Author Topic: Gateway Discussion Thread  (Read 49508 times)

Offline lrk

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Re: Gateway Discussion Thread
« Reply #140 on: 10/20/2021 03:36 pm »
Sorry for make question in an update only thread...
So, better here, ...has now the PPE part of Gateway 3 AEPS engines?
https://twitter.com/Maxar/status/1414584544301359104
Any idea of the reason?

I guess nobody ever answered this - the 3rd engine was added with the change to launch the HALO and PPE as a single co-manifested vehicle, as the PPE is now responsible for moving a significantly larger mass to NRHO. 

Offline russianhalo117

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Re: Gateway Discussion Thread
« Reply #141 on: 10/20/2021 04:46 pm »
Sorry for make question in an update only thread...
So, better here, ...has now the PPE part of Gateway 3 AEPS engines?
https://twitter.com/Maxar/status/1414584544301359104
Any idea of the reason?

I guess nobody ever answered this - the 3rd engine was added with the change to launch the HALO and PPE as a single co-manifested vehicle, as the PPE is now responsible for moving a significantly larger mass to NRHO. 
The center AEPS engine replaces ESA's HEAT engine. Originally 4 AEPS were planned in a square around HEAT.

https://russianspaceweb.com/imp-ppb.html
PPE SEP listed below.
https://www.rocket.com/space/space-power-propulsion/solar-electric-propulsion

Offline AS_501

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Re: Gateway Discussion Thread
« Reply #142 on: 11/10/2021 10:13 pm »
Changing subjects for a moment, assuming the Sun is always 'visible' from the Gateway HALO orbit, will it be necessary for the Solar arrays to track the Sun as it done with ISS?  Will there be times when Gateway enters the Moon's shadow?
(Asked by novice orbital mechanic. :) )
Thx
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Offline freddo411

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Re: Gateway Discussion Thread
« Reply #143 on: 11/10/2021 11:27 pm »
Researching and developing things costs money. This list would cost serious money. That money isn't available unless you get a lot of buy-in from across the agency and, to reduce the risk of cancellation, international partners. HSF gets more funding for development associated with actual crew flights than for tech-development without crew flights. If you want the above things done, you will not get adequate funding (or potentially, any funding) unless it's a significant part of the HSF program of record.

It sucks. It's not efficient. But it's just the reality of how Congress, WH, Agency and it's Centres interact.
☝ This. The official "scientific and engineering reasons" for building Gateway in NRHO may be "nice to have" from the perspectives of their respective fields, but they neither individually nor as a whole demand this particular architecture. As many have pointed out, most if not all of the officially stated goals for Gateway can be accomplished more cheaply in other ways. But they are not the real purpose of Gateway, merely the smoke and mirrors for the politicians. Gateway, like the Asteroid Redirect Mission before it, has always been a Trojan horse to give NASA an excuse to fund its (semi-official) program of record for landing humans on Mars. The politicians are not willing to drop $billions on Mars technology development because the political payoff is too far out. But by selling them on a Rube Goldberg plan for exploring the moon (or near-Earth asteroids, etc.) that "just happens" to revolve around a space station which is a thinly disguised technology demonstrator for the "Deep Space Transport" vessel at the heart of the Mars program of record, they can get the funding they need move the ball forward on Mars.

This is something Jim Bridenstine hinted at a lot when he talked about why the agency (and he personally) felt the Gateway was so important. The most important thing, he kept saying - more important than the scientific/engineering "goals" listed on the PowerPoints - was that it would create the programmatic and political momentum needed to build a long-term beyond-Earth-orbit human spaceflight program that Congress couldn't (and wouldn't want to) cancel as soon as a flag was planted. NASA had learned the political lessons of the ISS vs. Apollo; one had staying power, the other didn't. The ISS was very unpopular with Congress when it was first created (it originally passed the House by one vote); but the combination of astronauts continuously up in space "right now" who "need to be taken care of", and (real or perceived) diplomatic concerns about losing a successful international partnership, proved to be a powerful psychological force that turned the ISS from a white elephant into a sacred cow for Congress.

(I'm convinced that this is the biggest real reason why NASA is always so careful - even to the point of jumping through diplomatic hoops to keep Americans flying on Soyuz even in the absence of a formal exchange agreement - to be extra sure that the ISS is never left without an American on board at any time. Setting aside the "record book" prestige implications of continuous occupation, if the ISS were ever without an American for, say, a month or two due to a contingency that required a vehicle to come home early, that would risk breaking the psychological dam that makes the continuation of the ISS such an imperative in Congress's minds. Once the idea of part-time occupation became mentally real to Congress, they'd start cooking up ideas to cut the budget, much like we're seeing Russia do now as they envision ROSS as a part-time-crewed station. And from there, it's just a matter of time before you end up like after Apollo 17 and Congress asks "why can't we just take a break while we divert the money to a development program for the Next Big Thing". Meanwhile delays mount, and we end up with another 10-year gap in human spaceflight.)

