Is Orion really capable of reaching Mars?

[MATTBLAK]

As far as I'm aware; the only Mars Mission Design Reference Mission from the 'Constellation Canon' that was given serious consideration was DRM 5.0; where the Orion was a combination 'Taxi', Command & Control Module and Earth Return vehicle. This is portrayed in this DRM concept video. The Orion would have to become a 'Block III' or IV version to survive about two years in space.

[pochimax]

I imagine that the best 'parking spot' for the MTV would be one of the EML halo orbits. Hence Gateway - I think that NASA's forward planning for Mars is already assuming that they won't take an Orion all the way to Mars and back.

Yes, most of the architectures I've seen lately use NRHO (that's because SLS can't really do payload to LEO and NASA assumes SLS - let's not rehash this argument please) and have Orion serve pretty much solely as a crew transfer vehicle.

Yes, one example.

https://www.researchgate.net/publication/308007278_Commercial_Options_for_Hybrid_ChemicalElectric_Propulsion_Transportation_System_to_Support_Mars_Exploration

See this Figure for conops. It needs 2 Orion per flight to Mars.

https://www.researchgate.net/profile/Christopher_Jones49/publication/308007278/figure/fig1/AS:789972357505024@1565355495271/Mars-Hybrid-Crew-Mission-Concept-of-Operation-4.png

[the_other_Doug]

ISTR that MSFC was working on a transit hab for Mars flights that was the same diameter as the EUS, giving the Mars crews both enough room to stay sane, and also to pack up to three years' worth of food and water for four people.  The teensy mini-hab NASA wants to go with for the lunar gateway, if used for Mars, will likely not be conducive to a sane crew upon Mars arrival.  But that's not a problem, since you'd need five or more Cygni just to store the food and water needed for the mission anyway, so by using the lunar gateway as a pathfinder to develop your Mars transit hab, one of its stated goals, you're ensuring the crew won't get there alive anyway...

[AnnK]

Why can not the Orion and other vehicles get launched by a Falcon Heavy? Assemble in Earth orbit and then head towards Mars? It would sure save billions of dollars. For the price of a single SLS launch, get 40 Falcon heavy launches. Perhaps have no second stage like Skylab. Just some thoughts from an aviation engineer.

[Eric Hedman]

Why can not the Orion and other vehicles get launched by a Falcon Heavy? Assemble in Earth orbit and then head towards Mars? It would sure save billions of dollars. For the price of a single SLS launch, get 40 Falcon heavy launches. Perhaps have no second stage like Skylab. Just some thoughts from an aviation engineer.

These are as much political decisions as they are technical.  Politics often wins.

[Nomadd]

Why can not the Orion and other vehicles get launched by a Falcon Heavy? Assemble in Earth orbit and then head towards Mars? It would sure save billions of dollars. For the price of a single SLS launch, get 40 Falcon heavy launches. Perhaps have no second stage like Skylab. Just some thoughts from an aviation engineer.

Skylab wouldn't have gotten very far without a 2nd stage. It replaced the 3rd stage.

[Proponent]

Why can not the Orion and other vehicles get launched by a Falcon Heavy? Assemble in Earth orbit and then head towards Mars? It would sure save billions of dollars. For the price of a single SLS launch, get 40 Falcon heavy launches. Perhaps have no second stage like Skylab. Just some thoughts from an aviation engineer.

These are as much political decisions as they are technical.  Politics often wins.

Politics, indeed.  Recall that, faced with yet another SLS delay, in early 2019 Bridenstine proposed flying EM-1 (now known as Artemis 1) on something other than SLS.  There did not seem to be any fundamental reason it couldn't be done, but significant work would have been needed.  You can read all about it in these two interesting threads:

    NASA Launch Services Program outlines the alternative launcher review for EM-1 and
    NASA Considering Flying EM-1 With Commercial Launchers .

It was to be just for EM-1, with SLS being used for subsequent missions, but Sen. Shelby was very strongly opposed anyway.

