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APPLES: Architecture for PrePositioning Lunar Expedition Supplies�Strategic Logistics for Human Space Activity

CAITLYN ALEXANDER

ASTE 527

12/11/18

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What is caching?
What supplies should be cached?
Where should we cache?
How can commercial businesses help to lower cost?
What are the benefits and limitations?

Agenda

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Caching:

To store away in hiding for future use

Water cache for hikers on Pacific Crest Trail

Ammunition cache

Acorn Woodpeckers storing food in holes drilled in tree

Lewis and Clark expedition underground cache

Grey Squirrel burying nuts underground

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Critical mission supplies spread over multiple launches

Smaller launch vehicles = lower cost

Supplies available in key locations in case of unexpected need

Caches can be continuously resupplied, allowing for longer missions

Can take advantage of unused payload capability on other missions

The Case for Caching

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Consumables

Propellant, oxygen, water, food, medical supplies

Equipment and Supplies

Spare parts, rovers, habitat supplies, surface excavators, scientific equipment

Cache supplies will be tailored to specific mission needs

So what types of supplies would be well suited for caching?
Consumables would be a key resource to cache. Fuel in particular makes up a majority of the mass on any space mission. If that fuel load can be cut back by caching and resupplying en route, there can be huge cost savings.
Life support supplies, such as food, water, medical supplies, and oxygen, are also great candidates for caching for human missions
On the right side, we have some examples of equipment and supplies that could also be cached. Things such as rovers and habitat supplies could be sent ahead of human missions so that they are already on location and ready to go. Critical spare parts can also be stored in case of emergency.
Basically, anything that can help to lighten the load of the spacecraft and help with logistics on the moon surface would be good candidates for caching

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Caching in Space

L1 and L2

Easy access from both Earth and Moon

Low Earth Orbit

Allows for refuel en route to Moon
Recommend use of non-cryogenic (liquid, solid, or hybrid fuel) for ease of storage

Lunar Orbit

Can send supplies to various locations on lunar surface

L4 and L5

Stable Lagrange points that don’t require station keeping

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Russian Luna

Apollo

Surveyor

Proposed site

Shackleton Crater

Likely location of water ice

Peary Crater

Likely location of water ice

Various Equatorial Sites

Likely higher concentrations of helium-3
Can take advantage of free return trajectory to Earth

Marius Hills

Possible location of lava tubes

Caching on the

Moon

Speaking of the moon surface, this map shows some key points of interest that would also be great candidates for cache sites
The craters at the North and South poles likely contain water ice and are significant areas of interest for further exploration and development
There are also thought to be lava tubes on the moon surface, such as in the Marius Hills. These tubes can serve as a habitat structure for humans
Sites along the equator are also appealing because it is rich is natural resources and because missions to the equator can take advantage of a free return trajectory back to Earth.
One of the biggest benefits of caching supplies on the moon’s surface is to extend mission lengths. Rovers and astronauts can travel further distances if caches are set up with supplies for them ahead of time. They simply would need to travel to the next cache site rather than returning to a home base, which greatly expands their range.

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Sample Mission:

Human mission to lunar orbit with remote robotic surface exploration of Shackleton Crater

Not to scale

To put this concept in context, I want to show how this architecture can be applied to a near term mission. In this scenario, we have a human mission that will go to lunar orbit and perform remote surface exploration of the Shackleton Crater
So first the rocket launches from Earth. This is a relatively small, low cost launch vehicle
When it gets to Low Earth Orbit, it rendezvous with a propellant cache to refuel for the journey to the Moon
It continues around Earth orbit and then transfers into a trans lunar injection trajectory
Once it gets to lunar orbit, there is a cache waiting that contains human life support supplies to provide for the crew for the duration of their mission. There are also spare parts and scientific equipment stored
Finally, they are ready to perform the surface exploration and all their equipment has already been cached near their location of interest at the South Pole
As you can see, by utilizing caching, they were able to use a much smaller launch vehicle and mission logistics were streamlined by having all their required equipment and supplies ready to go precisely where they were needed

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Protecting Caches in a Harsh Environment

In the Space Environment

Use of non-cryogenic fuel greatly simplifies storage maintenance
Solid propellant solves boil off issue, but takes performance hit

