Author Topic: A bigger service module for Orion  (Read 11110 times)

Offline Eric Hedman

  • Senior Member
  • *****
  • Posts: 2319
  • The birthplace of the solid body electric guitar
  • Liked: 1957
  • Likes Given: 1148
A bigger service module for Orion
« on: 05/26/2023 03:32 am »
I have read plenty about the the shortfall in performance of the Orion Service Module.  I don't remember any discussion about boosting the performance of the service module.  The service module has a smaller diameter then Orion.  Is it possible to expand the diameter to store more propellant and give the service module enough extra delta V to be useful while maintaining the same height of the rocket?  Or would you have to stretch the service module to accomplish this?  The bottom line, would this give you anything useful such as entering low lunar orbit while still able to return to Earth?  Is this a practical idea?

Offline arthuroMo

  • Member
  • Posts: 40
  • Liked: 19
  • Likes Given: 17
Re: A bigger service module for Orion
« Reply #1 on: 05/26/2023 06:48 am »
I'm late to the party, so do you have any synthetic article/post/debate on Orion's shortfalls ?
Or a non-synthetic one  ;D

Offline jstrotha0975

  • Full Member
  • ****
  • Posts: 583
  • United States
  • Liked: 339
  • Likes Given: 2651
Re: A bigger service module for Orion
« Reply #2 on: 05/26/2023 01:51 pm »
Orion will probably need a bigger service module if they use it for Mars. Other than that I don't see the need.

Offline Pipess

  • Member
  • Posts: 4
  • Liked: 1
  • Likes Given: 0
Re: A bigger service module for Orion
« Reply #3 on: 05/26/2023 02:09 pm »
The planned lunar architecture uses the existing service module, so a more capable version would be superfluous (even a waste of resources if you want to be cynical) unless, as stated above, Orion goes to Mars or performs some other mission outside of being a ferry to Gateway.

Offline spacenut

  • Senior Member
  • *****
  • Posts: 5184
  • East Alabama
  • Liked: 2589
  • Likes Given: 2898
Re: A bigger service module for Orion
« Reply #4 on: 05/26/2023 02:47 pm »
Is there any way to cut Orion's mass?  It is way overweight. 

Offline DanClemmensen

  • Senior Member
  • *****
  • Posts: 5544
  • Earth (currently)
  • Liked: 4372
  • Likes Given: 1782
Re: A bigger service module for Orion
« Reply #5 on: 05/26/2023 02:55 pm »
The planned lunar architecture uses the existing service module, so a more capable version would be superfluous (even a waste of resources if you want to be cynical) unless, as stated above, Orion goes to Mars or performs some other mission outside of being a ferry to Gateway.
How long can Orion loiter in NRHO without Gateway? If a bigger service module extends the loiter time, then it is insurance against unavailability of Gateway for longer lunar missions. Of course, this assumes the bigger service module could be delivered before Gateway can be delivered.

Offline pochimax

  • Full Member
  • ***
  • Posts: 312
  • spain
  • Liked: 149
  • Likes Given: 80
Re: A bigger service module for Orion
« Reply #6 on: 05/26/2023 09:26 pm »
ESA could provide a bigger service module if it is requested by NASA.

It is impossible to have a bigger ESM before Gateway is in lunar orbit.

For missions to asteroids, you can pre-position Gateway as an outpost around the asteroid, but then you will need this bigger service module to reach the orbit of Gateway/asteroid. Then, Gateway returns to NRHO or whatever, Orion to reentry on Earth.

Offline pathfinder_01

  • Senior Member
  • *****
  • Posts: 2074
  • Liked: 271
  • Likes Given: 8
Re: A bigger service module for Orion
« Reply #7 on: 05/27/2023 12:27 am »
The planned lunar architecture uses the existing service module, so a more capable version would be superfluous (even a waste of resources if you want to be cynical) unless, as stated above, Orion goes to Mars or performs some other mission outside of being a ferry to Gateway.
How long can Orion loiter in NRHO without Gateway? If a bigger service module extends the loiter time, then it is insurance against unavailability of Gateway for longer lunar missions. Of course, this assumes the bigger service module could be delivered before Gateway can be delivered.

The limit would likely not be the service module. I don't know the current spec. but Orion was supposed to be able to support itself 3 months without a crew and 6 months when docked to a station when the program began.

