Simplified Aid For EVA Rescue (SAFER) is a small, self-contained, propulsive backpack system (

jet pack A jet pack, rocket belt, or rocket pack is a device worn on the back which uses jets of gas or liquid to propel the wearer through the air. The concept has been present in science fiction for almost a century and became widespread in the 1960s. ...

) worn during

spacewalk Extravehicular activity (EVA) is any activity done by an astronaut in outer space outside a spacecraft. In the absence of a breathable atmosphere of Earth, Earthlike atmosphere, the astronaut is completely reliant on a space suit for environmen ...

s, to be used in case of emergency only. If an untethered astronaut were to lose physical contact with the vessel, it would provide free-flying mobility to return to it. It is worn on spacewalks outside the

International Space Station The International Space Station (ISS) is the largest modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA ...

(ISS), and was worn on spacewalks outside the

Space Shuttle The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program na ...

. So far, there has not been an emergency in which it was needed. SAFER is a small, simplified version of the

Manned Maneuvering Unit The Manned Maneuvering Unit (MMU) is an astronaut propulsion unit that was used by NASA on three Space Shuttle missions in 1984. The MMU allowed the astronauts to perform untethered extravehicular spacewalks at a distance from the shuttle. T ...

(MMU), which was used for regular maneuvering.

Description

SAFER is fitted around the life support backpack of the space suit (EMU or

Extravehicular Mobility Unit The Extravehicular Mobility Unit (EMU) is an independent anthropomorphic spacesuit that provides environmental protection, mobility, life support, and communications for astronauts performing extravehicular activity (EVA) in Earth orbit. Introduc ...

). SAFER in no way interferes with suit mobility. The flight test unit was fitted with a single hand control module rigidly attached to the Display and Control Module (DCM) in front of the suit. The hand controller provided six degrees-of-freedom (DOF) maneuvering via 24 gaseous-nitrogen (GN2) thrusters. Vehicle weight is 85 pounds. The GN2 is stored in four cylindrical tanks, each charged to 3250 psi. Total fuel capacity is 3 pound which is sufficient to change the vehicle velocity approximately 10 feet/second (ΔV). The unit features very extensive self-test capability.

Application

SAFER is designed to be used as a self-rescue device if in spite of precautions such as tethers, safety grips, and the robot arm an EVA crewmember gets separated and no vehicles can provide rescue capability. SAFER is worn by every ISS crewmember using an

. SAFER was co-invented by former astronauts Joseph Kerwin, Paul Cottingham and Ted Christian under a Lockheed contract to NASA for

Space Station Freedom Space Station ''Freedom'' was a NASA project to construct a permanently crewed Earth-orbiting space station in the 1980s. Although approved by then-president Ronald Reagan and announced in the 1984 State of the Union address, ''Freedom'' wa ...

. It was later sponsored by the Space Shuttle Program and developed by Lockheed and NASA personnel. SAFER was the design solution to the Shuttle Program's requirement to provide a means of self rescue should an EVA crewmember become untethered during an EVA. SAFER was first flown on

STS-64 STS-64 was a Space Shuttle ''Discovery'' mission that was set to perform multiple experiment packages. STS-64 was launched from Kennedy Space Center, Florida, on 9 September 1994, and landed back on 20 September 1994 at Edwards Air Force Base. ...

September 9, 1994, where an untethered flight test was performed first by astronaut Mark Lee and then

Carl Meade Carl Joseph Meade (born November 16, 1950) is a former NASA astronaut. Personal data Born November 16, 1950, at Chanute Air Force Base, Illinois. Married. Two sons. Resides in Canyon Country, California. He enjoys woodworking, home-built aircraf ...

. Both astronauts flew the SAFER up and around the Shuttle's

Robotic Arm A robotic arm is a type of mechanical arm, usually programmable, with similar functions to a human arm; the arm may be the sum total of the mechanism or may be part of a more complex robot. The links of such a manipulator are connected by joints ...

along with a demonstration test of the SAFER's automatic attitude hold feature. This feature arrests uncontrolled rotation of a detached crewmember expected in an accidental separation. SAFER has a mass of approximately 83 lb (38 kg) and can provide a total change in velocity (

delta-v Delta-''v'' (more known as "change in velocity"), symbolized as ∆''v'' and pronounced ''delta-vee'', as used in spacecraft flight dynamics, is a measure of the impulse per unit of spacecraft mass that is needed to perform a maneuver such as ...

) of at least 10 ft/s (3 m/s). It was also tested during flight

STS-92 STS-92 was a Space Shuttle mission to the International Space Station (ISS) flown by Space Shuttle '' Discovery''. STS-92 marked the 100th mission of the Space Shuttle. It was launched from Kennedy Space Center, Florida, 11 October 2000. Crew ...

when astronauts

Peter Wisoff Peter Jeffrey Kelsay Wisoff (born August 16, 1958) is an American physicist and former NASA astronaut. Wisoff qualified as mission specialist and flew in four Space Shuttle missions, with his first launch in 1993 and his last in 2000. Career Wis ...

and

Michael López-Alegría Michael López-Alegría (born Miguel Eladio López Alegría on May 30, 1958) is an astronaut, test pilot and commercial astronaut with dual nationality, American and Spanish; a veteran of three Space Shuttle missions and one International Space ...

performed test maneuvers, flying up to 50 feet (15 m) while remaining tethered to the spacecraft.STS-92 NASA Mission Report #15
NASA, 2008-10-18.

Complications

The left side latch on the SAFER unit became unlatched during an EVA by astronaut

Piers Sellers Piers John Sellers (11 April 1955 – 23 December 2016) was a British-American meteorologist, NASA astronaut and Director of the Earth Science Division at NASA/GSFC. He was a veteran of three Space Shuttle missions. Sellers attended Cranbro ...

STS-121 STS-121 was a 2006 NASA Space Shuttle mission to the International Space Station (ISS) flown by . The main purposes of the mission were to test new safety and repair techniques introduced following the ''Columbia'' disaster of February 2003 as w ...

while testing shuttle repair techniques. The latch had been inadvertently bumped and moved to the unlatch position. As a precaution,

Mike Fossum Michael Edward Fossum (born December 19, 1957, in Sioux Falls, South Dakota) is a former American astronaut, engineer, and thChief Operating Officer of Texas A&M University at Galveston He flew into space on board the NASA Space Shuttle missions S ...

tethered it to him and the spacewalk continued. In subsequent spacewalks, the latches were secured with

Kapton Structure of poly-oxydiphenylene-pyromellitimide Kapton insulating pads for mounting electronic parts on a heat sink Kapton is a polyimide film used in flexible printed circuits (flexible electronics) and space blankets, which are used on spac ...

tape, a space-rated form of adhesive tape, to prevent the latches from inadvertently opening.

References

External links

*
Video of SAFER being attached
{{space suit Human spaceflight Extravehicular activity

Description

Application

Complications

See also

References

External links