Interstellar travel

Interstellar Travel includes all planned space missions in the interstellar space, including with the aim to reach another star system. The challenges lie in overcoming the large distances that are specified in light years and the consequent travel time as well as on carrying its own energy source. So far, there are only theoretical concepts.

• 2.1 Stage I: exploration of interstellar space 2.1.1 Frequently proposed propulsion systems
• 2.1.2 benefits of Interstellar Precursor Mission

• 2.2.1 Frequently proposed drive system

• 3.1 Manned Spaceship Concepts
• 3.2 Generation Ships
• 3.3 sleeper ships
• 3.4 embryos transport
• 3.5 planets and asteroids ships

• 6.1 Books
• 6.2 Article

Background

Current probes

Pioneer 10, Pioneer 11, Voyager 1, Voyager 2 and the New Horizons spacecraft, launched in 2006 could be considered as interstellar spacecraft, as they will leave the solar system permanently. Because of their very low speed (on the order of less than a thirty -thousandth the speed of light), several hundred thousand years until they reach the vicinity of another star. For them, so it is not about interstellar probes in the strict sense, since they were not originally built for an interstellar journey. Their main aim was to examine parts of the solar system. Accordingly, their devices are not designed for long trips and fall gradually.

A goal of NASA in this area was and is, to be able to determine the edge of the solar system. According to the NASA space probe Voyager 1 is said to have left the sphere of influence of the solar wind and is thus located in the interstellar space.

Conditions

Should a spacecraft ( manned or unmanned ) the inner solar system, this can no longer generate using solar panels from solar radiation, the energy needed, it needs its own power source. Previous probes used a radionuclide. Furthermore, the spacecraft would fly with a significant fraction of the speed of light to within a reasonable time (ie, within decades or centuries ) to be able to achieve the goal. This also gives rise to the problem of how to slow down the speed in a relatively short time again to get sufficient time for observation of the target object, or even to fly back. Such a spacecraft would operate autonomously, be able to address and investigate the destination without help from Earth, since signals from Earth would need to ship several years. The data signals would be sent continuously to the earth or to the spaceship. Another problem that arises from the distances, the mission duration and the reference to the life of the systems. Especially the electronics is affected. Due to the still-young technology branch ( beginning approximately in the 1960s ) still exist numerous open questions concerning the life of electronic components / systems. The service life of electronic components / Satellite is on such a mission but a critical but not an impossible aspect, since, for example, the ATS -3 satellite in 2008 had its 41 anniversary and it was still active.

In summary, the following parameters are important:

• As speed one-tenth the speed of light should be approximately achieved in order to reach the goal within a reasonable time can.
• The high speed protection systems requires, due to the bremsstrahlung, and against objects along the flight path.
• A separate power source is required.
• The radio transmission duration to Earth requires autonomous / artificially intelligent systems.
• The mission duration is a challenge for the operational life of the systems.

Destinations

The stellar neighborhood has some interesting destinations. The following table lists the star systems from the list of the nearest stars are listed that are closest to us. It can be seen that at a distance of a few light years, although some systems are in place, the destinations but drastically reduce, if one parameter as primarily one of our sun -like star ( among other things for energy production ), which is then also a Earth-like planet is home taken into account.

Space Propulsion

The problems of interstellar space can especially in the required energy conversion, that is, the use of an appropriate space ship drive to be seen. If the object is the nearest star within a reasonable period (~ half a century ) reach, the object must be within a short period on an approximately relativistic speed (eg, ~ 0.1 c ) accelerate and decelerate it also makes sense again. The challenge here can be illustrated with the Tsiolkovsky equation:

With

To obtain a high speed change (), a high effective exhaust velocity () of the reaction gas and a high specific impulse () ( engine code) is needed. Furthermore much fuel has to be converted () to generate the required energy. Therefore, a high shear force is necessary to produce the required acceleration power within a "short" period of time.

In this vein, therefore two engine categories may be excluded:

• While these engines have a high thrust force, but due to the use of chemical energy efficiency () of these engines is very small.

• The efficiency of these engines is high, however, is the fuel emissions due to the use of electrical charges and the repulsion among themselves, rather low.

