A Hard Upper Torso Assembly, or HUT, is a central component of several space suit

Space suit

A space suit is a garment worn to keep an astronaut alive in the harsh environment of outer space. Space suits are often worn inside spacecraft as a safety precaution in case of loss of cabin pressure, and are necessary for extra-vehicular activity , work done outside spacecraft...

s, notably Roscosmos' Orlan and NASA

NASA

The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

's Extravehicular Mobility Unit

Extravehicular Mobility Unit

The Space Shuttle/International Space Station Extravehicular Mobility Unit is an independent anthropomorphic system that provides environmental protection, mobility, life support, and communications for a Space Shuttle or International Space Station crew member to perform extra-vehicular activity...

 (EMU). The fiberglass

Fiberglass

Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...

 HUT forms a rigid enclosure about the upper body of the occupant, providing pressure containment for this part of the body. The HUT incorporates structural attachment points for the arms, Lower Torso Assembly (LTA), helmet, chest-mounted Display and Controls Module (DCM), and Primary Life Support Subsystem

Primary Life Support System

A Primary Life Support System , is a device connected to an astronaut's or cosmonaut's spacesuit, which allows extra-vehicular activity with maximum freedom, independent of a spacecraft's life support system. The PLSS is generally worn like a backpack...

 (PLSS) backpack.

The original HUT design for the EMU, first used in 1980, included bellowed shoulder bearings, which allowed for variation in the angle of the shoulder bearings. This allowed for one configuration to ease donning of the suit, and a different configuration to allow maximum mobility during EVA. However, the limited life of the bellows prompted a redesign in 1990 to a fixed shoulder bearing angle and position, referred to as the Planar HUT, resulting in reduced mobility and more difficult donning and doffing.

Because of the high cost of manufacturing, only three sizes of HUTs are produced for the EMU. This has the effect of limiting the number of people who can be properly fit for the suit. The three HUT sizes are supposed to accommodate occupants from the 5th to the 95th percentile

Percentile

In statistics, a percentile is the value of a variable below which a certain percent of observations fall. For example, the 20th percentile is the value below which 20 percent of the observations may be found...

.

The HUT also includes an In-Suit Drink Bag, with a plastic tube extending into the helmet, to allow the astronaut to stay hydrated.