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[ MUSIC ]

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>> HOW DO YOU GET

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FROM HERE TO MARS?

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HOW DO YOU GET

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FROM HERE TO THE MOON?

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PROBABLY MORE IMPORTANT TO YOU,

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HOW DO YOU GET FROM HERE

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TO YOUR HOME?

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WELL TO START, THE ANSWER TO

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ALL THREE IS VERY SIMILAR:

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YOU NEED TO KNOW WHERE YOU ARE,

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YOU NEED TO KNOW WHERE YOU'RE

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GOING, AND YOU NEED A MAP

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THAT CAN CONNECT THE TWO.

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NOW IN THE CASE OF GOING HOME,

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YOUR MAP WILL HAVE ALL OF

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THE ROADS BETWEEN WHERE YOU ARE

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AND WHERE YOUR HOME IS,

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SO YOU CAN PICK YOUR PATH,

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OR YOUR TRAJECTORY,

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AND DRIVE YOUR WAY HOME.

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IN THE CASE OF GOING TO MARS,

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OR TO THE MOON, OR TO ANY OF

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THE PLANETS OR PLANETARY BODIES

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WHERE WE'VE SENT HUMANS

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OR ROBOTICS-- ROBOTIC SPACECRAFT

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TO OVER THE YEARS,

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FINDING THAT PATH,

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OR THAT TRAJECTORY, IS PROVED

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ALL THE MORE DIFFICULT,

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BECAUSE WHERE YOU ARE

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AND WHERE YOU'RE GOING

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ARE ALWAYS IN MOTION.

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WHICH LEADS ME TO ORBITS

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AND TRAJECTORIES AND NASA'S

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RETURN TO THE MOON.

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MERRIAM-WEBSTER DEFINES AN ORBIT

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AS THE PATH DESCRIBED BY ONE BODY IN ITS REVOLUTION

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ABOUT ANOTHER, LIKE THE EARTH

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GOING AROUND THE SUN.

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OR, IN THE CASE OF THIS TALK,

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A SPACECRAFT GOING AROUND

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A GRAVITATIONAL BODY OR TWO.

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NOW, WE ENTER THE WORLD

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OF ROCKET SCIENCE.

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JOHANNES KEPLER, WITH THE HELP

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FROM VOLUMES AND VOLUMES OF

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DATA ON PLANETARY MOTION,

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CAPTURED BY TYCHO BRAHE,

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CALCULATED THAT THE PATHS THESE

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ORBITS TOOK IN THE PRESENCE

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OF A GRAVITATIONAL FIELD

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FOLLOWED CONIC SHAPES,

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LIKE CIRCLES,

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OR NEARLY CIRCULAR ELLIPSES.

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AND WITH THIS INFORMATION,

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SCIENTISTS FIGURED OUT

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HOW TO MOVE AN OBJECT--

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A SPACECRAFT--

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FROM ONE ORBIT TO ANOTHER.

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ONE OF THE MOST FAMOUS OF

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THESE SCIENTISTS IN

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ORBITAL MECHANIC CIRCLES IS

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WALTER HOHMANN, WHO CREATED

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WHAT BECAME KNOWN AS

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THE HOHMANN TRANSFER.

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THE HOHMANN TRANSFER,

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SIMPLY PUT,

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IS AN ELLIPTICAL ORBIT

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THAT WILL ALLOW YOU TO TRANSFER

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BETWEEN TWO CIRCULAR ORBITS

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OF DIFFERENT RADII

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IN THE SAME PLANE,

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ABOUT THE SAME CENTRAL BODY.

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SO, REMEMBER WHEN I ASKED YOU

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HOW YOU WOULD GET

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FROM HERE TO MARS?

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WELL, THE HOHMANN TRANSFER

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FROM EARTH TO MARS,

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SHOWN IN THIS ANIMATION,

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WOULD TAKE YOU THERE.

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NASA SCIENTISTS AND ENGINEERS

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HAVE GOTTEN REALLY CREATIVE

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IN CREATING TRAJECTORIES TO

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SEND ROBOTIC SPACECRAFT

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AROUND AND BEYOND

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OUR SOLAR SYSTEM.

