Space Station Fact Sheet
Option A - Modular Build-Up

Objective: Provide a modular buildup approach that provides a 
lower cost approach to Space Station Freedom while keeping a 
strong focus on user needs and International agreements. 

Key Design Drivers: Use current and simplified Space Station 
Freedom systems where cost-effective, and repackage, reduce and 
simplify elements to reduce overall costs, number of assembly 
flights and extravehicular activitity. 

Option A1: Modular build-up using Lockheed-built "Bus-1" 
spacecraft to provide guidance, navigation, control and propulsion.

Option A2: Modular build-up without the "Bus-1."

Option A1/A2 Characteristics:
Inclination:                    28.8 degrees inclined to the equator
Overall dimension at PHC:       A1 - 245 feet end-to-end
						A2 - 281 feet end-to-end
Assembly Altitude:              220 nautical miles
Shuttle flights:                        16 assembly flights to PHC
						 5 utilization/logistics flights per year

4-Phase Build-Up
Power Station (First Element Launch - October `97)
	o Achieved with 3 flights (12/97)
	o 1 photovoltaic array provides 23 kilowatts of power
	o Provides 3 attachment sites for external payloads
	o Orbiter with Spacelab docks to power station for human-tended 
research of up to 20 days (17 days of on-orbit research - 2 
missions per year)

Human Tended Capability (April `98)
	o Achieved with 4 flights
	o Adds a common core/lab module which houses laboratory 
equipment, 9 International Standard Payload Racks, subsystems 
and integrated berthing ports for International partner elements 
and logistics module
	o Adds Canadian Space Station Remote Manipulator System
	o Orbiter docks to station for human-tended research of up to 20 
days (17 days of on-orbit research - 4 missions per year)

International Human Tended Capability (December 1999)
	o Achieved with 12 flights
	o Adds Japanese Experiment Module/Exposed Facility and ESA's 
Columbus Attached Pressurized Module (adds 30 International 
Standard Payload Racks)
	o Adds cupola
	o Adds second PV array for total of 46 kilowatts of power (18 kW 
to users)
	o Orbiter docks to station for human-tended research of up to 20 
days (17 days of on-orbit research - 4 missions per year)

Permanent Human Capability (September 2000)
	o Achieved with 16 flights
	o Adds habitation module
	o Adds third PV array for total of 57 kilowatts of power (31 kW 
to users)
	o Uses Soyuz TM (2) spacecraft for assured crew return
	o Adds airlock for station-supported extravehicular activites
	

Major differences from Freedom: 
	Deletes truss segments  A1 - 5 segments/A2 - 3 segments
	Common modules in place of modules and nodes
	Core module outfitting approach for the laboratory
	Simplified solar array/battery system
	Deletes large rotary alpha joints
	Single-phase common radiators for PV arrays and station central 
radiators 
	Simplified data management system and associated software 
	Simplified and reduced size of Freedom airlock - delayed until 
permanent human capability
	Italian "stretched" mini-pressurized logistics module and new 
"closet" (pantry) module - deletes U.S. pressurized logistics module
	Reduce number of orbital replacement units and maintenance 
items by 30 percent
	Delete Mobile Transporter - use simplified EVA cart on monorail
	Reduce audio and video components
	Simplify atmosphere control and supply and temperature and 
humidity control system


Space Station Fact Sheet
Option B - Freedom Derived

Objective: Derived from mature Space Station Freedom designs, 
makes maximum use of current systems and hardware to provide an 
incrementally increasing capability, emphasing accommodations for 
users, adherence to International Partner commitments, flexibility 
and growth potential. 

Key Design Drivers: Option B configuration and assembly were 
guided by the orbit inclination, accommodation of International 
Partner elements, an assured crew return vehicle, the Space Shuttle 
as a launch vehicle and a permanent human presence in space. 
Other design factors included acommodation of microgravity and 
life science (including a 2.5 meter centrifuge), support to a 4 person 
crew for 10 years, and two-fault tolerance for crew and station 
survival.

Option B Characteristics:

Inclination:                    28.8 degrees inclined to the equator
Overall dimension at PHC:       331 feet end-to-end
Assembly Altitude:              220 nautical miles
Shuttle flights:                        20 assembly flights to PHC
						12 utilization/logistics flights
4-Phase Build-Up

Power Station (First Element Launch - October `97)
	o Achieved with 2 flights (11/97)
	o Major subsystems include active thermal control, S-Band 
communications, propulsion and control moment gyroscopes
	o 1 photovoltaic array provides 23 kilowatts of power (provides 
6.25 kW to orbiter and 4.9 kW to Spacelab payloads and external 
attached payload)
	o 1 external payload attachment point
	o Orbiter with Spacelab docks to power station for human-tended 
research of up to 20 days (17 days of on-orbit research - 2 
missions per year)