[Staticalliam7]

Unless I'm misinterpreting, NASA's overview of Orion:

https://www.nasa.gov/exploration/systems/orion/about/index.html

seems to indicate that Orion is intended for flights to Mars, or at least the vicinity of Mars, as well as to the Moon. I'm no expert on Mars missions, but from what I've read, a Mars mission would require a one-way journey of at least six to eight months, depending on the relative positions of the Earth and Mars at the time of launch.

Given Orion's Apollo-based design, I'm wondering how Orion will be able to carry sufficient oxygen, food, fuel etc. to support four (or even two) astronauts for such a period of time?

Also, I think anyone would go insane if they were stuck in Orion, which is probably pretty small even for 4 day missions.

[Staticalliam7]

Why can not the Orion and other vehicles get launched by a Falcon Heavy? Assemble in Earth orbit and then head towards Mars? It would sure save billions of dollars. For the price of a single SLS launch, get 40 Falcon heavy launches. Perhaps have no second stage like Skylab. Just some thoughts from an aviation engineer.

Falcon Heavy isn't powerful enough. Not sure the exact lunar orbit capacity, but I sent SpaceX an email to find out.

[Dalhousie]

Unless I'm misinterpreting, NASA's overview of Orion:

https://www.nasa.gov/exploration/systems/orion/about/index.html

seems to indicate that Orion is intended for flights to Mars, or at least the vicinity of Mars, as well as to the Moon. I'm no expert on Mars missions, but from what I've read, a Mars mission would require a one-way journey of at least six to eight months, depending on the relative positions of the Earth and Mars at the time of launch.

Given Orion's Apollo-based design, I'm wondering how Orion will be able to carry sufficient oxygen, food, fuel etc. to support four (or even two) astronauts for such a period of time?

Also, I think anyone would go insane if they were stuck in Orion, which is probably pretty small even for 4 day missions.

21 m3 pressurised volume.  Almost twice Starliner, more than twice Dragon 2 or Soyuz, over three times Apollo CM. Fine for lunar missions or Earth return from a MTV

[rakaydos]

Why can not the Orion and other vehicles get launched by a Falcon Heavy? Assemble in Earth orbit and then head towards Mars? It would sure save billions of dollars. For the price of a single SLS launch, get 40 Falcon heavy launches. Perhaps have no second stage like Skylab. Just some thoughts from an aviation engineer.

Falcon Heavy isn't powerful enough. Not sure the exact lunar orbit capacity, but I sent SpaceX an email to find out.

I thought I remember some older calculations that suggested a falcon heavy upper stage with nothing but a docking adaptor as payload, could dock with an Orion in LEO, and have enough juice left over for TLI.

[Coastal Ron]

The simple answer to this question is NO, as currently designed the Orion MPCV is NOT meant to be capable of reaching Mars.

The simple reason is that the current Orion MPCV design is oriented towards supporting missions to our Moon, with up to 21 days of active crew time plus 6 months quiescent spacecraft life. A Mars mission would last at least two years.

And sure, you could re-designate the Orion MPCV has a lifeboat on a Mars mission, but think about it, what happens if you jump into that lifeboat months into the mission? You're not going to last long, are you? And there is no way to resupply the Orion MPCV as designed today, so in reality it can't serve as a lifeboat on a Mars mission.

Which means you're only hauling all that mass along on a two year Mars mission so that you can use it for the last days of the mission - landing on Earth. But as I recall the current Orion MPCV heat shield is not rated for return from Mars, and the weight of the capsule could be too heavy in any case.

Could the currently designed Orion MPCV be massively redesigned to allow it to go to Mars? Sure, but then it wouldn't be the Orion anymore, it would be something very different, and it would be called something else.

Instead of trying to slather lipstick on this pig, we should just focus on building true space-only, fully reusable, space transportation that can go from Low Earth Orbit to destinations far away, and then return to Low Earth Orbit where passengers and cargo can transfer to the existing Commercial Crew vehicles for return to Earth. A much more simple architecture that is easy to upgrade.

[ncb1397]

The simple reason is that the current Orion MPCV design is oriented towards supporting missions to our Moon, with up to 21 days of active crew time plus 6 months quiescent spacecraft life. A Mars mission would last at least two years.