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BUT FOR HUMANS, THE FARTHEST

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THAT WE'VE GONE IS TO OUR MOON

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50 YEARS AGO.

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IN APOLLO 11, ON JULY 16TH,

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1969, THREE ASTRONAUTS WERE

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LAUNCHED ON A SATURN V ROCKET

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LEADING TO HUMANKIND'S

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FIRST GIANT LEAP.

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AFTER THE FIRST THREE SATURN,

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UM, ROCKETS--

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SATURN ENGINES BURNED,

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THE APOLLO SPACECRAFT WAS PLACED

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INTO A LOW CIRCULAR

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EARTH PARKING ORBIT,

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ROUGHLY 100 NAUTICAL MILES

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IN ALTITUDE, OR APPROXIMATELY

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THE DISTANCE BETWEEN

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CLEVELAND AND COLUMBUS.

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AFTER FINAL CHECKOUTS, THE, UH--

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SATURN V BURNED WHAT'S CALLED

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A TRANS-LUNAR INJECTION BURN,

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OR TLI, THAT PLACED THEM ON

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THE TRAJECTORY THAT WOULD

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TAKE THEM TO THE MOON.

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THERE THEY WOULD COAST

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FOR THREE DAYS BEFORE BEING

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CAPTURED BY THE MOON'S GRAVITY

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INTO A LOW LUNAR ORBIT.

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NOW AFTER THEY COMPLETED

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THEIR SURFACE MISSION,

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THE ASTRONAUTS RETURNED TO

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THE WAITING COMMAND MODULE,

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COLUMBIA, TO START THEIR

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TRIP HOME.

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THE COLUMBIA, LIKE

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THE TRANS-LUNAR INJECTION BURN,

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BURNED A TRANS EARTH

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INJECTION BURN TO PLACE THEM ON

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THE TRAJECTORY BACK TO EARTH.

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NOW, HAVING TRAVELED AN AVERAGE

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DISTANCE OF 240,000 MILES

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FROM THE EARTH TO THE MOON,

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THESE APOLLO MISSIONS STILL

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STAND AS THE FARTHEST THAT

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HUMANS HAVE EVER GONE FROM

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THE SURFACE OF THE EARTH.

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AND THIS IS

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A SIGNIFICANT DISTANCE.

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GIVEN THE DIAMETER OF THE EARTH,

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ROUGHLY 30 EARTH-SIZED PLANETS

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CAN FIT BETWEEN THE EARTH

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AND THE MOON.

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NOW SINCE APOLLO, THE FARTHEST

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WE'VE SENT HUMANS IS TO

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THE INTERNATIONAL SPACE STATION,

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LOCATED IN A LOW EARTH ORBIT

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ROUGHLY 400 KILOMETERS FROM

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THE SURFACE OF THE EARTH,

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OR ABOUT 250 MILES,

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OR APPROXIMATELY

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THE DISTANCE BETWEEN

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CLEVELAND AND CINCINNATI.

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NOW BECAUSE THE

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INTERNATIONAL SPACE STATION

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ORBITS SO CLOSE TO THE EARTH,

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THE COMBINED GRAVITATIONAL PULL

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OF THE EARTH, AS WELL AS

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THE ATMOSPHERIC DRAG ON

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THE STATION, MEANS IT'S IN

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A CONSTANT STATE OF

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FREE FALL AND REENTRY.

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AND PERIODICALLY,

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VISITING VEHICLES WITH

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PROPULSION SYSTEMS,

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WILL GIVE THE ISS A BOOST

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TO KEEP IT IN ITS ORBIT.

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NOW, WITH THIS BRINGS

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ARTEMIS ANNOUNCEMENT.

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NASA HAS ANNOUNCED PLANS

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TO RETURN HUMANS TO

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THE SURFACE OF THE MOON,

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LANDING THE FIRST WOMAN

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AND THE NEXT MAN ON ITS SURFACE

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BY 2024.