On the Moon

Regolith dust may need to be cleared from cache upon retrieval

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Space: the next commercial frontier

Use of smaller rockets encourages commercial launch vehicle development
More commercial competition drives down cost

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SpaceX

There are only a handful of American companies with the resources to build a heavy-lift rocket

Smaller launch vehicle = lower point of entry for more companies to enter market

United Launch Alliance

(Boeing & Lockheed Martin)

Blue Origin

Vulcan

New Glenn

NASA, Boeing, Aerojet Rocketdyne,

& Northrop Grumman

SLS

Falcon 9

Falcon Heavy

BFR

Delta IV Heavy

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Delta IV Heavy

Cost per launch: $400 million
Payload Capability to LEO: 28,790 kg
$/kg = $13,894

Falcon 9

Cost per launch: $61.2 million
Payload Capability to LEO: 22,800 kg
$/kg = $2,684

Atlas V

Cost per launch: $179 million
Payload Capability to LEO: 18,814 kg
$/kg = $9,514

Payload x2 = 37,628 kg

Payload x6 = 136,800 kg

Payload = 28,790 kg

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Lunar Landers

Astrobotic Griffin & Peregrine

Payload: 270 kg (Griffin); 35 kg (Peregrine)
First mission: 2019

Blue Origin Blue Moon

Payload: 1000+ kg
First mission: 2023?

Moon Express MX-1

Payload: 30 kg
First mission: 2019

Masten Space Systems XL1 & Xeus

Payload: 100 kg (MX-1); 10,000 kg (Xeus)
First mission: 2021

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SpaceX Falcon 9

Astrobotic Peregrine

2018

2019

2020

2021

2022

We are ready to begin caching in the early 2020’s

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To the Moon and beyond…

The same strategy can be applied to travel beyond cislunar space
Caches in LEO, lunar orbit, Mars orbit, and on the Mars surface would serve many benefits for a Mars mission

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Benefits

Lower cost due to use of smaller launch vehicles
Supplies readily available in key locations
Continuous resupply of caches allows for extended mission life

Limitations

If there is a failure involving the cache or transfer, mission could be left without critical supplies

Areas of Further Study

How will propellant and other supplies be safely stored (orbit station keeping, environmental controls, etc)
What specific orbits or surface locations would be best
How will fuel and other supplies be physically transferred

To summarize, the major benefits of caching are

Lower costs due to use of smaller rockets
Supplies readily available when needed
Continuous resupply of caches to extend mission life

There are some limitations as well, a large one being that if there is an issue with the cache or the supply transfer, the mission could be left without critical supplies.
Finally, there are some other areas of study that will need to be explored before this can be put into practice. The storage systems for on orbit and surface supplies will need to be fleshed out. Specific cache locations will need to be identified to best fulfill mission needs. The transfer mechanism for retrieving fuel and supplies will also need to be fully designed.
With that, I will conclude my presentation and would be happy to answer any questions.

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Questions?

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References

https://www.nasa.gov/press-release/nasa-space-launch-system-s-first-flight-to-send-small-sci-tech-satellites-into-space
http://www.spaceflightinsider.com/missions/commercial/astrobotic-awarded-nasa-contracts-to-develop-lunar-lander-technologies/
http://time.com/5342743/nasa-moon-mars/
https://www.theverge.com/2018/5/22/17380476/nasa-space-launch-system-block-1-europa-clipper-mission
https://www.astrobotic.com/
http://moonexpress.com/
https://www.geekwire.com/2018/blue-origin-targets-moon-landing-2023-early-step-toward-lunar-settlement/
https://www.masten.aero/xl1
https://www.ulalaunch.com/about/news/2017/07/26/astrobotic-and-united-launch-alliance-announce-mission-to-the-moon
http://www.planetary.org/blogs/jason-davis/2018/20180229-nasa-moon-landing-plan.html
https://www.nasa.gov/returntoflight/system/system_ET.html
Ahn, J., & De Weck, O. (n.d.). Mars Surface Exploration Caching from an Orbiting Logistics Depot. Journal of Spacecraft and Rockets, 47(4), 690–694. doi:10.2514/1.37694
https://www.gao.gov/assets/690/686613.pdf