
qualify them in space.

Maybe the spaceplane design that can return a used thruster was a happy
coincidence between two different programs, allowing them to do a destructive
teardown on a thruster that's been used for two years, to better determine its
possible failure modes.

Things in the same general category as this, but with new and radical designs.

[https://en.wikipedia.org/wiki/Ion_thruster](https://en.wikipedia.org/wiki/Ion_thruster)

Extremely high specific impulse thrusters can result in satellites with much
longer operating lives, for the same weight (in kilograms) of pressurized fuel
tank storage, and same volume. Either from LEO things that can accelerate
themselves periodically to maintain orbit, counteracting the effects of drag,
or for geostationary satellites, keeping position longer than a nominal 12-15
year life span.

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jcims
I bet somewhere on this planet there is now emprical evidence to the efficacy
or lack thereof of emdrive and/or other reactionless thruster designs.

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rdtwo
It has to be an extremely high value mission because it means they were unable
to use the craft for any additional launches during the 780 days.

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jcims
Good point. I wonder if this partially challenges the theory that the X-37B
has satellite recovery in its repertoire.

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manicdee
All this mission shows is that there was something the US Air Force wanted to
do that warranted two years of flight time ahead of any other project, even
recovering or stealing a satellite.

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Swenrekcah
Have people stolen satellites from orbit?

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doe88
It would be funny if its sole purpose was just trolling competing defense
agencies around the world into endlessly speculating about its capabilities
when in fact it would just turn around and around and around.

