Apollo 11: Hypergolic

Eagle approaches the command ship

It’s the day after The Day

            of the landing and moonwalk,

                 after a night of little sleep in out suits,

                                 helmets on so as not to breath the moon dust

                                       we’ve carried in with us,

                                            cramped and cold in the noisy cabin.

After 22 hours 37 minutes on the lunar surface,

                           it’s time to leave, to draw the blue planet back to us.

                               Houston calls, “Our guidance recommendation is Pings

                                                               and you’re cleared for take-off.”

                                 “Roger, we’re number one on the runway.”

Unlike most our systems which have multiple backups

             we’re now dependent on a single single engine,

                                         the APS  — Ascent Propulsion System —

                  designed as simply as possible.  It needs no ignitor

                                    as the propellants are hypergolic, meaning they burn on contact.

                   Still our lives depend on a single engine and something never attempted

                                                liftoff from the moon.

     “Nine, eight, seven, six, five — first stage engine on ascent.  Proceed.”

                      Ignition and from our boxy descent stage, serving as a launch pad,

                           a shower of gold foil insulation flies out horizontally.

                                     We have only a time for a glance

                                              as we shoot up like a champagne cork

                                                     and peg our eyes to the instruments.

A very smooth — and quiet — take off. 

                     In just ten seconds we rise to 250 ft. and pitch over 45 degrees

                           so that we are facing the lunar surface rushing by below

                                   already far beyond Tranquility Base

                                                now just a memory.

Our lightweight LM rocks like a cradle,

                   wallowing side to side

                as the RCS — Reaction Control System — jets constantly correct.

                        We are a ship at sea.

                                    Right on course.  We’re go on both Pings and Ags guidance systems.

                                          Pings and Ags, babe. 

You’ve gotta keep Pings and Ags aligned.

                         “We’ve got Sabine [crater] now to our right . . .”

Shutdown.  Very smooth.

                       The ascent has taken 7 minutes and 15 seconds

                                  into an orbit 10.5 by 51.4 statute miles,

                                  293 miles behind the command ship, Columbia.

We take a moment for a ceremonial call, “Eagle is back in orbit

                                                                    having left Tranquility Base

                                             and leaving behind a replica of our Apollo 11 patch

                                                                      with an olive branch.”

                                    Put on your ballet shoes

                               Now comes the intricate danceof rendezvous

                                     lasting more than three hours

                                  through one-and-a-half lunar orbits

                                             involving four major maneuvers

                                                       by two tired astronauts

                                                               kept on their toes.

In the first burn, Concentric Sequence Initiation, on the RCS jets,

                               comes on our first pass behind the moon.

                            Coming fifty minutes after achieving orbit,

                                   it circularizes our orbit at 50 miles.

   Back on the front side,

the second burn, the Constant Delta Height maneuver, comes 57 minutes after the first

          and places us in a orbit 17 miles below Columbia,

                      mirroring the command ship’s orbit except for being lower.

The third plateau towards rendezvous, Terminal Phase Initiation,

                  coming 45 minutes later,

                         lifts us into Columbia’s orbit,

                                  the 17-mile climb taking a third of an orbit.

                                        and leaving us 40 miles away from Columbia

                                                   as we go behind the moon again.

The last major burn, Terminal Phase Finalization,

                    occurs 42 minutes after the third,

                          and places us just ahead of Columbia,

                                     less than 100 ft. away.

                                  We hold station keeping position,

                        Turn so that our docking port is facing the command ship

                                        which will perform the docking.

At contact, Eagle yaws 15 degrees out of position.

                     In Columbia, Mike Collins swiftly adjusts and . . .

                            We’re docked, Houston,

                      3 hours 41 minutes after leaving Tranquility Base, we are docked.

We will not linger in lunar orbit.

                   We open the hatch to Columbia a couple hours after docking

                                     bringing a cloud of lunar dust with us

                              and enjoy Mike Collins grumbling that we are dirty his clean Command Module.

                                 Alas, once we’ve transfer the rock boxes and other items,

                                       we cast Eagle off — send it crashing to the surface.

                                               “There she goes.  She was a good one.”

                We’ve done enough and it’s time to head to home,

                          our destination, the Lunar Receiving Lab (LRL) in Houston.

Just five hours after opening the hatch to Columbia,

                      we approach TEI — TransEarth Injection.

Just before we go behind the moon, Houston calls, “Apollo 11, you are go for TEI.”

When we next appear, homeward bound, we call, “Tell them to open up the LRL doors.”

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