That is largely a limit on the service module O2 supply. Two tanks holding 33 kg each with astronauts breathing at .84 kg per day gives you...

(33 kg per tank * 2 tanks)/(.84 kg/day * 4 astronauts) ≈ 20

There is potentially another day or two of air in the cabin that isn't in the tanks at launch time.

Adding more O2 is potentially a relatively trivial matter. Replacing the 275 bar tanks with 800 bar tanks (equivalent to consumer available hydrogen fuel cell vehicle tanks) would increase O2 supply by a factor of  2.9 increasing crew air to ~61 days while not increasing footprint.

Read up on the EDO project for the Shuttle:

The Extended Duration Orbiter Cryogenic kit (EDO-pallet or CRYO) was a 15-foot-diameter (4.6 m) equipment assembly which attached vertically to the payload bay rear bulkhead of an orbiter, and allowed the orbiter to support a flight of up to 16 days duration.[1] The equipment included cryogenic tanks, associated control panels, and avionics equipment. Although Atlantis was partially upgraded to accommodate the EDO, only Columbia and Endeavour actually flew with the pallet. The pallet made its debut on STS-50, and was lost on STS-107.[4]

Initially, NASA considered adding a second EDO pallet to Endeavour, placed in front of the first, for a total of thirteen tank sets, that would have allowed an orbiter to remain in space for 28 days, but managers decided against it when the International Space Station assembly began, and instead removed the EDO capability from the orbiter, to reduce its weight and allow it to carry more cargo to the ISS.[1][5]

https://en.wikipedia.org/wiki/Extended_Duration_Orbiter

[Staticalliam7]

The simple reason is that the current Orion MPCV design is oriented towards supporting missions to our Moon, with up to 21 days of active crew time plus 6 months quiescent spacecraft life. A Mars mission would last at least two years.

That is largely a limit on the service module O2 supply. Two tanks holding 33 kg each with astronauts breathing at .84 kg per day gives you...

(33 kg per tank * 2 tanks)/(.84 kg/day * 4 astronauts) ≈ 20

There is potentially another day or two of air in the cabin that isn't in the tanks at launch time.

Adding more O2 is potentially a relatively trivial matter. Replacing the 275 bar tanks with 800 bar tanks (equivalent to consumer available hydrogen fuel cell vehicle tanks) would increase O2 supply by a factor of  2.9 increasing crew air to ~61 days while not increasing footprint.

Read up on the EDO project for the Shuttle:

The Extended Duration Orbiter Cryogenic kit (EDO-pallet or CRYO) was a 15-foot-diameter (4.6 m) equipment assembly which attached vertically to the payload bay rear bulkhead of an orbiter, and allowed the orbiter to support a flight of up to 16 days duration.[1] The equipment included cryogenic tanks, associated control panels, and avionics equipment. Although Atlantis was partially upgraded to accommodate the EDO, only Columbia and Endeavour actually flew with the pallet. The pallet made its debut on STS-50, and was lost on STS-107.[4]

Initially, NASA considered adding a second EDO pallet to Endeavour, placed in front of the first, for a total of thirteen tank sets, that would have allowed an orbiter to remain in space for 28 days, but managers decided against it when the International Space Station assembly began, and instead removed the EDO capability from the orbiter, to reduce its weight and allow it to carry more cargo to the ISS.[1][5]

https://en.wikipedia.org/wiki/Extended_Duration_Orbiter

I read somewhere that the ISS's solar panels actually produce water that can be used for oxygen, is this possible for a smaller  vehicle, or does it require bulky, heavy equipment?

[Coastal Ron]

The simple reason is that the current Orion MPCV design is oriented towards supporting missions to our Moon, with up to 21 days of active crew time plus 6 months quiescent spacecraft life. A Mars mission would last at least two years.

That is largely a limit on the service module O2 supply...

Adding more O2 is potentially a relatively trivial matter. Replacing the 275 bar tanks with 800 bar tanks (equivalent to consumer available hydrogen fuel cell vehicle tanks) would increase O2 supply by a factor of  2.9 increasing crew air to ~61 days while not increasing footprint.