So, the real purpose of Gateway is to create that same kind of "positive feedback loop" with a program that will be "too good for Congress to let go of". Congress loves the sunk cost fallacy. The trick for NASA is to exploit that for positive gain (programs that accomplish a lot and provide a jumping-off point to accomplish even more - like the ISS) instead of letting that natural tendency take the path of least resistance (programs that sink endless resources into development with massive delays that barely seem to matter to Congress - like a certain big orange rocket). Gateway, as evolved from the Asteroid Redirect Mission, seems to be the result of NASA finally figuring out how to make the sunk cost fallacy work for them, after learning the hard lessons of Constellation and its aftermath.

Thatís a very honest and compelling explanation.   Unfortunately, that might get you a gateway in NRHO that is very rarely visited by an astronomically expensive, tiny capsule atop an equally expensive expendable rocket.   Truly a low value proposition.

If that is all that the HSF program did for 2 or 3 decades, that would represent a huge lost opportunity.

A more compelling alternative is on display in Boca Chica.  Kudos to those in NASA that realize that a small part of NASA HSF funding can accomplish amazing new groundbreaking engineering, science and political goals

Offline Steven Pietrobon

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Re: Gateway Discussion Thread
« Reply #144 on: 11/11/2021 06:09 am »
Changing subjects for a moment, assuming the Sun is always 'visible' from the Gateway HALO orbit, will it be necessary for the Solar arrays to track the Sun as it done with ISS?  Will there be times when Gateway enters the Moon's shadow?
(Asked by novice orbital mechanic. :) )
Thx

As gateway is orbiting the Moon, there should be times when it is shadowed by the Moon. This will occur around when the Moon is half-full. During full or new Moons, there should be no shadowing.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline tbellman

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Re: Gateway Discussion Thread
« Reply #145 on: 11/11/2021 09:11 am »
As gateway is orbiting the Moon, there should be times when it is shadowed by the Moon. This will occur around when the Moon is half-full. During full or new Moons, there should be no shadowing.

There should be occasional periods of Earth shadowing as well.  I suppose they would happen roughly as often as (but not always coincident with) lunar eclipses.  Always at full moons, though.

Offline pochimax

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Re: Gateway Discussion Thread
« Reply #146 on: 11/11/2021 10:54 am »
I guess nobody ever answered this - the 3rd engine was added with the change to launch the HALO and PPE as a single co-manifested vehicle, as the PPE is now responsible for moving a significantly larger mass to NRHO.

Thanks.

I don' t remember well... did Aerojet Rocketdyne made 4 AEPS engines? So now they are putting there 3 of the (previously planned) four?

Offline Jim

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Re: Gateway Discussion Thread
« Reply #147 on: 11/11/2021 12:39 pm »
I guess nobody ever answered this - the 3rd engine was added with the change to launch the HALO and PPE as a single co-manifested vehicle, as the PPE is now responsible for moving a significantly larger mass to NRHO.

Thanks.

I don' t remember well... did Aerojet Rocketdyne made 4 AEPS engines? So now they are putting there 3 of the (previously planned) four?

there are 7 total engines.  4 are outboard.

Online primer_black

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Re: Gateway Discussion Thread
« Reply #148 on: 11/11/2021 01:50 pm »
Changing subjects for a moment, assuming the Sun is always 'visible' from the Gateway HALO orbit, will it be necessary for the Solar arrays to track the Sun as it done with ISS?  Will there be times when Gateway enters the Moon's shadow?
(Asked by novice orbital mechanic. :) )
Thx

As gateway is orbiting the Moon, there should be times when it is shadowed by the Moon. This will occur around when the Moon is half-full. During full or new Moons, there should be no shadowing.

In terms of frequency, the gateway will not see full eclipses often. Due to the complex motion, the station will only be in full eclipse about once a year for ~90 minutes at a time.