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THE CURRENT ARTEMIS PLANS ARE

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A BLEND OF THOSE APOLLO

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LUNAR SORTIE CAMPAIGNS

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AS WELL AS THE ISS

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SUSTAINABILITY ELEMENTS.

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AND THE FIRST KEY SUSTAINING

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PIECE OF THIS

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ARTEMIS PROGRAM PLAN IS

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THE GATEWAY TO BE ASSEMBLED

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IN ORBIT NEAR THE MOON.

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THE GATEWAY IS A MOBILE COMMAND

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AND SERVICE MODULE,

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AND IT WILL PROVIDE US WITH

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A PLACE TO AGGREGATE

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AND ASSEMBLE THE SPACECRAFT

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THAT WILL LAND ONTO THE MOON,

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AS WELL AS PROVIDE US WITH

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A COMMUNICATIONS RELAY TO

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SUPPORT ROBOTIC AND HUMAN

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MISSIONS ANYWHERE ON

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THE MOON'S SURFACE,

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BUT STARTING AT THE MOON'S

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SOUTH POLE.

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THE FIRST ELEMENT OF

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THE GATEWAY IS THE POWER

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AND PROPULSION ELEMENT MANAGED

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HERE IN CLEVELAND AT

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NASA GLENN RESEARCH CENTER,

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AND BUILT IN A PUBLIC

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PRIVATE PARTNERSHIP

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WITH MAXAR TECHNOLOGIES.

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NOW, SAID OUR ADMINISTRATOR,

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JIM BRIDENSTINE, OF THE PPE,

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"IT WILL BE THE KEY COMPONENT

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UPON WHICH WE WILL BUILD OUR

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LUNAR GATEWAY OUTPOST,

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THE CORNERSTONE OF NASA'S

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SUSTAINABLE AND REUSABLE

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ARTEMIS EXPLORATION ARCHITECTURE

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ON AND AROUND THE MOON."

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THIS POWER AND PROPULSION

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ELEMENT IS A HIGH POWER,

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50 KILOWATT CLASS

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SOLAR ELECTRIC

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PROPULSION SPACECRAFT.

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AND AT THAT,

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IT'S ROUGHLY THREE TIMES

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MORE POWERFUL THAN CURRENT

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STATE OF THE ART TECHNOLOGIES.

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NOW, THE GATEWAY WITH THIS PPE,

222
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WITH BOTH POWER AND PROPULSION,

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IS CAPABLE OF NOT ONLY HOLDING

224
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PLACE IN ONE ORBIT, BUT OF

225
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TRANSFERRING BETWEEN ORBITS,

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IN SUPPORT OF THIS SUSTAINABLE

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LUNAR ARCHITECTURE.

228
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FLYING THE PPE WILL

229
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PROVIDE US WITH

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INVALUABLE EXPERIENCE FOR

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FUTURE MISSIONS TO MARS,

232
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AND THE CURRENT PLAN

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IS TO LAUNCH

234
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THE POWER AND PROPULSION ELEMENT

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IN 2022.

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THE GATEWAY WILL BE ASSEMBLED

237
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IN A NEW TYPE OF ORBIT,

238
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PERFECTLY BALANCED BY

239
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THE GRAVITATIONAL PULLS OF

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THE EARTH AND THE MOON, CALLED

241
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A NEAR RECTILINEAR HALO ORBIT,

242
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OR NRHO, A FAMILY OF WHICH

243
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YOU CAN SEE IN THIS ANIMATION.

244
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NOW WHEN APOLLO

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WENT TO THE MOON,

246
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THE LOW LUNAR ORBIT IN WHICH

247
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THE COMMAND MODULE WAITED,

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WAS SO PULLED BY THE MOON'S

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GRAVITY, THAT WOULD--

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IT WAS NOT STABLE AND WOULD

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NOT HAVE ALLOWED FOR

252
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THE SPACECRAFT TO STAY FOR LONG.

