What is Spacecraft: Definition and 221 Discussions

A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, planetary exploration, and transportation of humans and cargo. All spacecraft except single-stage-to-orbit vehicles cannot get into space on their own, and require a launch vehicle (carrier rocket).
On a sub-orbital spaceflight, a space vehicle enters space and then returns to the surface, without having gained sufficient energy or velocity to make a full orbit of the Earth. For orbital spaceflights, spacecraft enter closed orbits around the Earth or around other celestial bodies. Spacecraft used for human spaceflight carry people on board as crew or passengers from start or on orbit (space stations) only, whereas those used for robotic space missions operate either autonomously or telerobotically. Robotic spacecraft used to support scientific research are space probes. Robotic spacecraft that remain in orbit around a planetary body are artificial satellites. To date, only a handful of interstellar probes, such as Pioneer 10 and 11, Voyager 1 and 2, and New Horizons, are on trajectories that leave the Solar System.
Orbital spacecraft may be recoverable or not. Most are not. Recoverable spacecraft may be subdivided by method of reentry to Earth into non-winged space capsules and winged spaceplanes. Recoverable spacecraft may be reusable (can be launched again or several times, like the SpaceX Dragon and the Space Shuttle orbiters) or expendable (like the Soyuz). In recent years, we are seeing more space agencies tending towards reusable spacecraft.
Humanity has achieved space flight but only a few nations have the technology for orbital launches: Russia (RSA or "Roscosmos"), the United States (NASA), the member states of the European Space Agency (ESA), Japan (JAXA), China (CNSA), India (ISRO), Taiwan (National Chung-Shan Institute of Science and Technology, Taiwan National Space Organization (NSPO), Israel (ISA), Iran (ISA), and North Korea (NADA). In addition, several private companies have developed or are developing the technology for orbital launches, independently from government agencies. The most prominent examples of such companies are SpaceX and Blue Origin.

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  1. B

    Find the Position of an Orbiting Spacecraft

    Homework Statement Lets say that there is a small spacecraft (mass doesn't matter due to Earth's huge mass) orbiting Earth with a current distance from the center at 6,700,000 m. This whole problem is on a 2D plane with the spacecraft 's current position at (0,6700000). It's current...
  2. alexmahone

    Special relativity spacecraft speed question

    A pursuit spacecraft from the planet Tatooine is attempting to catch up with a Trade Federation cruiser. As measured by an observer on Tatooine, the cruiser is traveling away from the planet with a speed of 0.6c. The pursuit ship is traveling at a speed of 0.8c relative to Tatooine, in the...
  3. Eirhead

    I have a spacecraft that can trave to Alpha Centauri in 1 week

    Am I going to absorb 4 years of light data from Alpha Centauri or is it just going massively blueshift?
  4. D

    Impacting an accelerating spacecraft

    What do I need to calculate to impact an accelerating spacecraft with an accelerating kinetic kill vehicle?
  5. R

    Creating Artificial Gravity for Spacecraft Travel

    I wrote a brief technical paper on the research and concepts for creating artificial gravity in space using centrifuges for my Mechanical Engineering class. I would just like to share it with the Physics world...
  6. B

    Light from Spacecraft Moving Faster than c: Appearance

    Appear refers to a ground observer, the answer should be physically sound not just some fancy sci-fi!
  7. A

    A spacecraft encounters a stationary dust cloud of density rho.

    I'm currently preparing for a prelim and just wondering if my solution to this problem is correct. I did a plot of v(t) and it looked reasonable. You can find the question and solution both at http://oi50.tinypic.com/2e3v4e8.jpg. The Problem states: A spacecraft of mass m_0 and...
  8. A

    Flexibility on spacecraft elements design

    I have no prior knowledge on engineering, but has just started my Msc dissertation about using nonlinear programming technique to model a problem that is related to spacecraft elements design. I am uncertain that whether I have fully understood the problem. The problem is to decide the...
  9. spacerock1

    Astronautics specializing in Spacecraft Propulsion: What Major?

