Astro Fisika: Penerbangan Manusia Ke-Antariksa

Thursday 20 June 2013

Penerbangan Manusia Ke-Antariksa

"Penelitian yang tekun untuk menguak rahasia langit kosmik mungkin akan mengantarkan manusia menuju keabadian di Syurga kelak"

*A.N*

Human spaceflight

Main article: Human spaceflight

The first human spaceflight was Vostok 1 on April 12, 1961, on which cosmonaut Yuri Gagarin of the USSR made one orbit around the Earth. In official Soviet documents, there is no mention of the fact that Gagarin parachuted the final seven miles.

The international rules for aviation records stated that "The pilot remains in his craft from launch to landing". This rule, if applied, would have "disqualified" Gagarins space-flight. Currently the only spacecraft regularly used for human spaceflight are Russian Soyuz spacecraft and the U.S. Space Shuttle fleet. Each of those space programs have used other spacecraft in the past. Recently, the Shenzhou spacecraft has been used twice for human spaceflight, as has SpaceshipOne.

Weightlessness

Main article: Weightlessness

Astronauts on the ISS in weightless conditions. Michael Foale can be seen exercising in the foreground.

In a microgravity environment such as that provided by a spacecraft in orbit around the Earth, humans experience a sense of "weightlessness." Short-term exposure to microgravity causes space adaptation syndrome, a self-limiting nausea caused by derangement of the vestibular system. Long-term exposure causes multiple health issues. The most significant is bone loss, some of which is permanent, but microgravity also leads to significant deconditioning of muscular and cardiovascular tissues.

Radiation

Once above the atmosphere, radiation due to the Van Allen belts, solar radiation and cosmic radiation issues occur and increase.

Further away from the Earth, solar flares can give a fatal radiation dose in minutes, and cosmic radiation would significantly increase the chances of cancer over a decade exposure or more.

Life support

Main article: Life support system

In human spaceflight, the life support system is a group of devices that allow a human being to survive in outer space. NASA often uses the phrase Environmental Control and Life Support System or the acronym ECLSS when describing these systems for its human spaceflight missions.

The life support system may supply: air, water and food. It must also maintain the correct body temperature, an acceptable pressure on the body and deal with the body's waste products. Shielding against harmful external influences such as radiation and micro-meteorites may also be necessary. Components of the life support system are life-critical, and are designed and constructed using safety engineering techniques.

Interplanetary spaceflight

Main article: Interplanetary spaceflight

See also: Space probe

An artist's imaginative impression of a vehicle entering a wormhole for interstellar travel

Interplanetary travel is travel between planets within a single planetary system. In practice, the use of the term is confined to travel between the planets of the Solar System.

Interstellar spaceflight

Main article: Interstellar travel

Five spacecraft are currently leaving the Solar System on escape trajectories. The one farthest from the Sun is Voyager 1, which is more than 100 AU distant and is moving at 3.6 AU per year.

In comparison Proxima Centauri, the closest star other than the Sun, is 267,000 AU distant. It will take Voyager 1 over 74,000 years to reach this distance. Vehicle designs using nuclear pulse propulsion might be able to reach the nearest star in a few decades however.

Intergalactic spaceflight

Main article: Intergalactic travel

Intergalactic travel involves spaceflight between galaxies, and is considered much more technologically demanding than even interstellar travel and, by current engineering terms, is considered science fiction.

Astrodynamics

Main article: Astrodynamics

Astrodynamics is the study of spacecraft trajectories, particularly as they relate to gravitational and propulsion effects. Astrodynamics allows for a spacecraft to arrive at its destination at the correct time without excessive propellant use.

Spacecraft propulsion

Main article: Spacecraft propulsion

Spacecraft today predominantly use rockets for propulsion, but other propulsion techniques such as ion drives are becoming more common, particularly for unmanned vehicles, and this can significantly reduce the vehicle's mass and increase its delta-v.

Costs, market and uses of spaceflight

Current spaceflights are frequently, but not invariably paid for by governments; but there are strong launch markets such as satellite television that is purely commercial, although the launchers themselves are often at least partly funded by governments.

Uses for spaceflight include:

Earth observation satellites such as Spy satellites, weather satellites
Space exploration
Space tourism is a small market at present
Communication satellites
Satellite navigation

There is growing interest in spacecraft and flights paid for by commercial companies and even private individuals. It is thought that some of the high cost of access to space is due to governmental inefficiencies; and certainly the costs of the governmental paperwork surrounding NASA is legendary.

If a commercial company were able to be more efficient, costs could come down significantly. Space launch vehicles such as Falcon I have been wholly developed with private finance, and the quoted costs for launch are lower.

Siapkah Kita Menjadi Astronot?

Antariksawan (lazim disebut astronot) adalah sebutan bagi orang yang telah menjalani latihan dalam program penerbangan antariksa manusia untuk memimpin, menerbangkan pesawat, atau menjadi awak pesawat antariksa. Istilah "astronot" juga kadang digunakan untuk merujuk secara spesifik kepada antariksawan yang berasal dari Amerika Serikat atau negara sahabat, berbeda dengan seorang kosmonot yang berasal dari Uni Soviet/Rusia.

Kosmonot pertama adalah Yuri Gagarin. Semenjak tahun 2003 dikenal pula istilah taikonot (meski bukan istilah resmi pemerintah Tiongkok), antariksawan dari Tiongkok. Taikonot pertama adalah Yang Liwei.

Antariksawan-antariksawan pertama, baik di AS maupun Uni Soviet, biasanya merupakan pilot pesawat tempur, umumnya pilot-pilot penguji dengan latar belakang militer. Antariksawan militer biasanya menerima tanda kualifikasi khusus, dikenal di AS dengan nama Astronaut Badge setelah menyelesaikan latihan dan mengikuti penerbangan ke luar angkasa.