science

Thor-Agena

Thor-Agena 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 Thor-Agena rather than just read about it. In short: Thor-Agena was a series of orbital launch vehicles. The launch vehicles used the Douglas-built Thor first stage and the Lockheed-built Agena second stages.

Key takeaways

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

Reference excerpt

Thor-Agena was a series of orbital launch vehicles. The launch vehicles used the Douglas-built Thor first stage and the Lockheed-built Agena second stages. They are thus cousins of the more-famous Thor-Deltas, which founded the Delta rocket family. The first attempted launch of a Thor-Agena was in January 1959. The first successful launch was on 28 February 1959, launching Discoverer 1. It was the first two-stage launch vehicle to place a satellite into orbit.

Missions Among other uses, the clandestine CORONA program used Thor-Agena from June 1959 until January 1968 to launch United States military reconnaissance satellites operated by the Central Intelligence Agency (CIA). During this program, Thor-Agena launch vehicles were used in 145 launch attempts, now known to have been part of satellite surveillance programs. OSCAR 1 The first non governmental satellite was launched on Thor-Agena B Discover 36 in December 1961 Also, Alouette 1, Canada's first satellite, was launched on a Thor-Agena B.

Versions The following table lists the different Thor-Agena versions, designations and configurations:

Thor-Agena A

Thor-Agena A (Thor-DM18 Agena-A) was used for 16 launches between 21 January 1959 and 13 September 1960 The Discoverer 14 satellite used in the CORONA spy satellite program was launched by a Thor-Agena A. On 19 August 1960, usable photographic film from the satellite was recovered by a Fairchild C-119 Flying Boxcar recovery aircraft. This was the first successful recovery of film from an orbiting satellite and the first mid-air recovery of an object returning from Earth orbit.

Thor-Agena B

Thor-Agena B (Thor-DM21 Agena-B or Thor-SLV2 Agena-B) was used for 44 launches between 26 October 1960 and 15 May 1966 Includes a variant with Solid Rocket Boosters (TAT Agena-B or Thor-SLV2A Agena-B) First successful launch: 12 November 1960 with Discoverer 17 Last launch: 15 May 1966 with Nimbus 2

Thor-Agena D

Thor-Agena D (Thor-DM21 Agena-D or Thor-SLV2 Agena-D) was used for 83 launches between 28 June 1962 and 17 January 1968 Includes a variant with Solid Rocket Boosters (TAT Agena-D or Thor-SLV2A Agena-D) First launch: 28 June 1962 with KH-4 19 Last launch: 17 January 1968 with Multigroup 3 and Setter 1B-2

1963 Mystery Cloud On 28 February 1963, the maiden flight of Thrust-Augmented Thor Agena (TAT Agena-D) launch vehicle carrying a spy satellite into orbit was launched from Vandenberg Air Force Base. The launch vehicle went off course and mission control detonated the launch vehicle at an altitude of 44 km (27 mi) before it could reach orbit. The launch vehicle detonation produced a large circular cloud that appeared over the southwestern United States. Due to its mysterious nature, appearing at a very high altitude and being visible for hundreds of miles, the cloud attracted widespread attention and was published by the news media. The cloud was featured on the cover of Science Magazine in April 1963, Weatherwise Magazine in May 1963, and had a full page image published in the May issue of Life Magazine. Prof. James MacDonald at the University of Arizona Institute for Atmospheric Physics investigated the phenomena and linked it to the Thor launch vehicle launch after contacting military personnel at Vandenberg Air Force Base. When the launch records were later declassified, the United States Air Force released a memo explaining that the cloud was the result of a military operation.

References

Illustrations

Worked examples

Example 1 — a first encounter with Thor-Agena

Start with the simplest possible case. Write down what Thor-Agena 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 Thor-Agena 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 Thor-Agena 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 Thor-Agena

In research: Thor-Agena 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 Thor-Agena 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: Thor-Agena is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1959 in spaceflight, 1962 in spaceflight, 1963 in spaceflight, so understanding it makes those chapters shorter.
In everyday life: Look for Thor-Agena 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 Thor-Agena in 20 minutes

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

Frequently asked questions

What is Thor-Agena in simple terms?

Thor-Agena was a series of orbital launch vehicles. The launch vehicles used the Douglas-built Thor first stage and the Lockheed-built Agena second stages.

Why does Thor-Agena 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 Thor-Agena?

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 Thor-Agena.