Do you ever feel spaced-out before you take a test? Yes or no, let’s go!
1. TRUE or FALSE?
It’s possible for a spacecraft to fly from Earth to Venus, to Mars, back to Earth, then to Saturn, out to Pluto, back to Jupiter, and come home to Earth on one tank of fuel.
2. It’s possible for a spacecraft to fly all over the solar system on one tank of fuel because of:
a. the sling-shot effect
b. gravity assist
d. all of the above
e. none of the above
The sling-shot effect, also known as a swing-by or gravity assist, is used to accelerate a spacecraft. Acceleration means to change the speed and/or the direction of a moving body. A spacecraft that is speeding up, slowing down, or following a curved path is accelerating.
Gravity accelerates objects everywhere in the Universe. When you ride your bike up a hill it takes a lot of effort to make it to the top because the Earth is massive compared to you, and gravity pulls you toward its center. When you coast down the other side, gravity is your friend!
Spacecraft can use the gravity of a planet to accelerate. Picture a spacecraft falling toward a planet. The spacecraft will crash unless it steers away.
3. As a spacecraft accelerates toward a planet, the motion of the planet is also affected by the gravity exerted by:
a. the spacecraft
b. the Sun
c. cosmic rays
d. both (a) and (b)
e. both (b) and (c)
f. all of the above
g. none of the above
All bodies in space, no matter how big or small, exert gravity on each other. Planets stay in orbit around the sun because of gravity. A planet is also affected by the tiny mass of a spacecraft. Gravity assist was used to increase the speed of Voyager 1 by 36,000 mph on its swing by Jupiter, which sling shot it to Saturn. And Jupiter slowed down infinitesimally, at a rate of 12 inches per one trillion years.
4. The person who discovered the math for using gravity assist to accelerate a spacecraft from planet to planet to planet…was:
a. Aristotle (384 B.C. to 322 B.C)
b. Galileo (1564-1642)
c. Sir Isaac Newton (1643-1727)
d. Katherine Johnson (1918- )
e. Michael Minovitch (1936- )
END OF TEST!
DON’T STOP WORKING.
GO TO THE LIBRARY TO FIND THE ANSWERS.
In this drawing a spacecraft gets an assist from Jupiter as it "slingshots" toward Saturn. Image courtesy of NASA/JPL
Voyager 1 and Voyager 2 used gravity assist to fly by the outer planets. Image courtesy of NASA
The twin Voyagers have no people on board on their interstellar journey, but carry The Golden Record, which contains messages, music, and pictures from Earth. Image courtesy of NASA/Alexandra Siy
In case you didn't make it to the library: In 1961, UCLA graduate student Michael Minovitch used math and the new IBM 7090-7094 computers to invent gravity assist trajectories for space flight. Used with permission of Michael Minovitch
Alexandra Siy's Voyager's Greatest Hits tells the story of the twin space probes that traveled to Jupiter, Saturn, Uranus, and Neptune, a journey beyond our solar system into interstellar space, where no probe has ventured before. Siy tells the fascinating story of how the Voyager probes work, where the probes have been and what they’ve seen, and what they carry on board.
Alexandra Siy is also a member of Authors on Call. You can bring her to your classroom via interactive videoconferencing and learn more from her and ask her questions. To find out more go here.
MLA 8 Citation
Siy, Alexandra. "Spaced Out." Nonfiction Minute, iNK Think Tank, 2 May 2018,
Science through the lens
A long time ago in a land far, far away…
The climate suddenly changes. It’s May, and a “Great Fog” appears in the sky. During the day it blocks out the sun and acts like a blanket trapping heat near the ground. A ten-year old boy notices that temperatures spike and sunsets are a spectacular display of colors. He doesn’t know that volcanoes in the “Ring of Fire” are spewing ash into the atmosphere creating massive clouds and causing the strange weather. All he knows is that he can’t take his eyes off the sky. The boy’s name is Luke Howard. The year is 1783, and his location is the English countryside. Luke records his observations in a journal. Although he doesn’t know it yet, he is on his way to becoming the “Father of Meteorology.”
