February 1983:the Manned Escape System

The frequent use of the Space Shuttle raises the possibility of astronauts being stranded in orbit should something go
wrong with their craft. Present rescue plans involve a second
Shuttle Orbiter flying to recover the stricken astronauts - a
lengthy process if another Orbiter is not immediately available. An alternative is to return the crew using reentry
capsules based on proven satellite designs up to 20 years old.

Introduction

A Manned Escape System (MES) could be a scaled-up
satellite reentry vehicle with provisions for a human payload
and autonomous deorbit capability. Accommodations for
humans would include attitude control for retrofire and impact
attenuation during landing. Life support would be provided
by pressure suits and not by the capsule itself.

The capsule would be equipped with contour couches, an
ingress hatch, power supply and communications equipment.
Up to four crew members could be seated around a central
console. This arrangement permits compact seating without
the need to fold back equipment for ingress and it allows
semi-prone positioning for good acceleration tolerance.

An ablative heat shield would be attached to the conical
portion of the reentry vehicle’s forebody. The basic structure
of the vehicle would be two nested semi-monocoque aluminium
shells of conventional fabrication connected through an aft
bulkhead.

The attitude control system would not be dependent on the
crew since they might be incapacitated or unqualified to fly
the craft. Thus a fully automated three axis attitude control
system using infrared horizon sensors and rate gyros would be
provided. It would automatically stabilize and position the
vehicle for retro fire.

Retro fire could be controlled by the crew or from a ground
station when the tracking network was in the best position to
determine the proper timing for touchdown.
A deorbit module would contain all the attitude sensing
components, the retro rocket, tankage, plumbing and other
items associated with the fuel and oxidizer supply.
A retardation system would consist of single or multiple
parachutes with associated drogue, reefing and deployment
devices. The shock of a land recovery would be reduced by an
inflated bumper deployed just before touchdown.
An Advanced Vehicle Recovery system with a gliding parachute could make corrections to the flight path of 25 miles or
more in calm air or moderate the effect of prevailing wind
conditions. It would also allow the crew to avoid obstacles.

MES Operation Modes

The basic Manned Escape System could be used in a variety
of.ways. In the “Ground Standby/Launch on Demand” method
the MES could be a ground-based unit mounted on its own
booster, the Titan IIIB, along with an orbital rendezvous
package. It would be maintained .on continuous standby for
prompt launch when required. The upper stage/MES would
manoeuvre to and rendezvous with the crippled craft. This
mode could replace the present Space Shuttle rescue method
in which another Shuttle is used as the rescue craft.

The major drawback of the "Launch on Demand” system
is that even under the best conditions there would be an
appreciable delay before the arrival of the rescue package to
help the astronauts. This could be overcome by maintaining
rescue packages in selected parking orbits. They would consist
of a basic escape vehicle/s mounted on a bus module to provide limited orbital transfer, rendezvous, manoeuvre and docking capability, plus pointing for retrfire.
Again, there is a drawback with this method. The rescue
module could be considerably displaced along the orbital track,
although at the same basic inclination as the stricken vehicle.
An appreciable time lag could therefore occur before
rendezvous.

The ‘life boat” method of operating the rescue package offers
the most readily available system at an economical cost. In this
mode the escape system is integrally mounted on the manned
system, such as the Orbiter or a Space Operations Center,
from the outset. A four-man escape system could be installed
in the Shuttle Orbiter with direct access by way of the airlock
and egress tunnel. The actual mounting interface between the
escapre package and the Space Operations Center is envisaged
as similar to a docking prort with the capability for repeated
separation and reattachment of replacement escapre vehicles.
The reentering escape package would remain within ± 50
miles along the ground track and ± 10 miles cross range. This
allows for selective choice of landing sites with a degree of
freedom limited only by the time in orbit before retro fire.