Author Topic: Will Gateway be used for Mars missions?  (Read 6344 times)

Offline Staticalliam7

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Will Gateway be used for Mars missions?
« on: 01/25/2021 06:28 pm »
NASA has said in the video "How We Are Going to the Moon", that the moon is practice for mars missions, but wasn't clear whether they would use Gateway for Mars.
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Offline the_other_Doug

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Re: Will Gateway be used for mars missions?
« Reply #1 on: 01/25/2021 06:39 pm »
Unless they add more hab/consumables storage modules to it, I can't imagine Gateway could keep a crew with normal personal space needs sane for more than a month.  Which so happens to be the maximum designed mission time for any Artemis occupation of the gateway... ;)
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Offline Zed_Noir

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Re: Will Gateway be used for mars missions?
« Reply #2 on: 01/25/2021 08:06 pm »
Unless they add more hab/consumables storage modules to it, I can't imagine Gateway could keep a crew with normal personal space needs sane for more than a month.  Which so happens to be the maximum designed mission time for any Artemis occupation of the gateway... ;)

Not if the Gateway is docked to a Starship.  ;)

Offline JacobTheInvestigator

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Re: Will Gateway be used for mars missions?
« Reply #3 on: 02/19/2021 08:43 am »
Gateway is not just a space laboratory. It's a communication hab and facility that's supposed to make the moon landing easier. NASA state that Gateway is a critically important experience. Let's not forget that most space agencies' main aim is to send people to Mars. Even though NASA doesn't say they'll use Gateway for Mars missions, they state that it should help them prepare for it.

Offline sdsds

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Re: Will Gateway be used for mars missions?
« Reply #4 on: 02/20/2021 03:20 am »
it should help them prepare for it.

Indeed. One aspect of the cis-lunar gateway is that it will provide opportunities to conduct surface sorties that originate at an orbit only loosely associated with the planetary body being visited. If it turns out that kind of architecture works well from the perspective of the human participants, one could imagine similar missions to the surface of Mars from a similarly loosely associated Martian orbit. I don't know of an official DRM like that, but it isn't like NASA's final Mars DRM is set in stone or anything!

(Note well that such architectures have been proposed for human exploration of the Martian moons.)
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Offline MATTBLAK

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Re: Will Gateway be used for mars missions?
« Reply #5 on: 02/20/2021 03:56 am »
In a non-SpaceX version of a NASA crewed mission to Mars, an 'uprated', 'upgraded' or otherwise beefed up version of the lunar Gateway might be used. Depending on the Mission Architecture and decisions surrounding it; I would think that the actual Crew Lander or Crew Ascent/Descent vehicle would be sent on ahead to Mars in a previous launch window and be waiting in Martian orbit. I also think any return to Earth propulsion module(s) would be likewise sent ahead.

My preference would be that these mission elements would be sent to Mars by a large combined Solar Electric & Chemical Propulsion tug. I would use pump-fed hypergolics for the in-space propulsion sets and LOX/LH2 for Earth departure, as that will be the strongest gravity well to overcome. What kind of a 'Gateway Mars Mission' might we expect? A crew of 4 or 6 Astronauts? Will they do an Opposition class mission with a short stay of 30-to-90 days? Or will it be a long stay, 500 day+ Conjunction class mission?

A 'Mars Gateway' vehicle would actually be the Earth-to-Mars, Mars-to-Earth transit system. You'd need enough life support, consumables and radiation protection for the crew of 4 or 6 and extreme system reliability. And how much Habitable volume per crew member? 500 cubic feet per person? 1000? And if based on proven Lunar Gateway modules; will the number of enlarged Cygnus-based Hab modules have to be increased to 2x or 3x modules to get the required Habitable volume and consumables storage?

Sounds like a subject for a good technical paper by someone qualified! "Mars Transit Habitat, Based on Lunar Gateway Concept"
« Last Edit: 02/21/2021 02:52 am by MATTBLAK »
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Offline high road

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Re: Will Gateway be used for mars missions?
« Reply #6 on: 02/20/2021 12:28 pm »
it should help them prepare for it.