Offline pochimax

  • Full Member
  • ***
  • Posts: 312
  • spain
  • Liked: 149
  • Likes Given: 80
Re: A bigger service module for Orion
« Reply #8 on: 05/28/2023 09:50 am »
3 months inside Orion and the crew will begin to killing each other  ;D

You need more space, for privacy and psychological health, for missions longer than a few days. Gateway is the right thing to solve it. The other possibility would be an expendable orbital module for Orion, which is undesirable. Better to have a reusable orbital module => Gateway.

Offline DanClemmensen

  • Senior Member
  • *****
  • Posts: 5544
  • Earth (currently)
  • Liked: 4372
  • Likes Given: 1782
Re: A bigger service module for Orion
« Reply #9 on: 05/28/2023 04:54 pm »
3 months inside Orion and the crew will begin to killing each other  ;D

You need more space, for privacy and psychological health, for missions longer than a few days. Gateway is the right thing to solve it. The other possibility would be an expendable orbital module for Orion, which is undesirable. Better to have a reusable orbital module => Gateway.
The initial Gateway (PPE+HALO) is tiny even compared to Orion. Even with I-HAB it's not huge. However, the 30-day mission probably only has two crew in NRHO while the others are in HLS.  If you want a bigger space in NRHO, just keep a Starship HLS up there. It's huge. However, I don't think Starship HLS is designed to sustain the Orion.

Offline TrevorMonty

Re: A bigger service module for Orion
« Reply #10 on: 05/28/2023 08:50 pm »
Only benefit more DV would provide is option for Orion to enter and return from LLO. So reducing lander's DV requirements.
If SLS EUS had few days of endurance it could  place Orion in LLO. Existing service module has enough DV to return from LLO.

Offline pochimax

  • Full Member
  • ***
  • Posts: 312
  • spain
  • Liked: 149
  • Likes Given: 80
Re: A bigger service module for Orion
« Reply #11 on: 05/28/2023 09:45 pm »
3 months inside Orion and the crew will begin to killing each other  ;D

You need more space, for privacy and psychological health, for missions longer than a few days. Gateway is the right thing to solve it. The other possibility would be an expendable orbital module for Orion, which is undesirable. Better to have a reusable orbital module => Gateway.
The initial Gateway (PPE+HALO) is tiny even compared to Orion. Even with I-HAB it's not huge. However, the 30-day mission probably only has two crew in NRHO while the others are in HLS.  If you want a bigger space in NRHO, just keep a Starship HLS up there. It's huge. However, I don't think Starship HLS is designed to sustain the Orion.

It is enough space. The important thing is the separte departments (Orion / Gateway). Not currently possible in Orion.

On the other hand, Gateway is far cheaper than an expendable Starship HLS mission for missions not landing on the Moon or for the whole lunar surface program. Remember I expect Gateway lifetime on the order of 30 years.

I expect in the future NASA will ask Europe for this bigger ESM+, for missions different than lunar landings (asteroids, lagrange points, etc.). Not all will be lunar surface. Moreover, as it will be possible to do lunar surface missions without Gateway NASA could do a lunar surface mission and, at the same time, move Gateway to an interesting destination (asteroid) for a rendezvous with Orion with ESM+.

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 37483
  • Cape Canaveral Spaceport
  • Liked: 21532
  • Likes Given: 428
Re: A bigger service module for Orion
« Reply #12 on: 05/28/2023 11:46 pm »
Remember I expect Gateway lifetime on the order of 30 years.

I expect in the future NASA will ask Europe for this bigger ESM+, for missions different than lunar landings (asteroids, lagrange points, etc.).

neither are going to happen.  Artemis (SLS/Orion) is only going to last a few missions.
« Last Edit: 05/28/2023 11:46 pm by Jim »

Offline DanClemmensen

  • Senior Member
  • *****
  • Posts: 5544
  • Earth (currently)
  • Liked: 4372
  • Likes Given: 1782
Re: A bigger service module for Orion
« Reply #13 on: 05/29/2023 02:27 am »
3 months inside Orion and the crew will begin to killing each other  ;D

You need more space, for privacy and psychological health, for missions longer than a few days. Gateway is the right thing to solve it. The other possibility would be an expendable orbital module for Orion, which is undesirable. Better to have a reusable orbital module => Gateway.
The initial Gateway (PPE+HALO) is tiny even compared to Orion. Even with I-HAB it's not huge. However, the 30-day mission probably only has two crew in NRHO while the others are in HLS.  If you want a bigger space in NRHO, just keep a Starship HLS up there. It's huge. However, I don't think Starship HLS is designed to sustain the Orion.
On the other hand, Gateway is far cheaper than an expendable Starship HLS mission for missions not landing on the Moon or for the whole lunar surface program. Remember I expect Gateway lifetime on the order of 30 years.
The first three Starship  HLS (unncrewed demo, Option A lander, Option B lander)  are already paid for and will end up in NRHO, so Gateway cannot be "cheaper".  Added stuff to convert any of them into a long term station might be expensive, but maybe less expensive than I-HAB.

