After almost 50 years since the Apollo Moon
landing missions ended, NASA announced that
they’re going to return to the surface of
the Moon with their Artemis mission, ideally
taking the first lunar footsteps in 2024.
NASA Administrator Jim Bridenstine asked for
additional funding to achieve this goal, and
the other branches of government haven’t
been as enthusiastic about this plan.
So don’t be surprised if the landing date
slips to 2028 or even farther.
But NASA is moving forward on its architecture
to return humans to the Moon, from its launch
rocket to the entire method of getting astronauts
down to the surface.
Exactly which rockets, modules and landing
systems that will be used are still getting
worked out, with different options still getting
considered.
Today I wanted to talk about all the different
hardware options that NASA has available to
it, and how their use might change the overall
plan for the Artemis mission.
Before we take a look at the Artemis strategy
to go to the Moon, let’s take a quick look
back at the Apollo methodology that actually
put humans on the Moon back in 1969 and through
the early 1970s.
First, there was the launch of the Saturn
V rocket, carrying three astronauts launched
from Cape Canaveral, Florida.
The first stage of the Saturn V blasted off
from the launch pad, carrying the rocket about
68 kilometers altitude.
Then the first stage detached, with the second
stage firing to carry the rocket to a higher
speed and 166 km altitude.
Then the third stage fired to carry the mission
into low Earth orbit, where it went around
the Earth.
Then the third stage fired again, to send
Apollo on a translunar injection orbit, carrying
it on a path that would bring it to the Moon.
Early on in the journey, the command module
detached from the rest of Apollo flipped around
and then reconnected with its nose, extracting
the lunar module from the top of the third
stage.
Once in orbit at the Moon, the lunar module
descended down to the surface, while the command
module continued to orbit.
Once it landed, the astronauts stepped out,
did some science, collected rocks and made
history.
Then they climbed back on board the lunar
module, which fired its ascent stage, leaving
part of the lander on the lunar surface.
The ascent stage docked with the command module
again which together, and the lunar module
was discarded.
Then the command module fired its rocket for
the transearth injection.
As it approached the atmosphere, the command
module was down to just a capsule carrying
the three astronauts, which re-entered the
Earth’s atmosphere, slowing down, and deploying
its parachutes.
In this way, three astronauts were carried
all the way to the surface of the Moon, and
then safely back to Earth.
So how does Artemis differ?
Unlike Apollo, Artemis will take the additional
step of building a way station between the
Earth and the Moon called the Lunar Gateway.
This will be a permanent space station in
a rectilinear halo orbit that brings the station
as close as 3,000 km of the Moon and as far
as 70,000 km.
It will give astronauts a place to live as
they go up and down from the surface of the
Moon, and transfer to and from the Earth.
The Lunar Gateway will begin as a simple two-module
shelter with Power and Propulsion Element
as well as the Minimal Habitation Module.
Over time additional modules will be attached
to the station to increase its capabilities.
At least six modules are planned for the Gateway,
but this is getting reconsidered too as the
international collaboration for the station
grows.
With Artemis, astronauts and their capsules
will be launched from Earth to the Deep Space
Gateway on a variety of launch systems.
There they’ll reconfigure and equip their
landing vehicles to descend down to the surface
of the Moon.
Although this will require more initial infrastructure,
it’ll allow more frequent and sustainable
trips to the Moon.
There’s also an emphasis on reuse, using
as much of the hardware as possible on multiple
missions.
The actual details are still getting worked
out.
So let’s talk about the various options.
In a recent presentation by Dr. Tim Kokan,
the Principal Engineer for Aerojet Rocketdyne,
he laid out the analysis they had done, considering
every single option for a lunar landing.
From transfer and refueling, ascent and descent,
as well as the types of engines available.
He and his team considered 20 billion different
potential options, settling on more than 326,000
factors they focused on in their study.
They assumed that they’d have 6 different
rockets available to blast off from Earth:
the United Launch Alliance Vulcan Heavy, the
SpaceX Falcon Heavy in expendable mode, the
Northrup Grumman OmegA Heavy, the Blue Origin
New Glenn in a reusable mode, the NASA Space
Launch System in both its Block 1 and Block
1B configuration.
While the smaller rockets like the New Glenn
can only send 10 metric tonnes on a translunar
injection, the monster SLS Block 1B could
hurl 40 metric tonnes at the Moon in a single
launch.
In getting to and from the Moon, there are
three components.
First, there’s the transfer module, which
acts as a reusable booster stage for the lunar
lander.
It provides the change in velocity to carry
the lander from the Lunar Gateway to lunar
landing trajectory.
Once it’s put the lander on the right trajectory,
it detaches and returns to the Gateway to
be reused for future missions.
Next, there’s the lunar landing descent
element, which carries the astronauts down
to the surface of the Moon.
This is similar to the lunar lander in the
Apollo missions.
This is the only part that remains on the
surface of the Moon and isn’t reused.
There’s the lunar landing ascent element,
which is similar to the ascent module in the
Apollo missions.
This would carry the astronauts from the surface
of the Moon back up to the Lunar Gateway.
Finally, there’s the Orion capsule, which
carries the astronauts to and from the Lunar
Gateway.
This is similar to the Command Module in the
Apollo era.
With all of these different puzzle pieces,
Aerojet Rocketdyne considered the best ways
to get them to the Moon.
The first configuration uses 4 rocket launches,
sending all the pieces of a lunar landing
mission on separate launchers.
First, the lunar landing ascent element would
be sent on a smaller rocket, like a Falcon
Heavy.
Then the descent element would follow on its
own launch, followed by the transfer vehicle
element.
Once these three parts were safely at the
Lunar Gateway, an SLS would launch carrying
the Orion Crew capsule with the astronauts
on board.
