Interstellar propulsion opportunities using near-term technologies (original) (raw)

Breakthrough Propulsion Study: Assessing Interstellar Flight Challenges and Prospects

2018

Progress toward developing an evaluation process for interstellar propulsion and power options is described. The goal is to contrast the challenges, mission choices, and emerging prospects for propulsion and power, to identify which prospects might be more advantageous and under what circumstances, and to identify which technology details might have greater impacts. Unlike prior studies, the infrastructure expenses and prospects for breakthrough advances are included. This first year's focus is on determining the key questions to enable the analysis. Accordingly, a work breakdown structure to organize the information and associated list of variables is offered. A flow diagram of the basic analysis is presented, as well as more detailed methods to convert the performance measures of disparate propulsion methods into common measures of energy, mass, time, and power. Other methods for equitable comparisons include evaluating the prospects under the same assumptions of payload, mission trajectory, and available energy. Missions are divided into three eras of readiness (precursors, era of infrastructure, and era of breakthroughs) as a first step before proceeding to include comparisons of technology advancement rates. Final evaluation "figures of merit" are offered. Preliminary lists of mission architectures and propulsion prospects are provided.

Interstellar Spaceflight Using Nuclear Propulsion And Advanced Techniques

Our present space technology has just put its first step outside our heliopause. With 2012, Voyager will be the first manmade object to exit our Solar System for the first time. As space technology develops and as the future of humanity demands more and more; the only way that the humanity can expand would be toward the stars. Even though this may seem to be a dream at this point, the continuing trend in the technology suggests that this will be possible in the next century or towards the end of the 21st century. Thus, the modes of transportation for interstellar distances need to be considered now, so that the necessary technology can be developed correspondingly. In terms of specific impulse, conventional methods are totally useless for any distances that are outside our solar system. Thus, more exotic means of space transport conditions need to be realized in order to make interstellar travel a reality. With current technology, using advanced nuclear propulsion techniques seem to be the best way, as they possess the ability to create high specific impulses in a short period of time. Continued acceleration will be a key to success in such an endeavor and more importantly, with advanced nuclear propulsion, it can be possible to meet the necessary power requirements for the mission. In addition, combination of antimatter propulsion as well as fusion propulsion can be combined to give even a higher specific impulse, as well as an ability to meet power demands for decades, which will be necessary for travelling even at those high speeds. This paper will examine the most probable possibilities regarding interstellar travel based upon the available science and technology that we have today. In addition, this paper will treat some advanced but hypothetical forms of interstellar travel by the utilization of space curvature to some extent. In the end, the humanity has nowhere to go but to the stars. In this paper, we will try to demonstrate with calculations, the most probable way of achieving these objectives.

Interstellar Propulsion Using Laser-Driven Inertial Confinement Fusion Physics

Universe

To transport a spacecraft to distances far beyond the solar heliosphere and around the planets of other stars will require advanced space propulsion systems that go beyond the existing technological state of the art. The release of fusion energy from the interaction of two low mass atomic nuclei that are able to overcome the Coulomb barrier offers the potential for ∼1011J/g specific energy release and implies that robotic missions to the nearby stars to distances of ∼5–10 ly may be possible in trip durations of the order of ∼50–100 years, travelling at cruise speeds of the order of ∼0.05–0.15 c. Such missions would be characterised with ∼kN-MN thrust levels, ∼GW-TW jet powers, ∼kW/kg-MW/kg specific powers. One of the innovative methods by which fusion reactions can be ignited is via the impingement of laser beams onto an inertial confinement fusion capsule, imploding it to a thermonuclear state. This paper gives an overview of the physics of inertial confinement fusion and the inter...

New frontiers in space propulsion sciences

Energy Conversion and Management, 2008

Mankind's destiny points toward a quest for the stars. Realistically, it is difficult to achieve this using current space propulsion science and develop the prerequisite technologies, which for the most part requires the use of massive amounts of propellant to be expelled from the system. Therefore, creative approaches are needed to reduce or eliminate the need for a propellant. Many researchers have identified several unusual approaches that represent immature theories based upon highly advanced concepts. These theories and concepts could lead to creating the enabling technologies and forward thinking necessary to eventually result in developing new directions in space propulsion science. In this paper, some of these theoretical and technological concepts are examined-approaches based upon Einstein's General Theory of Relativity, spacetime curvature, superconductivity, and newer ideas where questions are raised regarding conservation theorems and if some of the governing laws of physics, as we know them, could be violated or are even valid. These conceptual ideas vary from traversable wormholes, Krasnikov tubes and Alcubierre's warpdrive to Electromagnetic (EM) field propulsion with possible hybrid systems that incorporate our current limited understanding of zero point fields and quantum mechanics.