Thiis thread is about Orion. An extended Orion SM might allow Orion to operate for an extended period in conjunction wil one of thee HLSs.

Offline pochimax

  • Full Member
  • ***
  • Posts: 312
  • spain
  • Liked: 149
  • Likes Given: 80
Re: A bigger service module for Orion
« Reply #14 on: 05/29/2023 07:52 am »
The first three Starship  HLS (unncrewed demo, Option A lander, Option B lander)  are already paid for and will end up in NRHO, so Gateway cannot be "cheaper".  Added stuff to convert any of them into a long term station might be expensive, but maybe less expensive than I-HAB.

Thiis thread is about Orion. An extended Orion SM might allow Orion to operate for an extended period in conjunction wil one of thee HLSs.

The thread is about a more powerful Orion service module and its possible uses.

It is unlikely that it can be used for lunar low orbit missions. The ESMs are already being built for this decade, so if the decision is made to expand said module it will be in the 30s, for missions starting in 2030 or further in time.
By then the Gateway and lunar landers will be around a long time ago. The lunar landers will be designed to go up and down from NRHO orbit and billions will have been spent on their development with that capacity. It doesn't make sense to spend more money to make the Orion more powerful but the lunar landers less capable.

It doesn't make sense for the trip to Mars either, since that's what the Martian manned transfer vehicle is used for and the Orion just has to go to and from the parking orbit of the Martian transfer ship.

Therefore, only a more powerful Orion makes sense to move through cislunar space and Lagrangian points. Given the very small volume of the ship for long missions of this type, they only make sense with an orbital module for Orion. Such a expendable module does not make economic sense as NASA could be able to move the existing Gateway for such a mission. The only cost would be refuelling and this will be probably routinely do at the expenses of european o japonese colaboration in the program.

I think will be far cheaper to move Gateway for the mission than to made a new Lunaship specific for supporting such a mission.
« Last Edit: 05/29/2023 07:57 am by pochimax »

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 37483
  • Cape Canaveral Spaceport
  • Liked: 21532
  • Likes Given: 428
Re: A bigger service module for Orion
« Reply #15 on: 05/29/2023 12:11 pm »

Therefore, only a more powerful Orion makes sense to move through cislunar space and Lagrangian points.\

No, there is no reason for such a mission for NASA

Offline yg1968

  • Senior Member
  • *****
  • Posts: 17303
  • Liked: 7134
  • Likes Given: 3066
Re: A bigger service module for Orion
« Reply #16 on: 05/29/2023 12:51 pm »
Remember I expect Gateway lifetime on the order of 30 years.

I expect in the future NASA will ask Europe for this bigger ESM+, for missions different than lunar landings (asteroids, lagrange points, etc.).

neither are going to happen.  Artemis (SLS/Orion) is only going to last a few missions.

SLS and Orion will last as long as Congress continues to fund them. I expect SLS and Orion to last as long as there is no other BLEO alternatives such as crewed Starship.

Offline Zed_Noir

  • Senior Member
  • *****
  • Posts: 5490
  • Canada
  • Liked: 1811
  • Likes Given: 1302
Re: A bigger service module for Orion
« Reply #17 on: 05/29/2023 08:37 pm »
IF someone wants a "bigger" Orion service module. There always the option of docking the current Orion stack to a pre-positioned stripped down SpaceX HLS lander variant with no landing hardware and full tanks in LEO. Plus the bonus of the pressurized volume and pre-positioned cargo that will be available in the lander variant.

Of course getting the Orion to LEO with the SLS will be optional.  ;)

Offline pochimax

  • Full Member
  • ***
  • Posts: 312
  • spain
  • Liked: 149
  • Likes Given: 80
Re: A bigger service module for Orion
« Reply #18 on: 05/30/2023 08:16 pm »
IF someone wants a "bigger" Orion service module. There always the option of docking the current Orion stack to a pre-positioned stripped down SpaceX HLS lander variant with no landing hardware and full tanks in LEO. Plus the bonus of the pressurized volume and pre-positioned cargo that will be available in the lander variant.

