Introduction

Welcome to Apollo Lander, the Emulator.ca Systems lunar module descent simulator.

On July 20, 1969, two men guided a fragile spacecraft named Eagle through the final thirteen minutes of powered descent to the lunar surface. Their guidance computer threw alarms. Their intended landing site was strewn with boulders. Their fuel gauge crept toward empty. And yet, at 4:17 PM Eastern Time, Neil Armstrong radioed six words that changed history: "Houston, Tranquility Base here. The Eagle has landed."

Apollo Lander puts you in the commander's seat for those thirteen minutes. Choose from any of the six successful Apollo lunar landings -- Apollo 11 through Apollo 17 (excluding the ill-fated Apollo 13) -- and face the unique challenges each mission encountered. Manage the Apollo Guidance Computer's programmes, respond to alarms, control your descent rate, and nurse your fuel supply as the lunar surface rushes up to meet you.

The simulation models simplified but educational physics: lunar gravity at 1.62 m/s squared, the throttleable Descent Propulsion System, fuel consumption rates based on actual LM specifications, and a three-phase descent profile matching the real AGC programmes (P63 braking, P64 approach, P66 landing). Historical events are woven into each mission -- the 1202 alarms of Apollo 11, the lightning strike aftermath of Apollo 12, the abort switch malfunction of Apollo 14 -- and procedural events add replayability even to missions you have flown before.

Inspired by the BBC's 13 Minutes to the Moon podcast, this simulator is equal parts game, history lesson, and tribute to the extraordinary men and women who made Apollo possible.

Quick Start

1. Dial the Apollo line: ATDT555-1969
2. Press ENTER at the welcome screen
3. Select a mission (1-6) -- Apollo 11 is recommended for first-time players
4. Select a difficulty -- Training mode gives you extra fuel and fewer alarms
5. Read the mission briefing and note the descent controls
6. Type GO at the pre-PDI checklist to ignite the descent engine
7. Monitor your descent -- the autopilot handles most of the flying
8. Respond to events when alarms and situations demand your attention

Getting Connected

Dialling 555-1969 connects you to the Apollo Lander simulator. The system presents the programme title and awaits your input.

Connection Settings

The simulator uses ANSI escape codes for its real-time flight display. A VT100-compatible terminal is required for proper rendering.

Mission Selection

After the welcome screen, you choose which Apollo mission to fly. Six missions are available, each with a unique landing site, crew, and set of historical challenges.

Available Missions

Apollo 15's approach through the Apennine Mountains and along a kilometre-deep rille makes it the most demanding landing site. Apollo 12's flat terrain at the Ocean of Storms is the most forgiving.

Difficulty Levels

After selecting a mission, choose a difficulty level that modifies fuel supply, event frequency, and alarm rate.

Training mode is ideal for learning the mechanics. You have ample fuel reserves and events are rare, letting you focus on understanding the descent profile.

Historical mode recreates the actual mission parameters. Events fire at their historical probability. This is the intended experience once you understand the controls.

Nightmare mode is for those who want to test their mettle. Fuel is scarce, events are frequent, and alarms are relentless. Good luck, Commander.

Mission Briefing

Before descent, the simulator displays a briefing for your selected mission:

• Crew: Commander (CDR), Lunar Module Pilot (LMP), Command Module Pilot (CMP)
• Callsigns: LM and CM callsigns (e.g., Eagle and Columbia)
• Landing Site: Target location on the lunar surface
• Historical context: Mission-specific flavour text

The briefing also lists your descent controls, which are single-key commands active during flight.

The Descent

Pre-PDI Checklist

Before Powered Descent Initiation, the simulator runs through a systems checklist:

• LM systems nominal
• AGC loaded with P63 (Braking Phase programme)
• Descent engine armed
• Landing radar on standby
• Fuel quantity confirmed

Houston gives you the "GO for PDI" callout. Type GO to ignite the descent engine and begin the simulation.

Flight Display

Once descent begins, the screen switches to a compact real-time display showing:

• Altitude -- Distance above the lunar surface
• Descent Rate -- Vertical velocity (negative = descending)
• Horizontal Velocity -- Forward speed toward the landing site
• Fuel Remaining -- Percentage and estimated time
• Throttle -- Current engine throttle setting
• Phase/Programme -- Current AGC programme (P63, P64, or P66)
• Mission Time -- Seconds since PDI
• Mode -- AUTO or MANUAL
• Callouts -- Mission Control communications and alerts

The display updates once per second in real time.