Innovative Interstellar Explorer: Radioisotope Propulsion to the Interstellar Medium

41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2005

An interstellar "precursor" mission has been under discussion in the scientific community for over 25 years. Fundamental scientific questions about the interaction of the Sun with the interstellar medium can only be answered with in situ measurements that such a mission could provide. The Innovative Interstellar Explorer is a funded NASA Vision Mission Study that investigates the use of Radioisotope Electric Propulsion (REP) to enable such a mission. The problem is the development of a probe that can provide the required measurements and can reach a heliocentric distance of at least 200 astronomical units (AU) in a reasonable mission time. The required flyout speed in the direction of the inflowing interstellar medium is provided by a high-energy launch, followed by long-term, low-thrust, continuous acceleration. Trades from also using gravity assists have been studied along with trades between advanced Multi-mission radioisotope thermoelectric generators (MMRTGs) and Stirling radioisotope generators (SRGs), both powered by Pu-238. While subject to mass and power limitations for the instruments on board, such an approach relies on known General Purpose Heat Source (GPHS), Pu-238 technology and current launch vehicles for

Investigation of nuclear electric powered interstellar precursor missions

Acta Astronautica, 2011

Nuclear Electric Propulsion (NEP) is a technology conceptually proposed since the 1940s by E. Stuhlinger in Germany. The JIMO mission originally planned by NASA in the early 2000s produced at least two designs of ion thrusters fed by a 20-30 kW nuclear powerplant. When compared to conventional (chemical) propulsion, the major advantage of NEP in the JIMO context was recognized to be the much higher I sp (lab-tested at up to 15,000 s) and the capability for sustained power generation, up to 8-10 years when derated to I sp about 8000 s. The goal of this paper is to show that current or near term NEP technology enables missions far beyond our immediate interplanetary backyard. In fact, by extending the semi-analytical approach used by Stuhlinger, with reasonable ratios apower/mass of the propulsion system (i.e., 0.1-0.4 kW/kg), missions to the Kuiper Belt (40 AU and beyond) and even the so-called FOCAL mission (at 540 AU) become feasible with an attractive payload fraction and in times of order 10-15 years. Further results regarding missions to Sedna's perihelion/aphelion, and to Oort's cloud will also be presented, showing the constraints affecting their feasibility and mass budget.

Directed Energy Interstellar Propulsion of WaferSats

In the nearly 60 years of spaceflight we have accomplished wonderful feats of exploration and shown the incredible spirit of the human drive to explore and understand our universe. Yet in those 60 years we have barely left our solar system with the Voyager 1 spacecraft launched in 1977 finally leaving the solar system after 37 years of flight at a speed of 17 km/s or less than 0.006% the speed of light. As remarkable as this is, we will never reach even the nearest stars with our current propulsion technology in even 10 millennium. We have to radically rethink our strategy or give up our dreams of reaching the stars, or wait for technology that does not exist. While we all dream of human spaceflight to the stars in a way romanticized in books and movies, it is not within our power to do so, nor it is clear that this is the path we should choose. We posit a technological path forward, that while not simple; it is within our technological reach. We propose a roadmap to a program that will lead to sending relativistic probes to the nearest stars and will open up a vast array of possibilities of flight both within our solar system and far beyond. Spacecraft from gram level complete spacecraft on a wafer (" wafer sats ") that reach more than ¼ c and reach the nearest star in 15 years to spacecraft with masses more than 10 5 kg (100 tons) that can reach speeds of near 1000 km/s such systems can be propelled to speeds currently unimaginable with our existing propulsion technologies. To do so requires a fundamental change in our thinking of both propulsion and in many cases what a spacecraft is. In addition to larger spacecraft, some capable of transporting humans, we consider functional spacecraft on a wafer, including integrated optical communications, optical systems and sensors combined with directed energy propulsion. Since " at home " the costs can be amortized over a very large number of missions. The human factor of exploring the nearest stars and exo-planets would be a profound voyage for humanity, one whose non-scientific implications would be enormous. It is time to begin this inevitable journey beyond our home. Introduction We propose a system that will allow us to take the step to interstellar exploration using directed energy propulsion combined with miniature probes including some where we would put an entire spacecraft on a wafer to achieve relativistic flight and allow us to reach nearby stars in a human lifetime. With recent work on wafer scale photonics and directed energy, we can now envision combining these technologies to allow for a realistic approach of sending probes far outside our solar system and to nearby stars. By leaving the main propulsion system back in Earth orbit (or nearby) and propelling wafer scale highly integrated spacecraft that include cameras, bi-directional optical communications, power and other sensors we can achieve gram scale systems coupled with small laser driven sails to