Of course getting the Orion to LEO with the SLS will be optional.  ;)

You need to connect that kind of Moonship with Orion with all the requirements... At that point, will be far cheaper to modify the ESM instead of making that "Moonshipstein". Moreover if it is the eurpeans who pay for it as a contribution for Artemis or whatever the name of the NASA cislunar / mars space program in the '30s, '40s, etc.

Offline Zed_Noir

  • Senior Member
  • *****
  • Posts: 5490
  • Canada
  • Liked: 1811
  • Likes Given: 1302
Re: A bigger service module for Orion
« Reply #19 on: 05/30/2023 09:52 pm »
IF someone wants a "bigger" Orion service module. There always the option of docking the current Orion stack to a pre-positioned stripped down SpaceX HLS lander variant with no landing hardware and full tanks in LEO. Plus the bonus of the pressurized volume and pre-positioned cargo that will be available in the lander variant.

Of course getting the Orion to LEO with the SLS will be optional.  ;)

You need to connect that kind of Moonship with Orion with all the requirements... At that point, will be far cheaper to modify the ESM instead of making that "Moonshipstein". Moreover if it is the eurpeans who pay for it as a contribution for Artemis or whatever the name of the NASA cislunar / mars space program in the '30s, '40s, etc.

You do realize that the SpaceX HLS lander is supposed to docked with Orion and act as a mothership, prior to the Gateway platform being available.

IIRC, the length of the Orion ESM is limited by roof ceiling in the VAB. Could make the ESM wider. But that is basically developing a new spacecraft. The European ESM derived from the ATV is the form factor it is because it cost too much change from it's previous form factor.

The Europeans should be considering something else to contributed in the future instead of more Orion ESM to the Artemis program.

Offline pochimax

  • Full Member
  • ***
  • Posts: 312
  • spain
  • Liked: 149
  • Likes Given: 80
Re: A bigger service module for Orion
« Reply #20 on: 06/03/2023 09:10 pm »
Not really the same to be docked (as Apollo Lunar Module) than integrated / connected (as Apollo Service Module to capsule).

No way that kind of "Moonshipstein" idea could do the same work as an ESM+.

Offline whitelancer64

Re: A bigger service module for Orion
« Reply #21 on: 06/07/2023 07:26 pm »
IF someone wants a "bigger" Orion service module. There always the option of docking the current Orion stack to a pre-positioned stripped down SpaceX HLS lander variant with no landing hardware and full tanks in LEO. Plus the bonus of the pressurized volume and pre-positioned cargo that will be available in the lander variant.

Of course getting the Orion to LEO with the SLS will be optional.  ;)

You need to connect that kind of Moonship with Orion with all the requirements... At that point, will be far cheaper to modify the ESM instead of making that "Moonshipstein". Moreover if it is the eurpeans who pay for it as a contribution for Artemis or whatever the name of the NASA cislunar / mars space program in the '30s, '40s, etc.

You do realize that the SpaceX HLS lander is supposed to docked with Orion and act as a mothership, prior to the Gateway platform being available.

IIRC, the length of the Orion ESM is limited by roof ceiling in the VAB. Could make the ESM wider. But that is basically developing a new spacecraft. The European ESM derived from the ATV is the form factor it is because it cost too much change from it's previous form factor.

The Europeans should be considering something else to contributed in the future instead of more Orion ESM to the Artemis program.

The door height of the VAB is 456 ft.

The ML-1 tower when on the crawler transporter is about 400 ft tall. There's plenty of clearance for a taller rocket. The EUS on the Block 1B will increase the height of the SLS by about 30 ft.
"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk
"There are lies, damned lies, and launch schedules." - Larry J

Offline cplchanb

  • Full Member
  • *
  • Posts: 166
  • Toronto
  • Liked: 103
  • Likes Given: 32
Re: A bigger service module for Orion
« Reply #22 on: 06/12/2023 06:43 pm »
IF someone wants a "bigger" Orion service module. There always the option of docking the current Orion stack to a pre-positioned stripped down SpaceX HLS lander variant with no landing hardware and full tanks in LEO. Plus the bonus of the pressurized volume and pre-positioned cargo that will be available in the lander variant.

