Wahana Antariksa Pengorbit

Sounding rockets are normally used for brief, inexpensive space and microgravity experiments. 

Current human-rated suborbital launch vehicles include SpaceShipOne and the upcoming SpaceShipTwo, among others (see space tourism). 

The delta-v needed for orbital launch using a rocket vehicle launching from the Earth's surface is at least 9,300 m/s (31,000 ft/s). 

This delta-v is determined by a combination of air-drag, which is determined by ballistic coefficient as well as gravity losses, altitude gain and the horizontal speed necessary to give a suitable perigee. 

The delta-v required for altitude gain varies, but is around 2 km/s (1.2 mi/s) for 200 km (120 mi) altitude.

Minimising air-drag entails having a reasonably high ballistic coefficient, which generally means having a launch vehicle that is at least 20 m (66 ft) long, or a ratio of length to diameter greater than ten. Leaving the atmosphere as early on in the flight as possible provides an air drag of around 300 m/s (980 ft/s). 

The horizontal speed necessary to achieve low earth orbit is around 7,800 m/s (26,000 ft/s). 

The calculation of the total delta-v for launch is complicated, and in nearly all cases numerical integration is used; adding multiple delta-v values provides a pessimistic result, since the rocket can thrust while at an angle in order to reach orbit, thereby saving fuel as it can gain altitude and horizontal speed simultaneously

Mengenal Wahana Peluncur Antariksa

In spaceflight, a launch vehicle or carrier rocket is a rocket used to carry a payload from the Earth's surface into outer space. A launch system includes the launch vehicle, the launch pad and other infrastructure.

Usually the payload is an artificial satellite placed into orbit, but some spaceflights are sub-orbital while others enable spacecraft to escape Earth orbit entirely. 

A launch vehicle which carries its payload on a suborbital trajectory is often called a sounding rocket. Launch vehicles, particularly orbital launch vehicles, have at least two stages, but sometimes up to 4 are employed.

Sumber:

http://en.wikipedia.org/wiki/Space_Launch_System

Plasma Cosmology

In 1965, Hannes Alfvén proposed a "plasma cosmology" theory of the universe based in part on scaling observations of space plasma physics and experiments on plasmas in terrestrial laboratories to cosmological scales orders-of-magnitude greater.

Taking matter–antimatter symmetry as a starting point, Alfvén together with Oskar Klein proposed the Alfvén-Klein cosmology model, based on the fact that since most of the local universe was composed of matter and not antimatter there may be large bubbles of matter and antimatter that would globally balance to equality. The difficulties with this model were apparent almost immediately.

Matter–antimatter annihilation results in the production of high energy photons which were not observed. While it was possible that the local "matter-dominated" cell was simply larger than the observable universe, this proposition did not lend itself to observational tests.

Like the steady state theory, plasma cosmology includes a Strong Cosmological Principle which assumes that the universe is isotropic in time as well as in space. Matter is explicitly assumed to have always existed, or at least that it formed at a time so far in the past as to be forever beyond humanity's empirical methods of investigation.

While plasma cosmology has never had the support of most astronomers or physicists, a small number of plasma researchers have continued to promote and develop the approach, and publish in the special issues of the IEEE Transactions on Plasma Science.

A few papers regarding plasma cosmology were published in other mainstream journals until the 1990s. Additionally, in 1991, Eric J. Lerner, an independent researcher in plasma physics and nuclear fusion, wrote a popular-level book supporting plasma cosmology called The Big Bang Never Happened. 

At that time there was renewed interest in the subject among the cosmological community along with other non-standard cosmologies. This was due to anomalous results reported in 1987 by Andrew Lange and Paul Richardson of UC Berkeley and Toshio Matsumoto of Nagoya University that indicated the cosmic microwave background might not have a blackbody spectrum.

However, the final announcement (in April 1992) of COBE satellite data corrected the earlier contradiction of the Big Bang; the popularity of plasma cosmology has since fallen.

Sumber;

Wikipedia