Interstellar travel is the hypothetical travel of spacecraft from one star system, solitary star, or planetary system to another. Interstellar travel is expected to prove much more difficult than interplanetary spaceflight due to the vast difference in the scale of the involved distances. Whereas the distance between any two planets in the Solar System is less than 30 astronomical units (AU), stars are typically separated by hundreds of thousands of AU, causing these distances to typically be expressed instead in light-years. Because of the vastness of these distances, non-generational interstellar travel based on known physics would need to occur at a high percentage of the speed of light; even so, travel times would be long, at least decades and perhaps millennia or longer.
As of 2022, five uncrewed spacecraft, all launched and operated by the United States, have achieved the escape velocity required to leave the Solar System as part of missions to explore parts of the outer system. They will therefore continue to travel through interstellar space indefinitely. However, they will not approach another star for hundreds of thousands of years, long after they have ceased to operate (though in theory the Voyager Golden Record would be playable in the event that the spacecraft is retrieved by an extraterrestrial civilization).
The speeds required for interstellar travel in a human lifetime far exceed what current methods of space travel can provide. Even with a hypothetically perfectly efficient propulsion system, the kinetic energy corresponding to those speeds is enormous by today's standards of energy development. Moreover, collisions by spacecraft with cosmic dust and gas at such speeds would be very dangerous for both passengers and the spacecraft itself.
A number of strategies have been proposed to deal with these problems, ranging from giant arks that would carry entire societies and ecosystems, to microscopic space probes.
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Spacecraft propulsion is any method used to accelerate spacecraft and artificial satellites. In-space propulsion exclusively deals with propulsion systems used in the vacuum of space and should not be confused with space launch or atmospheric entry. Several methods of pragmatic spacecraft propulsion have been developed, each having its own drawbacks and advantages. Most satellites have simple reliable chemical thrusters (often monopropellant rockets) or resistojet rockets for orbital station-keeping and some use momentum wheels for attitude control.
Project Orion was a study conducted in the 1950s and 1960s by the United States Air Force, DARPA, and NASA into the viability of a nuclear pulse spaceship that would be directly propelled by a series of atomic explosions behind the craft. Early versions of the vehicle were proposed to take off from the ground; later versions were presented for use only in space. The design effort took place at General Atomics in San Diego, and supporters included Wernher von Braun, who issued a white paper advocating the idea.
Space exploration is the use of astronomy and space technology to explore outer space. While the exploration of space is carried out mainly by astronomers with telescopes, its physical exploration is conducted both by uncrewed robotic space probes and human spaceflight. Space exploration, like its classical form astronomy, is one of the main sources for space science. While the observation of objects in space, known as astronomy, predates reliable recorded history, it was the development of large and relatively efficient rockets during the mid-twentieth century that allowed physical space exploration to become a reality.
The main objective of the course is to provide an overview of space propulsion systems. The course will also describe the basic design principles of propulsion systems.
Covers the modeling of fluid instabilities with linear perturbation theory and explores the origin of unpredictability in turbulence through the Navier-Stokes equations.
Explores the characteristics of typical plasmas from interstellar space to solar corona, discussing temperature, number density, collision processes, and properties.
Fluctuation dynamos occur in most turbulent plasmas in astrophysics and are the prime candidates for amplifying and maintaining cosmic magnetic fields. A few analytical models exist to describe their behavior, but they are based on simplifying assumptions. ...
In the current JWST era, rest-frame UV spectra play a crucial role in enhancing our understanding of the interstellar medium (ISM) and stellar properties of the first galaxies in the epoch of reionization (z > 6). Here, we compare well-known and reliable o ...
Bristol2024
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The PHANGS collaboration has been building a reference data set for the multiscale, multiphase study of star formation and the interstellar medium (ISM) in nearby galaxies. With the successful launch and commissioning of JWST, we can now obtain high-resolu ...