Of course getting the Orion to LEO with the SLS will be optional.  ;)

You need to connect that kind of Moonship with Orion with all the requirements... At that point, will be far cheaper to modify the ESM instead of making that "Moonshipstein". Moreover if it is the eurpeans who pay for it as a contribution for Artemis or whatever the name of the NASA cislunar / mars space program in the '30s, '40s, etc.

You do realize that the SpaceX HLS lander is supposed to docked with Orion and act as a mothership, prior to the Gateway platform being available.

IIRC, the length of the Orion ESM is limited by roof ceiling in the VAB. Could make the ESM wider. But that is basically developing a new spacecraft. The European ESM derived from the ATV is the form factor it is because it cost too much change from it's previous form factor.

The Europeans should be considering something else to contributed in the future instead of more Orion ESM to the Artemis program.

The door height of the VAB is 456 ft.

The ML-1 tower when on the crawler transporter is about 400 ft tall. There's plenty of clearance for a taller rocket. The EUS on the Block 1B will increase the height of the SLS by about 30 ft.

not to mention that the VAB itself was designed to be able to be heightened further when taller rockets are a reality.
i wouldnt worry about height limits at all unless they try to stuff in something taller than a starship on an ML.

Offline Rik ISS-fan

  • Full Member
  • ****
  • Posts: 1525
  • the Netherlands
  • Liked: 622
  • Likes Given: 212
Re: A bigger service module for Orion
« Reply #23 on: 11/18/2023 07:25 pm »
I was in doubt of starting a new topic or using this one. I decided to do the later.

ESA supplies the Orion ESM (European Service Module), as barter element contribution to ISS and Gateway.
The ESM's for Orion 1 to 6 are under construction. I as European want ESA to be relieved from this contribution (/burden) to the Artemis program. So it can be used to fund a European payload return (human) launch capability.
This would cause a problem for NASA, because Orion doesn't function without ESM.
NASA would be required to fund the development of a new Orion service module; possibly this could go alongside with enlarging it.   

In my opinion launching Orion (humans) on a launcher with giant solid rocket motors is not wise.
It causes very stingent requirements for the launch escape system.
This leads me to the idea to launch Orion from a commercial launch vehicle.
If the launch escape system is integrated into the service module; similar to Boeing Starliner, the reduced mass for the launch escape system can be traded by increasing the size and propulsive capability of the service module. I think MethaLOx would be a good choice for the new service module & launch escape system.

How are you thinking about this?
« Last Edit: 11/18/2023 07:37 pm by Rik ISS-fan »

Offline Hog

  • Senior Member
  • *****
  • Posts: 2846
  • Woodstock
  • Liked: 1700
  • Likes Given: 6866
Re: A bigger service module for Orion
« Reply #24 on: 11/18/2023 08:35 pm »
I was in doubt of starting a new topic or using this one. I decided to do the later.

ESA supplies the Orion ESM (European Service Module), as barter element contribution to ISS and Gateway.
The ESM's for Orion 1 to 6 are under construction. I as European want ESA to be relieved from this contribution (/burden) to the Artemis program. So it can be used to fund a European payload return (human) launch capability.
This would cause a problem for NASA, because Orion doesn't function without ESM.
NASA would be required to fund the development of a new Orion service module; possibly this could go alongside with enlarging it.   

In my opinion launching Orion (humans) on a launcher with giant solid rocket motors is not wise.
It causes very stingent requirements for the launch escape system.
This leads me to the idea to launch Orion from a commercial launch vehicle.
If the launch escape system is integrated into the service module; similar to Boeing Starliner, the reduced mass for the launch escape system can be traded by increasing the size and propulsive capability of the service module. I think MethaLOx would be a good choice for the new service module & launch escape system.

How are you thinking about this?
I'm sure there's advantages to swapping boosters, but not because SLS uses solids.  STS supply streams were to be leveraged so the hi-performance hydrogen/oxygen sustainer and large segmented solid booster engines powering a 1 and a half stage orbiter to the edge of orbit.

The 4 segment RSRM is one of the most studied large motors and with reuse you could gauge performance post flight. The 5 segment RSRMV leverages the data from STS but loses the capability to ascertain post flight inspection of the booster as the RSRMVs are expended into the sea.  In order to retain the reusable equipment while supplying 5 segment thrust levels was to require 5.5 segment SRMs similar to the older Constellation proposals with IIRC 6 RS-68s?.
At least in SLS the astros lave a LAS and are at the pointy end of the rocket and not riding aside the propellant tanks and SRBs as in shuttle.

