Like those of the Apollo Program, Constellation program missions would involve its main vehicle, the Orion spacecraft, flying missions in
low Earth orbit to service the International Space Station, and in conjunction with the
Altair and
Earth Departure Stage vehicles, on crewed flights to the polar regions of the Moon. There were no well-defined plans at the time of cancelation for a crewed flight to
Mars, the ultimate goal of the project, but a
mission to a Near-Earth asteroid was in the initial planning phase as of 2008.
International Space Station and low-Earth orbit flights After being manufactured at private plants, the parts of the Ares I/Orion stack would be tested and assembled at the
Vehicle Assembly Building at the
Kennedy Space Center. Once assembly was completed and a launch date was set, the
crawler-transporter would transport the completed stack, along with the launch support tower and the
Mobile Launcher-1, out to
LC-39B. Once the crawler-transporter reached the pad, the stack and the Launcher Platform would be left in place and the crawler-transporter removed to a safe distance. After final safety checks, the ground crew would fill up the second stage with liquid hydrogen (LH2) and liquid oxygen (LOX) fuel, and the crew, wearing
all-purpose spacesuits, would enter the spacecraft three hours before liftoff. Once they were locked in, and after all systems were cleared by controllers at both the Cape and
Mission Control in Houston, the Ares I would then launch. After a two-day orbital chase, the
Orion spacecraft, having jettisoned much of the initial stack during takeoff, would meet with the
International Space Station. After getting the go ahead from Houston, Orion would then dock with the ISS. The six-man crew (at a maximum) would then enter the station in order to perform numerous tasks and activities for the duration of their flight, usually lasting six months, but possibly shortened to four or lengthened to eight, depending upon NASA's goals for that particular mission. Once completed, the crew would then reenter the Orion, seal itself off from the ISS, and then undock from the station. Once the Orion reached a safe distance from the ISS, the Command Module (after having jettisoned the disposable service module) would re-enter in the same manner as all NASA spacecraft prior to the Shuttle, using the ablative heat shield to both deflect heat from the spacecraft and to slow it down from a speed of to . After reentry was completed, the forward assembly would be jettisoned, and two drogue parachutes released, followed at by three main parachutes and airbags filled with nitrogen (N2), which does not combust when exposed to heat, allowing the spacecraft to splashdown. The Command Module would then be returned to Kennedy Space Center for refurbishment for a later flight. Unlike the Apollo CM, which was used only for one flight, an Orion CM could theoretically be used up to ten times under normal operating conditions.
Lunar sortie flights in lunar orbit Unlike the Apollo missions, where both the
Apollo command and service module and the
Apollo Lunar Module were launched together on the
Saturn V rocket, the crewed Orion spacecraft would be launched separately from the uncrewed
EDS and lunar lander. The Ares V/Altair stack would be assembled at the
Vehicle Assembly Building and then transported to
LC-39A, and the Ares M/Orion stack would be transported to the adjacent Pad 39B. The Ares V/EDS/Altair stack would be launched first, into a high circular orbit. Approximately 90 minutes later, the Ares I/Orion would then launch with the crew into a nearly identical orbit. The Orion would then
rendezvous and dock with the Altair/EDS combination already in low-Earth orbit. After the necessary preparations for lunar flight, the EDS would fire for 390 seconds in a
translunar injection (TLI) maneuver, accelerating the spacecraft to . After this burn, the EDS would be jettisoned. During the three-day trans-lunar coast, the four-man crew would monitor the Orion's systems, inspect their Altair spacecraft and its support equipment, and correct their flight path as necessary to allow the Altair to land at a near-polar landing site suitable for a future lunar base. Approaching the lunar far side, the Orion/Altair combination would orient the Altair's engines forward and make the
lunar orbit insertion (LOI) burn. Once in lunar orbit, the crew would refine the trajectory and configure the Orion spacecraft for uncrewed flight, allowing all four crew members to transfer to the Altair vehicle and land on the Moon, while the Orion waits for their return. Upon receiving clearance from Mission Control, the Altair would undock from the Orion and perform an inspection maneuver, allowing ground controllers to inspect the spacecraft via live TV mounted on Orion for any visible problems that would prevent landing (on Apollo this was done by the Command Module Pilot). After receiving approval from ground controllers, the two craft would separate to a safe distance and the Altair's descent engines would fire again for powered descent to a pre-determined landing spot previously selected by
uncrewed spacecraft. Upon landing, the crew would put on their
extravehicular activity (EVA) spacesuits and commence the first of five to seven lunar EVAs, collecting samples and deploying experiments. After completing their Lunar Sortie operations, the crew would then enter the Altair and fire the ascent stage engine to lift off from the surface, using the descent stage as a launchpad (and leaving it as a platform for future base construction). Upon entering orbit, the Altair would rendezvous and dock with the waiting Orion spacecraft, and the crew would then transfer, along with samples collected on the Moon, back to the Orion. After jettisoning the Altair, the crew would perform the
Trans Earth Injection (TEI) burn for the return trip to Earth. After a two-and-a-half-day coast, the crew would jettison the Service Module (allowing it to burn up in the atmosphere) and the CM would reenter the Earth's atmosphere using a special reentry trajectory designed to slow the vehicle from its speed of to and thus allow a Pacific Ocean splashdown. The Crew Module would then be flown back to Kennedy Space Center for refurbishment, while lunar samples would be routed to the
Johnson Space Center's (JSC)
Lunar Receiving Laboratory for analysis.
