How Does NASA Practice Landing on the Moon? - Smarter Every Day 252

The moon's gravity is 1/6th of Earth's gravity, creating different control problems for spacecraft compared to Earth's 1g environment

• Lunar Lander Research Facility • Lunar Landing Training Vehicle (LLTV) • Multiple training locations used by Apollo astronauts

Neil Armstrong developed an algorithm in his head from flying the Lunar Lander Test Vehicle that he used during his descent to the lunar surface

Today's approach uses robotic test vehicles that can be loaded with different software and flown repeatedly with simulated lunar gravity

Early 2010s NASA program using small robotic landers to test algorithms and sensors for lunar missions

• Crawl phase: Cold Gas Test Article with compressed air for 10 seconds of flight time • Walk phase: Mighty Eagle using 90% hydrogen peroxide fuel • Run phase: Advanced testing with hazard avoidance systems

90% hydrogen peroxide is a green propellant that decomposes when passed over silver and nickel catalyst screens, producing steam and thrust without toxic byproducts

Cold Gas Test Article completed over 100 flights in nine months, successfully validating the approach before moving to the more complex Mighty Eagle

An Earth Gravity Canceling thruster offsets 5/6ths of the vehicle's weight on Earth to simulate lunar gravity where the vehicle weighs only 1/6th as much

• Earth Gravity Canceling thruster: Variable throttle, continuously offsets gravity • Descent thrusters: Three pulse thrusters that lift and lower the vehicle • Attitude Control System thrusters: Twelve total thrusters for orientation and rotation

Inertial Measurement Unit provides the vehicle's inner ear with accelerometers and gyroscopes on each axis to sense movement and send commands to thrusters

The vehicle adjusts throttle during flight based on fuel consumption estimates because as it burns propellant, it must reduce thrust to maintain simulation accuracy

New hardware or software is first tested while tethered to the ground with soft stops as dampeners, then freed for untethered flight if successful

• Tethers attached at multiple lifting points prevent uncontrolled flight • Soft stops with nylon dampeners absorb shock if tether becomes taut • Steel cable backup prevents injury from sudden stops

Pre-flight operations conducted from a blockhouse with scripted procedures including safe and arm keys, airspace clearance, and coordinated team communication

The tethered test confirmed the new control system was safe, validating the vehicle's ability to hover and maneuver before proceeding to hazard avoidance testing

Neil Armstrong had to avoid craters and hazards when landing Apollo 11, requiring pilots to make real-time decisions about landing site safety

• Custom terrain field with volcanic ash from Arizona crater • Field included craters and boulders to simulate lunar surface • Vehicle altitude: approximately 30-50 meters for testing

Two onboard cameras with stereo vision provide three-dimensional sight like human eyes, allowing the vehicle to identify safe landing areas and avoid hazards

Mighty Eagle successfully tested algorithms and sensors for lunar missions and developed subject matter expertise that had been absent since the 1970s

Morpheus was developed at Johnson Space Center and conducted flights at Kennedy Space Center with different design philosophy than Mighty Eagle

• Morpheus lacked an Earth Gravity Canceling thruster • Used different propellant and sensor systems • Designed more for human lander applications versus robotic

Since 2013, Mighty Eagle and Morpheus teams consolidated into unified NASA lander expertise group working on various lander technologies

All lander development work feeds into Artemis program to return humans to the moon, with Human Landing System being the crewed component

While software test beds like Mighty Eagle prove control algorithms, astronauts must have stick time flying landers in 1/6g lunar gravity to make real-time decisions

• Software testbeds validate algorithms before human involvement • Modern stability augmentation systems make landing easier • Humans needed for real-time override when unexpected situations occur

NASA released a Request for Information about building a new lunar lander test vehicle with modern technology like drones and electric propellers

Artemis astronauts must experience piloting a vehicle in 1/6g environment because the changed angles and dynamics fundamentally alter how to land safely