If we get away from SLS/Orion in Artemis and go commercial, it will be total. I don't see Orion on another launcher. just my thoughts.
Paul

Offline vp.

  • Full Member
  • *
  • Posts: 181
  • France
  • Liked: 58
  • Likes Given: 6
Re: A bigger service module for Orion
« Reply #25 on: 11/19/2023 06:40 am »

ESA supplies the Orion ESM (European Service Module), as barter element contribution to ISS and Gateway.
The ESM's for Orion 1 to 6 are under construction. I as European want ESA to be relieved from this contribution (/burden) to the Artemis program. So it can be used to fund a European payload return (human) launch capability.
This would cause a problem for NASA, because Orion doesn't function without ESM.
NASA would be required to fund the development of a new Orion service module; possibly this could go alongside with enlarging it.   


+1

Offline TomH

  • Senior Member
  • *****
  • Posts: 2938
  • Vancouver, WA
  • Liked: 1868
  • Likes Given: 909
Re: A bigger service module for Orion
« Reply #26 on: 11/21/2023 06:20 am »
The original conceptual Orion SM, during CPX, was larger. The original Orion CM diameter was to be a far too large ~6m, and was downsized to a still too massive 5.02m. The original SM was to be the same diameter prior to the ESA taking the contract for it. The ESA builds the current SM on a common bus which they already use for multiple purposes. This is why it has a smaller diameter and also requires jetisonable cover panels. In the Apollo program, the size ratio of SM to CM was > the same ratio between Orion SM and CM. This is because the Apollo SM had to provide the ΔV of the full stack for LOI, and then the ΔV for the CSM for TEI. In the CPX program, the Altair lander would have utilized Hydrolox prop (high iSP, low density, high volumetric tank requirements) for the ΔV of the full stack into LOI, and then the same engine and tanks for landing. The Orion SM in CXP would only have to provide ΔV for the CSM for TEI. As the Orion was carried over to the Artemis Program, its SM still only has to provide ΔV for TEI and no ΔV for LOI. Since Artemis/Orion lunar orbit will be NRHO, LOI requirements are quite different from Apollo. Edit to add:Getting into and out of Apollo's LLO requires much more ΔV than Orion's NRHO.
« Last Edit: 11/21/2023 07:14 am by TomH »

Offline Eric Hedman

  • Senior Member
  • *****
  • Posts: 2319
  • The birthplace of the solid body electric guitar
  • Liked: 1957
  • Likes Given: 1148
Re: A bigger service module for Orion
« Reply #27 on: 11/21/2023 07:10 am »
The original conceptual Orion SM, during CPX, was larger. The original Orion CM diameter was to be a far too large ~6m, and was downsized to a still too massive 5.02m. The original SM was to be the same diameter prior to the ESA taking the contract for it. The ESA builds the current SM on a common bus which they already use for multiple purposes. This is why it has a smaller diameter and also requires jetisonable cover panels. In the Apollo program, the size ratio of SM to CM was > the same ratio between Orion SM and CM. This is because the Apollo SM had to provide the ΔV of the full stack for LOI, and then the ΔV for the CSM for TEI. In the CPX program, the Altair lander would have utilized Hydrolox prop (high iSP, low density, high volumetric tank requirements) for the ΔV of the full stack into LOI, and then the same engine and tanks for landing. The Orion SM in CXP would only have to provide ΔV for the CSM for TEI. As the Orion was carried over to the Artemis Program, its SM still only has to provide ΔV for TEI and no ΔV for LOI. Since Artemis/Orion lunar orbit will be NRHO, LOI requirements are quite different from Apollo.
If I remember correctly, the NRHO orbit was picked instead of LLO because of the limitations in ΔV of the service module.  Performance limited requirements instead of requirements driving performance.  NASA had created a chart of ΔV requirements to get to different possible place to park Orion and they had little choice but to choose NRHO since it fit what they had in development.

Offline TomH

  • Senior Member
  • *****
  • Posts: 2938
  • Vancouver, WA
  • Liked: 1868
  • Likes Given: 909
Re: A bigger service module for Orion
« Reply #28 on: 11/21/2023 07:17 am »
If I remember correctly, the NRHO orbit was picked instead of LLO because of the limitations in ΔV of the service module.  Performance limited requirements instead of requirements driving performance.  NASA had created a chart of ΔV requirements to get to different possible place to park Orion and they had little choice but to choose NRHO since it fit what they had in development.