    Hello, I'm entering my senior year in high school and I can't decide what I want to major in in college. I am DECENT (not too good) at engineering, but I am good with math, science, and the like. Currently, I want to work with Spacecraft Propulsion after college, especially high efficiency...
  10. C

    SpaceX SpaceX Makes History As First Company to Dock a Spacecraft At ISS

    I have been following this for the last few days, they launched the Falcon 9 rocket with the Dragon capsule on Tuesday, then Thursday had to perform a series of tests to make sure the Dragon spacecraft was working fine, now they are docking. They had to perform multiple tests on it to make...
  11. G

    Futuristic propulsion of spacecraft

    I read about ion thrusters. If they had enough energy, is it possible, that the descendants of the current engines fires the ions with relativistic speeds, and a small yacht could go from LEO to Moon and back, with small amount of propellant, in hours?
  12. A

    Calculating Work to Put Spacecraft in Orbit

    Homework Statement How much work is done moving a 1500 kg spacecraft from the Earth's surface into a fixed orbit at a height of 300 km above the Earth's surface? Homework Equations Eg = -Gm1m2/r Ek = 1\2mv^2 mass of earth: 5.98 x 10^24 kg radius of earth: 6.38 x 10^6 m The...
  13. O

    Solving Spacecraft Slingshot Homework

    Homework Statement Spacecrafts can gain in mechanical energy as they encounter a planet. This may appear as a violation of the conservation of mechanical energy, but it is not. The gained energy is at the expense of the orbital energy of the planet. The easiest way to see how this works in...
  14. G

    Signal to Noise Ratio Between Spacecraft Transmitter and Receiver Antenna

    Homework Statement Determine the SNR for the spacecraft that uses a transmitter power of 16 W at a frequency of 2.4 GHz. The transmitter and receiver antenna gain are 28 dBi and 60 dBi, respectively. The distance from the space- craft to ground is 2 ϫ 1010 m, the effective noise temperature...
  15. C

    Is Fusion Practical for Spacecraft?

    Would fusion make for practical applications in high speed interplanetary propulsion? Or would beamed propulsion be better?
  16. B

    Circular Motion - Spacecraft in Orbit

    Homework Statement A spacecraft moves in a circular orbit with a speed of 7.60E+0 km/s with a period of 95.1 min. What is the radius of the spacecraft 's orbit? My answer, which is correct, is 6.90×106 m What is the radial acceleration of the satellite? 8.37 m/s^2 was my answer, and it...
  17. C

    New velocity between two spacecraft moving in opposing directions

    Homework Statement A 60-tonne (1 t = 1000 kg) spacecraft moving in the + x-direction at 0.70 m/s docks with a 65-tonne craft moving in the -x-direction at 0.64 m/s Find the velocity of the joined spacecraft Homework Equations Conservationg of kinetic energy? KE_i=KE_f The...
  18. Z

    Lorentz Factor / Spacecraft to Star

    Homework Statement A star is located 4.2 light years from Earth. At what constant velocity must a spacecraft travel from Earth if it is to reach the star in 3.0 years time? Homework Equations I've been working on this for a couple of days, but I'm not entirely sure which equation to use...
  19. C

    Placement of Reaction Control System on a Spacecraft

    Suppose you have a reaction wheel or a control moment gyroscope on your spacecraft for attitude control. This would be a self contained unit, with 3-axis control. Either device utilizes the conservation of angular momentum, trading angular momentum between the unit and the spaceship frame as...
  20. I

    Newtons third law regarding spacecraft engines

    Hello PF members, I was wondering whether Newtons third law was exclusive to spacecraft thrust; space being empty and without enough particles for a force to push against. That in order to produce thrust in space, you would need to carry the fuel that you plan to eject with you...
  21. J

    How fast can we truly ever hope to make a spacecraft?

