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Altair Lunar Lander

Altair Lunar LanderThe Altair lunar lander was a key component in the Bush Administration’s Constellation Program, a combination of spacecraft, launch vehicles and missions that would return human explorers to the moon and ultimately would allow them to explore other destinations in the solar system. As of 2008 it was planned that the Altair lunar lander would deliver crews and lunar surface system hardware to the moon by 2020, with its first test flight was scheduled for 2018.

Altair is named for the brightest star in the constellation Aquila (the Eagle), a tribute to the first Apollo lunar module that carried explorers Neil Armstrong and Buzz Aldrin to the moon in 1969. The word Altair originates from an Arabic term meaning “the flying one,” and it joins Orion and Ares as the vehicles of the Constellation program. Altair is a multi-role vehicle capable of landing crews of four astronauts anywhere on the lunar surface and supporting them for missions of up to seven days before returning them to orbit. In addition, Altair can deliver crew members to a lunar outpost facility and remain with them for up to six months, including delivery of up to 17 mt of cargo to support the buildup of the lunar outpost itself.

Each vehicle uses a common descent stage, with combinations of an ascent stage, an airlock and cargo added for specific missions. To accomplish its mission, Altair and its Earth departure stage will be launched into a low-Earth orbit using an Ares V launch vehicle, followed by a separate launch of an Orion spacecraft lifted by an Ares I launch vehicle. Once Altair and Orion rendezvous and dock in Earth orbit, the Earth departure stage ignites its engines to place the crew on a trans-lunar trajectory. After discarding the Earth departure stage, Altair takes over the duty of flying itself and Orion on the correct trajectory to the moon. Following a three-day coast, Altair’s descent engine is fired to bring the Orion-Altair stack into low lunar orbit. The crew then transfers into the lander, undocks from Orion and begins its decent to the lunar surface. The Orion vehicle remains unoccupied and parked in lunar orbit. The Altair descent propulsion system completes the 2.5-hour descent to the surface with a soft landing. The crew then transitions the vehicle for surface operations.

In the sortie mode, Altair can place the crew of four astronauts and up to 500 kg (1,100 pounds) of science equipment anywhere on the lunar surface and provide living quarters for the crew for up to seven days. Altair features an airlock to allow the crew to transition from its pressurized habitat to the dusty vacuum of the lunar surface. In outpost mode, Altair can deliver the four crew members to the site of a permanent lunar outpost, where it can loiter on the surface for up to 210 days, waiting to return the crew to lunar orbit at the end of their outpost stay. At the conclusion of the surface mission, the crew boards the Ascent Module with their collected science samples and begins a 2.5 hour ascent to the Orion module waiting for them in lunar orbit. The crew docks with Orion, transfers to Orion and disposes the ascent module. Orion’s service module engine ignites to place the crew on a trajectory towards home, and after a three-day journey toward Earth, the mission concludes with the Orion spacecraft parachuting back to the Earth’s surface.

The Altair lander also can be used to transport large cargo elements to the lunar surface. In cargo mode, the descent module is configured to autonomously land at a preselected site with up to 14,500 kg (31,900 pounds) of science equipment, lunar rovers, habitat modules, power systems, resource utilization equipment and outpost logistics. The ability to land large cargo elements is critical to the deployment of the lunar outpost.

NASA had maintained a core capability for lunar vehicle design since the conclusion of the Apollo missions. Apollo veterans are now assisting the next generation of engineers in the design of this next generation lunar lander. Since 2005, more than 100 lunar lander concepts have been studied, with the best features captured in the current Altair design. The present lunar lander bears some similarities to the Apollo lunar module, a result of the physics of spaceflight reflected in the design of the vehicle. Like Apollo, Altair is a two stage vehicle. The large descent module is a large propulsion stage consisting primarily of propellant tanks, a main engine, landing gear and supporting structure. The small ascent module contains the pressurized crew cabin, life support systems, docking systems, avionics, and the propellant and engine required for lunar ascent.

