Every mission to the moon cost more than $300 million which was a massive amount of money. The bulk of this amount was spent on the rockets that would be powerful enough to lift the spacecraft and push it beyond escape velocity. In an effort to reduce the cost of each mission, the development of a reusable spacecraft was proposed. Christopher Freville points out that the Space Shuttle was created to fulfill this specific need. Shaped in the form of an airplane, the shuttle would be launched into space like a regular rocket. However, while returning back to earth, it would glide back to a runway without power for propulsion.

Officially, the Space Shuttle is termed as a Space Transportation System. The Shuttles are routinely used for conducting scientific space experiments, launching interplanetary probes and numerous satellites, and the construction and servicing of the international space station. Christopher Freville explains that during launch, the shuttle is fitted with an external fuel tank that is dark orange-colored and a pair of solid rocket boosters. The tail of the shuttle houses three main engines which are fueled by liquid oxygen and liquid hydrogen stored in the external tank. The solid rocket boosters have solid fuel and once they are in operation, they cannot be shut off. The twin rocket boosters and the three main engines of the shuttle provide the thrust for lifting the payload into orbit. The two rocket boosters operate for the first two minutes of the flight which constitutes the first stage of the ascent. Thereafter, they are released and allowed to fall back into the ocean. The boosters are then retrieved from the ocean for reuse in subsequent missions. The rest of the ascent in powered by the three main engines housed in the shuttle. After the shuttle goes into orbit around the earth, the external tank is jettisoned towards the earth. As the tank falls through the atmosphere it burns up and totally disintegrates.

A fleet of Shuttles has been in operation since the early 1980s and is scheduled to be retired in 2010. The spacecrafts would have then been in operation for 30 years estimates Christopher Freville with over 130 missions of which two ended in loss of life of the entire flight crew and the loss of the vehicle as well.

Now, there are two general categories for telescopes that are optical- first is the refracting-type telescope, and the second is the reflecting-type telescope. What is a refracting telescope? A refracting telescope has three general parts (which means, no matter how modern a refracting telescope is, it would still have these main parts as foundation for other parts): the telescope tube, the objective lens and the eye piece lens. The simplest explanation for a refracting telescope would be this: a refracting telescope is composed of two lenses that are convex, which are generally more thick in the very center than at the edges. This design allows colors and light to be focused more clearly and transmitted more efficiently to the eye piece lens.

The part of the telescope that is more near to the object being observed (may it be a turtle, a star or someone in a far away window) is called the objective lens. What happens technically is that this particular lens collects the color and light from a particular source, and takes focuses this as an image that is upside down inside the tube of the telescope. In simpler telescopes, the images remain inverted; but in the more modern versions, the images can be righted by special lenses inside the telescope. Other modern versions of the telescope also have recording devices located near the eye piece lens, so you may be able to record the things that you are observing. These types of telescopes are useful especially if you like observing meteor showers, and other types of celestial phenomena that don’t visibly happen very often in the world’s open skies.

Reflecting telescopes, on the other hand, utilize a different type of lens. Instead of having a convex lens, reflecting telescopes have a curved lens that were specifically crafted to bring back and magnify images. The power of a reflecting telescope to gather and focus light from a source can be achieved by increasing the area of the reflecting telescope’s mirror. Large reflecting telescopes that may be found in astronomical installations were built specifically to observe the skies twenty four hours a day.