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BUT THE NEAR RECTILINEAR

254
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HALO ORBIT, BALANCING AS IT DOES

255
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BETWEEN THE EARTH AND THE MOON

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IN GLOWING YELLOW HERE,

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MEANS THAT THE POWER

258
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AND PROPULSION ELEMENT

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ONLY NEED TO PERFORM SMALL

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ORBIT MAINTENANCE MANEUVERS

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TO STAY PERMANENTLY.

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THE GRAVITY WILL BALANCE--

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OKAY.

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UM.

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THE NEAR RECTILINEAR HALO

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ORBIT IS DIFFERENT THAN THOSE

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CIRCULAR ORBITS THAT I MENTIONED

268
00:07:52,260 --> 00:07:53,460
THAT KEPLER DISCOVERED,

269
00:07:53,600 --> 00:07:54,560
LIKE THE ORBIT THAT THE MOON

270
00:07:54,600 --> 00:07:55,840
TAKES AROUND THE EARTH.

271
00:07:56,000 --> 00:07:57,140
THESE THREE VIEWS HERE

272
00:07:57,140 --> 00:07:58,100
SHOW YOU THAT THE NEAR

273
00:07:58,200 --> 00:07:59,260
RECTILINEAR HALO ORBIT

274
00:07:59,380 --> 00:08:01,060
IS AN ORBIT ABOUT THE EARTH,

275
00:08:01,220 --> 00:08:02,640
BUT AT THE DISTANCE OF THE MOON,

276
00:08:02,640 --> 00:08:04,240
SO IT'S TUGGED BY THE MOON,

277
00:08:04,340 --> 00:08:05,500
AND THESE EARTH-MOON

278
00:08:05,700 --> 00:08:06,960
INTERACTIONS MEAN THAT FOR

279
00:08:07,300 --> 00:08:08,640
EVERY TWO ORBITS THAT

280
00:08:08,640 --> 00:08:10,200
THE MOON MAKES ABOUT THE EARTH,

281
00:08:10,240 --> 00:08:11,240
THE SPACECRAFT,

282
00:08:11,440 --> 00:08:12,440
THE GATEWAY IN THIS

283
00:08:12,560 --> 00:08:14,060
NEAR RECTILINEAR HALO ORBIT,

284
00:08:14,200 --> 00:08:15,100
WILL MAKE NINE OF THESE

285
00:08:15,300 --> 00:08:16,660
LEAPFROGS OVER AND UNDER

286
00:08:16,780 --> 00:08:17,660
THE MOON.

287
00:08:17,820 --> 00:08:19,080
AND THE PERIOD OF THIS NEAR

288
00:08:19,320 --> 00:08:20,720
RECTILINEAR HALO ORBIT, OR

289
00:08:20,940 --> 00:08:22,360
THE PERIOD BETWEEN THESE LEAPS,

290
00:08:22,480 --> 00:08:24,360
IS ROUGHLY SIX AND A HALF DAYS,

291
00:08:24,680 --> 00:08:26,100
WITH ONLY FOUR HOURS OUT OF THAT

292
00:08:26,280 --> 00:08:28,020
ALMOST WEEK SPENT OUT OF VIEW

293
00:08:28,300 --> 00:08:29,720
OF THE MOON'S SOUTH POLE.

294
00:08:29,880 --> 00:08:30,940
NOW, IF YOU VIEW IT FROM

295
00:08:31,100 --> 00:08:32,760
THE EARTH, THE NEAR RECTILINEAR

296
00:08:32,920 --> 00:08:34,320
HALO ORBIT LOOKS LIKE A LONG

297
00:08:34,620 --> 00:08:35,920
ELLIPTICAL ORBIT ABOUT

298
00:08:36,020 --> 00:08:37,620
THE MOON, OR A HALO,

299
00:08:37,620 --> 00:08:38,920
THUS THE NAME.

300
00:08:38,980 --> 00:08:40,780
AND THIS ONE HAS ITS CLOSEST

301
00:08:40,980 --> 00:08:41,980
APPROACH TO THE MOON AT

302
00:08:42,000 --> 00:08:43,300
THE MOON'S NORTH POLE,

303
00:08:43,500 --> 00:08:44,440
AND IT'S FARTHEST APPROACH

304
00:08:44,520 --> 00:08:46,020
AT THE MOON'S SOUTH POLE.