Descent Phases

The descent follows three phases matching the real Apollo Guidance Computer programmes:

P63 -- Braking Phase (15,000 m to 2,300 m)

The longest phase. The descent engine fires at high throttle, pitched nearly horizontal to kill orbital velocity. The autopilot manages a controlled descent rate while bleeding off horizontal speed.

• Duration: several minutes
• Throttle: moderate to high (20%-90%)
• Attitude: mostly horizontal, gradually pitching upright

P64 -- Approach Phase (2,300 m to 150 m)

The LM pitches upright, giving the crew their first visual look at the landing site. The Landing Point Designator (LPD) allows the commander to evaluate the terrain.

• Duration: about one minute
• Throttle: moderate (15%-75%)
• Attitude: transitioning to near-vertical

P66 -- Landing Phase (150 m to touchdown)

Final descent with fine rate-of-descent control. The commander has direct control of descent rate. This is where Armstrong took manual control during Apollo 11 to fly past the boulder field.

• Duration: 30-90 seconds
• Throttle: near hover (10%-60%)
• Attitude: nearly vertical

Flight Controls

During descent, single-key commands are active (no ENTER required):

Autopilot vs. Manual

In AUTO mode, the AGC guidance programmes control throttle and pitch automatically. The autopilot follows the standard descent profile and will land the LM if no events intervene.

In MANUAL mode, you control the throttle directly with + and -. The autopilot still manages pitch angle, but thrust is entirely in your hands. Manual mode is essential when the autopilot's landing point is unsafe (boulder fields, crater rims).

Events and Alarms

Events are the heart of the simulation. They interrupt the descent and demand your response. There are two categories:

Historical Events

Each mission includes events that actually occurred during the real landing. These fire at their historical time offset from PDI:

Procedural Events

Random events from a pool of possible situations add variety and replayability:

• Computer Alarms (1201, 1202, gimbal lock) -- usually safe to continue
• Mechanical Issues (throttle lag, RCS anomaly) -- monitor, do not overreact
• Guidance Problems (radar lock lost, LPD error) -- patience is usually correct
• Communication Issues (static, uplink failure) -- continue on onboard systems
• Terrain Hazards (boulder fields, crater rims, dust) -- manual control or redesignate

Responding to Events

When an event triggers, the simulation pauses and displays:

1. Event name and severity (colour-coded)
2. AGC alarm code (if applicable)
3. Description of the situation
4. Available response options
5. Time limit (if any)

Type your response exactly as shown in the options list and press ENTER.

Correct responses allow the descent to continue normally. Incorrect responses trigger consequences: fuel loss, time delays, forced abort, or even a crash. No response within the time limit is treated as an incorrect response.

Landing

Safe Landing Criteria

To land successfully, the LM must touch down with:

• Vertical velocity below 3.0 m/s
• Horizontal velocity below 2.0 m/s

Landing Ratings

Scoring

Your final score is based on:

The score is displayed after a successful landing along with your fuel remaining and distance from the target.

Pause Menu

Press P during descent to pause the simulation. The pause menu displays current status and offers three options:

Aborting from the pause menu stages the ascent engine and initiates rendezvous with the Command Module. The crew is safe, but the landing is scrubbed.

After Landing

Whether you land, crash, or abort, the post-flight screen offers three choices:

Command Reference

Menu Navigation (ENTER required)

Mission Select     1-6        Select Apollo mission
Difficulty Select  1-3        Training / Historical / Nightmare
Pre-PDI            GO         Initiate powered descent
Event Response     (varies)   Type the response option shown
Post-Flight        1-3        Replay / New Mission / Disconnect

Flight Controls (single keypress, no ENTER)

P       Pause / Resume
M       Toggle Auto / Manual mode
+       Increase throttle 10% (manual only)
-       Decrease throttle 10% (manual only)
A       Abort mission

