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Exploration through Navigation Challenge
Challenge Questions

Challenge Question 1:

The winners are:
Bern Home School
Karpf Home School

One of the first responses we received deserves honorable mention because the detailed explanation of how they calculated answer 2! There was only one "small" flaw: they reversed their meters and feet in Question #1. NASA itself has made that mistake as you probably know -- and we lost a space vehicle as a result. This is a good time to learn how costly a mistake can be.

The Question:
Challenge Question #1
1. What is the highest point of the Tahitian Islands (mountain & elevation)?
2. On a clear day, how far out at sea in a Polynesian canoe can you see the island of Bora Bora, Tahiti based on its highest elevation?

Acceptable Answers to 1 = Mont Orohena @ 2241 meters (7352 feet)

Acceptable answers to 2 = Using the formula on page 12 of the Educator Guide (the Polynesian Voyaging Society formula for seeing objects at sea), and considering the height of Mount Otemanu (727 m, 2385 ft.) and the canoe mast height of 25 feet, you should have gotten about 54 nautical miles. If you had trouble with this one, give it a try again using Mont Orohena! It's good practice for your voyage to Easter Island!


Challenge Question 2:

The winners are: Archway 5th Graders
St. Joseph School

The Question:
What are the doldrums, and how can they affect an ocean voyage?

The Answer:
The Doldrums is an area of the Atlantic Ocean and the Pacific Ocean, usually located between 5° north and 5° south of the equator, affected by the Intertropical Convergence Zone (ITCZ), a low-pressure area around the equator where the prevailing winds are calm. This environment can lead to light or variable winds and more severe weather, in the form of heavy squalls, thunderstorms and hurricanes. Sailors noticed the stillness of the rising (and not blowing) air near the equator and gave the region the depressing name "doldrums."

Because of the unpredictable weather patterns, the Doldrums became notorious with sailors because this region's periods of deadly calm could trap ships for days or weeks on end as they waited for enough wind to power their sails


Challenge Question 3:

The winners are:
Rebecca Currier (Orleans Elementary School, VT)
& Andrew Chung (Kamehameha Elementary School, HI)
We got a lot of great answers!
Honorable mention to:
Nikkolas Stroughter , Holly Bern & Esther Karpf (All three different Home Schools in CA)

Topic: Clouds

In The Complete Sailor:  Learning the Art of Sailing, David Seidman writes, “Clouds are the harbingers of weather.  Their shape, height, color, and sequence foretell coming events.”  

Question
How can the shape, height, and color of clouds help an ocean navigator to predict oncoming weather?

Answer
"High clouds are associated with the upper atmosphere and distant weather systems up to six hours away. If they are wispy and white, the weather will be fine. Lower clouds relate to the current weather or that which is soon to come. If they are dense and dark, change is imminent, usually for the worse. Notice if clouds are lowering or lifting, and if they are gathering or dispersing. Lowering or gathering usually brings wet weather. Lifting or dispersing means the weather will improve. A cloud's color seems obvious: the darker, the more dangerous. And a sharp-edged dark cloud is the most dangerous of all. In shape, flat clouds are characteristic of stable air, while lumpy, well-rounded clouds live in unstable air."

"If the rain cloud is black, the wind isn't strong. If the cloud is brown, the wind is probably strong. If the cloud is high, there's not much wind, but maybe a lot of rain. If it's low, probably lots of wind.”

High Clouds – generally indicate fair or passing weather

Middle Clouds – good indication of a new storm development at sea with poor visibility, large waves, and heavy swell

Low Clouds – usually indicate rain and wind raging from a steady drizzle to a severe thunderstorm


Challenge Question 4:

The winners are:
Holly Bern Homeschool (Oakland, CA)
St. Josephs School (Garden City, NY)

The Question
The most potent danger faced by the modern-day voyager are high winds and seas, which could cause... flooding, capsizing, breaking apart, and crew members being washed overboard.

Situation
In mid-May, you and your crew began a voyage from Hawai’i to Rapa Nui.  Seven days into your journey, your canoe’s rudder became damaged and you had to spend two days making repairs at sea.  This unforeseen delay has placed you in the path of an oncoming storm containing high winds and waves.  It is midday when you first observe the storm in the distance.  You are too far from land to take safe harbor, so you will have to weather the storm for hours which will arrive around nightfall and persist until the following late afternoon.

Questions (please respond to both)

1. How will your crew prepare themselves and the canoe for the oncoming storm?  (Hint: Think about strong winds and storm surge and how these can be a danger to a sailing vessel and crew.)

2. Once the storm passes and the weather clears, how will you determine your location at sea and get back on course to Rapa Nui?  (Hint: For the past few weeks, you have been learning about many methods of navigating at sea.  Which of these methods would be most useful following a 24-hour period of disorienting winds, waves, and dark skies?)