Online deadman1204

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Re: Gateway Discussion Thread
« Reply #149 on: 11/11/2021 02:41 pm »
Changing subjects for a moment, assuming the Sun is always 'visible' from the Gateway HALO orbit, will it be necessary for the Solar arrays to track the Sun as it done with ISS?  Will there be times when Gateway enters the Moon's shadow?
(Asked by novice orbital mechanic. :) )
Thx
Even if its mostly in the sun, won't the angle of sunlight change? This would require the panels to track

Online DanClemmensen

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Re: Gateway Discussion Thread
« Reply #150 on: 11/11/2021 03:10 pm »
Changing subjects for a moment, assuming the Sun is always 'visible' from the Gateway HALO orbit, will it be necessary for the Solar arrays to track the Sun as it done with ISS?  Will there be times when Gateway enters the Moon's shadow?
(Asked by novice orbital mechanic. :) )
Thx
Even if its mostly in the sun, won't the angle of sunlight change? This would require the panels to track
ISS is an Earth observation platform (among other duties). Gateway is not really a Moon observation platform because NRHO is a really bad location for that. Therefore, there is no particular reason for Gateway to orient on the Moon. Just keep the entire Gateway oriented with its panels facing the Sun.

Offline pochimax

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Re: Gateway Discussion Thread
« Reply #151 on: 11/11/2021 04:15 pm »
I guess nobody ever answered this - the 3rd engine was added with the change to launch the HALO and PPE as a single co-manifested vehicle, as the PPE is now responsible for moving a significantly larger mass to NRHO.

Thanks.

I don' t remember well... did Aerojet Rocketdyne made 4 AEPS engines? So now they are putting there 3 of the (previously planned) four?

there are 7 total engines.  4 are outboard.

4 of the engines are BHT-6000, the other 3 AEPS, from Aerojet. Anyway, i now think AR has not made yet the engines... I thought the original 4 AEPS were made long ago, but now I don' t think so, while reviewing this tweet.

https://www.busek.com/bht6000

https://twitter.com/AerojetRdyne/status/1424802682901078019

« Last Edit: 11/11/2021 04:16 pm by pochimax »

Offline cohberg

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Re: Gateway Discussion Thread
« Reply #152 on: 11/11/2021 06:29 pm »
NASA Johnson released some additional renders of gateway.

What is the module attached to I-HAB with all the exposed pallets?

Offline Paul451

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Re: Gateway Discussion Thread
« Reply #153 on: 11/11/2021 08:10 pm »
NASA Johnson released some additional renders of gateway.

Love how the lander shown isn't the one actually selected.
Huh. Ironically, the aim of utilising cheap-launch is to make launch costs significant again.

Offline dchenevert

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Re: Gateway Discussion Thread
« Reply #154 on: 11/11/2021 09:15 pm »
NASA Johnson released some additional renders of gateway.

Love how the lander shown isn't the one actually selected.

When NASA releases an image of Gateway docked with Starship I'm going to absolutely lose my <ability to be civil>.

Offline jdon759

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Re: Gateway Discussion Thread
« Reply #155 on: 11/12/2021 02:50 am »
NASA Johnson released some additional renders of gateway.
Love how the lander shown isn't the one actually selected.
It looks pretty generic, not really based on any of the proposals.  Probably to avoid legal issues.

Online DanClemmensen

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Re: Gateway Discussion Thread
« Reply #156 on: 11/12/2021 03:14 am »
NASA Johnson released some additional renders of gateway.
Love how the lander shown isn't the one actually selected.
It looks pretty generic, not really based on any of the proposals.  Probably to avoid legal issues.
I'm guessing it's trying to be the "Advanced Exploration Lander", which (apparently) was NASA's reference concept design during the initial NextSTEP solicitation for HLS designs in 2018.

Online Zed_Noir

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Re: Gateway Discussion Thread
« Reply #157 on: 11/12/2021 04:51 am »
NASA Johnson released some additional renders of gateway.
Love how the lander shown isn't the one actually selected.
It looks pretty generic, not really based on any of the proposals.  Probably to avoid legal issues.


It looks similar to the National Team's three elements lander. Which is mostly based on the reference NASA design. The flicker image might be a really old generic NASA reference design for a Moon lander.

Offline Paul451

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Re: Gateway Discussion Thread
« Reply #158 on: 11/12/2021 06:04 am »
None of which answers Cohberg's original question.

But perhaps it suggests that the mystery module is a generic stand-in for something else, such as the proposed airlock module?
« Last Edit: 11/12/2021 06:08 am by Paul451 »
Huh. Ironically, the aim of utilising cheap-launch is to make launch costs significant again.

Offline woods170

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Re: Gateway Discussion Thread
« Reply #159 on: 11/12/2021 08:52 am »
NASA Johnson released some additional renders of gateway.

What is the module attached to I-HAB with all the exposed pallets?

That is the newly proposed non-Russian docking-and-airlock module.
Remember, orginally NASA wanted Russia to provide an airlock module (featuring an additional docking port). Rogozin et al. said no. But Gateway still needs an airlock module with additional docking port. So right now NASA, ESA and JAXA are looking into using a modified IHab design for the airlock/docking module.
That's reflected in the latest updated Gateway renders.

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