science

Transit 3B

Transit 3B is a science 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 Transit 3B rather than just read about it. In short: Transit 3B was an American satellite which was launched in 1961 and operated by the United States Navy. It was a replacement for Transit 3A, which was lost in a launch failure the previous year.

Key takeaways

Transit 3B belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Transit 3B to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Transit 3B from memory before moving on to harder problems.

Reference excerpt

Transit 3B was an American satellite which was launched in 1961 and operated by the United States Navy. It was a replacement for Transit 3A, which was lost in a launch failure the previous year. It carried instruments to demonstrate navigation and timing systems, and study geodesy to support the development of the Transit satellite navigation system.

History The launch of Transit 3B was conducted at 03:45 UTC on 22 February 1961, using a Thor DM-21 Ablestar rocket flying from Launch Complex 17B at the Cape Canaveral Air Force Station. The LOFTI-1 satellite was launched aboard the same rocket. The rocket and upper stage used had the serial numbers Thor 313 and Ablestar 007 respectively. The launch resulted in a partial failure, with the spacecraft being placed in a more eccentric orbit than planned, and failing to separate from the upper stage. Transit 3B was a 113-kilogram (249 lb) spacecraft, which was powered by 6,600 solar cells charging a nickel-cadmium battery. It ended up in a low Earth orbit with a perigee of 167 kilometres (104 mi), an apogee of 1,002 kilometres (623 mi), and 28.3 degrees of inclination. It had an orbital period of 96.4 minutes. Due to the low perigee of its orbit, Transit 3B decayed quickly, and reentered the atmosphere on 30 March 1961, less than 37 days after launch. Despite being in the wrong orbit and operating for less time than had been planned, some useful data was returned from the mission. The systems demonstrated by Transit 3B included a digital clock to control timing signals, uploading programs into the onboard computer's memory whilst in orbit, data retention and FM encoding, and the use of phase modulation for data transmission without affecting the satellite's Doppler signal. The satellite's computer had a memory capacity of 48 bytes.

References

Illustrations

Worked examples

Example 1 — a first encounter with Transit 3B

Start with the simplest possible case. Write down what Transit 3B claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Transit 3B 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 Transit 3B 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 Transit 3B

In research: Transit 3B appears in science 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 Transit 3B 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: Transit 3B is common in secondary-school and first-year university syllabi. It links to neighbouring topics American spacecraft stubs, Navigation satellites, Satellite launch anomalies, so understanding it makes those chapters shorter.
In everyday life: Look for Transit 3B 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 Transit 3B in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Transit 3B 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 Transit 3B out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Transit 3B in simple terms?

Transit 3B was an American satellite which was launched in 1961 and operated by the United States Navy. It was a replacement for Transit 3A, which was lost in a launch failure the previous year.

Why does Transit 3B matter?

Because it connects several science 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 Transit 3B?

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 Transit 3B.