One presumes…the same way White Knight Two (https://en.wikipedia.org/wiki/Scaled_Composites_White_Knight_Two) does it
High-lift wings, and engines designed for high altitude
June 20, 2020 at 10:32AM
via reddit https://www.reddit.com/r/aviation/comments/hcag1z/how_did_the_u2_spy_plane_fly_at_70000_feet/fvfyf2r?utm_source=ifttt