In some concepts, therefore, is mainly the nuclear pulse propulsion favors which would be implemented from today's perspective. Also, the antimatter drive could be promising in the future. Because of the energy input to accelerate the fuel masses prefer some scientists gasoline- drive, which accelerates the object by means of force by external fields (see, inter alia, Breakthrough Propulsion Physics Project). One possible issue here is whether the gravitational fields of the neighboring star systems could have an influence on the flight path of an object. In an ESA study it was shown that a multi- body problem in interstellar space is negligible, which means that only the sphere of influence of a stellar system is of importance. This means that an object can be in interstellar space outside the spheres of influence, take a position without being dissuaded by the gravitational forces of the star systems substantially from the position.

Concepts for an unmanned interstellar travel

The knowledge concerning the interstellar medium and the heliosphere is currently still low, so that the first interstellar missions are first researching these areas. Some missions, such as the IBEX probe that can deliver initial findings from the earth, but only one can probe locally the nature of space ( distribution of matter, magnetic fields, etc. ) to analyze and confirm or refute the current models. Is interstellar space, once you know fundamentally, this could be the next target, in a few decades to centuries, be another star system.

Level I: exploration of interstellar space

One of the first draft, in addition to the one Interstellar Precursor Mission ( 1977), which provided only the advance in the interstellar space in order to perform experiments can, the TAU was mission. This design of NASA / JPL ( 1980 ) should already tested technology with up to 1000 AU ( Astronomical Units Thousand ) cover. Than ionic propulsion drive system has been provided with a radionuclide, and xenon as a fuel as an energy source. The mission duration should be 50 years. A similar concept, but for interplanetary exploration missions, led NASA in 2003 with the Prometheus and the now painted JIMO project. The RTG power source in combination with an ion drive is a common concept (see, inter alia ), but there are other suggestions.

These are based on the progressive development in the field of satellite lightweight construction and the solar sail technology. One of these proposals includes a 250- kg light probe to reach by means of a solar sail with a radius of about 200 m and some gravity -assist maneuvers, a distance of 200 AU within 15 years. The awning is to be rejected after the acceleration phase of about 5 AU ( see also another concept ).

Frequently proposed propulsion systems

• Awning
• Ion propulsion - Solar Electric Propulsion (SEP ) / Nuclear Electric Propulsion (NEP )
• Additionally Gravity - Assist Maneuver in the sun and when Jupiter

Benefits of Interstellar Precursor Mission

The objectives of such a mission are the (Section 1.0.2):

Another benefit in answering these questions can serve to locate a solution to use the interstellar medium for the drive system or the power supply. If such a possibility exists, the cost of an interstellar spaceship to the nearest star system could be significantly reduced.

Level II: exploring other star systems

While on a trip to the interstellar space only some 100 AU have to be covered, a trip to other star systems involves traversing a distance of some 100,000 AU ( 1 ly ~ 63 KAU ). This change of scale is recognizable especially in the selection of the drive system. Main drive system in the projects Orion, Daedalus, Longshot and Icarus is the nuclear pulse propulsion. This applies, of all the proposed systems, as most technically feasible. Other topics treated in the projects and are protective mechanisms against radiation and microparticles, artificially intelligent systems and mission operations. In addition to these studies, further proposals exist concerning missions to other star systems.

Another idea is to send small probes ( ~ 50 kg) to neighboring star systems that reproduce themselves at the destination, communication receiver and transmitter set up and a possible colonization should prepare by humans. The raw materials get the nanorobots using in- situ technology on site. The advantage of this mission is the reduced expenditure of energy, as opposed to a fully functional probe (eg, Cassini -Huygens mission with 5364 kg ) to shoot such a sample to another star system. Another option is to build a communication network to come into contact with another civilization that might exist or an extraterrestrial communication network to find (theory / speculation). Electromagnetic waves are, due to their speed and good communication can also be used for a one-way transmission of information.

Frequently proposed drive system

• Nuclear pulse propulsion

Concepts for a manned interstellar travel

For the manned interstellar travel the same conditions as for the unmanned interstellar spaceflight apply. In addition, other challenges are added, due to the payload "man." The goal of a manned interstellar space travel will be more alien solar systems exploration and colonization. Although there are already unmanned missions to some publications exist for manned missions only a few. One of these publications is the Wayland Report, which was written based on the Icarus study ( unmanned ). The Wayland report focuses on a generation ship.