    OK I'm not sure if this is the proper place to post this question, but since there probably is no correct definitive answer but hypothesis ...here goes... What is the fastest speed in the form of percentage of light speed, that we will realistically probably ever be able to get a spacecraft...
  22. F

    In Atmosphere Ion Drive(Assess Viability For Spacecraft)

    For starters, watch this video to see what I'm talking about. It has been done, so I know it can work, but I want to assess viability for maneuvering while in the thermo-sphere (space shuttle/ISS orbit) You can skip to 2:20...
  23. E

    Landing a Spacecraft: Understanding Gravity in Space

    how do space ships come to rest when they get into space?
  24. MattRob

    Gas Dynamic Mirror Fusion as Spacecraft Propulsion

    Hello again, Physics Forums. I'm designing a Sci-Fi story and I'm fleshing out the background details. For it's sake, education, and my own curiosity, I was wondering if I could have some help with a few things related to the physics of it. A bit of an armchair Rocket Engineer, I'm using...
  25. J

    Space-Time Distortion: Matterless Vacuums in Space

    Imagine a spacecraft containing a perfect vacuum, hurtling through space at 0.9c. This movement distorts the space the matter of the ship occupies. But what happens to the space inside the ship? It contains no matter. Is space irrelevant without matter?
  26. M

    Thought Expirement, Tethered Spacecraft travelling near light speed

    I have two spacecraft originating from the same point each at velocity .9c in opposite directions. One spacecraft has a chord attached to it rigidly. The other has a spindle attached that can freely unwind the chord with no friction. We can measure the speed of the chord unwinding on this...
  27. A

    Pioneer 10 Spacecraft travelling in space

    Homework Statement To escape from the solar system, how fast did the Pioneer 10 have to be traveling as it passed the orbit of Jupiter? Assume the mass of the solar system is essentially concentration in the Sun. The mass of the Sun is 1.99 x 10^30 kg and the radius of Jupiter's orbit is 7.78...
  28. M

    How far can spacecraft fly?

    How far can spacecraft fly? Why ?
  29. ?

    Constatly accelerating spacecraft

    This is not a homework problem. It is personal project of mine. Pleases help Say you have a spacecraft that for some advanced propulsion technology is able to accelerate at 1 gee or more indefinitely. This allows the crew walk around as in a gravity and, I think, permit slower than travel...
  30. X

    Spacecraft launched from the earth

    1. A spacecraft is to be launched from the surface of the Earth so that it will escape from the solar system altogether. Find the speed relative to the center of the Earth with which the spacecraft must be launched. Take into consideration the gravitational effects of both the Earth and...
  31. A

    How Should a Spacecraft Navigate Towards a Pulsar to Optimize Its Path?

    Homework Statement In the year 2212, humans send an unmanned spacecraft towards a faraway pulsar. The pulsar sends the signals in a plane (say plane A) which passes through the Earth. The spacecraft is designed in such a way that it has a continuous and a constant magnitude of...
  32. Eagle9

    Unmanned spacecraft and maximal g-load

    As well-known, the humans (astronauts) can withstand the g-load about several g-s. What about the unmanned spacecraft s? I have heard that they can withstand up to 200-300 g-s, is it right? Actually, what maximal g-load can the sophisticated spacecraft withstand and for what time?:smile:
  33. F

    Harnessing Light for Spacecraft Propulsion

    It is said that aiming a laser from earth, the moon, etc, could be used to propel a spacecraft receiving such a laser beam. It is also said that a solar sail could use the reflection of photons to move through space. Now my question is, while impractical what stops an on board laser being...
  34. M

    Verifying Circular Orbit of a Spacecraft: A Step-by-Step Guide

    Homework Statement If given a speed of a spacecraft , and a radius from the sun, how do you prove that it was or was not in a circular orbit about the sun? Homework Equations The Attempt at a Solution To prove it is not do I just find the mass of the spacecraft and the size of...
  35. G

    HELP on a spacecraft mission to saturn for the injection velocity

    HELP on a spacecraft mission to saturn for the injection velocity i beg you please Homework Statement on intial approach to Saturn, the spacecraft mass is 3500 kg. To enter orbit around Saturn , the vehicle has a 400N thrust primary propulsion engine, with a specific impulse of 310 sec...
  36. S

    Calculating Specific Mechanical Energy in a spacecraft

    Homework Statement My math is horrible and I'm in an orbital mechanics class which I'm way over my head...my question is... "What is the specific mechanical energy, e, of an orbit with a semimajor axis of 42,160km" Homework Equations I used a formula that took -3.986x10^5 / 2x...
  37. kreil

    Spacecraft orbit homework problem

    Homework Statement Suppose a spacecraft of speed v_c is in a circular orbit around the Earth at a height H from the surface of the earth. The rocket motor is fired in the opposite direction of motion to reduce the satellite's speed to v_0 and make the orbit elliptical. Let R denote the...
  38. E

    Forces resulting from rotation of a spacecraft.

