Open main menu
Home
Random
Recent changes
Special pages
Community portal
Preferences
About Wikipedia
Disclaimers
Incubator escapee wiki
Search
User menu
Talk
Dark mode
Contributions
Create account
Log in
Editing
Spaceflight
(section)
Warning:
You are not logged in. Your IP address will be publicly visible if you make any edits. If you
log in
or
create an account
, your edits will be attributed to your username, along with other benefits.
Anti-spam check. Do
not
fill this in!
== Phases == === Launch === {{Main|Space launch}} Rockets are the only means currently capable of reaching orbit or beyond. Other [[non-rocket spacelaunch]] technologies have yet to be built, or remain short of orbital speeds. A [[rocket launch]] for a spaceflight usually starts from a [[spaceport]] (cosmodrome), which may be equipped with launch complexes and [[launch pad]]s for vertical rocket launches and runways for takeoff and landing of carrier airplanes and winged spacecraft. Spaceports are situated well away from human habitation for noise and safety reasons. [[Intercontinental ballistic missile|ICBMs]] have various special launching facilities. A launch is often restricted to certain [[launch window]]s. These windows depend upon the position of celestial bodies and orbits relative to the launch site. The biggest influence is often the rotation of the Earth. Once launched, orbits are normally located within relatively constant flat planes at a fixed angle to the axis of the Earth, and the Earth rotates within this orbit. A [[launch pad]] is a fixed structure designed to dispatch airborne vehicles. It generally consists of a launch tower and flame trench. It is surrounded by equipment used to erect, fuel, and maintain launch vehicles. Before launch, the rocket can weigh hundreds of tons. The [[Space Shuttle Columbia|Space Shuttle ''Columbia'']], on [[STS-1]], weighed 2030 metric tons (4,480,000 lb) at takeoff. === Reaching space === The most commonly used definition of [[outer space]] is everything beyond the [[KΓ‘rmΓ‘n line]], which is {{convert|100|km|mi|sp=us}} above the Earth's surface. (The United States defines outer space as everything beyond {{convert|50|mi|km|sp=us}} in altitude.) [[Rocket engines]] remain the only currently practical means of reaching space, with planes and [[high-altitude balloons]] failing due to lack of atmosphere and alternatives such as space elevators not yet being built. Chemical propulsion, or the acceleration of gases at high velocities, is effective mainly because of its ability to sustain thrust even as the atmosphere thins. ==== Alternatives ==== {{Main|Non-rocket spacelaunch}} Many ways to reach space other than rocket engines have been proposed. Ideas such as the [[space elevator]], and [[momentum exchange tether]]s like [[Rotovator (tether propulsion)|rotovators]] or [[Skyhook (structure)|skyhooks]] require new materials much stronger than any currently known. Electromagnetic launchers such as [[launch loop]]s might be feasible with current technology. Other ideas include rocket-assisted aircraft/spaceplanes such as [[Reaction Engines Skylon]] (currently in early stage development), [[scramjet]] powered spaceplanes, and [[Rocket-based combined cycle|RBCC]] powered spaceplanes. Gun launch has been proposed for cargo. === Leaving orbit === {{Main|Escape velocity|Parking orbit}}On some missions beyond [[Low Earth orbit|LEO (Low Earth Orbit)]], spacecraft are inserted into parking orbits, or lower intermediary orbits. The parking orbit approach greatly simplified Apollo mission planning in several important ways. It acted as a "time buffer" and substantially widened the allowable [[launch window]]s. The parking orbit gave the crew and controllers time to thoroughly check out the spacecraft after the stresses of launch before committing it for a long journey to the Moon.<ref name="lauwin">{{cite web |title=Apollo lunar landing launch window: The controlling factors and constraints |url=https://history.nasa.gov/afj/launchwindow/lw1.html |publisher=NASA}}</ref>[[Image:RIAN archive 510848 Interplanetary station Luna 1 - blacked.jpg|thumb|upright|Launched in 1959, [[Luna 1]] was the first known artificial object to achieve escape velocity from the Earth ''(replica pictured)''.<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1959-012A |title=NASA β NSSDC β Spacecraft β Details |publisher=Nssdc.gsfc.nasa.gov |access-date=November 5, 2013}}</ref>]] Robotic missions do not require an abort capability and require radiation minimalization only for delicate electronics, and because modern launchers routinely meet "instantaneous" launch windows, space probes to the Moon and other planets generally use direct injection to maximize performance by limiting the boil off of [[cryogenic propellant]]s. Although some might coast briefly during the launch sequence, they do not complete one or more full parking orbits before the burn that injects them onto an Earth escape trajectory. The escape velocity from a celestial body decreases as the distance from the body increases. However, it is more fuel-efficient for a craft to burn its fuel as close as possible to its [[periapsis]] (lowest point); see [[Oberth effect]].<ref name="Escape Velocity of Earth">[http://van.physics.uiuc.edu/qa/listing.php?id=1053 Escape Velocity of Earth] {{Webarchive|url=https://web.archive.org/web/20070713212922/http://van.physics.uiuc.edu/qa/listing.php?id=1053 |date=2007-07-13 }}. Van.physics.uiuc.edu. Retrieved on 2011-10-05.