But where the physics of spaceflight has remained unchanged, technology has matured and Altair’s missions are well beyond what the Apollo system was capable of performing. Altair will feature current technology advances in advanced computers, guidance and navigation systems, composite structures, precision landing ability and high efficiency propulsion systems. Additionally, each Altair lander will double the crew size of Apollo’s lunar module, and more than double the sortie mission time spent on the lunar surface. Altair will also provide an airlock to allow split crew operations and to control lunar dust.

The Altair lunar lander Project Office comprised experts recruited from every NASA Center. The Altair Project Office was located at NASA’s Johnson Space Center, and also includes former Apollo astronauts and project managers, former Apollo Lunar Module engineers and managers, and NASA Mission Control veterans among its consultant team. The Altair team is utilizing an innovative “risk-informed” design process that allows the team to design a vehicle with the best safety and reliability characteristics. NASA planned to choose an industrial partner to construct the Altair lander.

Apollo Lunar Module Altair Lunar Lander
Crew Size (max) 2 4
Surface Duration (max) 3 days 7 days (Sortie missions),
Up to 210 days (Outpost missions)
Landing site capability Near side, equatorial Global
Stages 2 2
Overall height 7.04 m (23.1 ft.) 9.9 m (32.5 ft.)
Width at tanks 4.22 m (13.8 ft.) 8.8 m (28.9 ft.)
Width at footpads (diag.) 9.45 m (31 ft.) 14.9 m (48.9 ft.)
Crew module pressurized volume 6.65 m3 (235 cu. ft.) 17.5 m3 (618 cu. ft.) – crew module + airlock
Ascent Stage mass 4,805 kg (10,571 lbs.) 6141 kg (13,510 lbs.)
Ascent Stage engines 1 – UDMH-NTO 1 – MMH-NTO
Ascent engine thrust 15.6 Kn (3,500 lbf.) 24.5 Kn (5,500 lbf.)
Descent Stage mass 11,666 kg (25,665 lbs.) 37,045 kg (81,500 lbs.)
Descent Stage engines 1 – UDMH-NTO 1 – pump-fed, throttling, LOX/LH2
Descent engine thrust 44.1 Kn (9,900 lbf.) 83.0 Kn (18,650 lbf.)

Lunar Surface Access Module (LSAM)

Constellation Spiral 2 consisted of the Spiral 1 elements, or derivatives of those elements, plus the Earth Departure Stage (EDS) to transport elements to the lunar vicinity as well as the Lunar Surface Access Module (LSAM) that would provide the capability for the crew to access the lunar surface. The CEV would provide crew habitation from launch to lunar orbit and return to the Earth surface, including aborts during Earth ascent.

The EDS would provide the propulsive accelerations needed to transfer the various flight elements (CEV and LSAM) from Low Earth Orbit to lunar orbit and would provide the deceleration for lunar orbit insertion.

The EDS stage serves the same role as the Apollo S-IVB. The LSAM descent stage places the LSAM/CEV into lunar orbit.

The LSAM would provide the crew habitation and transportation functions from lunar orbit, to the lunar surface, and return back to lunar orbit. In addition, the LSAM would provide the capability for the crew to conduct science and perform routine EVA on the surface of the Moon.

The LSAM design has two basic parts. The descent stage is a four-legged platform with rocket engines that take the craft to the moon's surface. The ascent stage serves as a crew compartment and carries the crew back to lunar orbit when their mission is complete. The LSAM had a horizontal layout that put the airlock hatch close to the ground. This eases the task of unloading cargo from the cargo variant.

The lander would remain on the lunar surface for about a week. An airlock would allow a crew of four astronauts to leave the ship. The lander had only two astronauts during the Apollo missions. The craft is designed to carry up to 23 tons of cargo and could be used to rotate crews living at a lunar base.

The ascent stage engines are designed to burn liquid-methane propellant. This would be a test for future missions to Mars, since small amounts of methane are thought to be present in Mars' atmosphere. Mars mission astronauts might be able to produce their own rocket fuel instead of carrying it with them. Unlike Apollo, the robust vehicle was not the CEV [the CSM-equivalent], but the LSAM [the LEM-equivalent]. The CEV is designed primarily for Earth-orbital station operations, so lunar-related capacities would be wasted if it flown to the Station on every mission.

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Page last modified: 26-03-2019 18:35:09 ZULU