Indeed. One aspect of the cis-lunar gateway is that it will provide opportunities to conduct surface sorties that originate at an orbit only loosely associated with the planetary body being visited. If it turns out that kind of architecture works well from the perspective of the human participants, one could imagine similar missions to the surface of Mars from a similarly loosely associated Martian orbit. I don't know of an official DRM like that, but it isn't like NASA's final Mars DRM is set in stone or anything!

(Note well that such architectures have been proposed for human exploration of the Martian moons.)

'Sorties from a loosely associated orbit' goes against any ISRU refueling, or am I seeing that wrong? If you have ISRU refueling, exploring he planet from a single fuel/power/consumables production plant seem tp make more sense.

Offline sdsds

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Re: Will Gateway be used for mars missions?
« Reply #7 on: 02/21/2021 01:32 am »
Human or robotic exploration, the Moon or Mars, sorties or outposts, gateways or ISRU; it's all great stuff to ponder.

If off-Earth propellant production becomes feasible there might be a case for a propellant depot somewhere other than the location where the production takes place. A "Cislunar Way Station" is the fuller vision of a gateway. Such a facility would accept water from the lunar surface and convert it into cryogenic propellant.

As background for the reader interested in how NASA became explicitly directed to include ISRU in its planning I recommend, Return to the Moon: Outpost or sorties? by the late, great lunar scientist Paul Spudis. It's an easy read and — given it was published in 2009 — is still remarkably relevant. https://www.airspacemag.com/daily-planet/return-to-the-moon-outpost-or-sorties-152877488/

Also worthwhile — albeit even older — is the "renewed spirit" document from 2004. https://purl.fdlp.gov/GPO/LPS72574

Specifically regarding propellant ISRU and gateways: in Mission and Implementation of an Affordable Lunar Return Spudis and Lavoie presented a plausible way to combine EELV and Shuttle-derived heavy lift launches resulting in a human-tended lunar outpost producing 150 tons of water per year. Their plan included a Cislunar Way Station providing a propellant depot near the Moon. The .pdf for that proposal is attached.
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Offline jongoff

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Re: Will Gateway be used for mars missions?
« Reply #8 on: 02/24/2021 05:09 am »
I'm in the process of pulling together an article about "high orbit depots" like Gateway could potentially become. High orbit depots could make sense if you're baselining an SEP-based Earth/Mars transportation system. You'd like the point where you get on/off your SEP system to be as close to escape as possible, and NRHO (or other EML halo orbits) are relatively easy to get into/out of with a low-thrust system. So I could see it serving as a transit node in a world where low-thrust Earth/Mars transits end up being the way we go.

With chemical transit, it's more of an open question. If we end up in a world where Lunar ISRU pans out, I could see a depot in a high-orbit like NRHO potentially making sense. I personally prefer an EML-2 halo to NRHO, but both take relatively modest dV to get out of into a highly elliptical earth orbit with a low perigee. While leaving from a lunar high orbit into such an HEEO does constrain the inclination of the HEEO quite a bit, for most typical interplanetary missions, to places like Mars/Venus, the required Vinf declination is low enough that you can often make things line up, especially with a 3-burn departure.

I'm rambling a bit, but long-story short is that in a world where Starship is the only Earth/Mars transport, a high-orbit gateway is of marginal utility. There might still be ways to use it that do help vs the baseline, but it's not a slam dunk. But if lunar ISRU pans out, Starship doesn't happen, or you want to do low-thrust transports, gateways become a lot more interesting.

~Jon

Offline sdsds

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Re: Will Gateway be used for mars missions?
« Reply #9 on: 02/24/2021 05:52 am »
[...] in a world where Starship is the only Earth/Mars transport, a high-orbit gateway is of marginal utility. There might still be ways to use it that do help vs the baseline, but it's not a slam dunk. But if lunar ISRU pans out, Starship doesn't happen, or you want to do low-thrust transports, gateways become a lot more interesting.

What's your assessment of schemes where Starship is the only Earth/Mars transport but some of the oxygen it uses is produced on the lunar surface, presumably from ilmenite, with storage at a high lunar orbit depot? Granted it doesn't provide the complete solution for Starship propellant, but LOX is relatively easy to transport and store, and oxygen has other uses than being a propellant. Is such a depot really of only "marginal utility?"

