Interplanetary spaceflight or interplanetary travel is the crewed or uncrewed travel between stars and planets, usually within a single planetary system. In practice, spaceflights of this type are confined to travel between the planets of the Solar System. Uncrewed space probes have flown to all the observed planets in the Solar System as well as to dwarf planets Pluto and Ceres, and several asteroids. Orbiters and landers return more information than fly-by missions. Crewed flights have landed on the Moon and have been planned, from time to time, for Mars and Venus. While many scientists appreciate the knowledge value that uncrewed flights provide, the value of crewed missions is more controversial. Science fiction writers propose a number of benefits, including the mining of asteroids, access to solar power, and room for colonization in the event of an Earth catastrophe.
Mars Direct is a proposal for a human mission to Mars which purports to be both cost-effective and possible with current technology. It was originally detailed in a research paper by Martin Marietta engineers Robert Zubrin and David Baker in 1990, and later expanded upon in Zubrin's 1996 book The Case for Mars. It now serves as a staple of Zubrin's speaking engagements and general advocacy as head of the Mars Society, an organization devoted to the colonization of Mars.
The Constellation program was a crewed spaceflight program developed by NASA, the space agency of the United States, from 2005 to 2009. The major goals of the program were "completion of the International Space Station" and a "return to the Moon no later than 2020" with a crewed flight to the planet Mars as the ultimate goal. The program's logo reflected the three stages of the program: the Earth (ISS), the Moon, and finally Mars—while the Mars goal also found expression in the name given to the program's booster rockets: Ares. The technological aims of the program included the regaining of significant astronaut experience beyond low Earth orbit and the development of technologies necessary to enable sustained human presence on other planetary bodies.
The Vision for Space Exploration (VSE) was a plan for space exploration announced on January 14, 2004 by President George W. Bush. It was conceived as a response to the Space Shuttle Columbia disaster, the state of human spaceflight at NASA, and as a way to regain public enthusiasm for space exploration.
The hypothetical colonization of Mars has received interest from public space agencies and private corporations, and has received extensive treatment in science fiction writing, film, and art.
The Space Transportation System (STS), also known internally to NASA as the Integrated Program Plan (IPP), was a proposed system of reusable crewed space vehicles envisioned in 1969 to support extended operations beyond the Apollo program.. The purpose of the system was two-fold: to reduce the cost of spaceflight by replacing the current method of launching capsules on expendable rockets with reusable spacecraft; and to support ambitious follow-on programs including permanent orbiting space stations around the Earth and Moon, and a human landing mission to Mars.
The Exploration Systems Architecture Study (ESAS) is the official title of a large-scale, system level study released by the National Aeronautics and Space Administration (NASA) in November 2005 in response to American president George W. Bush's announcement on January 14, 2004 of his goal of returning astronauts to the Moon and eventually Mars — known as the Vision for Space Exploration. The Constellation Program was cancelled in 2010 by the Obama Administration and replaced with the Space Launch System, later renamed as the Artemis Program in 2017 under the Trump Administration.
In orbital mechanics, a free-return trajectory is a trajectory of a spacecraft traveling away from a primary body where gravity due to a secondary body causes the spacecraft to return to the primary body without propulsion.
In space exploration, in situ resource utilization (ISRU) is the practice of collection, processing, storing and use of materials found or manufactured on other astronomical objects that replace materials that would otherwise be brought from Earth.
The Ares V was the planned cargo launch component of the cancelled NASA Constellation program, which was to have replaced the Space Shuttle after its retirement in 2011. Ares V was also planned to carry supplies for a human presence on Mars. Ares V and the smaller Ares I were named after Ares, the Greek god of war.
NASA Design Reference Mission 3.0 was a NASA study for a human space mission to the planet Mars in the 1990s. It was a plan for a human exploration architecture for Mars, and was released in 1998 as an addendum to the early design plans released in 1994. The plan is for a series of multiple launches to send various space transpiration, surface exploration hardware, and human crew to Mars, and to return the crew to Earth in the early 21st century. Various technologies are explored to launch the payloads into space, to send them to Mars, and to reduce overall weight of the mission by various technologies or techniques including nuclear, solar, aerobraking, and in-situ resource use.