Use of Mini-Mag Orion and superconducting coils for near-term interstellar transportation

Acta Astronautica, 2007

Interstellar transportation to nearby star systems over periods shorter than the human lifetime requires speeds in the range of 0.1-0.15 c and relatively high accelerations. These speeds are not attainable using rockets, even with advanced fusion engines because at these velocities, the energy density of the spacecraft approaches the energy density of the fuel. Anti-matter engines are theoretically possible but current physical limitations would have to be suspended to get the mass densities required. Interstellar ramjets have not proven practicable, so this leaves beamed momentum propulsion or a continuously fueled Mag-Orion system as the remaining candidates. However, deceleration is also a major issue, but part of the Mini-Mag Orion approach assists in solving this problem. This paper reviews the state of the art from a Phases I and II SBIT between Sandia National Laboratories and Andrews Space, applying our results to near-term interstellar travel. A 1000 T crewed spacecraft and propulsion system dry mass at .1 c contains ∼ 9×10 21 J. The author has generated technology requirements elsewhere for use of fission power reactors and conventional Brayton cycle machinery to propel a spacecraft using electric propulsion. Here we replace the electric power conversion, radiators, power generators and electric thrusters with a Mini-Mag Orion fission-fusion hybrid. Only a small fraction of fission fuel is actually carried with the spacecraft, the remainder of the propellant (macro-particles of fissionable material with a D-T core) is beamed to the spacecraft, and the total beam energy requirement for an interstellar probe mission is roughly 10 20 J, which would require the complete fissioning of 1000 ton of Uranium assuming 35% power plant efficiency. This is roughly equivalent to a recurring cost per flight of 3.0 billion dollars in reactor grade enriched uranium using today's prices. Therefore, interstellar flight is an expensive proposition, but not unaffordable, if the nonrecurring costs of building the power plant can be minimized.

The Path to Interstellar Flight

2020

Large scale directed energy offers the possibility of radical transformation in a variety of areas, including the ability to achieve relativistic flight that will enable the first interstellar missions as well as rapid interplanetary transit. In addition, the same technology opens a wide mission space that allows a diverse range of options from long range beamed power to remote spacecraft and outposts to planetary defense to remote composition analysis and manipulation of asteroids, among others. Directed energy relies on photonics, which like electronics is an exponentially expanding growth area driven by diverse economic interests that allows transformational advances in space exploration and capability. In order to begin to fully exploit this capability it is important to understand not only the possibilities enabled by it, but also the technological challenges involved and to have a logical roadmap to exploit this option. This capability is both synergistic with conventional pro...

Fission-based electric propulsion for interstellar precursor missions

This paper reviews the technology options for a fission-based electric propulsion system for interstellar precursor missions. To achieve a total AV of more than 100 km/s in less than a decade of thrusting with an electric propulsionsystemof 10,000s Isp requires a specificmass for the power systemof less than 35 kg/kWe.Three possible configurationsare described:(1) a UZrH-fueled,NaK-cooledreactor with a steamRankineconversionsystem,(2) a UNfueled gas-cooledreactor with a recuperatedBrayton conversion system, and (3) a UN-fieled heatpipe-cooledreactor with a recuperatedBrayton conversionsystem. All three of these systemshave the potential to meet the specificmass requirementsfor interstellarprecursormissionsin the near term. Advancedversionsof a fission-basedelectricpropulsion systemmighttravel as much as severallightyears in 200 years.