(Additionally the ilmenite approach allows production of metals on the lunar surface, and water too if you bring your own hydrogen. It also avoids the permanently-shadowed polar challenges....)
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Offline tbellman

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Re: Will Gateway be used for mars missions?
« Reply #10 on: 02/24/2021 09:48 am »
What's your assessment of schemes where Starship is the only Earth/Mars transport but some of the oxygen it uses is produced on the lunar surface, presumably from ilmenite, with storage at a high lunar orbit depot? Granted it doesn't provide the complete solution for Starship propellant, but LOX is relatively easy to transport and store, and oxygen has other uses than being a propellant. Is such a depot really of only "marginal utility?"

(Additionally the ilmenite approach allows production of metals on the lunar surface, and water too if you bring your own hydrogen. It also avoids the permanently-shadowed polar challenges....)

(I'm not Jon, but I'll give my take anyway.)
(And this is not really related to the Lunar Gateway, but rather propellant depots in general.  Suggestions of a better thread to continue this in?)
(EDIT: Also, why is this thread in the Orion board?)

The problem with refuelling in any kind of lunar orbit, be it EML1, EML2 or NRHO, is that to reach them from LEO, you need roughly 3.5 km/s of Δv, but from there on to Mars, is only 1 km/s (or perhaps even less).  Going directly from LEO to Trans-Mars Injection, is some 3.6-4.5 km/s, depending on synod.  That means that the refuelling at the high lunar orbit (HLO) only saves you a little bit on the refuelling in LEO; and even less if you only refuel the oxidizer at the Moon depot.

So let's say we have a ship massing 200 tonne dry (including cargo), running on hydrolox.  It will need 210-250 tonnes of propellant to go from LEO to the HLO depot (depending on if it is in NRHO, EML1 or EML2), arriving with empty tanks.  There it will need to be refuelled with on the order of 50 tonnes of propellant, plus/minus a factor two, depending on depot position and Mars synod.  On the other hand, going directly from LEO to Mars, would require maybe 300 tonnes of propellant in LEO (as little as 230 tonnes in an optimal synod, maybe 350 tonnes in a bad synod and/or if you want faster-than-Hohmann transfer).  It's a saving, but not a huge saving.

If methalox is used for propellant, then you need to leave the HLO depot with around 60 tonnes of propellant; 13 tonnes methane, and 47 tonnes oxygen (again, figure a factor two up or down depending on synod and which HLO is used).  If only oxygen can be provided at the HLO depot, then you need to have 267 tonnes of oxygen and 85 tonnes of methane in LEO, totalling 350 tonnes.  Going directly from LEO to TMI requires somewhere between 350 and 550 tonnes of methalox, depending on synod.  So you actually save a bit more with the HLO depot in the methalox case than in the hydrolox case, but it's still not a huge saving (and I haven't taken into account that a hydrolox ship will be heavier than a methalox ship, due to needing larger and better isolated tanks).

If you have a massive transit ship for going from the HLO to Mars, and use a tiny "taxi" for going between LEO and HLO, it would make more sense to do refuelling at HLO.  But a large portion of the ships' dry masses will be the cargo (including passengers) transported between Earth and Mars, which means that in practice you are not going to see huge differences in size between the LEO-HLO taxi and the HLO-Mars ship.  Unless the Mars transit ship is a luxury liner where each passenger gets their own swimming pool. :)

For higher energy trajectories, e.g. when you want to go to Ganymede in a hurry, refuelling in HLO makes more sense.
« Last Edit: 02/24/2021 09:51 am by tbellman »

Offline Timber Micka

Re: Will Gateway be used for Mars missions?
« Reply #11 on: 05/07/2021 03:27 pm »
Slightly late, but here's the answer:
https://en.wikipedia.org/wiki/Deep_Space_Transport

Online yg1968

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Re: Will Gateway be used for Mars missions?
« Reply #12 on: 05/07/2021 07:40 pm »
Slightly late, but here's the answer:
https://en.wikipedia.org/wiki/Deep_Space_Transport

Yes. Gateway was originally called the Deep Space Habitat and it was meant to be used with the Deep Space Transport, which is also called the Mars Transit Vehicle:
https://en.wikipedia.org/wiki/Deep_Space_Habitat

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