The idea of sending humans to Mars has been the subject of aerospace engineering and scientific studies since the late 1940s as part of the broader exploration of Mars. Some have also considered exploring the Martian moons of Phobos and Deimos. Long-term proposals have included sending settlers and terraforming the planet. Proposals for human missions to Mars came from e.g. NASA, Russia, Boeing, SpaceX, and the Inspiration Mars Foundation. As of 2021, only rovers have been on Mars. The farthest humans have been beyond Earth is the Moon.
A parking orbit is a temporary orbit used during the launch of a spacecraft. A launch vehicle boosts into the parking orbit, then coasts for a while, then fires again to enter the final desired trajectory. The alternative to a parking orbit is direct injection, where the rocket fires continuously until its fuel is exhausted, ending with the payload on the final trajectory. The technology was first used by the Soviet Venera 1 mission to Venus.
The NASA Mars Design Reference Mission ("DRM") refer to a series of NASA conceptual design studies of the missions to send humans to Mars. The related term, Design Reference Architecture (DRA), refers to the entire sequences of missions and supporting infrastructure.
An orbital propellant depot is a cache of propellant that is placed in orbit around Earth or another body to allow spacecraft or the transfer stage of the spacecraft to be fueled in space. It is one of the types of space resource depots that have been proposed for enabling infrastructure-based space exploration. Many different depot concepts exist depending on the type of fuel to be supplied, location, or type of depot which may also include a propellant tanker that delivers a single load to a spacecraft at a specified orbital location and then departs. In-space fuel depots are not necessarily located near or at a space station.
Space architecture is the theory and practice of designing and building inhabited environments in outer space. This mission statement for space architecture was developed at the World Space Congress in Houston in 2002 by members of the Technical Aerospace Architecture Subcommittee of the American Institute of Aeronautics and Astronautics (AIAA). The architectural approach to spacecraft design addresses the total built environment. It is mainly based on the field of engineering, but also involves diverse disciplines such as physiology, psychology, and sociology.
Mars to Stay missions propose astronauts sent to Mars for the first time should intend to stay. Unused emergency return vehicles would be recycled into settlement construction as soon as the habitability of Mars becomes evident to the initial pioneers. Mars to Stay missions are advocated both to reduce cost and to ensure permanent settlement of Mars. Among many notable Mars to Stay advocates, former Apollo astronaut Buzz Aldrin has been particularly outspoken, suggesting in numerous forums "Forget the Moon, Let’s Head to Mars!" and, in June 2013, Aldrin promoted a crewed mission "to homestead Mars and become a two-planet species". In August 2015, Aldrin, in association with the Florida Institute of Technology, presented a "master plan", for NASA consideration, for astronauts, with a "tour of duty of ten years", to colonize Mars before the year 2040. The Mars Underground, Mars Homestead Project / Mars Foundation, Mars One, and Mars Artists Community advocacy groups and business organizations have also adopted Mars to Stay policy initiatives.
The space policy of the Barack Obama administration was announced by U.S. President Barack Obama on April 15, 2010, at a major space policy speech at Kennedy Space Center. He committed to increasing NASA funding by $6 billion over five years and completing the design of a new heavy-lift launch vehicle by 2015 and to begin construction thereafter. He also predicted a U.S.-crewed orbital Mars mission by the mid-2030s, preceded by the Asteroid Redirect Mission by 2025. In response to concerns over job losses, Obama promised a $40 million effort to help Space Coast workers affected by the cancellation of the Space Shuttle program and Constellation program.
SpaceX's Mars program is a development program initiated by Elon Musk and SpaceX in order to facilitate the eventual colonization of Mars. The program includes fully reusable launch vehicles, human-rated spacecraft, on-orbit propellant tankers, rapid-turnaround launch/landing mounts, and local production of rocket fuel on Mars via in situ resource utilization (ISRU). SpaceX's aspirational goal has been to land the first humans on Mars by 2024, but in October 2020 Elon Musk named 2024 as goal for an uncrewed mission. At the Axel Springer Award 2020 Elon Musk said that he is highly confident that the first crewed flights to Mars will happen in 2026.
The International Lunar Resources Exploration Concept (ILREC) was a proposed mission architecture under President George H. W. Bush's Space Exploration Initiative (SEI) by Kent Joosten, an engineer at Johnson Space Center. The plan would have used the help of international partners, mainly the Soviet Union, to assemble a lunar base and sustainable lunar transportation service.
