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USK Cosmonaut Self-Rescue Device

Orlan-M with USK

The Russian Orlan-M spacesuit with the USK attached.

This propulsive backpack, analogous to the U.S. EMU SAFER, was to be utilized in the near future during Russian ISS spacewalks wearing Orlan spacesuits.

It is called the USK, Установка Самоспасения Космонавта (Ustanovka Samospaseniya Kosmonavta, Cosmonaut self-rescue device); a shorter version is «Спасатель» (Spasatel’, Rescuer).

A report in Novosti Kosmonavtiki news release No.454 (11 February 2005) mentioned the devices and the reason they had not yet been delivered: no room could be spared for them on the Progress ships as Russia was supporting the Station after the Columbia accident and needed every available kilo for essential supplies. It is uncertain if the USKs will ever be flown up. The system of two tethers used has so far proven reliable, so there is no pressing need for the USK.

Technical data

The following information was extracted from the book Russian Spacesuits.

The Orlan-M USK specifications
No. Parameter Value
1 Working medium Air
2 Working medium storage (kg) ~1.3
3 Bottle pressure (MPa) at T = 20°C 35
4 Number of gas thrusters 16
5 Thrust of one gas thruster (Newtons) 3.5÷4.0
6 Total increment of velocity (m s-1) 3.6
7 Available linear acceleration (m s-2) 0.03÷0.06
8 Available angular acceleration (°s-2) 5.8÷8.7
9 Doubling-up the pneumatic system Provided by automatic switch-over
10 Number of self-rescue cycles 5
11 Number of (VKD/EVAs) throughout its lifetime 40
12 Recovery of serviceability after self-rescue Gas storage assembly changes are forseen

As is known, the safety of crew members wearing the Orlan-M suit while moving along the station’s surface is provided by two safety tethers. When a crewmember disengages one of the safety tethers, he or she grips the handrail additionally. This method has been successfully used for 25 years on board Russian orbiters. In order to improve EVA safety, in case of two failures or mistakes of the crew, the possibility of equipping the ISS Orlan-M spacesuit with SAFER was considered along the same lines as NASA’s EMU spacesuit.

In 1998 Zvezda began to develop such a device for the ISS Orlan-M spacesuit under a contract with Rosaviakosmos. Between 1999 and 2000 this work continued with the financial participation of NASA. At the same time the technical performance requirements of the Russian SAFER and its operation logic were wearing an approximated as much as possible to those of the US EMU SAFER, with the purpose of eventual unification of the system and ease of crew training. Yet the Russian SAFER considerably differs from the EMU SAFER in design, pneumatic flow diagram, means of attachment to the spacesuit, controls, etc.

In 2001, NASA’s financial participation stopped; nevertheless, between 2001 and 2002 Zvezda completed development of SAFER through its contract with Rosaviakosmos and manufactured the flight samples for delivery to the ISS.

SAFER is attached to the spacesuit at four points. At the same time, it is possible to maintain the spacesuit on board the ISS, perform suit-donning/doffing, pass through the normal Ø 1 m hatch and effect emergency entry into ISS compartments through the Ø 0.8 m hatch. The possibility of detaching SAFER from the suit in case of emergency during EVA (with assistance of the second crew member) is provided. SAFER is powered from the Orlan-M battery and actuated by a toggle switch located on the suit control panel. The HCM of SAFER is unlocked and deployed in the working position manually after SAFER actuation.

SAFER’s MCS was developed by the Ramenskoye Instrument Engineering Design Bureau according to Zvezda’s performance specifications. The MCS has three operation modes: half-automatic control mode, direct control mode and emergency control mode.

The half-automatic control mode provides for:

  • automatic dissipation of angular rates obtained at the moment of separation;
  • attitude hold relative to three axes with an accuracy of ±5°;
  • manual turn to one of the axes with attitude hold relative to two other axes;
  • manual dissipation or gain of the linear rate along three axes.

The direct control mode provides for:

  • manual angular rate dissipation and turn about any axis;
  • manual dissipation or gain of the linear rate.

The emergency control mode is similar to the direct control mode, but at the same time the control commands and power supply are sent by independent lines.

The MCS, besides its control function, monitors the status of SAFER’s pneumatic system and generated the commands to change the pneumatic system’s configuration and operation in case of failure of a single gas thruster. The gas storage assembly can be replaced by a new one, when necessary after expenditure.

A large team of Zvezda specialists took part in the design and development of means for cosmonaut transference and manoeuvrability. The manager in charge of work on UPMK for the SKV and Yastreb spacesuits as well as on the 21KS 1 was V.A. Frolov and for SAFER it was S.S. Pozdnyakov. Management of the computational and theoretical part of the work was mainly done by A.N. Livshits.

(1 Designation of the UPMK, УПМК, Cosmonaut Transference and Maneuvering Equipment backpack that was tested by A. Serebrov and A. Viktorenko during their stay on Mir in 1990.)

News & articles

From Spaceflight magazine, Vol. 42, September 2000:

Russia Develops Spacewalk Safety Unit

The Moscow-based Zvezda spacesuit manufacturer is developing a cosmonaut safety aid for use during spacewalks. The miniature, independent manoeuvring unit, called USK is analogous to the SAFER unit which has already been worn operationally during EVAs from the Space Shuttle.

The Russian and US units would be used if a spacewalker’s tether broke or came loose and he or she was left stranded, drifting away. The frame-like, 40 kg USK device fits around the backpack of the Orlan EVA suit that the Russians have been using since the 1970, and can be used for up to eight hours.

USK is equipped with two sets of eight compressed air thrusters each with 500 grams thrust. An autonomous computer system provides automatic attitude control.

NPO Zvezda is testing the new tool and expects to fly the machine in space within a year. USK is to be fitted on all new Orlan suits which can be resupplied and adapted to the size of any cosmonaut on orbit The gas canisters in Orlan can be used up to 100 times.

Because of its rigid construction, the pressure inside the suit can be brought lower than in the NASA suits. As a result, Russian suits provide greater freedom of movement and no pre-breathing is necessary, which saves hours of preparation time.

The Orlan suits will be modified for work on the International Space Station. Communications and airlock connections are to be unified so that both US and Russian suits are cornpatible with the equipment on the station. It is planned to operate US and Russian suits side by side.

NPO Zvezda says it will also provide the toilet for ISS. Based on the device used on Mir, the Russian design is preferred by both US and Russian astronauts. On Shuttle-Mir missions, the American astronauts always moved over to Mir to answer nature’s calls.

– Luc Van Den Abeelen

From ESA’s “News from Moscow” bulletin, March 2005:

New Cosmonaut Rescue System Developed

A jet-assisted system for the rescue of crew members engaged in extravehicular activities has been developed at Russia’s Zvezda Scientific and Production Association. Two jet thrusters using liquefied gas are mounted on either side of the Orlan-M backpack. If the cosmonaut, for some reason or other, fails to hitch himself up to external rails of the station and is pulled away, the device will help him, when he switches on the thrusters, to get his bearings and go back to the station.


USK, УСК, installation on the Orlan–M suit (18 KB). Source: Russian Spacesuits.

Zvezda: Установка спасения космонавта УСК (Installing astronaut saver USC)

Updated 18 Jul 2015