305
00:08:46,200 --> 00:08:46,960
AND AS I SAID,

306
00:08:47,200 --> 00:08:48,440
THIS NEAR RECTILINEAR HALO ORBIT

307
00:08:48,520 --> 00:08:49,800
IS ONE OF-OF LARGE FAMILY,

308
00:08:49,860 --> 00:08:51,280
AND IT WAS DESIGNED SPECIFICALLY

309
00:08:51,400 --> 00:08:52,760
TO PROVIDE FOR MAXIMUM LUNAR

310
00:08:52,860 --> 00:08:54,320
COVERAGE OF THE SOUTH POLE,

311
00:08:54,460 --> 00:08:55,660
AS WELL AS TO PROVIDE THAT

312
00:08:55,700 --> 00:08:57,000
A SPACECRAFT IN THIS ORBIT,

313
00:08:57,060 --> 00:08:58,720
THE GATEWAY, STAYS IN AS MUCH

314
00:08:58,820 --> 00:09:01,820
DIRECT SUNLIGHT AS POSSIBLE.

315
00:09:01,820 --> 00:09:03,820
NOW, NEAR RECTILINEAR HALO

316
00:09:03,980 --> 00:09:06,220
ORBITS ARE VERY FAVORABLE FOR

317
00:09:06,420 --> 00:09:08,320
TRANSFERRING INTO AND OUT OF,

318
00:09:08,400 --> 00:09:09,300
WHICH IS NICE WHEN YOUR

319
00:09:09,460 --> 00:09:10,520
SPACECRAFT IS MEANT TO BE

320
00:09:10,580 --> 00:09:12,400
A STAGING AREA FOR EXPLORATION,

321
00:09:12,500 --> 00:09:13,220
WITH OTHER SHIPS

322
00:09:13,220 --> 00:09:14,520
COMING AND GOING.

323
00:09:14,740 --> 00:09:16,280
IN THIS TRAJECTORY ANIMATION

324
00:09:16,460 --> 00:09:18,080
SHOWS THE PATH THAT THE ORION

325
00:09:18,240 --> 00:09:19,460
WITH THE CREW IN IT WOULD TAKE

326
00:09:19,500 --> 00:09:20,600
AS THEY DEPART EARTH,

327
00:09:20,660 --> 00:09:21,940
HEAD TOWARD A POWER LUNAR FLYBY

328
00:09:22,000 --> 00:09:23,280
TO PUT THEM INTO THE GATEWAY

329
00:09:23,420 --> 00:09:25,460
IN THE NRHO, STAY IN THE NRHO

330
00:09:25,460 --> 00:09:27,180
FOR ONE AND A HALF ORBITS

331
00:09:27,320 --> 00:09:28,840
BEFORE DEPARTING TO HEAD BACK

332
00:09:28,840 --> 00:09:30,720
TO ANOTHER POWERED LUNAR FLYBY

333
00:09:30,980 --> 00:09:32,320
TO PUT THEM ON THE TRAJECTORY

334
00:09:32,740 --> 00:09:34,080
THAT WOULD TAKE THEM BACK HOME.

335
00:09:38,500 --> 00:09:40,440
NOW, RECALL THAT THE GATEWAY,

336
00:09:40,720 --> 00:09:41,580
WITH THE POWER AND PROPULSION

337
00:09:41,940 --> 00:09:43,700
ELEMENT, IS CAPABLE NOT JUST

338
00:09:43,960 --> 00:09:45,660
OF HOLDING PLACE IN ONE ORBIT,

339
00:09:45,660 --> 00:09:46,620
BUT ALSO OF TRANSFERRING

340
00:09:46,620 --> 00:09:47,920
BETWEEN ORBITS.

