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 I’d like to thank:
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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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