Answers:

Part 1: We were looking for any or all of:

  • Take down sails.
  • Stow or secure (tie down food equipment)
  • No equipment on deck unless essential
  • Eat a nutriceous meal - higher in carbs for energy
  • Have safety briefing with crew (where med kit is, easy food, raingear, life preservers)
  • Check flashlights, know where there are batteries.
  • Secure masts and hulls in preplanned fashion per boat design,
  • throw unessentials overboard

Part 2: We were looking for: What we have learned thus far:

  • Sun, moon and stars at night
  • Land debris (floatstam) in water
  • Flight of birds.
  • You knew which general way the storm was blowing, and storm surge was coming from.
    Estimate where we were when storm started and direction of storm and number of hour for "what if" estimates of location

Challenge Question #5:

Situation
Over the past several weeks, you have learned about and observed many aspects of the movement of stars across the night sky and their relationship to a sailor’s latitude and longitude at sea.  The ancient Polynesians memorized the locations and patterns of important wayfaring stars; however, today we have modern tools to help us easily access this information.  (In fact, part II of this Challenge “Charting a Course Through Space,” will introduce you to some of the instruments and modern technologies that are used in space navigation.)  As a class, use some web-based resources to help you answer the following question:

Question
If you were navigating a Polynesian canoe in the ocean waters near French Polynesia during the late spring, which stars would be most useful to you one hour after sunset and one hour before sunrise?  Use the table below as a tool for helping you find your answer.

Answer

Latitude:  11ºS Longitude: 147ºW Week:  May 10–16, 2009
Time of sunrise: 5:55a
Time of sunset: 1734 (5:34p)
Navigational stars
(between 4:55a and 5:55a)
generally moving from east to west
  • (Big) Dipper) NE horizon
  • Denebola and Regulus (Leo) NE
  • Spica (Virgo) Eastern horizon
  • Castor and Pollux (Gemini) North
  • Capella (Auriga) NW
  • Betelgeuse and Rigel (Orion) West
  • Procyon (Canis Minor) overhead
  • Sirius (Canis Major) overhead
  • Acrux (Southern Cross) SE horizon
  • Canopus (Carina) South

Navigational stars
(between 5:34p and 6:34p)
generally moving from east to west
  • Enif (Pegasus) NE
  • Deneb (Cygnus) N
  • Vega (Lyra) NW
  • Altair (Aquila) NW
  • Antares and Shaula (Scorpius) SW
  • Mercury and Saturn
  • Venus, Mars, and Jupiter

Brief explanation:

  • Used US Naval Observatory web site to determine sunrise and sunset times.
  • Used Time Zone map to determine time compared to GMT.
  • Used Heavens Above web site to view star charts for May 10 and May 16 between the hours of 4:55a – 5:55a and 5:34p – 6:34p.
  • Used Wikipedia to identify navigational stars and their position in the constellations shown on the Heavens Above star charts.

Discussion of Question 5

As mentioned by our own NASA Quest Hawaiian Captain and Navigator Kälepa Baybayan during the December 9 webcast, celestial navigation requires a number of bright, dependable stars and planets (as well as our own star, the Sun) to keep an ocean vessel on course.

For Question 5, the steps we recommend to help answer this last Challenge question are as follows:

Use Wikipedia to identify navigational stars and their position in the constellations shown on the Heavens Above star charts.

We used the list of 50 Bright Stars from : http://www.cosmobrain.com/cosmobrain/res/brightstar.html

Celestial navigation is a science but it features a bit of art and individual taste.  Based on a collection of considerations, sun location, constellation location in horizon (N or S vs. center), and star brightness/color, here is what we found in our investigation of possible answers for Question 5:

Morning Sky

Since sun will be rising in East, we favor bright objects in the western sky:

Deneb in Cygnus
Vega in Lyra
Antares in Scorpius
Peacock in Pavo
Altair in Aquila (although perhaps too close to our zenith)
Planets Mars, Venus and Jupiter – for a period of time

Suggested by our NASA Quest students, the constellations Lupus, Libra, Corona Borealis

Evening Sky

Since the sun will be setting in the West, we favor bright object in the eastern sky:

Dubhe in Ursa Major
Arcturus in Bootes
Spica in Virgo
Alphard in Hydra (although perhaps too close to our zenith)
Canopus in Carina
Sirius in Canis Major
Pollux in Gemini
The Planet Saturn – for a period of time

Suggested by our NASA Quest students, the constellations Crux (the Southern Cross), Lupus



 FirstGov  NASA


Editor: Linda Conrad
NASA Official: Liza Coe
Last Updated: October 2008