Author Topic: Gateway Discussion Thread  (Read 102740 times)

Offline MATTBLAK

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Re: Gateway Discussion Thread
« Reply #40 on: 11/11/2020 12:59 am »
If NASA had an HLS with enough delta-v in the works (like Constellation's 'Altair') they would not need a Gateway station at all. If Orion met a Lander in the Halo orbit that was 'fat with propellant', the crew could transfer to that and get down to the lunar surface. Perhaps the 'National Team' design with a big enough transfer element would fit the bill?

However; such a beast would have to get out to the Halo orbit in three launches of Commercial rockets. Taking another SLS launch out of the critical path of the mission architecture would be a good thing. 2x launches of Vulcan-Centaur V with 6x solid motors could probably get that Lander out to the Moon. Or 1x Falcon Heavy and 2x Atlas V's.

Also; without a Gateway, it would be difficult to implement a reusable Lander. So perhaps, at least the first two missions would have to use an expendable Lander?
« Last Edit: 11/11/2020 01:01 am by MATTBLAK »
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Offline yg1968

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Re: Gateway Discussion Thread
« Reply #41 on: 11/11/2020 01:44 am »
Without veering into politics: would it be possible to review or cancel the gateway and keep the rest of Artemis, meaning SLS and HLS?

Plans were already made to land without the gateway and it's not clear if any of the HLS participants require it.
There are already several international partners, so pretty unlikely I guess

Plus, Gateway was actually initiated (but not funded) by the Obama Administration.
« Last Edit: 11/11/2020 11:38 am by yg1968 »

Offline whitelancer64

Re: Gateway Discussion Thread
« Reply #42 on: 11/11/2020 02:58 pm »
If NASA had an HLS with enough delta-v in the works (like Constellation's 'Altair') they would not need a Gateway station at all. If Orion met a Lander in the Halo orbit that was 'fat with propellant', the crew could transfer to that and get down to the lunar surface. Perhaps the 'National Team' design with a big enough transfer element would fit the bill?

However; such a beast would have to get out to the Halo orbit in three launches of Commercial rockets. Taking another SLS launch out of the critical path of the mission architecture would be a good thing. 2x launches of Vulcan-Centaur V with 6x solid motors could probably get that Lander out to the Moon. Or 1x Falcon Heavy and 2x Atlas V's.

Also; without a Gateway, it would be difficult to implement a reusable Lander. So perhaps, at least the first two missions would have to use an expendable Lander?

Without the Gateway, also the NRHO would not be required. Lander / Orion could enter a circular lunar orbit (just not a low orbit) at any given inclination, and landing at any point on the lunar surface (rather than just the south pole) would be an option.
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Offline Proponent

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Re: Gateway Discussion Thread
« Reply #43 on: 11/11/2020 04:13 pm »
If NASA had an HLS with enough delta-v in the works (like Constellation's 'Altair') they would not need a Gateway station at all. If Orion met a Lander in the Halo orbit that was 'fat with propellant', the crew could transfer to that and get down to the lunar surface.

The plan is to build an HLS with the delta-V to go between the halo orbit and the lunar surface, isn't it?  The lander might have a single stage (SpaceX's Starship derivative) or two or three, but it would have the delta-V to take a crew from a halo orbit to the lunar surface and back.
Quote
... without a Gateway, it would be difficult to implement a reusable Lander.

Why?  While parked in a halo orbit, the lander needs to maintain thermal and attitude control and do some station keeping.  Maybe docking it to a gateway helps with that, but it's really not obvious to me that a gateway is terribly valuable.

My understanding of the value of a gateway is that it can mitigate one of the drawbacks of halo-orbit staging, namely the infrequent opportunities for return to Earth.  Unlike LLO staging with adequate delta-V, staging in halo orbit may require a wait of several days before a trans-Earth window opens.  In that case, a gateway station might serve as a backup for keeping a crew alive.

Offline yg1968

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Re: Gateway Discussion Thread
« Reply #44 on: 11/11/2020 05:26 pm »
That's not much of an advantage. You are better off building redundant habitats on the Moon. In my view, the main advantage of Gateway is that it is its own destination, just like the ISS is.
« Last Edit: 11/11/2020 06:01 pm by yg1968 »

Offline RonM

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Re: Gateway Discussion Thread
« Reply #45 on: 11/11/2020 05:54 pm »
That's not much of an advantage. You are better building redundant habitats on the Moon. In my view, the main advantage of Gateway is that it is its own destination, just like the ISS is.

And promotes international cooperation just like ISS, making the Artemis program more likely to be funded.

Offline MATTBLAK

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Re: Gateway Discussion Thread
« Reply #46 on: 11/11/2020 10:41 pm »
If NASA had an HLS with enough delta-v in the works (like Constellation's 'Altair') they would not need a Gateway station at all. If Orion met a Lander in the Halo orbit that was 'fat with propellant', the crew could transfer to that and get down to the lunar surface.

The plan is to build an HLS with the delta-V to go between the halo orbit and the lunar surface, isn't it?  The lander might have a single stage (SpaceX's Starship derivative) or two or three, but it would have the delta-V to take a crew from a halo orbit to the lunar surface and back.
Quote
... without a Gateway, it would be difficult to implement a reusable Lander.

Why?  While parked in a halo orbit, the lander needs to maintain thermal and attitude control and do some station keeping.  Maybe docking it to a gateway helps with that, but it's really not obvious to me that a gateway is terribly valuable.