They would assemble their lunar landing hardware
at the station and leave the Orion module
parked in orbit at the Gateway.
The transfer element would help them complete
most of their journey to the surface of the
Moon, and then it would detach and fly back
up to the Lunar Gateway for a future mission.
The descent module would then carry the astronauts
down to the surface of the Moon, and help
support them for a one-week lunar mission.
Once their mission was complete, the astronauts
would hop into their ascent stage and return
to the Lunar Gateway, leaving the descent
stage on the surface of the Moon.
Then they would return to Earth in the Orion
Capsule, leaving the Gateway ready for the
next crew to visit the Moon.
Future missions to the Moon would only take
two launches now, a new descent module and
an Orion Capsule to carry the crew to and
from the Gateway, as well as any resupply
launches to bring new propellant and supplies
to the station.
The next option is to use only 3 launches,
focusing less on reusability.
This would replace the separate transfer and
descent elements with a much larger single-use
lunar lander, like the Apollo era, that has
enough propulsion to carry the entire lander
from the Gateway down to the surface of the
Moon.
This much larger lunar lander could only be
launched on a stronger rocket SLS Block 1A.
The ascent stage would still launch separately
on a smaller rocket, and they would be assembled
at the Gateway by the astronauts when they
arrive in their Orion Capsule.
The last option brings the total number of
launches down to just two SLS flights.
The entire ascent/descent system would be
launched in a single giant SLS Block 1B launch,
sending it to dock with the Lunar Gateway.
Astronauts would then follow on in their own
SLS-launched Orion Crew capsule.
No assembly is required, they just climb into
their lunar landing system, fly down to the
surface of the Moon, carry out their mission
and then return to the station in their ascent
module, which could then be reused in the
future missions.
Which option is best?
They all have their advantages, and it all
depends on NASA’s priority and the maturity
of the various hardware to go along with it.
With the SLS be complete in time?
What about the heavier Block 1B configuration?
Will they build their own lunar lander or
go with a commercial solution?
Speaking of commercial options, let’s talk
about NASA’s plans for lunar landers.
I’ll get to that in a second, but first
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In September 2019, NASA sent out a request
for a proposal from companies that can supply
them with a lunar lander system for the Artemis
program.
A range of traditional and newer companies
responded, including Boeing, Blue Origin,
SpaceX and others.
We should see NASA announce the winners any
day now.
In order to carry astronauts up to the International
Space Station, NASA decided to bring on two
providers for redundancy.
There’s SpaceX, with its Crew Dragon that’s
expected to launch to the station in a couple
of months, and Boeing’s Starliner, which
is experiencing some delays and could take
a lot longer to fly to space.
NASA is planning to follow this same strategy
with its lunar lander systems, hoping to have
multiple lander systems from different providers,
so they don’t have all their eggs in one
basket.
It could be that a single provider wins the
contract, but more likely, we’re going to
see money flow to several groups, who will
be competing with each other - as well as
collaborating - to bring astronauts to the
surface.
At a meeting in September 2019, NASA official
Marshall Smith said that they’d be selecting
two companies to develop landers.
One would supply the 2024 mission, and the
next provider would handle 2028.
Then they’d continue future missions going
back and forth as necessary.
NASA is open to a direct mission to the Moon
by 2024 if someone thinks they can pull it
off, but providers need to show how they plan
to integrate the Lunar Gateway for 2028 and
beyond for long-term sustainability.
The lander concept we know the most about
right now is Blue Origin’s Blue Moon, which
Jeff Bezos announced at a conference in May
2019.
The spacecraft looks familiar to the original
Apollo Lunar Lander but updated with modern
knowledge about the Moon.
The landing pads, for example, are much smaller,
now that we know that the surface of the Moon
isn’t a fluffy powder.
It’ll use the new BE-7 engines powered by
liquid hydrogen and oxygen, and not the hypergolic
fuel used by Apollo.
This is partly to demonstrate that hydrogen
and oxygen work well as a fuel on the Moon,
should we ever get around to mining ice from
the lunar regolith and using it for rocket
fuel.
Blue Moon is bigger and heavier than the Apollo
landers, weighing almost 4 times as much,
and capable of delivering over tonnes of payload
to the surface of the Moon.
Just to give you some examples, the Curiosity
Rover weighs just under a tonne, so it could
carry 4 of them.
Or it could carry an astronaut module to the
surface of the Moon, an ascent module like
we talked about earlier.
At another meeting in October, Bezos announced
a partnership with Lockheed Martin and Northrup
Grumman to team up to build a lunar landing
stack.
Blue Origin would build Blue Moon for the
descent stage, and be the primary contractor
launching with their New Glenn rocket.
Northrup Grumman will provide the transfer
element and Lockheed Martin will provide the
ascent stage.
If all goes well, we’ll see the first tests
of New Glenn in 2021, providing a reusable
first stage that rivals the lift capability
of the SpaceX Falcon Heavy, racing the development
of the SpaceX Starship.
Things are going to get interesting.
2024 is getting closer every day.
If NASA seriously plans to return to the Moon
by this date, they’re going to need to make
a final decision about the configuration of
various elements of the Artemis program.
What I like about the overall strategy is
that it constantly builds up infrastructure
out at the Moon, allowing more and more missions
down to the surface, to more scientifically
interesting regions, like the Moon’s southern
pole.
It brings in multiple providers, ensuring
that NASA doesn’t get locked into a single
company’s technology.
If NASA does return to the Moon, this time,
I think they’ll stay.
Allowing for longer and longer missions.
Hopefully, future generations will always
be able to look up and the Moon and know that
there are humans there right now.
What do you think?
Let me know your thoughts in the comments.
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