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    Oct 15, 2003
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ENVIRONMENTAL EARTH SCIENCE

Venus Exploration

Name: ______________________________ Per: ___ Date: _______________

INTRO: In the NOVA "Venus Unveiled" video on the exploration of Venus (the theme music is "Venus in Blue Jeans" an old fifties song) the first part of video that we will not see is on the historical exploration of Venus. Venus has always fascinated people because it the closest planet to us, it is similar in size and mass, and so should be made of the same materials. Venus is often referred to as a twin planet to ours. The video described the difficulties in getting information about the cloud covered surface of Venus from telescopes, then about the USSR lander missions. The old Soviet Union sent several landers to the surface before one finally succeeded in getting one photo and some measurements from the surface. That lander lasted all of 65 minutes before the intense heat, crushing pressure and sulfuric acid atmosphere destroyed it. An early American orbiter was able to get crude radar images that showed some craters and mountains.

Read the following questions before the video, then answer during the video and by sharing information with other people after the video ends. Some of the answers require math. Take note of the appropriate numbers during the video, do the math afterward.

1. How was the Magellan spacecraft built for less money than originally planned?

 

 

 

 

2. How much did the Magellan mission cost each American (cost/population)?

 

 

 

3. When and how did it reach Venus? How old were you then?

 

 

 

 

4. How did the scientific community create a competition of this exploration?

 

 

 

 

 

 

 

 

5. How did Magellan explore Venus?

 

 

 

 

 

6. What did Magellan find?

 

 

 

 

 

7. Why were the scientists looking for heat loss evidence?

 

 

 

 

 

8. How does cratering tell the age of a planet's surface?

 

 

 

 

 

 

9. What was so weird about the spread of impact craters on the surface of Venus?

 

 

 

 

 

10. Was is the "catastrophic" explanation for the distribution of craters and the lack of young volcanos on the surface of Venus?

 

 

 

 

 

11. Why doesn't every scientist accept the catastrophic explanation, preferring a uniformitarianism explanation instead?

 

 

 

 

 

 

12. Why is determining the thickness of the Venus lithosphere (crust) through gravity measurements so important?

 

 

 

 

 

 

13. Why did they have to change Magellan's orbit? What was the danger?

 

 

 

 

 

14. What did the gravity measurements show?

 

 

15. Why do the mountains on Venus stay so steep?

 

 

 

 

16. After the video, write your own conclusion about what is happening on Venus, referring to evidence from the video:

 

 

 

 

 

 

 

 

 

 

17. What happened to Magellan? How old were you?

 

 

 

 

 

 

18. What is needed to resolve the questions about Venus?

 

 

 


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HONORS ENVIRONMENTAL EARTH SCIENCE

Venus Exploration Homework

1. How long was Magellan in orbit around Venus?

 

2. How old were you when the mission ended?

 

 

3. Predict how old you think you will be when we send something to the Venus surface.

 

 

 

4. Why do think it will take that long?

 

 

 

 

 

 

 

5. How much would you be willing to spend to send another spacecraft to Venus? Why that much and not more or less? If everyone in the U.S. spent that much, how much money would be available?

 

 

 

 

 

 

6. In a paragraph, compare the process we use to acquire information from videos with the process used by scientists to acquire knowledge of other planets during the brief time that spacecraft are near other planets.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ANSWERS:

1. How was the Magellan spacecraft built for less money than originally planned?

2. How much did the Magellan mission cost each American (cost/population)? Magellan program started as larger spacecraft, cut by Reagan era to cost of $250 million, with 1 radar only. $250,000,000/275,000,000 people = 91 cents each.

3. When and how did it reach Venus? How old were you then? 1989 launched from Shuttle Atlantis. 15 month trip to Venus, around Sun 1.5 times

4. How did the scientific community create a competition of this exploration? scientists predicted hypotheses of what it would find. Most predicted some variation on earth processes.

5. How did Magellan explore Venus? Each orbit radar mapped a narrow strip, then spacecraft would turn to aim antenna at Earth.

6. What did Magellan find? Overall map showed features completely unlike Earth surface. Long lava channel, mountains steeper than Earths, no plate tectonic features, no active volcanos, no heat loss evidence.

7. Why were the scientists looking for heat loss evidence? if Venus is similar to Earth, it should lose energy (heat) from its interior in a way similar to ours: by the formation of mountains, lava eruptions, volcanos, earthquakes.

8. How does cratering tell the age of a planet's surface? Old surfaces in solar system have lots of impact craters, young surfaces are smoothed.

9. What was so weird about the spread of impact craters on the surface of Venus? Venus discovered to have an even distribution - whole surface 500 million years old = uniformly young surface.

10. Was is the "catastrophic" explanation for the distribution of craters and the lack of young volcanos on the surface of Venus?

one hypo - complete resurfacing of planet at same time - not seen on any other planet. Random computer runs produced the same crater distribution./ Catastrophic explanation: Dead surface, inner heat build up hypo - whole surface becomes liquid, cools, recrusts over again for 500 million years.

11. Why doesn't every scientist accept the catastrophic explanation, preferring a uniformitarianism explanation instead? Catastrophic geology explanations for Earth processes were replaced by uniformitarianism last century. Uniformitarianism is the principle that the rate of the processes that form Earth features is nearly constant, so all features are the result of the same slow, long term changes that are now occurring.

12. Why is determining the thickness of the Venus lithosphere (crust) so important? if Venus has thin lithosphere crust, it allows gradual heat loss, steady processes. / Catastrophic process would require thick crust.

13. Why did they have to change Magellan's orbit? Magellan's orbit would not allow gravity measurements - had to be slowed by atmosphere, which could have destroyed spacecraft.

14. What did the gravity measurements show? Gravity data conclusions open to debate. basic, good natured disagreements in interpretations of measurements.

15. Why do the mountains on Venus stay so steep? Earth rocks dried to Venus condition, up to 10 times stronger, so Venus mt stay steep.

16. Write your own conclusion about Venus: Video's conclusion: Scientists still disagree on thin/thick litho. Evidence of craters cannot be explained by uniformitarianism.

17. What happened to Magellan? Oct 1994 - Magellan finally crashed.

18. What is needed to resolve the questions about Venus? need to put seismometers on surface for Venusquakes.