OK, now the crew in the cramped capsule can survive 61 days of a 780 day trip. I'm not sure you're solving the basic problem here - there is no use for an Orion spacecraft on a Mars journey until you get really close to Earth, in which case you've been hauling this massive weight around the solar system for little ROI.

The "Orion MPCV" as currently designed is for traveling to the Moon. Period. If the want to scavenge the Orion MPCV design for usable parts for a Mars vehicle, great, but it won't be called the "Orion MPCV" anymore, will it?

Plus, why keep trying to put lipstick on this pig. For the same amount of effort you can likely just design a new space-only fully-reusable spacecraft that can be used to go to Mars.

[ncb1397]

The "Orion MPCV" as currently designed is for traveling to the Moon. Period. If the want to scavenge the Orion MPCV design for usable parts for a Mars vehicle, great, but it won't be called the "Orion MPCV" anymore, will it?

I don't know? What did we call the Block II Apollo CSM? What did we call the Shuttle with EDO modifications (and after they were removed?). What do we call the ISS when Nauka is launched? What did we call the Orion MPCV with the unitary heatshield design rather than block design?

The simple reason is that the current Orion MPCV design is oriented towards supporting missions to our Moon, with up to 21 days of active crew time plus 6 months quiescent spacecraft life. A Mars mission would last at least two years.

That is largely a limit on the service module O2 supply. Two tanks holding 33 kg each with astronauts breathing at .84 kg per day gives you...

(33 kg per tank * 2 tanks)/(.84 kg/day * 4 astronauts) ≈ 20

There is potentially another day or two of air in the cabin that isn't in the tanks at launch time.

Adding more O2 is potentially a relatively trivial matter. Replacing the 275 bar tanks with 800 bar tanks (equivalent to consumer available hydrogen fuel cell vehicle tanks) would increase O2 supply by a factor of  2.9 increasing crew air to ~61 days while not increasing footprint.

Read up on the EDO project for the Shuttle:

The Extended Duration Orbiter Cryogenic kit (EDO-pallet or CRYO) was a 15-foot-diameter (4.6 m) equipment assembly which attached vertically to the payload bay rear bulkhead of an orbiter, and allowed the orbiter to support a flight of up to 16 days duration.[1] The equipment included cryogenic tanks, associated control panels, and avionics equipment. Although Atlantis was partially upgraded to accommodate the EDO, only Columbia and Endeavour actually flew with the pallet. The pallet made its debut on STS-50, and was lost on STS-107.[4]

Initially, NASA considered adding a second EDO pallet to Endeavour, placed in front of the first, for a total of thirteen tank sets, that would have allowed an orbiter to remain in space for 28 days, but managers decided against it when the International Space Station assembly began, and instead removed the EDO capability from the orbiter, to reduce its weight and allow it to carry more cargo to the ISS.[1][5]

https://en.wikipedia.org/wiki/Extended_Duration_Orbiter

I read somewhere that the ISS's solar panels actually produce water that can be used for oxygen, is this possible for a smaller  vehicle, or does it require bulky, heavy equipment?

They take water shipped from the ground and produce hydrogen and oxygen. Hydrogen and CO2 is also combined to generate methane and oxygen. The methane is dumped overboard. At mars distance, the Orion solar array wings would produce about half of the rated 11.2 kw or ~5 kw. To produce 3.5 kg of oxygen would take on the order of 35 kwh of electricity. So, about 7 hours of each 24 hour period or 30% of the power output would have to go to electrolyzing water if you store your oxygen as water (worst case scenario). But the main advantage of storing as water is density and the density in terms of O2 content of liquid water is not much better than 800 bar oxygen.  It then comes down to a risk calculation. What is the risk of the 800 bar tank rupturing? And what is the risk of your O2 generator breaking down?

OK, now the crew in the cramped capsule can survive 61 days of a 780 day trip. I'm not sure you're solving the basic problem here - there is no use for an Orion spacecraft on a Mars journey until you get really close to Earth, in which case you've been hauling this massive weight around the solar system for little ROI.

I thought this was just a lifeboat? So, the duration would not be 780 days but the earth to mars or mars to earth transfer time. Anyways, you could replace the two N2 tanks with oxygen tanks and go to low pressure environment like Apollo. That would double your O2 supply again.

