physics

Viking 2

Viking 2 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 Viking 2 rather than just read about it. In short: The Viking 2 mission is part of the American Viking program to Mars, and consisted of an orbiter and a lander essentially identical to that of the Viking 1 mission. Viking 2 was operational on Mars for 1281 sols (1,316 days; 3 years, 221 days).

Key takeaways

Viking 2 belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Viking 2 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Viking 2 from memory before moving on to harder problems.

Reference excerpt

The Viking 2 mission is part of the American Viking program to Mars, and consisted of an orbiter and a lander essentially identical to that of the Viking 1 mission. Viking 2 was operational on Mars for 1281 sols (1,316 days; 3 years, 221 days). The Viking 2 lander operated on the surface for 1,316 days, or 1281 sols, and was turned off on April 12, 1980, when its batteries eventually failed. The orbiter worked until July 25, 1978, returning almost 16,000 images in 706 orbits around Mars.

Mission profile The craft was launched on September 9, 1975. Following launch using a Titan/Centaur launch vehicle and a 333-day cruise to Mars, the Viking 2 Orbiter began returning global images of Mars prior to orbit insertion. The orbiter was inserted into a 1,500 x 33,000 km, 24.6 h Mars orbit on August 7, 1976, and trimmed to a 27.3 h site certification orbit with a periapsis of 1,499 km and an inclination of 55.2 degrees on August 9. The orbiter then began taking photographs of candidate landing sites, which were used to select the final landing site. The lander separated from the orbiter on September 3, 1976, at 22:37:50 UT and landed at Utopia Planitia. The normal procedure called for the structure connecting the orbiter and lander (the bioshield) to be ejected after separation. However, due to problems with the separation process, the bioshield remained attached to the orbiter. The orbit inclination was raised to 75 degrees on September 30, 1976.

Orbiter The orbiter's primary mission ended on October 5, 1976, at the beginning of solar conjunction. The extended mission commenced on December 14, 1976, after the solar conjunction. On December 20, 1976, the periapsis was lowered to 778 km, and the inclination raised to 80 degrees. Operations included close approaches to Deimos in October 1977, and the periapsis was lowered to 300 km and the period changed to 24 hours on October 23, 1977. The orbiter developed a leak in its propulsion system that vented its attitude control gas. It was placed in a 302 × 33,176 km orbit and turned off on July 25, 1978, after returning almost 16,000 images in about 700–706 orbits around Mars.

Lander

The lander and its aeroshell separated from the orbiter on September 3, 1976, at 19:39:59 UT. At the time of separation, the lander was orbiting at about 4 km/s. After separation, rockets fired to begin lander deorbit. After a few hours, at about 300 km attitude, the lander was reoriented for entry. The aeroshell with its ablative heat shield slowed the craft as it plunged through the atmosphere.

The Viking 2 lander touched down about 200 km west of the crater Mie in Utopia Planitia at 48.269°N 225.990°W / 48.269; -225.990 at an altitude of -4.23 km relative to a reference ellipsoid with an equatorial radius of 3,397.2 km and a flattening of 0.0105 (47.967°N 225.737°W / 47.967; -225.737 (Viking 2 landing site planetographic) planetographic longitude) at 22:58:20 UT (9:49:05 a.m. local Mars time). Approximately 22 kg (49 lb) of propellants were left at landing. Due to radar misidentification of a rock or highly reflective surface, the thrusters fired an extra time 0.4 seconds before landing, cracking the surface and raising dust. The lander settled down with one leg on a rock, tilted at 8.2 degrees. The cameras began taking images immediately after landing. The Viking 2 lander was powered by radioisotope generators and operated on the surface until its batteries failed on April 12, 1980. In July 2001, the Viking 2 lander was renamed the Gerald Soffen Memorial Station after Gerald Soffen (1926–2000), the project scientist of the Viking program.

Results from the Viking 2 mission

Landing site soil analysis The regolith, referred to often as "soil", resembled those produced from the weathering of basaltic lavas. The tested soil contained abundant silicon and iron, along with significant amounts of magnesium, aluminum, sulfur, calcium, and titanium. Trace elements, strontium and yttrium, were detected. The amount of potassium was one-fifth of the average for the Earth's crust. Some chemicals in the soil contained sulfur and chlorine that were like those remaining after the evaporation of seawater. Sulfur was more concentrated in the crust on top of the soil than in the bulk soil beneath. The sulfur may be present as sulfates of sodium, magnesium, calcium, or iron. A sulfide of iron is also possible. The Spirit rover and the Opportunity rover both found sulfates on Mars. Minerals typical weathering products of mafic igneous rocks were found. All samples heated in the gas chromatograph-mass spectrometer (GCMS) gave off water. However, the way the samples were handled prohibited an exact measurement of the amount of water. But, it was around 1%. Studies with magnets aboard the landers indicated that the soil is between 3 and 7 percent magnetic materials by weight. The magnetic chemicals could be magnetite and maghemite, which could come from the weathering of basalt rock. Subsequent experiments carried out by the Mars Spirit rover (landed in 2004) suggest that magnetite could explain the magnetic nature of the dust and soil on Mars.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Viking 2

Start with the simplest possible case. Write down what Viking 2 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 Viking 2 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 Viking 2 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 Viking 2

In research: Viking 2 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 Viking 2 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: Viking 2 is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1975 in Florida, 1975 in spaceflight, 1976 on Mars, so understanding it makes those chapters shorter.
In everyday life: Look for Viking 2 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 Viking 2 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Viking 2 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 Viking 2 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Viking 2 in simple terms?

Why does Viking 2 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 Viking 2?

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 Viking 2.