Orion asteroid mission The
Orion Asteroid Mission was a proposed NASA mission to a
near-Earth asteroid (NEA) which would use the standard
Orion spacecraft, and a landing module based on a modified
Altair lunar lander. Most of its specific details are now deprecated by the cancellation of the Constellation Program and related designs. Such a mission could assess the potential value of water, iron, nickel, platinum and other resources on the asteroid; test possible ways to extract them; and possibly examine or develop techniques which could be used to protect the Earth from
asteroid impacts. This would be the first crewed mission to any extraterrestrial body besides the Moon, and would represent a step towards a
human mission to Mars. The mission would start in a similar fashion to the
lunar landing mission described above, using an Ares V to launch the landing module into
Low Earth orbit, followed by the launch of an Orion spacecraft, with a two- or three-person crew (as opposed to a four-person crew for lunar missions) on an Ares I rocket. Once the Orion spacecraft docked with the landing module and the
Earth Departure Stage (EDS), the EDS would then fire again and propel the Orion spacecraft to a nearby near-Earth asteroid where the crew would then land and explore its surface. Once the task was completed, the Orion spacecraft would then depart from the asteroid and, upon reaching the vicinity of Earth, would jettison both the
service module and the landing module in a manner similar to that of
Apollo 13 before entering the atmosphere for a Pacific Ocean splashdown.
Orion Mars mission The ultimate goal of NASA's Constellation program was a crewed mission landing humans on
Mars in the 2030s as a spiritual successor to the
Apollo Applications Program in the 1960s. The mission would utilize the hardware of the Constellation Project, primarily the Orion spacecraft (or a variation based on the Orion), and the Ares V cargo-launch vehicle. A design study utilizing Constellation launch vehicles, known as
Design Reference Architecture 5.0, was completed in 2009. In DRA 5.0, a Mars mission would have involved multiple launches of an Ares V rocket, as well as an Ares I to launch the crew. In the first Mars
launch window, two cargo payloads would be launched into Earth orbit, as well as a
nuclear thermal rocket stage for each payload, in order to boost them to Mars. Alternatively, chemical (specifically liquid hydrogen/liquid oxygen) propellant stages could have been used, although this would have required more launches. One cargo payload would include a Mars Ascent Vehicle (MAV), as well as
In-situ resource utilization equipment to generate propellant for the MAV. The second cargo payload would be a habitat that the astronauts would live in during the stay on the surface. In the next launch window, 26 months after the first, the crew would go to Mars in an interplanetary transfer vehicle with nuclear thermal rocket and propellant modules assembled in Earth orbit. Once at Mars, the crew would rendezvous with the Mars habitat in orbit, land on Mars, and explore for 500 days. The crew would use the MAV to return to their interplanetary vehicle in Mars orbit, which would then be used to return to Earth. The mission would conclude with the re-entry and landing of the Orion capsule.
Justification for a return to the Moon NASA lists a number of reasons for a human return to the Moon on its website: • to extend human
colonization, • to further pursue
scientific activities intrinsic to the Moon, • to test new technologies, systems, flight operations and techniques to serve future
space exploration missions, • to provide a challenging, shared and peaceful activity to unite nations in pursuit of common objectives, • to expand the economic sphere while conducting research activities that benefit our home planet, • to engage the public and students to help develop the high-technology workforce that will be required to address the challenges of tomorrow. In the words of former NASA Administrator,
Michael D. Griffin, "The goal isn't just scientific exploration.... It's also about extending the range of human habitat out from Earth into the
Solar System as we go forward in time.... In the long run a single-planet species will not survive.... If we humans want to survive for hundreds of thousands or millions of years, we must ultimately populate other planets ... colonize the Solar System and one day go beyond." A report published in June 2014 by the
US National Academy of Sciences called for clear long-term space goals at NASA. The report said that the agency's current course invited "failure, disillusionment, and [loss of] the longstanding international perception that human space-flight is something that the United States does best." The report recommended that Mars be the next major goal of human space flight. Several possible paths for reaching the planet by 2037 were explored in the report, which noted that returning to the Moon would offer "significant advantages" as an intermediate step in the process. The
National Space Society (NSS), a private nonprofit, regards a return to the Moon as a high priority for the US space program, in order to develop the body of scientific knowledge of the Moon, particularly in regards to its potential for the creation of new industries, in order to provide further funding for further space exploration. ==Budget and cancellation==