Ammonia as a storage medium for Mars Shipment

tahanson43206 · 2025-05-15 14:54:39

In another topic, kbd512 recently suggested considering ammonia as an energy storage medium for shipment to Mars for a variety of purposes. One distinctive benefit of shipping Nitrogen to Mars is it's value for plant growth, completely aside from the potential for other uses.

I asked Google's Gemini to run a quick scan of the literature, and it found several instances of mention.

Conversation with Gemini
Hi Gemini! Thanks for your assistance with many previous questions! This one is to try to help a member of a forum. The member has proposed using ammonia as a way to ship propellant to Mars. To my knowledge, no one has written about that idea, but my knowledge is limited, compared to yours. Please run a quick scan to see if anyone has written up that idea.

Show thinking
Ammonia as a Propellant for Mars Missions: An Explored Concept
The idea of utilizing ammonia as a propellant for missions to Mars, including shipping it to the Red Planet, has indeed been discussed and explored in various contexts within the aerospace community, though it may not be as mainstream as other proposed propellants like methane or hydrogen.
Key Areas of Discussion and Research:
Ammonia as a Hydrogen Carrier: One notable concept involves transporting hydrogen to Mars via anhydrous ammonia (NH
3
). A paper from Embry-Riddle Aeronautical University outlines a method where ammonia, which is easier to store and transport than pure hydrogen, would be shipped to Mars. Upon arrival, a specialized reactor (such as a patented microwave electro-thermal plasma reactor called "Plasmonia") would dissociate the ammonia into hydrogen and nitrogen. The hydrogen could then be used as a high-performance fuel or for other in-situ processes. This approach leverages ammonia's favorable storage density compared to cryogenic hydrogen.
Nuclear Thermal Propulsion (NTP): Ammonia has been seriously considered and studied by NASA and other research entities as an alternative propellant for Nuclear Thermal Propulsion systems for Mars missions. In NTP, a nuclear reactor heats a propellant like hydrogen or ammonia to very high temperatures, expelling it through a nozzle to create thrust. Studies have compared ammonia to hydrogen for NTP applications, noting ammonia's advantage of higher density (leading to smaller, lighter propellant tanks) and easier (non-cryogenic or less-cryogenic) storage. However, ammonia generally offers a lower specific impulse (I
sp
), a measure of engine efficiency, compared to hydrogen in NTP systems. Some analyses have also considered sourcing ammonia from in-situ resources, for instance, on the Moon, for such propulsion systems.
In-Situ Resource Utilization (ISRU) Context: The production of ammonia on Mars using local resources (nitrogen from the atmosphere, hydrogen from water ice) has been a topic of discussion. This ISRU-produced ammonia could then be used as a propellant. In this context, some have argued that if complex on-Mars manufacturing of ammonia proves too challenging, shipping ammonia from Earth might be a more straightforward alternative.
Direct Use as a Bipropellant or Monopropellant: While less common in detailed mission architectures compared to methane/LOX (liquid oxygen) or hydrogen/LOX, ammonia can be used as a fuel with an oxidizer (like LOX) or potentially as a monopropellant (decomposed over a catalyst to produce hot gas for thrust). Its performance (specific impulse) as a chemical bipropellant is generally lower than methane or hydrogen.
Advantages of Ammonia as a Space Propellant:
Higher Density than Liquid Hydrogen: This allows for smaller and potentially lighter propellant tanks, which is a significant advantage in spacecraft design.
Easier Storage than Liquid Hydrogen: Ammonia can be stored as a liquid at moderate pressures and temperatures (-33 °C), making its handling and long-term storage in space less complex and energy-intensive than managing cryogenic liquid hydrogen.
Carbon-Free: Combustion of ammonia with oxygen produces nitrogen and water, avoiding the production of carbon dioxide, which can be relevant for certain applications or if considering planetary protection.
Existing Industrial Infrastructure: Ammonia is widely produced and transported on Earth, meaning there's extensive experience with its handling, although space applications have unique requirements.
Disadvantages and Challenges:
Lower Specific Impulse (I
sp
): Compared to hydrogen or methane when used in chemical rockets, ammonia generally provides a lower I
sp
, meaning more propellant mass is needed for the same change in velocity (ΔV).
Toxicity: Ammonia is toxic to humans and corrosive to some materials, requiring careful handling procedures and material compatibility considerations.
ISRU Challenges on Mars: While nitrogen is present in the Martian atmosphere (about 2.6%), its extraction and combination with hydrogen (from scarce water ice) to synthesize ammonia on Mars present significant technical hurdles.
Shipping Costs and Logistics: Transporting any propellant from Earth to Mars is a massive undertaking due to the sheer quantities required. The trade-off between shipping ammonia versus other propellants, or versus investing in ISRU capabilities, is a complex architectural decision for Mars missions. Most current Mars mission architectures lean towards ISRU production of methane and oxygen, or shipping these propellants, due to performance characteristics and the perceived availability of Martian resources (CO2 for carbon and oxygen, water ice for hydrogen).
Conclusion:
The concept of using ammonia as a propellant for Mars, including the scenario of shipping it there, is not an unexamined idea. It has appeared in technical papers, NASA studies (particularly concerning NTP), and forum discussions. Researchers have recognized its storage and handling benefits over hydrogen. However, its lower performance compared to other chemical propellants and the significant push towards developing ISRU capabilities on Mars (primarily for methane and oxygen) mean that shipping ammonia from Earth as a primary propellant for chemical rockets is currently a less favored option in mainstream Mars mission planning. The idea of using it as a hydrogen carrier or in NTP systems continues to be an area of interest.

Thank you ** very ** much for your assistance in scanning the literature! This service saves us time, and helps us to focus on the resources available.

Show thinking
You're very welcome! I'm glad I could assist you and the forum member by providing a scan of the available information. Saving you time and helping you focus your research is exactly what I aim to do.
If you or the forum have any more questions in the future, please don't hesitate to ask!

(th)

tahanson43206 · 2025-05-15 14:55:59

This post is reserved for an index to posts that may be contributed by NewMars members over time.

This topic has potential for growth, due to the multiple applications for Nitrogen, in addition to uses for the Hydrogen.

Index:
Calliban re compare shipment of ammonia to hydrogen:
https://newmars.com/forums/viewtopic.ph … 76#p231676

(th)

Calliban · 2025-05-15 15:41:21

Liquid ammonia has a higher hydrogen density than liquid hydrogen and can be stored at about 6bar vapour pressure at room temperature. The obvious disadvantage is that ammonia has molecular weight of 17amu. To transport 3kg of hydrogen, we need to send 17kg of ammonia to Mars. Still, it might be a positive tradeoff. Another advantage is that ammonia (or methane) shipped to Mars can be used as rocket fuel without further synthesis.

Void · 2025-05-15 17:36:32

You are very useful. I would like to see Ammonia as a rocket fuel for a Mars Surface<>Phobos<>Deimos sub-network. That and Oxygen of course, and Carbon. Maybe Ammonia and CO as fuels.

While the die-hard members want to do the Musk Dream on Mars, I also want to do the Bezos Dream in orbit of Mars.

I will borrow from you now.

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#1 2025-05-15 14:54:39

Ammonia as a storage medium for Mars Shipment

#2 2025-05-15 14:55:59

Re: Ammonia as a storage medium for Mars Shipment

#3 2025-05-15 15:41:21

Re: Ammonia as a storage medium for Mars Shipment

#4 2025-05-15 17:36:32

Re: Ammonia as a storage medium for Mars Shipment

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