Flash forward twenty years. It’s 1803, and Luke Howard is a successful businessman. But in his spare time, ever since the summer of 1873, he’s been watching the clouds and thinking up new ideas about the weather. He writes and publishes a scientific paper and presents his ideas to a group of fellow amateur scientists. His article, “On the modification of clouds, and on the principles of their production, suspension and destruction,” classifies clouds into groups using Latin words: heaped (cumulus), layered (stratus), fibrous (cirrus), and rain (nimbus). By combining terms into names such as Cirro-cumulus, which he describes as "small, well-defined roundish masses, in close horizontal arrangement," Luke identifies many kinds of clouds.
Luke’s passion for clouds inspires him to make watercolor sketches and write a book called The Climate of London, which introduces new ideas about lightening and the causes of rain. In 1864, Luke Howard dies at the age of ninety-two, leaving behind a cloud naming system that is still used today.
A long time ago in a land far, far away, Luke Howard names the clouds—and in our imagination we see him turning to a friend and saying, “May the clouds be with you.”
To see photos of many kinds of clouds go to NOAA Sky Watcher Chart
Spidermania: Friends on the Web debunks myths about spiders and takes an extremely close look at creatures that have both fascinated and terrified humans. An introduction explains what makes spiders unique. Then ten species are highlighted with incredible electron micro-graph images and surprising facts. From diving bell spiders that live in bubbles underwater, to spitting spiders that shoot sticky streams of spit at their prey, to black widows and wolf spiders, this unusual book will intrigue readers and help cure arachnophobia. For more information, click here.
MLA 8 Citation
Siy, Alexandra. "Luke Skywatcher." Nonfiction Minute, iNK Think Tank, 27 Apr.
Science through the lens
Do you know about the “birds and the bees?” If you don’t, don’t worry. You will learn soon enough.
When it comes to flowers there’s nothing to hide. There’s just no way around it—flowers are sexy. Their colorful, curvy petals are soft as velvet and as fragrant as the most expensive perfumes. Their nectar is as sweet as…well, honey. Besides being pretty, flowers have power. Their pollen is packed with protein. No wonder the birds and the bees, and insects of many kinds, find them so irresistible.
Pollen may be the perfect food for bees, but it is also the way plants get together. Think about it. Plants can’t walk, crawl, swim, or fly. So, how does boy meet girl?
In order to reproduce, the pollen from the male has to have direct contact with the female (and I don’t mean texting). Pollen grains are carried on the legs of bees and in the beaks of birds, from one flower to another. A few grains become engaged, hitched, and literally stuck on the sticky female flower part called the stigma. Sugar from the stigma fuels the pollen grain to sprout a tube. This pollen tube grows downward through the female part called the pistil and into the chambers that contain tiny bubble shaped eggs. When the tip of the pollen tube finally reaches an egg chamber it releases a male sperm cell. The sperm and the egg unite, and a brand-new cell is formed. This is the beginning of a seed.
Picture an apple. Before the apple was a fruit containing seeds, it was a very sexy flower. So the next time someone asks you if you know about the birds and the bees, tell them about flower power. They might be surprised how plants get together to make baby plants, which in scientific terms is an interesting example of the process called sexual reproduction.
Pollen is contained in the anthers, which are the six slipper shaped sacs at the end of the stamens. The female stigma is the rounded tip located at the top of the style. The pollen tube is a microscopic tube that grows through the style and into the ovary, which is hidden inside the base of this flower. Hanging down, at the lower right side of the photo are the remains of another flower. The petals and stamen have fallen off revealing the entire pistil: the stigma, style, and the ovary (green structure), which holds the eggs. Photo credit © Alexandra Siy
Why not watch some web-spinners do their thing with the help of this stunning and superlative book by Alexandra Siy? You can read more about it here.
Alexandra Siy is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.
MLA 8 Citation