RSS Feeds

Earth Science

Space Science

Life Science

Fields of Scientific Study

Nanotechnology

Cancer

Definitions of The Fields of Scientific Study

Pinpoint accuracy with the Proba camera

June 04, 2002

A new star tracker allowing a satellite to determine its orientation in space with an accuracy never seen before has proved its worth aboard ESA`s Proba mission.

Proba (Project for On-Board Autonomy) built by Verhaert (Belgium) for ESA was launched in Autumn 2001 and is now fully operational, carrying out a series of Earth observations with extreme accuracy. Such accuracy is only possible because the satellite knows its own orientation in space so precisely.

One of the aims of Proba is to test a number of new principles for satellite control. Compared with traditional satellites Proba is virtually autonomous. The majority of problems arising during daily operations can be handled by the satellite with no need for intervention from the ground.

An important part of the secret behind the autonomy of the satellite is a star tracker developed at the Technical University of Denmark. The camera is similar to that onboard the Danish Ã˜rsted satellite launched three years ago but it has been improved in a number of ways.

"The new camera is the only one in the world able to online and fully automatically adjust for the relativistic aberration", says head of project John Leif Jorgensen, of the Technical University of Denmark.

Aberration is the displacement of a star`s position due to the Earth`s movement around the Sun combined with the finite speed of light. Aberration is thus a relativistic effect - expressing the difference in the position of the star when viewed by an observer standing still compared with one that is moving (we on Earth are moving, as of course is a satellite in orbit).

The relativistic aberration can be as much as 25 graduated arc seconds (one degree is divided into 60 graduated arc minutes, which are again each divided into 60 graduated arc seconds). As the displacement of the star varies with the relative speed of the satellite the aberration will keep changing as the satellite orbits the Earth.

"In other words it will be impossible to obtain arc second accuracy, as is the ambition with Proba, if one cannot fully compensate for the aberration", John Leif Jorgensen states.

Other advantages of the new camera are that it is very compact and extremely tolerant to fast movements. This makes it possible to steer the spacecraft during one pass to make multiple images of an area while the satellite moves along its orbit. The tracker therefore makes an essential contribution to Proba`s high manoeuvrability.

European Space Agency (ESA)

Science Research Departments

	Scientific Explorer's Mind Blowing Science Kit for Young Scientists by Scientific Explorer Mind blowing experiments to delight and educate young scientists! Erupt a color changing volcano. Mix up magic ooze with a mind of its own. Play with sand that never gets wet. Mix safe chemicals and watch colors change before your eyes. You'll amaze yourself and your friends as you explore the science behind these truly remarkable reactions.
	The Everything Kids' Science Experiments Book: Boil Ice, Float Water, Measure Gravity-Challenge the World Around You! (Everything Kids Series) by Tom Robinson (Author) Science has never been so easy - or so much fun! With The Everything Kids' Science Experiments Book, all you need to do is gather a few household items and you can recreate dozens of mind-blowing, kid-tested science experiments. High school science teach Tom Robinson shows you how to expand your scientific horizons - from biology to chemistry to physics to outer space. You'll discover answers to questions like: Is it possible to blow up a balloon without actually blowing into it? What is inside coins? Can a magnet ever be "turned off"? Do toilets always flush in the same direction? Can a swimming pool be cleaned with just the breath of one person? Get ready to enter the laboratory and learn how to conduct cool experiments, understand scientific terms...
	Scientific Explorer's Disgusting Science - A Kit for Studying the Science of Revolting Things by Scientific Explorer Grow your own friendly germs and fuzzy molds. Mix up a batch of coagulating fake blood. Even make a stinky intestine. learn the science behind unmentionable bodily functions while doing some truly NASTY Experiments. Ages 8+
	The Science Book: Everything You Need to Know About the World and How It Works (National Geographic) by National Geographic (Author), Marshall Brain (Foreword) A delight for the casual reader, yet so complete and wide-ranging that science buffs and students will welcome it, The Science Book encapsulates centuries of scientific thought in one richly illustrated volume. Natural phenomena, revolutionary inventions, and the most up-to-date investigations are explained in detailed text, and 2,000 vivid illustrationsincluding 3-D graphics and pictogramsmake the information even more accessible and amazing to discover. The Science Book offers both a general overview of topics for the browsing reader and more specific information for those seeking deeper insight into a particular subject. Six major sections, ranging from the universe and planet Earth to biology, chemistry, physics, and mathematics, encompass everything from microscopic life...
	Scientific Explorer's The Magic Science Wizard's Kit by Scientific Explorer Cast real smoke from your fingertips, make a wizard wand, and whip up color-changing potions in your test tube laboratory. Also included are laminated cards with wizard facts, an instruction booklet with 11 activities, lab equipment, and mysterious wizard powders that will mix together to mystify you!
	Scientific Explorer's Tasty Science Chemistry in the Kitchen Kit by Scientific Explorer Who knew science could taste so good? With this kit, you’ll whip up cupcakes, cookies, candy, and more—all in the name of science! Learn what makes cakes rise, candy crystallize, and more real chemistry happen in the kitchen. Tasty Science is packed with ingredients, recipes, activity cards, a test tube laboratory, and lots more to explore the science of taste.
	The Complete Book of Science, Grades 5-6 by School Specialty Publishing (Author) The Complete Book of Science for grades 5 to 6 teaches children important science skills! Children complete a variety of exercises that help them develop a number of skills in this 352 page workbook. Including a complete answer key this workbook features a user-friendly format perfect for browsing, research, and review. Over 4 million in print! The best-selling Complete Book series offers a full complement of instruction, activities, and information about a single topic or subject area. Containing over 30 titles and encompassing preschool to grade 8 this series helps children succeed in every subject area! ...
	Magic School Bus Journey into the Human Body Science Kit by Young Scientist Club The Magic School Bus and Ms. Frizzle take Young Scientists on a wild ride into the human body with these breathtaking experiments. Young Scientists bend bones, make joints, map taste buds, expand lungs, build a stethoscope, measure lung capacities and heart rates, perform the iodine starch test, spin glitter, simulate synovial fluid, create a human body poster, and much, much more! This exciting kit includes a life-size poster with eight sheets of body part stickers. So put on your seat belts, students, and get ready to discover The Human Body!
	Scientific Explorer's Glow in the Dark Fun Lab Science Kit by Scientific Explorer You will love setting up your own Glow in the Dark Fun Lab. Create a light wand, make your own glow stick, and even generate a human-powered light.
	What Is the World Made Of? All About Solids, Liquids, and Gases (Let's-Read-and-Find-Out Science, Stage 2) by Kathleen Weidner Zoehfeld (Author), Paul Meisel (Author) Did you ever walk through a wall? Drink a glass of blocks? Have you ever played with a lemonade doll, or put on milk for socks? This latest addition to the Let's-Read-and-Find-Out Science series introduces the youngest readers to an important science concept: the differences between solids, liquids, and gases. Any child who wants to know why he can't walk through a wall will enjoy Kathleen Zoehfeld's simple text and Paul Meisel's playful illustrations.