341
00:09:47,920 --> 00:09:49,080
THE NASA GLENN RESEARCH CENTER

342
00:09:49,180 --> 00:09:50,380
POWER AND PROPULSION ELEMENT

343
00:09:50,460 --> 00:09:51,700
MISSION AND DESIGN TEAM HAS

344
00:09:51,920 --> 00:09:53,620
DESIGNED SEVERAL TRAJECTORIES,

345
00:09:53,620 --> 00:09:54,660
TAKING THE GATEWAY FARTHER

346
00:09:54,900 --> 00:09:56,460
AND FARTHER FROM EARTH TO OTHER

347
00:09:56,620 --> 00:09:57,820
ORBITS WHERE MISSION SCENARIOS

348
00:09:57,960 --> 00:09:59,580
AND SCIENCE CAN BE COMPLETED.

349
00:10:00,400 --> 00:10:01,760
FLYING THESE TRANSFERS

350
00:10:01,800 --> 00:10:03,200
WILL ALLOW US TO GAIN

351
00:10:03,200 --> 00:10:05,200
INVALUABLE EXPERIENCE OPERATING

352
00:10:05,200 --> 00:10:06,780
THESE TYPES OF LARGE,

353
00:10:06,780 --> 00:10:09,360
HUMAN TENDED SYSTEMS IN SPACE,

354
00:10:09,360 --> 00:10:10,920
AND ALONG THE LENGTHY TRANSFERS

355
00:10:10,980 --> 00:10:11,800
WE'RE GOING TO NEED TO

356
00:10:12,020 --> 00:10:13,320
ACCOMPLISH IF WE'RE GOING

357
00:10:13,480 --> 00:10:14,740
TO BE ABLE TO SEND HUMANS

358
00:10:14,960 --> 00:10:16,420
TO OUR CLOSEST NEIGHBOR,

359
00:10:16,420 --> 00:10:18,420
THE RED PLANET, MARS.

360
00:10:20,940 --> 00:10:23,100
NOW, THE CURRENT ARTEMIS PLANS

361
00:10:23,200 --> 00:10:24,260
WILL TAKE PLACE IN

362
00:10:24,560 --> 00:10:26,100
A TWO-PHASED APPROACH,

363
00:10:26,100 --> 00:10:28,120
WITH THE FIRST FOCUSED ON SPEED,

364
00:10:28,120 --> 00:10:29,020
LANDING ON THE MOON

365
00:10:29,060 --> 00:10:31,000
BY 2024 AS WE DISCUSSED,

366
00:10:31,060 --> 00:10:32,560
AND THE SECOND TO ESTABLISH

367
00:10:32,620 --> 00:10:34,520
A SUSTAINED LUNAR PRESENCE ON

368
00:10:34,520 --> 00:10:37,160
AND AROUND THE MOON BY 2028.

369
00:10:37,160 --> 00:10:38,560
FLYING THE GATEWAY AND

370
00:10:38,700 --> 00:10:40,600
THE POWER AND PROPULSION ELEMENT

371
00:10:40,700 --> 00:10:41,900
WILL ALLOW US TO ACCOMPLISH

372
00:10:42,240 --> 00:10:43,840
BOTH THE FIRST, BY GIVING US

373
00:10:44,080 --> 00:10:45,200
A PLACE TO AGGREGATE

374
00:10:45,560 --> 00:10:47,000
AND ASSEMBLE THE SPACECRAFT

375
00:10:47,100 --> 00:10:48,500
THAT WILL LAND ON THE MOON,

376
00:10:48,500 --> 00:10:49,700
AS WELL AS THE SECOND BY

377
00:10:49,800 --> 00:10:50,800
PROVIDING US A PLACE TO

378
00:10:51,180 --> 00:10:52,480
REFURBISH AND REFUEL

379
00:10:52,680 --> 00:10:53,880
THE LUNAR ELEMENTS FOR

380
00:10:54,100 --> 00:10:55,240
SUBSEQUENT LUNAR MISSIONS

381
00:10:55,440 --> 00:10:57,340
OR REORIENT TO FOCUS ON OTHER

382
00:10:57,500 --> 00:10:59,700
AREAS ON AND AROUND THE MOON.