Quick Reference Card

+=====================================================+
|         APOLLO LANDER QUICK REFERENCE               |
+=====================================================+
|                                                     |
| FLIGHT CONTROLS (no ENTER needed)                   |
| ──────────────────────────────────────────────────  |
| P  Pause/Resume        M  Toggle Auto/Manual        |
| +  Throttle up 10%     -  Throttle down 10%         |
| A  Abort mission                                    |
|                                                     |
| DESCENT PHASES                                      |
| ──────────────────────────────────────────────────  |
| P63  Braking    15,000m - 2,300m   Kill velocity    |
| P64  Approach    2,300m - 150m     Visual acq.      |
| P66  Landing       150m - 0m       Fine control     |
|                                                     |
| LANDING CRITERIA                                    |
| ──────────────────────────────────────────────────  |
| Vertical velocity:   < 3.0 m/s                      |
| Horizontal velocity: < 2.0 m/s                      |
|                                                     |
| MISSIONS                                            |
| ──────────────────────────────────────────────────  |
| 11  Sea of Tranquility     14  Fra Mauro            |
| 12  Ocean of Storms        15  Hadley Rille         |
| 16  Descartes Highlands    17  Taurus-Littrow       |
|                                                     |
| FUEL CALLOUTS                                       |
| ──────────────────────────────────────────────────  |
| "60 seconds"  60 sec of fuel left                   |
| "30 seconds"  LAND NOW                              |
| "FUEL EMPTY"  Engine shutdown imminent              |
+=====================================================+

Strategy Guide

General Principles

1. Trust the autopilot during P63 braking. It manages the complex velocity-killing manoeuvre better than manual control.
2. Switch to manual only when terrain demands it -- boulder fields, crater rims, or when the LPD shows an unsafe landing point.
3. Watch your fuel, not your altitude. Altitude is just a number; fuel is survival.
4. Respond quickly to events. Timeouts are treated as incorrect responses and often have severe consequences.
5. Study the history. The correct event responses are historically accurate. Knowing what the real astronauts did gives you the answers.

Mission-Specific Tips

Apollo 11: The 1202 and 1201 alarms are safe to continue through. When the boulder field appears, switch to MANUAL -- this is what Armstrong did.

Apollo 12: The lightning strike effects are cosmetic -- MONITOR and carry on. The precision landing challenge rewards accuracy near the Surveyor 3 probe.

Apollo 14: The abort switch malfunction is critical -- accept the PATCH from MIT. If the landing radar is late to acquire, WAIT for it rather than flying blind.

Apollo 15: The mountain approach between the Apennines requires a STEEP descent angle. When the contact light triggers early on the slope, CUT the engine immediately.

Apollo 16: The CSM gimbal oscillation nearly scrubbed the mission. PROCEED with the landing -- the analysis shows it is safe.

Apollo 17: Stay CENTERED during the valley approach between the massifs. This is the last Apollo landing -- make it count.

Appendix: Troubleshooting

Display Appears Garbled

Problem: The flight display shows corrupted characters or misaligned data.

Solution: The simulator uses ANSI cursor positioning for its real-time display. Ensure your terminal emulates VT100 or later. The display is optimised for 80x24 terminals. At the 2400 baud V.22bis profile, allow the initial frame to render before the simulation begins.

Simulation Feels Sluggish

Problem: Updates seem delayed or jerky.

Solution: The V.22bis profile is still paced like a dial-up link, so display update bandwidth is limited compared with an instant local terminal. The simulator calculates transmission time and paces updates accordingly.

Crashed Despite Low Velocity

Problem: The landing report says "MISSION FAILED" even though velocity seemed low.

Solution: Both vertical AND horizontal velocity must be within limits. Check that horizontal velocity was below 2.0 m/s at touchdown. During P66, the autopilot works to kill horizontal drift, but manual throttle changes can introduce instability.

Fuel Ran Out Before Landing

Problem: "FUEL EMPTY" appears with significant altitude remaining.

Solution: Extended hovering is the primary fuel drain. In manual mode, avoid holding throttle at hover level for extended periods. Let the LM descend at a steady 1-2 m/s rather than hovering. On Nightmare difficulty, fuel margins are extremely thin -- every second counts.

Event Response Rejected

Problem: Typing a response produces "Invalid response."

Solution: Type the response exactly as shown in the options list (e.g., CONTINUE, ABORT, MANUAL). Responses are case-insensitive but must match one of the listed options precisely.

Cannot Control Throttle

Problem: The + and - keys have no effect.

Solution: Throttle control is only available in MANUAL mode. Press M to switch from AUTO to MANUAL before adjusting throttle.

See Also

• Pioneer Trail (555-0765) -- Survive the journey west by wagon
• Weather Service (555-0720) -- Cached forecast before your next call
• ELIZA (555-0354) -- Talk to the original chatbot psychotherapist
• BASIC Interpreter (555-0300) -- Write your first program
• Phonebook (/phonebook/) -- The full Golden Directory of dial-up numbers