My understanding of the value of a gateway is that it can mitigate one of the drawbacks of halo-orbit staging, namely the infrequent opportunities for return to Earth.  Unlike LLO staging with adequate delta-V, staging in halo orbit may require a wait of several days before a trans-Earth window opens.  In that case, a gateway station might serve as a backup for keeping a crew alive.
I'd say it would be difficult, but not impossible to have a Reusable Lander at the Halo orbit without a Propellant Depot - or Gateway - of some sort. Why? Well; the Lander could of course be reusable, but without a Depot or Gateway - a propellant Tanker/s would have to refill that Lander between missions. Either an expendable Tanker or a reusable one (based where?) to fill the Lander. And if a reusable Tanker; who refills that one? And where? I'd say a Depot or Gateway at a certain (floating) location is best, refilled by a series of Commercially procured propellant deliveries. And maybe someday; LOX can be generated In-Situ on the Moon.
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Offline Robotbeat

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Re: Gateway Discussion Thread
« Reply #47 on: 11/13/2020 08:47 pm »
Gateway isn’t needed at all for the Moon.

Gateway exists because of Mars. It’s a prototype Mars Transfer Vehicle, and the main reason to stage a lander from Gateway is it’s operational practice for doing the same thing at Mars.
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Offline testguy

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Re: Gateway Discussion Thread
« Reply #48 on: 11/13/2020 10:32 pm »
Gateway isn’t needed at all for the Moon.

Gateway exists because of Mars. It’s a prototype Mars Transfer Vehicle, and the main reason to stage a lander from Gateway is it’s operational practice for doing the same thing at Mars.
Your reason for Gateway is the first one that makes any sense to me. I don’t remember seeing it in print anywhere.  Have you?  If so please provide source.

Offline Robotbeat

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Re: Gateway Discussion Thread
« Reply #49 on: 11/13/2020 11:12 pm »
I heard it discussed at one of the recent FISO telecoms.
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Offline ncb1397

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Re: Gateway Discussion Thread
« Reply #50 on: 11/14/2020 12:11 am »
Gateway isn’t needed at all for the Moon.

Gateway exists because of Mars. It’s a prototype Mars Transfer Vehicle, and the main reason to stage a lander from Gateway is it’s operational practice for doing the same thing at Mars.
Your reason for Gateway is the first one that makes any sense to me. I don’t remember seeing it in print anywhere.  Have you?  If so please provide source.

Here is a slide from a NASA Advisory Council meeting a couple years ago. Note the final bullet point.


Offline RonM

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Re: Gateway Discussion Thread
« Reply #51 on: 11/14/2020 12:49 am »
Google deep space transport. It would be tested at Gateway.

Offline DreamyPickle

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Re: Gateway Discussion Thread
« Reply #52 on: 11/14/2020 09:16 pm »
Isn't the PPE derived from the asteroid redirect mission? These projects have found ways to change their objective but still remain alive. I have no hope for the "deep space transport" as a method of reaching Mars, it's just a way to spend money on promises 10 years into the future.

It would be much better to focus strictly on the Moon's surface because it is actually reachable with humans and offers far more opportunities for international collaboration and commercial development.

Offline yg1968

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Re: Gateway Discussion Thread
« Reply #53 on: 11/14/2020 09:53 pm »
Isn't the PPE derived from the asteroid redirect mission?

Yes, it is.

Offline Robotbeat

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Re: Gateway Discussion Thread
« Reply #54 on: 11/14/2020 11:26 pm »
Isn't the PPE derived from the asteroid redirect mission?

Yes, it is.
...and the PPE on the asteroid redirection mission was justified as a pathfinder for solar electric propulsion for a Mars Transport Vehicle. (Deep Space Transport)


In fact, during hearings, they regularly justified ARRM as testing deep space hardware relevant to Mars, which I thought was a strategic mistake because the actual mission was well worth doing, IMHO, regardless of Mars.
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Offline Joseph Peterson

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Re: Gateway Discussion Thread
« Reply #55 on: 02/05/2021 05:52 pm »
Question:  Have we seen a Gateway Systems Operations & Maintenance line item estimate yet?

Note:  I'd ask the person who posted the billion per year figure in a different media outlet's comment section directly for a source but he isn't talking to me because politics.  If that isn't a made up figure I definitely have an NSF worthy opinion to post.

Offline woods170

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Re: Gateway Discussion Thread
« Reply #56 on: 02/06/2021 11:18 am »
Google deep space transport. It would be tested at Gateway.

Yes. Lunar Gateway is the former Deep Space Habitat with a new name tag slapped onto it.

Offline yg1968

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Re: Gateway Discussion Thread
« Reply #57 on: 02/06/2021 01:39 pm »
See also this presentation on the Deep Space Gateway and the Deep Space Transport (probably from 2017):
https://nvite.jsc.nasa.gov/presentations/D1_DSG%20perspective_Caram.pdf
« Last Edit: 02/06/2021 02:39 pm by yg1968 »

Offline yg1968

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Re: Gateway Discussion Thread
« Reply #58 on: 02/06/2021 01:45 pm »
Question:  Have we seen a Gateway Systems Operations & Maintenance line item estimate yet?

Note:  I'd ask the person who posted the billion per year figure in a different media outlet's comment section directly for a source but he isn't talking to me because politics.  If that isn't a made up figure I definitely have an NSF worthy opinion to post.

See these posts:
https://forum.nasaspaceflight.com/index.php?topic=51452.msg2171510#msg2171510
https://forum.nasaspaceflight.com/index.php?topic=51452.msg2171381#msg2171381
« Last Edit: 02/06/2021 01:47 pm by yg1968 »

Offline yg1968

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Re: Gateway Discussion Thread
« Reply #59 on: 02/06/2021 01:48 pm »
Google deep space transport. It would be tested at Gateway.

Yes. Lunar Gateway is the former Deep Space Habitat with a new name tag slapped onto it.

It's changed a lot since then. It's not just the name.

https://en.wikipedia.org/wiki/Deep_Space_Habitat
« Last Edit: 02/06/2021 02:38 pm by yg1968 »

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