# Why does the Minotaur I wear a yellow jacket that "banana-peels" off as it launches?

Videos available of the recent Minotaur I launch at Wallops for NROL-111 show a yellow jacket on most of the four stage SRB-to-orbit launch vehicle. I read or heard somewhere that wires attached to the ground "banana-peel" the yellow jacket off the rocket as it launches.

I could imagine an insulating jacket on a rocket with cryopropellants, perhaps with clean dry air blown underneath to prevent ice build up, but I can't imagine why this cover would be necessary on an SRB whose heritage is a (presumably) robust ICBM.

Question: Why does the Minotaur I wear a yellow jacket that "banana-peels" off as it launches?

NASA Wallops video "NRO L-111 Launch" cued at about 12 seconds before launch, with a lot of introductory information:

cued at 28:15 There is a lot of cogent discussion in the video before the launch which may be helpful; for some inexplicable reason the NASA Spaceflight narrators suddenly and temporarily loose composure just moments before launch:

Source

The Near Field Infrared Experiment (NFIRE) military satellite in April 2007 with a Minotaur-1 missile

• That last photo is really nice. Jun 16 at 1:04
• @OrganicMarble ya, after the fact I happened to notice the flexible ducting connecting to the bottom of the jacket(s).
– uhoh
Jun 16 at 1:53
• Your second video explains the history/design and reason for the jacket (which is as Organic Marble says below) from approximately 5:50. Jun 17 at 11:09
• @RobGilliam lol! Maybe I should start watching the videos in the questions. Jun 17 at 13:11

The jacket is to control the Propellant Mean Bulk Temperature, a critical factor in solid rocket motor performance.

The silos for the missiles that the launcher was derived from were air-conditioned for this reason.

the Minuteman boosters in the Lower Stack were designed to be launch (sic) from a climate controlled silo with virtually no outside weather effects until launch.