astronomy

TDRS-1

TDRS-1 is a astronomy 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 TDRS-1 rather than just read about it. In short: TDRS-1, known before launch as TDRS-A, was an American communications satellite, operated by NASA as part of the Tracking and Data Relay Satellite System. It was constructed by TRW and launched by Space Shuttle Challenger on its maiden flight, STS-6.

Key takeaways

TDRS-1 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect TDRS-1 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of TDRS-1 from memory before moving on to harder problems.

Reference excerpt

TDRS-1, known before launch as TDRS-A, was an American communications satellite, operated by NASA as part of the Tracking and Data Relay Satellite System. It was constructed by TRW and launched by Space Shuttle Challenger on its maiden flight, STS-6.

History While on the pad, problems were detected with Challenger main engines and repairs began. During this time, a severe storm contaminated TDRS-1 while it was in the Payload Change-out Room on the Rotating Service Structure at the launch pad. The satellite had to be returned to its checkout facility, where it was cleaned and rechecked. Challenger finally lifted off from Launch Complex 39A of the Kennedy Space Center at 18:30:00 UTC on 4 April 1983.

Operations Following deployment from Challenger, TDRS-1 was to be raised to its operational geosynchronous orbit by means of an Inertial Upper Stage having two solid rocket motors, the first used to raise the orbital apogee, the second its perigee. The first burn was successful, but the Inertial Upper Stage went out of control during the second burn. TDRS-1 separated from the upper stage in a lower than planned orbit. It was eventually raised to geosynchronous orbit using its attitude control system. To achieve this, a team of engineers from the Goddard Space Flight Center in Greenbelt, Maryland worked for nearly three months using six one-pound thrusters on the errant satellite to push it 8,600 miles (13,800 km) higher in space. The failure was later identified as a collapsed second-stage nozzle techroll seal, a flexible ring which allows the nozzle to pivot and provide directional control. The Goddard engineers' successful effort required 39 adjustment burns to correct the elliptical orbit to the 22,300 mi (35,900 km) geosynchronous orbit desired for TDRS-1. Goddard Space Flight Center on 26 November 1984 honored a group of 34 individuals for the rescue with the Robert H. Goddard Award of Merit, the highest level of recognition the Goddard Space Flight Center can bestow on its employees. In 1989 satellite operations were affected by a geomagnetic storm. TDRS-1 formed part of the first pole-to-pole phone call on 28 April 1999, with TDRS-1 being used at the South Pole, and an Iridium phone being used at the North Pole (recorded in Ripley's Believe It Or Not and Guinness World Records in April 1999).

Mission duration TDRS-1 had a design life of ten years, but in April 2008, it remained operational on the twenty-fifth anniversary of its launch. Over the years, the orbital inclination was allowed to increase so that, for portions of the day (approximately 5 hours), it could be used for communications with the North and then the South Pole. Along with Marisat F2, GOES 3 and LES-9, it was one of a number of satellites that were transferred to the US National Science Foundation in 1998, for communications with the Amundsen–Scott South Pole Station. After Marisat was retired, TDRS-1 became the primary means of communication with the research station. The last functioning traveling-wave tube amplifier aboard TDRS-1 failed in October 2009, rendering the spacecraft unusable for communications.

TDRS-1 proved helpful during a 1999 medical emergency at the NSF's Antarctic Amundsen–Scott South Pole Station. The satellite's high-speed Internet connectivity allowed personnel to conduct telemedicine conferences. Doctors in the United States aided Dr. Jerri Nielsen, who had breast cancer, to perform a self-biopsy and administer chemotherapy. Later, in 2002, doctors used TDRS-1 to perform another telemedicine conference with the station to assist in knee surgery for a meteorologist. Because of its orbit, the satellite was able to link the North and South Poles and relayed the first pole-to-pole phone call. TDRS-1 also transmitted the first internet connection and live webcast from the North Pole and supported the first global television from the South Pole Station - a worldwide television broadcast to commemorate the beginning of the year 2000.

Decommissioned The spacecraft was retired on or about 21 October 2009, after 26 years. Decommissioning was started on 5 June 2010 and passivation completed on 27 June 2010. As of 2009, NASA repositioned TDRS-3 to assume the duties of TDRS-1.

Illustrations

Worked examples

Example 1 — a first encounter with TDRS-1

Start with the simplest possible case. Write down what TDRS-1 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, 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 TDRS-1 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 TDRS-1 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 TDRS-1

In research: TDRS-1 appears in astronomy 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 TDRS-1 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: TDRS-1 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Derelict satellites orbiting Earth, Satellite launch anomalies, Spacecraft decommissioned in 2009, so understanding it makes those chapters shorter.
In everyday life: Look for TDRS-1 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 TDRS-1 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what TDRS-1 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 TDRS-1 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is TDRS-1 in simple terms?

Why does TDRS-1 matter?

Because it connects several astronomy 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 TDRS-1?

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 TDRS-1.