Popular Mechanics - USA (2019-07-Special)

@PopularMechanics _ July/August 2019 71

Challenge 1

You can’t just point and

shoot. Do that and your

spacecraft will miss Mars.

So, rocket scientists use a

maneuver called a Hohmann

transfer orbit to send a vehi-

cle from a small circular orbit

(say, Earth’s) to a larger one

(Mars’s). The transfer orbit

must be timed precisely so

that when the spacecraft

leaves Earth it arrives at des-

tination orbit at the same

time Mars reaches the same

position. Earth and Mars only

come into the right orbital

alignment for a Hohm-

ann transfer once every 26

months to allow a surviv-

able six-month journey with

the use of available propul-

sion techniques. How Going

Back to the Moon Helps: It

would be relatively easy for a

Mars-bound vehicle to “stop

by” Gateway at its very high

orbit at a relatively low cost

in terms of propellant and

velocity change.

Challenge 2

We’ll have to stay a while.

Astronauts will need to

remain on Mars or orbiting

it for months at a time. A sin-

gle Mars mission, from start

to finish, would likely take

more than two years. That’s

a long while to be away from

our home planet, breathing

recycled air in the cramped

quarters of a laboratory

environment. And with a

40-minute lag between send-

ing messages to Earth and

receiving responses back,

astronauts will need to make

autonomous decisions. All

of this will contribute to

extreme feelings of alien-

ation.How Going Back to

the Moon Helps: NASA

hopes to learn how astronauts

respond psychologically to

living for extended periods

on the moon. Scientists will

also monitor the effects of

microgravity and space radi-

ation on astronauts’ bodies to

develop solutions for longer

Mars missions.

Challenge 3

Huge rockets will be

needed to send big

payloads. A Mars lander

and the trans-Martian

cruise vehicle will likely be

built from payloads deliv-

ered into orbit by NASA’s

mammoth Space Launch

System (SLS) rocket and

Orion spacecraft over

several missions. How

Going Back to the Moon

Helps: NASA will develop

that deep-space capability

by using the SLS and Orion

vehicles to build the Gate-

way lunar orbiting platform

and moon-based habitats.

Challenge 4

Resupply isn’t an easy

option. While astronauts at

the International Space Sta-

tion can receive fresh supplies

within a few hours of a launch

from Earth, Mars explorers

might have to wait two years.

That means enough food and

fuel must be brought from

home or made on Mars. How

Going Back to the Moon

Helps: Our lunar base might

be the proving ground for

technologies that’ll produce

propellant fuel from water

ice mined beneath the sur-

face of the moon, if, of course,

the same technology can be

adapted for Mars.

Challenge 5

We’ll need a more versatile

space station. As NASA

and its army of aerospace

contractors complete work

on SLS, a new, space-sta-

tion-sized cruiser, known

as Deep-Space Trans-

port (DST) will have to be

developed to shuttle crews

between Earth and Mars.

How Going Back to the

Moon Helps: Key systems

for DST, such as radiation

shielding and closed-loop

life-support, will be flight-

proven on Gateway.

Challenge 6

There will be expected and

unforeseen problems. The

DST will only go to the orbit

of Mars, which means that a

large lander, capable of mak-

ing soft touchdown on the

Red Planet, would have to be

built in space. NASA’s key

contractor, Lockheed Mar-

tin, proposed a giant space

plane, which would use the

SLS rocket for launch from

Earth. Then there is the newly

emerged juggernaut of space

business, SpaceX, which

hopes to build the Big Fal-

con Rocket, BFR, to haul into

Earth’s orbit a 150-ton trans-

Martian cruiser with 40 crew

cabins. To escape the Earth’s

gravity, the huge ship would

need four refueling tank-

ers and another refueling on

Mars using a prebuilt propel-

lant production plant. How

Going Back to the Moon

Helps: NASA believes new

moon missions will accel-

erate a mission to Mars by

speeding up the development

of technologies needed to get

there. But even before NASA

diverted from Mars to the

moon, an independent study

estimated that the first realis-

tically achievable window for

a crewed Mars mission would

open in 2037. —Anatoly Zak

THE

MARCH

TO

MARS

The complexity of
landing astronauts on
Mars and returning them
safely is monumental.
Here’s why and how our
return to the moon may
help us ultimately
reach the Red Planet.

Mars (^) Orbit
M a r s a t
Launch
E a r t h a t
Launch
E a r t h a t
Arrival
M a r s a t A r r i v a l
RoutetoM Earth^ Orbit
ars