Topic - Forces on a spacecraft as it exits the Earth's atmosphere

A spacecraft is a craft or machine designed for spaceflight. On a sub-orbital spaceflight, a spacecraft enters space then returns to the Earth. For an orbital spaceflight, a spacecraft enters a closed orbit around the planetary body. Spacecraft used for human spaceflight carry people on board as crew or passengers. Spacecraft used for robotic space missions operate either autonomously or telerobotically. Robotic spacecraft that leave the vicinity of the planetary body are space probes. Robotic spacecraft that remain in orbit around the planetary body are artificial satellites. Starships, which are built for interstellar travel, are so far a theoretical concept only.
Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and space tourism. Spacecraft and space travel are common themes in works of science fiction.

File:Atlantis Docked to Mir.jpg
File:Atlantis Docked to Mir.jpg

File:Atlantis Docked to Mir.jpg

http://upload.wikimedia.org/wikipedia/commons/b/b9/Atlantis_Docked_to_Mir.jpg



Rocket Motion

Suppose we have a rocket of total mass 2M, of which M is payload and M is fuel. As the fuel is burned, it is ejected with an average velocity V relative to what the rocket had at the start.
mvmvv
To avoid this (the full derivation requires calculus) let us just define the mean velocity V by conservation of momentum, without trying to puzzle out its relation to the jet speed v. At burn-out, we say, the jet has imparted momentum MV to the payload, and has itself carried an equal and opposite momentum backwards.]
The payload now has gained velocity V.
But we need more! So we build a rocket of mass 4M, of which 2M is fuel, while the payload, also of mass 2M, is the smaller rocket described above, serving as second stage. When the fuel of the big rocket is finished, we reach a velocity V, then the second stage is ignited, adding another V to the velocity, for a total of 2V.
Still faster! Now the rocket has mass 8M of which 4M is fuel of the first stage, while 4M is the two-stage rocket of the preceding design. The first stage gives velocity V, to which the other two add 2V, for a total of 3V.
By now you can see the trend. If the mass of the final payload is M, then
Total mass
Gives final velocity
2M
V
4M
2V
8M
3V
16M
4V
32M
5V
64M
6V
Each time the velocity increases by one notch, the mass doubles.
One cannot avoid this sort of thing by giving up staging--say, in the rocket of mass 8M, by firing all the 7M of fuel in one blast. That is because (as already noted), as the payload (+ remaining fuel) gain speed, less and less momentum is transferred, the jet first having to overcome the forward motion, Indeed, the correct derivation (which uses calculus) gives the equivalent of a huge number of little stages, fired one after the other. The same exponential result is still obtained.
This is one of the great problems of spaceflight, especially with the first stages which rise from the ground: even a small payload requires a huge rocket. Perhaps some day space explorers will be able to shave off some fuel weight by using air-breathing rockets ("scramjets") but those seem practical only for the lowest 1/4 to 1/3 of the orbital velocity. Launching from a high-flying airplane--like Burt Rutan's "SpaceshipOne", or the "Pegasus" solid-fuel rocket, used in launching some small satellites--also helps cut air resistance, another factor. But no other shortcuts are in sight. Once in orbit, of course, more efficient but more gradual ways of generating thrust can be enlisted, like**ion propulsion**. ( http://www.iki.rssi.ru/mirrors/stern/stargaze/Srocket.htm )

Essay

In order for a rocket to leave the Earths atmosphere it must first leave the earth's surface. The Force of gravity on any object is equal to the product of the object's weight and downward acceleration. (Fg=ma) in this case a is equal to 9.81m/s/s. A rocket launch's primary stage is to create enough force to overcome the force of gravity on the rocket. This force is created by burning fuel and directing the energy created downward. This action is carried out by the rockets boosters. Once this Fg on the space craft is overcome the space craft can literally take off. This process however, is not enough to propel the rocket into o the depths of space. The atmosphere's outer border is about 580km away from the surface. (www.enchantedlearning.com/subjects/astronomy/planets/earth/Atmosphere.shtml, en.wikipedia.org/wiki/Earth) In order for the rocket to breakthrough the atmosphere it must burn enough fuel to create the energy equivalent of the rocket's potential energy outside at the limit of the earth’s atmosphere. (PE=mgh where m = mass of the objet, a = the acceleration due to gravity and h = the height of the object. in this case 580km or 580,000m.
Outer space exploration research started in the early 1900’s with the first successful launch of a man made space probe taking place on October 4th, 1957. Followed by the first moon landing by America on July 20th, 1969. Since then satellites, robotic reconnaissance missions to other planets and space mapping probes have all been launched to outer space by various countries. (http://en.wikipedia.org/wiki/Space_exploration)
List of Achievements

· First planetary orbit – Sputnik – 1957
· First animal spaceflight – Laika – 1957
· First human spaceflight – Vostok 1, Yuri Gagarin – 1961
· First woman in space – Vostok 6, Valentina Tereshkova – 1963
· First interplanetary flight mission – Mariner 2, Venus – 1962
· First interplanetary flight mission to return data – Venera 7 – 1970
(http://en.wikipedia.org/wiki/Space_exploration)

Current projects
Thanks to the advancements of space technology Pluto was been demoted from planet to dwarf planet in October of 2006. This has however increased interest in the obelisk among asteroids with the first mission to Pluto being launched on January of 2006 and is expected to begin its approach on July 14th 2015. (
"Pluto Mission a Go! Initial Funding Secured". space.com.)

The Future
The future of the rocket launch was the orbit. The future of the orbit was the exploration. Now the future of the exploration is colonization. Many philosophers, scientists, and politicians agree that having outer space colonization as an option to the people of earth is essential to our survival. Nuclear war, shortage of natural resources, world wide epidemics, these potential problems, that have at some point in history all became realities are the foundations for the support of the space colonization. (
"Colonies in space may be only hope, says Hawking". Telegraph.co.uk) Just as many intellectuals are against the idea. Arguing that over the course of history humans have colonized many areas and have had few, if any, positive experiences to back them.
The future of seems to be leaning towards colonization but with scientist working around clock a new development could shift the direction of technology at any minute.



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Sam Edwards - What effect does wind play on spacecraft launch?
Sonia Bansal - is there significant pressure inside the spaceship as it leave the atmosphere?
Angad Sidhu - How much energy does it take to launch a spacecraft into space?
Robert lopez - Why do you believe that scientists are unable to figure out a way to lower the size of rockets for small payloads?
Nauma Haider - Have scientists come close to finding out how to create the air-breathing rockets/scramjets?
James Song-Would it be practical to bring fluids or other materials into space?
Greg Sturm - If the energy created by burning fuel is directed downward during the launch, does the ground underneath the rocket get damaged? If so, are there any precautions taken so that it isn't completely destroyed?
Brandon Siegenfeld- Are there any more efficient types of fuel usage such as solid fuels that are more dense and take up less room than liquid fuel?
Kevin Norris - Is is possible to retrieve or reuse the secondary (discarded) stages of a multistage rocket?
William Chan - How does the shape of a spacecraft affect the forces acting on it?
Ari Horowitz - Is colonization in space an objective that will be achieved soon?
Douglas Chin - Earth's gravity decreases negligibly as the distance from the surface increases, but couldn't such a minute change still affect some spacecraft, even so slightly?