The Red Angel suit was a powered time-travel suit developed by Section 31 under Project Daedalus, worn by Gabrielle Burnham and later by her daughter Michael.
Section 31 began work on the suit as a response to fears that the Klingons were developing time travel. Gabrielle Burnham completed it and used it to escape a Klingon attack, only to be pulled far into the future, from which she made repeated trips into the past.
Her appearances as the mysterious Red Angel of 2257 drew Discovery into a crisis involving the rogue artificial intelligence Control. Michael Burnham built a second suit powered by a time crystal and used it to lead Discovery into the 32nd century, keeping the Sphere data out of Control's reach.