Manned Spaceship Concepts

The previously existing ideas come in part from the science-fiction literature, but this does not mean that they will not one day be possible. An example of this was the experiment Biosphere 2, in which an attempt was made to hold a closed system in the ecological balance. The project is considered a failure because not all conditions have been considered and were previously known. However, such a biosphere could be necessary for the transport of people, if they are to be held over several decades while awake alive. Not all concepts presuppose such a habitat.

Generation ships

The name of this spaceship concept comes from the fact that new generations are born on the space ship while traveling to another star system and grow. The generation ships are self-sufficient habitats, that is on board the ship would have, for example, for food production, water and oxygen recycling are possible. Models of thought to such habitats in the near-Earth space or in our solar system are the O'Neill colonies or the Bernal sphere. A key issue in this approach, which is hardly yet been answered is that the crew size and composition. The crew size is decisive for the total mass of the spacecraft, as a person, a certain resource requirements must be attributed (room, food etc. ). On May 23, 2007, a research paper under the direction of Arturo Casadevall was published that deals with fungi that convert (probably by means of melanin ) radioactive radiation into usable energy for your body. It is conceivable that with the help of such fungi during space flights food for astronauts can be produced. In space, more background radiation is everywhere present as usable plant light.

Sleeper ships

The crew of the spaceship concept is offset to the departure from the earth in a so-called Kryoschlaf, a kind of " artificial hibernation" and alert on arrival at the target again. The advantage of this concept is that it can be dispensed with large-scale food production and entertainment facilities. However, the effects of such Kryoschlafs, it would be technically possible in humans is still unknown. In science fiction, this concept is pretty common, including in the movies / series Alien, Avatar, Demolition Man, Pandorum, Prometheus - and Star Trek.

Embryo transport

In this type of spaceship frozen human embryos would be sent on their way. A few years before, with or after arrival at the destination would be thawed this, bred and raised by robots. This form of transportation would be, if possible, the most effective form, since no complex habitat structures for a journey of several decades would have to be carried. Then the local resources could be used, so that robots could build the necessary habitats on site. Apart from technical challenges, this method is controversial from an ethical point of view. At present, it is unclear whether and if so how to grow up without adult human models changed the psyche of children. It would have to be constructed robot that can reproduce a human upbringing. Last but not least would have an artificial uterus are developed, in which the embryo could grow.

Planets and asteroids ships

An inhabited planet is brought out of its orbit (eg, by collision with another celestial body ), and if possible on an accelerated speed with which he can leave the solar system. The advantage would be the great mass of energy available for further travel. However, the collision with another celestial body wipe out a large part of life on the planet. Would make more sense, therefore, the movement on a smaller celestial body (such as an asteroid ) with the at least one would come to the edge of the solar system. The idea to draw the earth from your path, you will find, among other things in the science fiction series Perry Rhodan.

Others

SETI researchers suggested to look for drive and energy signatures of spacecraft of extraterrestrial, technological civilizations.

NASA - Marshall, JPL and AIAA led by 1999 theoretical studies to use annihilation of antimatter and fusion drives for future space vehicles. In early 2011 launched DARPA and NASA Ames, the 100 - Year Starship project. In this research and evaluation program, the opportunities and challenges are explored by manned interstellar long flights and designed strategies. In September 2011, the 100 - Year Starship Symposium was held in Orlando ( Florida), in which detailed lecture on required technologies, implementation, organization and financing of such a project and has been discussed. 2012 took over the former astronaut Mae Jemison Carol lead the project. Funding is provided by the Defense Advanced Research Projects Agency and NASA. Since 2011, every year is held a public symposium in Houston.

Some private, non-profit research initiatives, such as the Tau Zero Foundation, Icarus Interstellar and the Institute for Interstellar Studies, also deal with the exploration of new technologies and opportunities for future interstellar spaceflights. In April 2013 took place in San Diego, a symposium with Freeman Dyson, Paul Davies, Gregory and James Benford, Jill Tarter, Robert Zubrin, Neal Stephenson, Geoffrey A. Landis, in August in Dallas a convention, including with Friedreich Wardt Winterberg, David Messerschmitt and Marc Millis, instead.