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STS-95: Home | The Crew | Cargo | Timeline | EVA

Spacecraft Comparison:
Mercury/Friendship 7 and Space Shuttle Discovery

Category Mercury CapsuleDiscovery Orbiter
LaunchFeb. 20, 1962Oct. 29, 1998
Launch Time8:47:39 a.m. CST1:19 p.m. CST
SiteLaunch Complex 14, Cape Canaveral, Fla.Launch Pad 39B, Kennedy Space Center, Fla.
SpacecraftMercury Capsule 13, Vehicle Number 109-DSpace Shuttle Orbiter Vehicle 103 (25th flight)
NameFriendship 7 (one flight) Discovery (25 flights as of STS-95)
MilestonesFabrication begins May 1960; capsule arrives at Cape Canaveral on Aug. 27, 1961; mated to Atlas booster on pad on Jan. 3, 1962. Fabrication of aft fuselage begins July 5, 1977; Crew module fabrication begins March 3, 1980; Discovery rolls out of Rockwell plant in Palmdale, Calif. on Oct. 16, 1983; arrives Kennedy Space Center on Nov. 9, 1983; Flight Readiness Firing of three main engines on June 2, 1984 for 18 seconds; maiden launch on STS-41D mission on Aug. 30, 1984; Discovery launched on Sept. 29, 1988 on STS-26 mission to mark Shuttle program return to flight after Challenger accident; For STS-95, Discovery moves to Launch Pad 39-B in late September 1998; Flight Readiness Review conducted on Oct. 9, 1998
CountdownInitial launch dates of Dec. 20, 1961, Jan. 16, 1962, and Jan. 23, 1962 were moved to Jan. 27, 1962 when the Mercury-Atlas rocket was finally fueled; countdown was scrubbed at T-13 minutes by adverse weather; subsequent launch attempts on Feb. 13, 14, 15, and 16 were also scrubbed by adverse weather or technical problems and the launch was reset for Feb. 20. Began Oct. 29, 1998
Altitude261 x 160 kilometers
(162.2 x 100 statute miles)
523 kilometers
(325 statute miles)
Inclination32.54 degrees28.45 degrees
Orbits3 orbits134 orbits during STS-95
Orbital Period88 minutes, 29 secondsAbout 90 minutes
Duration4 hours, 55 minutes, 23 seconds 8 days, 21 hours, 44 minutes
Distance Flown121,794 kilometers
(75,679 statute miles)
Approximately 5,793,638 kilometers
(3,600,000 miles)
Velocity28,234 kilometers
(17,544 miles) per hour
28,163 kilometers
(17,500 miles) per hour
Maximum G's7.73
Payload Spacehab Research Module; Hubble Orbital Systems Test Platform (HOST); SPARTAN-201-05 Reflight; International Extreme Ultraviolet Hitchhiker (IEH-03); Getaway Special Canisters
LandingFeb. 20, 1962, 1:43:02 p.m. CST, 800 miles southeast of BermudaNov. 7, 1998, Kennedy Space Center Shuttle Landing Facility at 11:04 a.m. CST
RecoveryNavy Destroyer U.S.S. Noa; Friendship 7 hoisted onto the deck 21 minutes after splashdown 
Total mission time aloft for Mercury program and Shuttle program53 hours, 55 minutes, 27 seconds (six missions) 18,132 hours, 43 minutes, 30 seconds (89 missions)
Total individual spacecraft mileage121,793 kilometers
(75,679 statute miles); one mission
14,223,091 kilometers
(8,837,819 statute miles); 23 Discovery orbiter missions
Total number of spacecraft orbits3 orbits2,658 orbits (23 Discovery orbiter missions)
Maximum mission duration1.5 days18+ days
Weight1,931 kilograms (4.256 pounds); 1,205 kilograms (2,657 pounds) at re-entry69,771 kilograms (153,819 pounds) (Orbiter empty but with three Main Engines)
Lift-off thrust360,000 pounds; Atlas Launch Vehicle 7,000,000 pounds; SSMEs and Solid Rocket Boosters
Launch systemOne and one-half stage liquid propellant Atlas launch vehicle with one sustainer and two booster enginesTwo solid rocket boosters and three space shuttle main engines fueled by an external tank
Windows110 (six forward, two overhead, two aft)
Crew size12-7
Electrical powerBattery, 3 primary, 9000 Ah3 fuel cells; 7 kilowatts continuous each
Electrical buses4110
Circuit breakers20961
Total measurements (Number of sensors) 1007,800+
Thermal controlCabin gas cooling, water boilerTwo Freon-21 coolant loop systems, cold plate networks for cooling avionics units, liquid/liquid heat exchangers, radiators, flash evaporators, ammonia boilers
Onboard computersnone5 general purpose computers (4 primary and 1 backup)
Guidance and Navigation and attitude referenceThree gyroscopes, Horizon scannerThree inertial measurement units, Star tracker, Radar, Tactical Air Navigation system, Microwave Scan Beam Landing System
Volume (habitable) 1 cubic meter
(36 cubic feet)
Crew compartment of 66 cubic meters (2,325 cubic feet). During Mercury, a crewmember had 1 cubic meter (36 cubic feet), compared to the 9.4 cubic meters (332 cubic feet) per crewmember aboard Discovery. Discovery's crew compartment could hold 66 crew members if each was allotted just 1 cubic meter (36 cubic feet).
Cabin atmosphere100% O2 21% O2/79% N2 at 14.7 pounds per square inch or 27% O2/73% N2 at 10.2 pounds per square inch
Items stowed48about 2,600
Work stations19
Total cockpit display components1432,312
Toggle switches56856
Pushbutton switches8219
Event indicators19559
Landing system3 solid-fuel rockets for reentry retrofire maneuvers, drag braking, main and drogue-stabilization parachutes, ocean landingTraditional aircraft tricycle configuration with nose landing gear and a left and right main landing gear; each has a shock strut with two wheel and tire assemblies; nose gear is steerable
Parachute diameterMain parachute: 19.2-meter (63-foot diameter), drogue stabilizer: 1.8-meter (6-foot) diameterDrag chute: 11.9-meter (39-foot diameter)
Thermal protectionAblative heatshield on the blunt face and heat-radiating shingles on the afterbody. Reinforced carbon-carbon tiles on nose cap and wing leading edges; High-temperature reusable surface insulation tiles mainly on lower surface; Low-temperature reusable surface insulation tiles on upper wing and fuselage side; Advanced flexible reusable surface insulation -- Coated Nomex felt -- on parts of payload bay doors, sides of fuselage, and upper wing.
Automated vs. crew controlAlthough designed to have automatic control, the pilot's ability to manually control the spacecraft attitude allowed the mission to be completed successfully when the automatic system malfunctioned.Ascent, orbit, and re-entry are typically automatic. However, rendezvous with or fly around of another spacecraft is manual. Once the orbiter has slowed to subsonic speeds after re-entry, the landing is manual. During automatic mode, the crew usually has the option of switching to manual operation of the orbiter.
Interior environmentAstronaut JohnGlenn was restrained by his couch harness assembly and by the limited space in the interior. Only one stowage compartment was available. Other items were stowed in bags, in pouches, or on specific attachments to the interior structure. During ascent and descent the crew members are strapped into seats on either the flight deck or the middeck. The flight deck holds four persons, while the middeck is usually equipped for three. (STS-71 saw Atlantis bring eight members down, four on each deck.) On orbit, crewmembers have a free range of movement throughout the crew compartment, as well as the SPACEHAB in the payload bay.

Curator: Kim Dismukes | Responsible NASA Official: John Ira Petty | Updated: 03/04/2003
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