    In Sean Carroll's "From Eternity to Here", pages 69-70, the author says that people in a sealed spaceship out in space can tell when they accelerate (they are pushed "down" to the floor say by a rocket firing at the rear of the craft), or when they rotate (an object perfectly positioned at the...
  39. C

    Apollo spacecraft Homework Help

    Homework Statement On April 11, 1970, Apollo 13 was launched at Kennedy Space Flight center, Florida LC 39A. Appollo 13 carried Astronaunts James A. Lovel, John L Swigert, and Fred W. Haise on their voyage to the moon. However, two days into the flight and 321,860 km from Earth when stirring...
  40. J

    Pioneer Spacecraft: Exploring SR Effects on Gravitational Fields

    Pioneer Spacecraft: As far as I know, the "extra" apparent acceleration towards the sun is yet to be adequately explained or shown to be an empirical error. Given the ad-hoc nature of this experiment it may require a better one to resolve this, but it got me thinking about what is unique about...
  41. C

    Calculate the force of Earth's gravity on a spacecraft

    I am in a classical physics class and the class requires that we use mastering physics for our homework. The only problem is that I can't get what mastering physics claims is the right answer to these problems. Can someone try these calculations to see if I am right or wrong? Problem 6.1 ...
  42. M

    LEO Spacecraft Construction

    I am looking for any information on the feasibility of spacecraft construction in LEO. Does anybody know of any papers or lectures on the subject. Any Help in appreciated, thanks!
  43. D

    What would happen inside a spacecraft with no power?

    Hey guys, A friend and I were wondering what would happen if you were trapped inside a spacecraft with no power to run any life support systems such as heating/cooling. Assume there is plenty of usable air. Would the spacecraft interior get hotter due to warmth generated by the human...
  44. G

    How would you steer a spacecraft?

    Hi, First of all I'm sorry for choosing the "general physics" forum, but I didn't find anything better suited. I have been watching Star Trek and other Science-Fiction series and I am interested in how you would, in theory, make spacecraft s navigate in space. Most SciFi Spacecraft designs...
  45. L

    Pioneer spacecraft - what cosmological direction are they travelling?

    Can anyone tell me how I could find out the exact direction that the Pioneer spacecraft are travelling? I need to figure out what direction they are traveling relative to the cosmic microwave background radiation. Thanks. ( http://en.wikipedia.org/wiki/Pioneer_anomaly )
  46. A

    How Can Spacecraft Travel Faster Than Light?

    Lets just pretend we have a spaceship traveling in the vacuum of space with no friction from space dust whatsoever. It accelerates at a meager 10m/s. Eventually in millions of years it will near the speed of light. If nothing can go faster than the speed of light than what prevents said...
  47. N

    Self contained U transit drive for spacecraft

    First of all this is not a perpetual motion machine. This type of transit drive works in theory by having two combustion chambers positioned parallel to the spacecraft 's width and perpendicular to its length. Each of the two exhaust nozzles are also positioned parallel to the spacecraft 's...
  48. S

    Special Relativity and spacecraft

    Homework Statement A spacecraft is traveling around Earth at 1.8x10^8m/s relative to the earth. If the spacecraft determines two events on Earth to be 32H, what time interval would they find if the spacecraft is traveling at 2.82x10^8m/s? Homework Equations delta Tm=delta...
  49. M

    Universal Gravitation and spacecraft

    Homework Statement Very far from Earth (r = infinity), a spacecraft has run out of fuel and its kinetic energy is zero. If only the gravitational force of the Earth were to act on it (i.e., neglect the forces from the sun and other solar system objects), the spacecraft would eventually...
  50. S

    Spacecraft landing on an alien planet

    Homework Statement A spacecraft of mass m0 is descending with velocity v0 to land on an alien plant where the value of g is 1/6 of g on the earth. In order to land safely (meaning the final velocity upon landing is zero), fuel has to be burnt at a constant rate dm/dt=-k, where k is a...
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