Page No. 104/20/23

On The Need for Lunar Lander Simulations: A Human Factors Perspective

Robert S. McCann

Human-Systems Integration Division

NASA Ames Research Center

Go For Lunar Landing Conference

March 5 2008

Page No. 204/20/23

Human Factors of Lunar Landing Simulations

Apollo: all landings near-side equatorialo LEM operations concept heavily dependent on real-time communications

loop with the ground

Preliminary Altair Concept of Operations:o Anywhere, anytime landing capabilities

o Includes polar and far-side targets

Strong possibility of autonomous descent and landing operations requirement

Page No. 304/20/23

Lunar Lander Descent and Landing Operations

Inner-loop Flight Control

Trajectory Management

Systems Health Management

Mission Decision Making

What is the workload associated with the task?

What are the task related crew-vehicle interfaces?

Page No. 404/20/23

Lessons Learned from Apollo 11 Operations: Workload

Apollo Operational Workload Assessment:

“The most difficult part [of the entire mission] from my perspective, and the one that gave me the most pause, was the final descent to landing”

“far and away the most complex part of the flight”

“systems were very heavily loaded at that time”

“the unknowns were rampant”

“there were just a thousand things to worry about… It was hardest for the system and it was hardest for the crews to complete that part of the flight successfully”

- Neil Armstrong, September 2001

Page No. 504/20/23

Apollo 11 LEM Descent and Landing Operations

102:38:26 Armstrong: (With the slightest touch of urgency) Program Alarm.

102:38:30 Armstrong: (To Houston) It's a 1202.

102:38:32 Aldrin: 1202. (Pause)

102:38:42 Armstrong (on-board): (To Buzz) What is it?

(To Houston) Give us a reading on the 1202 Program Alarm.

102:38:53 Duke: Roger. We got you...(With some urgency in his voice)

“We're Go on that alarm.”

Page No. 604/20/23

Apollo 11 Operations

“Our most knowledgeable NASA software engineer advised Mission Control to inform the astronauts to push on. It was a gutsy call.”

- Fred H. Martin, M.I.T. Instrumentation Laboratory

“I was very much in the dark when this came up.”

- Buzz Aldrin

Systems Health Management

Mission Decision Making

Page No. 704/20/23

Apollo LEM Operations

Second Malfunction: Descent and Landing Phase

Inner-loop Flight Control

Trajectory Management

Systems Health Management

Mission Decision Making

Page No. 804/20/23

Lessons Learned from Apollo 11 Operations

102:44:45 Aldrin: 100 feet, 3 1/2 down, 9 forward. Five percent (fuel remaining). Quantity light.

• Quantity light indicated that 5.6% of the original propellant load remained • Started a 94-second countdown to a 'Bingo' fuel call which meant ‘land in 20 seconds or abort’ • If you're 50 feet up at 'bingo fuel' with all of your horizontal rates nulled and are coming down to a good spot, you could certainly continue to land… At anything over 100 feet, you'd punch the abort button and say goodbye to the moon

• Quantity light was based on erroneous sensor reading

Page No. 904/20/23

Lessons Learned from Apollo 11 Operations

• “As we got lower, the visibility continued to decrease.

• The thing that was confusing to me was that it was hard to pick out what your lateral and downrange velocities were, because you were seeing a lot of moving dust that you had to look through to pick up the stationary rocks and base your translational velocity decisions on that.

• I found that to be quite difficult.

• As we approached the ground, I still had a left translational rate which made me reluctant to shut the engine off while I still had that rate. I was also reluctant to slow down my descent rate anymore than it was, or stop (the descent), because we were close to running out of fuel. We were hitting our abort limit."

- Neil Armstrong

Page No. 1004/20/23

Lessons Learned from Apollo 11 Operations

• Workload with Apollo’s (or even shuttle’s) level of onboard decision-making and systems management support could very likely have overloaded the crew

• Autonomous operational concept for descent/landing requires the development of various forms of onboard decision support tools:

• Systems health management tools (e.g. Advanced Caution and Warning System)

•Automated flight control tools

•Automated mission management support tools

Page No. 1104/20/23

Lessons Learned from Apollo 11 Operations

• Infusing automated support tools for autonomous descent and landing operations raises a host of operational concept definition issues, such as:

• Determining the appropriate crew-machine functional allocation (level of automation) from the well-known levels of automation scales (e.g., Sheridan-Verplank)

• Designing crew interfaces with automation to

• A) enable crew to maintain situation awareness of automated actions and their causes

• B) enable smooth reversion to manual control in the event of automation failure

• Promoting effective crew resource management

Page No. 1204/20/23

Altair Ops Concepts Definition

• These operational concept development issues create an urgent need to design, develop, test, and validate:

• Decision support software

• Autonomous operational concepts that involve the decision support software via human-in-the-loop simulation

• Failure to do so in a timely manner raises considerable risk that autonomous descent and landing operations will fail constellation human-system integration requirements for operational error and crew workload