astronomy

Solar Maximum Mission

Solar Maximum Mission 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 Solar Maximum Mission rather than just read about it. In short: The Solar Maximum Mission satellite (or SolarMax) was designed to investigate Solar phenomena, particularly solar flares. It was launched on February 14, 1980.

Key takeaways

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

Reference excerpt

The Solar Maximum Mission satellite (or SolarMax) was designed to investigate Solar phenomena, particularly solar flares. It was launched on February 14, 1980. The SMM was the first satellite based on the Multimission Modular Spacecraft bus manufactured by Fairchild Industries, a platform which was later used for Landsat 4 and Landsat 5 as well as the Upper Atmosphere Research Satellite. After an attitude control failure in November 1980 it was put in standby mode until April 1984 when it was repaired by a Shuttle mission. The Solar Maximum Mission ended on December 2, 1989, when the spacecraft re-entered the atmosphere and burned up over the Indian Ocean.

Instruments

Failure and repair

The white-light coronagraph/polarimeter (C/P) took coronal images for about six months from March 1980 before suffering an electronics failure in September that prevented operation. In November 1980, the second of four fuses in SMM's attitude control system failed, causing it to rely on its magnetorquers in order to maintain attitude. In this mode, only three of the seven instruments on board were usable, as the others required the satellite to be accurately pointed at the Sun. The use of the satellite's magnetorquers prevented the satellite from being used in a stable position and caused it to "wobble" around its nominally sun-pointed attitude. SMM was left in standby mode for 3 years. The first orbiting, uncrewed satellite to be repaired in space, SMM was notable in that its useful life compared with similar spacecraft was significantly increased by the direct intervention of a crewed space mission. During STS-41-C in April 1984, the Space Shuttle Challenger rendezvoused with the SMM, astronauts James van Hoften and George Nelson attempted to use the Manned Maneuvering Unit to capture the satellite and to bring it into the orbiter's payload bay for repairs and servicing. The plan was to use an astronaut-piloted Maneuvering Unit to grapple the satellite with the Trunnion Pin Attachment Device (TPAD) mounted between the hand controllers of the Maneuvering Unit, null its rotation rates, and allow the Shuttle to bring it into the Shuttle's payload bay for stowage. Three attempts to grapple the satellite using the TPAD failed. The TPAD jaws could not lock onto Solar Max because of an obstructing grommet on the satellite not included in its blueprints. This led to an improvised plan which nearly ended the satellite's mission. The improvisation had the astronaut use his hands to grab hold of a solar array and null the rotation with a push from the Maneuvering Unit's thrusters. Instead, this attempt induced higher rates and in multiple axes; the satellite was tumbling out of control and quickly losing battery life. SMM Operations Control Center engineers shut down all non-essential satellite subsystems and with a bit of luck were able to recover the satellite minutes before total failure. The ground support engineers then stabilized the satellite and nulled its rotation rates for capture with the Shuttle's robotic arm. This proved to be a much better plan. The satellite had been fitted with one of the arm's grapple fixtures so that the robotic arm was able to capture and maneuver it into the shuttle's payload bay for repairs. During the mission, the SMM's entire attitude control system module and the electronics module for the coronagraph/polarimeter instrument were replaced, and a gas cover was installed over the X-ray polychromator. Their successful work added five more years to the lifespan of the satellite. The mission was depicted in the 1985 IMAX movie The Dream Is Alive.

Discovery of comets

10 comets were discovered in images from the SMM, all of which are members of the Kreutz sungrazer group. Robert M. MacQueen estimated that the comets seen by SMM had nuclei no greater than 16 m (52 ft) in radius.

Findings

Significantly, the SMM's ACRIM instrument package showed that contrary to expectations, the Sun is actually brighter during the sunspot cycle maximum (when the greatest number of dark 'sunspots' appear). This is because sunspots are surrounded by bright features called faculae, which more than cancel the darkening effect of the sunspot. The major scientific findings from the SMM are presented in several review articles in a monograph.

End of mission SMM's orbit slowly decayed due to atmospheric drag taking it down into denser regions. The March 1989 geomagnetic storm was reported to have led to SMM dropping half a kilometre at the start of the storm and 5 kilometres over the whole period. The satellite eventually lost attitude control on November 17, 1989, and re-entry and burn-up occurred on December 2, 1989, over the Indian Ocean.

Illustrations

Worked examples

Example 1 — a first encounter with Solar Maximum Mission

Start with the simplest possible case. Write down what Solar Maximum Mission 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 Solar Maximum Mission 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 Solar Maximum Mission 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 Solar Maximum Mission

In research: Solar Maximum Mission 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 Solar Maximum Mission 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: Solar Maximum Mission is common in secondary-school and first-year university syllabi. It links to neighbouring topics NASA satellites orbiting Earth, Satellites formerly orbiting Earth, Solar space observatories, so understanding it makes those chapters shorter.
In everyday life: Look for Solar Maximum Mission 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 Solar Maximum Mission in 20 minutes

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

Frequently asked questions

What is Solar Maximum Mission in simple terms?

The Solar Maximum Mission satellite (or SolarMax) was designed to investigate Solar phenomena, particularly solar flares. It was launched on February 14, 1980.

Why does Solar Maximum Mission 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 Solar Maximum Mission?

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 Solar Maximum Mission.