[the_other_Doug]

A few points, here, if I may...

The lifeboat concept is more, I think, for certain situations where your transit hab module loses pressure or electrical redundancy.  I doubt you'd be talking about casting away from all of the supplies and consumables needed to get home alive and then try holding your breath inside the Orion.  Rather, you might have to rig data and air lines from the tanks in the hab into the Orion and live in it.  Or, in a less broad interpretation of lifeboat, use Orion's systems to provide supplemental redundancy for some hab systems.

Obviously, without a completely different, and much larger/heavier, service module, Orion cannot all by itself come back from anywhere significantly into a trans-Mars trajectory.  And in any event would require a logistics module of some kind to carry the food and spare parts you'd need to get home alive.  I don't think any design reference mission is suggesting anything different.

That said, if NASA cheaps out like they have and flies basically a Cygnus module as their transit hab, more than half of its volume filled with food and consumables storage, you ain't giving a 4-person crew with normal personal space needs enough space to stay sane for more than a month or so in the first place.  If you hand-pick your crews for their ability to get along, and not suffer from lack of personal space, they can probably manage in an Orion capsule's interior for several months as well as they could in that maybe a net of 1.5 times that volume -- enough room for one, maybe two people at a time to stretch out a bit, and that's it.

Orion is big enough, and the hab concepts they're likely to spring for if the lunar gateway is any indication, are small enough, that you're wrong in thinking of it as an Apollo connected to a Skylab, or a Soyuz connected to a Salyut.  It's more like an Apollo docked with a LM, flying for months and months with just the total living volume of the two spacecraft.  You'd need to use the Orion internal volume if your "hab" won't fit your crew all at the same time...

[Zed_Noir]

The only way that the Orion capsule goes to Mars with crew is by using a Moonship (Starship variant) or something that big as the "service module" and transit habitat. 

[Coastal Ron]

A few points, here, if I may...

The lifeboat concept is more, I think, for certain situations where your transit hab module loses pressure or electrical redundancy.  I doubt you'd be talking about casting away from all of the supplies and consumables needed to get home alive and then try holding your breath inside the Orion.  Rather, you might have to rig data and air lines from the tanks in the hab into the Orion and live in it.  Or, in a less broad interpretation of lifeboat, use Orion's systems to provide supplemental redundancy for some hab systems.

NSF tends to be populated with lots of people that are engineering biased, and not enough that focus on the business case for doing something.

For instance, could the Orion MPCV as designed today be modified with taxpayer money to allow it to travel to Mars? Sure. It's just a hunk of hardware, and given enough time and money it could be modified into anything. It could be modified to replace the ISS if we wanted, just as an example of extreme silliness.

The real question though is whether there is a use case for modifying the Orion MPCV, or whether it makes sense to just design a vehicle from the ground up to satisfy the need to send humans to Mars and back.

As an example, do we need a vehicle with a heatshield in order to go to Mars? And if so why? And what would be the alternatives?

If we assume that we're not doing a direct launch to Mars from the surface of Earth, and instead we are assembling our "fleet" somewhere in Earth or lunar orbit, then maybe this Mars vehicle doesn't need a heatshield for the end of it's journey, since the end of the journey will just end back where it started - in Earth or lunar orbit.

And if we are sending more than one vehicle to Mars at the same time, ala the Nina, the Pinta, and the Santa Maria (the fleet Columbus had), then each of those vehicles is the lifeboat for the others. So no need for a vehicle that only performs one function.

So pull out a clean sheet of paper, or start a new file, and list what is actually needed for this trip to Mars. And only after listing out the requirements should you start looking around to see what existing hardware you can use to satisfy that need. And if you do that, I am pretty sure the Orion MPCV will not satisfy any need for leaving Earth-local space.

[ncb1397]

So, here is my operational concept for an Orion flight to mars orbit and back.