</ref> === Astrodynamics === {{Main|Orbital mechanics}} 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. An [[orbital maneuvering system]] may be needed to maintain or change orbits. Non-rocket orbital propulsion methods include [[solar sail]]s, [[magnetic sail]]s, [[Mini-magnetospheric plasma propulsion|plasma-bubble magnetic systems]], and using [[gravitational slingshot]] effects. {{multiple image |direction = vertical |align = right |width = 200 |image1 = Space Shuttle Atlantis in the sky on July 21, 2011, to its final landing.jpg |image2 = Keyhole capsule recovery.jpg |caption1 = Ionized gas trail from [[Space Shuttle|Shuttle]] reentry |caption2 = Recovery of [[Discoverer 14|Discoverer 14]] return capsule by a [[C-119 Flying Boxcar|C-119]] airplane }} === Transfer energy === The term "transfer energy" means the total amount of [[energy]] imparted by a rocket stage to its payload. This can be the energy imparted by a [[First stage (rocketry)|first stage]] of a [[launch vehicle]] to an upper stage plus payload, or by an upper stage or spacecraft [[Apogee kick motor|kick motor]] to a [[spacecraft]].<ref>{{cite book |author=Erickson |first=Lance K. |title=Space Flight: History, Technology, and Operations |publisher=Government Institutes |year=2010 |page=187}}</ref><ref>{{cite press release |title=Musk pre-launch backgrounder on Falcon 9 Flight 20 |url=http://www.spacex.com/news/2015/12/21/background-tonights-launch |date=22 December 2015 |access-date=28 December 2015 |publisher=SpaceX |archive-date=8 March 2017 |archive-url=https://web.archive.org/web/20170308172650/http://www.spacex.com/news/2015/12/21/background-tonights-launch |url-status=dead }}</ref> === Reaching space station === {{main|Space rendezvous|Docking and berthing of spacecraft}} In order to reach a [[space station]], a spacecraft would have to arrive at the same [[orbit]] and approach to a very close distance (e.g. within visual contact). This is done by a set of orbital maneuvers called [[space rendezvous]]. After rendezvousing with the space station, the space vehicle then docks or berths with the station. Docking refers to joining of two separate free-flying space vehicles,<ref name=her>{{citation|url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110010964.pdf|title=ISS Interface Mechanisms and their Heritage|first1=John |last1=Cook|first2=Valery |last2=Aksamentov|first3=Thomas |last3=Hoffman|first4=Wes |last4=Bruner|date=1 January 2011|publisher=Boeing|access-date=31 March 2015|location=Houston, Texas|quote=Docking is when one incoming spacecraft rendezvous with another spacecraft and flies a controlled collision trajectory in such a manner so as to align and mesh the interface mechanisms. The spacecraft docking mechanisms typically enter what is called soft capture, followed by a load attenuation phase, and then the hard docked position which establishes an air-tight structural connection between spacecraft. Berthing, by contrast, is when an incoming spacecraft is grappled by a robotic arm and its interface mechanism is placed close to the stationary interface mechanism. Then typically there is a capture process, coarse alignment and fine alignment, and then structural attachment.|via=NASA}}</ref><ref name="nasa20090317">{{cite web |title=International Docking Standardization |url=https://ntrs.nasa.gov/api/citations/20090014038/downloads/20090014038.pdf |publisher=NASA |access-date=2011-03-04 |page=15|date=2009-03-17 |quote=Docking: The joining or coming together of two separate free flying space vehicles}}</ref><ref name=ARDS>{{cite book|last=Fehse|first=Wigbert|title=Automated Rendezvous and Docking of Spacecraft|publisher=Cambridge University Press|location=Cambridge, UK|date=2003|isbn=978-0521824927}}</ref><ref name="AdvanDock">{{cite web|title=Advanced Docking/Berthing System β NASA Seal Workshop |url=http://gltrs.grc.nasa.gov/reports/2005/CP-2005-213655-VOL1/15Robertson.pdf |publisher=NASA |access-date=2011-03-04 |page=15 |date=2004-11-04 |quote=Berthing refers to mating operations where an inactive module/vehicle is placed into the mating interface using a Remote Manipulator System-RMS. Docking refers to mating operations where an active vehicle flies into the mating interface under its own power. |url-status=dead |archive-url=https://web.archive.org/web/20110922084406/http://gltrs.grc.nasa.gov/reports/2005/CP-2005-213655-VOL1/15Robertson.pdf |archive-date=September 22, 2011 }}</ref> while berthing refers to mating operations where an inactive vehicle is placed into the mating interface of another space vehicle by using a [[robotic arm]].<ref name=her/><ref name=ARDS/><ref name=AdvanDock/> === Reentry === {{Main|Atmospheric reentry}} Vehicles in orbit have large amounts of kinetic energy. This energy must be discarded if the vehicle is to land safely without vaporizing in the atmosphere. Typically this process requires special methods to protect against [[aerodynamic heating]]. The theory behind reentry was developed by [[Harry Julian Allen]]. Based on this theory, reentry vehicles present blunt shapes to the atmosphere for reentry. Blunt shapes mean that less than 1% of the kinetic energy ends up as heat reaching the vehicle, and the remainder heats the atmosphere. === Landing and recovery === The [[Project Mercury|Mercury]], [[Project Gemini|Gemini]], and [[Apollo command module|Apollo]] capsules [[Splashdown|splashed down]] in the sea. These capsules were designed to land at relatively low speeds with the help of a parachute. Soviet/Russian capsules for [[Soyuz (spacecraft)|Soyuz]] make use of a big parachute and braking rockets to touch down on land. [[Spaceplane]]s like the [[Space Shuttle]] land like a [[Glider (aircraft)|glider]]. After a successful landing, the spacecraft, its occupants, and cargo can be recovered. In some cases, recovery has occurred before landing: while a spacecraft is still descending on its parachute, it can be snagged by a specially designed aircraft. This [[mid-air retrieval]] technique was used to recover the film canisters from the [[Corona (satellite)|Corona]] spy satellites.
Edit summary
(Briefly describe your changes)
By publishing changes, you agree to the
Terms of Use
, and you irrevocably agree to release your contribution under the
CC BY-SA 4.0 License
and the
GFDL
. You agree that a hyperlink or URL is sufficient attribution under the Creative Commons license.
Cancel
Editing help
(opens in new window)