Human Tended Capability (December `98)
	o Achieved with 8 flights
	o Adds the U.S. laboratory module which houses laboratory 
equipment, subsystems, a node and an airlock. 
		13 International Standard Payload Racks and 3 non-standard 
		 payload rack locations
	o 2 external payload attachment points
	o 1 photovoltaic array provides 8.5 kilowatts of power to users
	o 50 Mbps downlink and 72 kbps uplink data streams
	o Operates with and without an orbiter docked
	o Orbiter with Spacelab docks to power station for human-tended 
research of up to 20 days (17 days of on-orbit research - 4 
missions per year)

International Human Tended Capability (March 2001)
	o Achieved with 17 flights
	o Adds port side truss
	o Adds Japanese Experiment Module/Exposed Facility and 
Columbus Attached Pressurized Module
		Total payload volume increased to 48.5 rack sites
		JEM provides 10 external attached payload sites
	o Adds Canadian Space Station Remote Manipulator System
	o Adds cupola
	o Adds second and third PV array for total of 68 kilowatts of 
power (greater than 30kW to users)
	o Orbiter docks to station for human-tended research of up to 20 
days (17 days of on-orbit research - 4 missions per year)

Permanent Human Capability (December 2001)
	o Achieved with 20 flights
	o Adds habitation module
	o Adds second node
	o Adds 3 additional external attached payload sites (total of 15) 
covering ram, wake, zenith and nadir viewing
	o Uses Soyuz TM (2) spacecraft for assured crew return
	
Major differences from Freedom: 
	Deletes 1 truss segment         
	3rd PV array on port side of truss to improve microgravity 
environment
	Modified data management and communications and tracking 
systems; minor changes to environmental control and life 
support and thermal control systems

Space Station Fact Sheet
Option C - Single Launch

Objective: Uses a Shuttle-derived launch vehicle to place a space 
station into orbit with a single launch, retaining as much 
commonality as possible with existing Space Shuttle systems, and 
moving as much equipment as possible inside the large core module 
to cut down on extravehicular activities. 

Key Design Drivers: Use Shuttle hardware and software for all 
aspects of ascent flight control and retain all features of the Shuttle 
main propulsion system. Minimize impact to KSC launch facilities 
and take advantage of Shuttle hardware components to provide 
common logistics support for Shuttle and Station and maximize use 
of current Shuttle ground infrastructure.

Option C Characteristics:
Inclination:                    28.8 degrees inclined to the equator
Assembly Altitude:              220 nautical miles
Shuttle flights:                        10 assembly flights to PHC
						 2 utilization/logistics flights

Single Launch Core Station Module (Launch - Sept. `99)
	o Orbiter aft fuselage and aerodynamic fairings attached to 92-
foot long common core module and attached to standard Space 
Shuttle external tank and solid rocket boosters 
	o On-orbit pressurized module is 64 feet long and 22 feet in 
diameter with 10-foot long unpressurized equipment bays on 
each end
o 2 fixed photovoltaic arrays. Depending on flight mode (Solar 
Inertial or Local Vertical) and Sun angle, arrays can provide a 
maximum of 57.6 kW (47.6 kW to users) and a minimum of 
34.2 kW (24.2 kW to users)
	o Body-mounted and deployed radiators
	o Canadian Space Station Remote Manipulator System
	o Docking ports on both ends for Shuttle or Soyuz
	o 7 berthing ports - 2 for Soyuz ACRV and 5 for International 
Partner modules and logistics module
	o 6 optical windows
	o 26,000 cubic feet of volume divided into seven decks
	o Accommodates 40 payload racks (72 with International Partner 
modules)
	o 50 Mbps downlink and 72 and 128 kbps uplink data streams


Permanent Human Presence Capability (November `99)
	o Achieved with 3 flights
	o Includes 2 Soyuz TM spacecraft for assured crew return
	o Canadian Special Purpose Dexterous Manipulator

International Permanent Human Presence (July 2000)
	o Achieved with 9 flights
	o Adds and fully outfits Japanese Experiment Module/Exposed 
Facility and Columbus Attached Pressurized Module 
	o Adds user racks

Permanent Human Capability (January 2001)
	o Achieved with 10 flights
	o Adds third PV array for total of 76 kilowatts of power (26 kW 
to users in the local vertical flight mode)
	
	
Major differences from Freedom: 
Hardware - source for subsystem orbital replacement units and 
major assemblies
	47 percent from Space Station Freedom   
	37 percent from existing orbiter hardware
	16 percent new design
	No airlock - EVAs accomplished only when Shuttle is docked at station