-two launches of SLS Block 1B/2 vehicles. Block 1B gets between 31.6 t and 34.3 t to the Mars C3 of ~10 km^2/sec^2.
-each SLS launch carries an Orion crew capsule with 2 crew each. The two orions will dock during trans-mars transits. They may or may not undock during mars orbit insertion and mars departure burns. They of course undock prior to earth re-entry.
-departure is Nov-29-2028, earth return is Sep-19-2031, duration is 1025 days.
-Orion gas delivery system contains 4 O2 tanks rather than 2/3 O2 tanks and 1/2 N2 tanks.
-O2 tanks are 550 bar(double baseline) holding 66 kg of O2 each or 264 kg.
-280 kg of water is stored in the ESM (baseline capacity)
-an additional 2.7 t(2.7 cubic meter) water tank is constructed in each Orion (see diagrams for rough geometry.
-In addition, a urine processor, solid oxide electrolyzer unit similar to Mars 2020 Moxie (but an order of magnitude higher capacity), water electrolyzer and improved bathroom/waste management system is installed in each Orion replacing where two of the seats would be in the baseline Orion
-Mars insertion delta-v is 854 m/s, Mars departure delta-v is 519 m/s, total delta-v required to be provided by Orions is 1.37 km/s.

O2 requirements are 1024 days * 4 astronauts * .84 kg/day = 3.44 t
 -each Orion carries .264 t in the ESM gas delivery system (.528 t total)
 -each Orion carries 2.98 t of water (5.96 t total). ~89% of the water content is O2 or 5.3 t. Water is recycled through the urine processor and then electrolyzed. Hydrogen is vented.
 -The solid oxide electrolyzer recovers half of O2 content in CO2 as recycled O2, giving margin.

water requirements are 1024 days * 4 astronauts * 1.5 kg or 1.5 liters/day = 6.144 t
 -each Orion carries 2.98 t of water in integral containers(5.96 t total).
 -an additional 184 kg is carried as logistics in Orion logistics boxes.

food requirements 1024 days * 4 astronauts * 1 kg/day = 4.096 t
 -each Orion carries ~2 t each

Baseline Orion masses: 25,848 kg
 + 132 kg gas due to higher capacity tanks
 + 100 kg gas tank mass
 + 2700 kg in water in water tanks
 + 300 kg internal water tank dry mass and support structure
 + 170 kg SOXE (10x Moxie)
 + 400 kg electrolyzer
 - 50 kg reduced seat mass
 +400 kg improved bathroom
 +2000 kg dehydrated food

Mass estimate: 32 t compared to a Block 1B estimated capacity of 31.6 - 34 t (c3=10 km^2/sec^2, slightly higher than baseline trajectory of 8.2 km^2/sec^2) and Block 2 estimate of 37.6 t.

Orion Total delta-v capability: 316*9.8*ln(32,000 kg/23,400 kg) = 969 m/s.

There is a 400 m/s delta-v shortfall with the existing Orion propellant tanks because of the added mass (Orion without the upgrades would be a lot closer). Pretty amazing how close it is to closing though. A few possible solutions...

-Space station in mars orbit pre-stocked with supplies and/or fuel
-reduction of logistics (but how?)
-increased fuel in ESM (this almost definately pushes it into the Block 2 category).
-dump waste before mars orbit insertion/trans earth injection
-account for gas venting/dumps.

edit: So, fixing a few issues with the architecture. The service module needs stretched propellant tanks by about 2.5 feet to carry an extra 3-4 t of propellant. Logistics (water, food, etc.) gets moved to a USA carried logistics module with 2 Orion compatible docking ports. This module needs to mass under 2 t. One of these is ejected prior to mars orbit insertion, the other one is ejected prior to trans earth injection. This allows for trash disposal every 1 year and moves most of the water, food, etc. out of Orion on launch. Total mass to trans mars injection ends up at 37-38 t (Block 2 territory). Block 2 might need to be sized slightly bigger to fit this mission. So, to wrap up...

Crew Module - heat shield upgrade, improved bathroom module, improved ECLSS
Service Module - higher pressure O2 tanks, stretched propellant tanks.
-Orion Cargo Module (OCM) - this is new, ~3 meter diameter and 3 meter length, must mass under 2000 kg. Could be Cygnus derived.