STS-51-D was the 16th flight of

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

Space Shuttle program The Space Shuttle program was the fourth human spaceflight program carried out by the U.S. National Aeronautics and Space Administration (NASA), which accomplished routine transportation for Earth-to-orbit crew and cargo from 1981 to 2011. Its ...

, and the fourth flight of Space Shuttle ''Discovery''. The launch of STS-51-D from

Kennedy Space Center The John F. Kennedy Space Center (KSC, originally known as the NASA Launch Operations Center), located on Merritt Island, Florida, is one of the NASA, National Aeronautics and Space Administration's (NASA) ten NASA facilities#List of field c ...

(KSC),

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

, on April 12, 1985, was delayed by 55 minutes, after a boat strayed into the restricted

Solid Rocket Booster A solid rocket booster (SRB) is a solid propellant motor used to provide thrust in spacecraft launches from initial launch through the first ascent. Many launch vehicles, including the Atlas V, SLS and Space Shuttle, have used SRBs to give laun ...

(SRB) recovery zone. STS-51-D was the third shuttle mission to be extended. On April 19, 1985, after a week-long flight, ''Discovery'' conducted the fifth shuttle landing at KSC. The shuttle suffered extensive brake damage and a ruptured tire during landing. This forced shuttle landings to be done at

Edwards Air Force Base Edwards Air Force Base (AFB) is a United States Air Force installation in California. Most of the base sits in Kern County, California, Kern County, but its eastern end is in San Bernardino County, California, San Bernardino County and a souther ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

for the next five years until the development and implementation of nose wheel steering made landings at KSC more feasible.

Crew

Spacewalk

* Personnel: Hoffman and Griggs * Date: April 16, 1985 (≈12:30–15:30 UTC) * Duration: 3hours, 6minutes

Crew seat assignments

Mission summary

During STS-51-D, the shuttle crew deployed two

communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a Transponder (satellite communications), transponder; it creates a communication channel between a source transmitter and a Rad ...

s: Telesat-I ( Anik C1) and Syncom IV-3 (also known as Leasat-3); both were Hughes-built satellites. Telesat-I was attached to a

Payload Assist Module The Payload Assist Module (PAM) is a modular upper stage designed and built by McDonnell Douglas (Boeing), using Thiokol Star-series solid propellant rocket motors. The PAM was used with the Space Shuttle, Delta, and Titan launchers and carried ...

(PAM-D) motor and successfully deployed. Syncom IV-3, however, failed to initiate antenna deployment and spin-up, or ignite its perigee kick motor upon deployment. The mission was consequently extended by two days to ensure that the satellite's spacecraft sequencer start lever was in its proper position. Griggs and Hoffman performed an unscheduled

Extravehicular Activity 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 environme ...

(EVA) to attach homemade "Flyswatter" devices to the shuttle's Remote Manipulator System ( Canadarm). Seddon then engaged the satellite's start lever using the RMS, but again the post-deployment sequence did not begin. The satellite was subsequently retrieved, repaired and successfully redeployed during the STS-51-I mission later that year. ''Discovery''s other mission payloads included the Continuous Flow Electrophoresis System III (CFES-III), which was flying for sixth time; two Shuttle Student Involvement Program (SSIP) experiments; the American Flight Echo-cardiograph (AFE); two Getaway specials (GASs); a set of Phase Partitioning Experiments (PPE); an astronomical photography verification test; various medical experiments; and "Toys in Space", an informal study of the behavior of simple toys in a

microgravity Weightlessness is the complete or near-complete absence of the sensation of weight, i.e., zero apparent weight. It is also termed zero g-force, or zero-g (named after the g-force) or, incorrectly, zero gravity. Weight is a measurement of the fo ...

environment, with the results being made available to school students upon the shuttle's return. ''Discovery'' landed on Runway 33 of the

Shuttle Landing Facility The Shuttle Landing Facility (SLF), also known as Launch and Landing Facility (LLF) , is an airport located on Merritt Island, Florida, Merritt Island in Brevard County, Florida, Brevard County, Florida, United States. It is a part of the Kennedy ...

at Kennedy Space Center at 13:54:28UTC (8:54:28amEST local time at the landing site). As the orbiter approached the runway, it was buffeted by a

crosswind A crosswind is any wind that has a perpendicular component to the line or direction of travel. This affects the aerodynamics of many forms of transport. Moving non- parallel to the wind direction creates a crosswind component on the object and t ...

from the right, which pushed the orbiter left of the runway's center line as the rear landing gear touched down. As the orbiter rolled out, the crosswind continued to push it towards the left, causing it to drift from the center line of the runway. At this point, Commander Bobko began to counteract the drift by applying more pressure to the right-wheel brakes, a technique called

differential steering Differential steering is the means of steering a land vehicle by applying more drive torque to one side of the vehicle than the other. Differential steering is the primary means of steering tracked vehicles, such as tanks and bulldozers, is al ...

, which brought the orbiter back to the center of the runway. However, he had to apply twice as much force to the right brakes and about before stopping the brakes on the right-side inboard tire locked up and before stopping the brakes on the right-side outboard tire locked up and the inboard tire blew. The incident prompted NASA to add nose wheel steering to the orbiters, which was complete by late 1985. Until that work was completed, NASA would land the orbiters at the Edwards Air Force Base which offered the option of landing on a long and wide dry lake bed from more directions. Nose wheel steering was also implemented shortly before the Challenger disaster, which would ground the shuttle program for a time. Ultimately, it would be five years until a mission would again land at the SLF, when STS-38 had to divert there due to bad weather at Edwards.

Wake-up calls

NASA began a tradition of playing music to astronauts during the

Project Gemini Project Gemini () was the second United States human spaceflight program to fly. Conducted after the first American crewed space program, Project Mercury, while the Apollo program was still in early development, Gemini was conceived in 1961 and ...

, and first used music to wake up a flight crew during

Apollo 15 Apollo 15 (July 26August 7, 1971) was the ninth crewed mission in the Apollo program and the fourth Moon landing. It was the first List of Apollo missions#Alphabetical mission types, J mission, with a longer stay on the Moon and a greate ...

. Each track is specially chosen, often by the astronauts' families, and usually has a special meaning to an individual member of the crew, or is applicable to their daily activities.

Gallery

File:STS-51-D Telesat-1 deployment.jpg, Telesat-I during deployment File:STS-51-D Syncom IV-3 deployment.jpg, Syncom IV-3 during deployment File:STS-51-D flyswatter on RMS.jpg, Hoffman and Griggs attach the flyswatter device to the end of the Canadarm.

References

External links

NASA mission summary

{{Orbital launches in 1985 Space Shuttle missions 1985 in spaceflight 1985 in the United States Spacecraft launched in 1985 Spacecraft which reentered in 1985