383
00:10:59,700 --> 00:11:01,040
THE CURRENT PLANS FOR ARTEMIS

384
00:11:01,220 --> 00:11:02,640
HAVE SEVERAL ELEMENTS

385
00:11:02,700 --> 00:11:03,720
THAT ARE SIMILAL--

386
00:11:03,820 --> 00:11:05,420
SIMILAR TO APOLLO.

387
00:11:05,640 --> 00:11:06,880
THE YEARS MAY CHANGE, BUT

388
00:11:06,880 --> 00:11:08,460
THE PHYSICS REMAINS THE SAME.

389
00:11:08,460 --> 00:11:10,220
FIRST, THE CREW IS LAUNCHED

390
00:11:10,260 --> 00:11:11,920
IN THE ORION SPACECRAFT ON

391
00:11:12,060 --> 00:11:13,520
A SPACE LAUNCH SYSTEM,

392
00:11:13,740 --> 00:11:16,080
OR SLS ROCKET, ON A TRAJECTORY

393
00:11:16,140 --> 00:11:16,980
THAT WILL TAKE THEM

394
00:11:17,200 --> 00:11:18,900
DIRECTLY TO THE NRHO,

395
00:11:18,960 --> 00:11:20,900
WHICH YOU'VE ALREADY SEEN.

396
00:11:20,900 --> 00:11:21,920
ONCE THE ORION DOCKS

397
00:11:22,100 --> 00:11:23,240
WITH THE GATEWAY,

398
00:11:23,280 --> 00:11:24,420
THE TWO CREW MEMBERS WHO WILL GO

399
00:11:24,440 --> 00:11:26,000
TO THE SURFACE TRANSFER FROM

400
00:11:26,080 --> 00:11:27,680
THE ORION INTO THE WAITING

401
00:11:27,760 --> 00:11:29,440
LUNAR LANDER SYSTEM.

402
00:11:29,680 --> 00:11:30,840
CURRENT CONCEPTS FOR

403
00:11:31,160 --> 00:11:32,620
THE LUNAR LANDER SYSTEM ARE

404
00:11:32,920 --> 00:11:34,980
COMPOSED OF THREE PARTS:

405
00:11:34,980 --> 00:11:36,620
FIRST A TRANSFER MODULE,

406
00:11:36,620 --> 00:11:38,280
THEN AN ASCENT MODULE,

407
00:11:38,440 --> 00:11:39,660
AND A DESCENT MODULE.

408
00:11:39,860 --> 00:11:40,960
THE TRANSFER MODULE WILL TAKE

409
00:11:41,160 --> 00:11:43,220
THE ENTIRE STACK AND THE CREW

410
00:11:43,460 --> 00:11:45,240
TO A LOW LUNAR PARKING ORBIT.

411
00:11:45,240 --> 00:11:47,080
FROM THERE, THE DESCENT MODULE

412
00:11:47,280 --> 00:11:48,680
WILL TAKE THE ASCENT MODULE

413
00:11:48,880 --> 00:11:49,740
WITH THE CREW

414
00:11:49,920 --> 00:11:51,360
DOWN TO THE SURFACE.

415
00:11:51,380 --> 00:11:52,440
WHEN THEY'VE COMPLETED

416
00:11:52,640 --> 00:11:53,940
THEIR MISSION, THE ASCENT MODULE

417
00:11:54,020 --> 00:11:55,260
WILL RETURN THE CREW

418
00:11:55,460 --> 00:11:56,740
BACK TO THE GATEWAY.

419
00:11:56,740 --> 00:11:58,200
CURRENT PLANS HAVE

420
00:11:58,220 --> 00:11:59,280
LUNAR SURFACE MISSIONS

421
00:11:59,280 --> 00:12:01,040
ROUGHLY THREE TO SEVEN DAYS,

422
00:12:01,080 --> 00:12:02,380
AFTER WHICH THE ASTRONAUTS

423
00:12:02,400 --> 00:12:03,400
WILL RETURN TO THE GATEWAY,