physics

STS-51-I

STS-51-I is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand STS-51-I rather than just read about it. In short: STS-51-I was the 20th mission of NASA's Space Shuttle program and the sixth flight of Space Shuttle Discovery. During the mission, Discovery deployed three communications satellites into orbit.

Key takeaways

STS-51-I belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect STS-51-I to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of STS-51-I from memory before moving on to harder problems.

Reference excerpt

STS-51-I was the 20th mission of NASA's Space Shuttle program and the sixth flight of Space Shuttle Discovery. During the mission, Discovery deployed three communications satellites into orbit. The mission launched from Kennedy Space Center, Florida, on August 27, 1985, and landed at Edwards Air Force Base, California, on September 3, 1985.

Crew

Spacewalks EVA 1 Personnel: Fisher and van Hoften Date: August 31, 1985 (≈12:10–19:10 UTC) Duration: 7 hours, 20 minutes EVA 2 Personnel: Fisher and van Hoften Date: September 1, 1985 (≈12:10–16:30 UTC) Duration: 4 hours, 26 minutes

Crew seat assignments

Launch

Mission summary Discovery launched at 6:58 a.m. EDT on August 27, 1985. Two earlier launch attempts, one on August 24 and another on August 25, were scrubbed – the first because of poor weather, and the second because the backup orbiter computer failed and had to be replaced. The successful launch on August 27, 1985, took place just as an approaching storm front reached the launch pad area. The five-man STS-51-I crew included Joe H. Engle, commander; Richard O. Covey, pilot; and James D. A. van Hoften, John M. Lounge, and William F. Fisher, mission specialists. Their primary mission was to deploy three commercial communications satellites and retrieve and repair the Syncom IV-3 (Leasat-3) satellite, which had been deployed during the STS-51-D mission in April 1985, but had malfunctioned. In addition, a mid-deck materials processing experiment, the Physical Vapor Transport Organic Solid Experiment (PVTOS), was flown aboard Discovery. The three communications satellites were Aussat-1, a multi-purpose spacecraft owned by Australia; ASC-1, owned and operated by the American Satellite Corporation (ASC); and Syncom IV-4 (Leasat-4), leased to the Department of Defense (DoD) by its builder, Hughes Space and Communications. Both Aussat-1 and ASC-1 were deployed on the day of the launch, August 27, 1985. Syncom IV-4 (Leasat-4) was deployed two days later. All three achieved their planned geosynchronous orbits and became operational. On the fifth day of the mission, astronauts Fisher and van Hoften began repair efforts on the malfunctioning Syncom IV-3, following a successful rendezvous maneuver by Discovery. The effort was slowed by a problem with the Remote Manipulator System (Canadarm) elbow joint. After a second EVA by Fisher and van Hoften, the satellite's control lever was repaired, permitting commands from the ground to activate the spacecraft's systems and eventually send it into its proper geosynchronous orbit. The two EVAs lasted a total of 11 hours and 46 minutes. Discovery landed on Runway 23 at Edwards Air Force Base at 6:16 a.m. PDT on September 3, 1985. The flight lasted a total of 7 days, 2 hours, 18 minutes and 42 seconds, during which the shuttle completed 112 orbits of the Earth.

Mission insignia The insignia depicts an American bald eagle, trailing red and white stripes, and pushing a boundary layer forward. The 19 stars, along with the eagle, are references to the 20th shuttle mission (with the eagle representing the orbiter and thus being the 20th "star"). Lining the patch are the surnames of the crew members.

Wake-up calls NASA began a tradition of playing music to astronauts during the Project Gemini, and first used music to wake up a flight crew during Apollo 15. 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

Illustrations

Worked examples

Example 1 — a first encounter with STS-51-I

Start with the simplest possible case. Write down what STS-51-I claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to STS-51-I before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about STS-51-I ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of STS-51-I

In research: STS-51-I appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses STS-51-I in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: STS-51-I is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1985 in spaceflight, 1985 in the United States, Edwards Air Force Base, so understanding it makes those chapters shorter.
In everyday life: Look for STS-51-I outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study STS-51-I in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what STS-51-I means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain STS-51-I out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is STS-51-I in simple terms?

STS-51-I was the 20th mission of NASA's Space Shuttle program and the sixth flight of Space Shuttle Discovery. During the mission, Discovery deployed three communications satellites into orbit.

Why does STS-51-I matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study STS-51-I?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on STS-51-I.