That is completely correct. I stated this partially in my last sentence above, and have edited to expand that. I was just looking at that chart which is embedded in this article: https://space.stackexchange.com/questions/23992/why-is-a-near-rectilinear-halo-orbit-proposed-for-lop-g-formerly-known-as-deep

Offline woods170

  • IRAS fan
  • Senior Member
  • *****
  • Posts: 12099
  • IRAS fan
  • The Netherlands
  • Liked: 18210
  • Likes Given: 12171
Re: A bigger service module for Orion
« Reply #29 on: 11/21/2023 08:23 am »
The original conceptual Orion SM, during CPX, was larger. The original Orion CM diameter was to be a far too large ~6m, and was downsized to a still too massive 5.02m. The original SM was to be the same diameter prior to the ESA taking the contract for it.

That is incorrect. The size of the SM had been shrunk to what we see today FIVE years BEFORE ESA got involved. I suggest you educate yourself first in the multiple Design Analysis Cycles (DACs) that Orion went thru under Constellation program (CxP). The Service Module design that was current, when Constellation got canceled in 2010, was the 606/607 design from LockMart.
ESA did not get involved until 2012, which was two years after CxP cancelation. ESA was handed the basics of the 606/607 SM design requirements by NASA, with the order to go from there.

The ESA builds the current SM on a common bus which they already use for multiple purposes.

Once again, this is incorrect. Although the ESM has it roots in the technology developed for the ATV Service Module, they are not the same. There is no such thing as a common bus. The structure for ESM is unique and radically different from that of the ATV SM. The ATV legacy technology used in ESM consists of individual components and heavily redesigned systems. But NOT a common bus.


This is why it has a smaller diameter and also requires jetisonable cover panels.

This is also incorrect. As I explained above, the current size of the ESM is directly derived from the physical dimensions of the original LockMart 606/607 SM designs. The shrinkage of the Orion SM to its current size happened during the Constellation program. It was caused by the severe underperformance of the Ares I design. That required a lot of mass to be shaved from the Orion design. And NASA started doing that by down-sizing the Service Module first. Its length shrunk between the 604 and 605 DACs. And then its diameter shrunk between the 605 and 606 DACs. See the attached image, as well as the attached PDF (from NTRS). The jettisonable panels were a part of the 606/607 design. Which, once again, was the final NASA/Lockheed Martin design of the Orion SM before CxP got axed.

Mass saving efforts drove all those down-sizing design changes and most (if not all) were driven by the upmass limitations of the Ares I launcher design.
« Last Edit: 11/29/2023 10:18 am by woods170 »

Offline Spaceguy5

  • Member
  • Posts: 70
  • Liked: 149
  • Likes Given: 9
Re: A bigger service module for Orion
« Reply #30 on: 11/24/2023 03:25 pm »

If I remember correctly, the NRHO orbit was picked instead of LLO because of the limitations in ΔV of the service module.  Performance limited requirements instead of requirements driving performance.  NASA had created a chart of ΔV requirements to get to different possible place to park Orion and they had little choice but to choose NRHO since it fit what they had in development.

There's a lot more to it than that, though that is a factor. LLO is also incredibly unstable. Just a few days in LLO can turn your spacecraft in a crater, and even if you don't fall out of orbit, it's hard to maintain nav in LLO because of the instability. Especially since the moon doesn't have something like GPS. LLO is just not a good pick if you want to have long duration missions on the moon.

Not to mention LLO has frequent blackout periods of communication with earth and the landed lander or lunar outpost, and frequent shadow (not great if your spacecraft is solar powered and has large power consumption requirements)

NRHO fixes all of that. Almost zero shadow, almost constant communication with earth, a lot more communication coverage with parts of the lunar surface, very stable, etc.

Not to mention having gateway long-term at NRHO gives you a place to stage landers, crew spacecraft, and supplies (with all the advantages and orbit stability listed above). And will demonstrate technologies needed to built a mars transit vehicle for future exploration.


That is completely correct. I stated this partially in my last sentence above, and have edited to expand that. I was just looking at that chart which is embedded in this article: https://space.stackexchange.com/questions/23992/why-is-a-near-rectilinear-halo-orbit-proposed-for-lop-g-formerly-known-as-deep

No it's not completely correct. if you look at that chart, there's a lot more factors than Orion SM DV being traded. A few of which I mentioned above.
« Last Edit: 11/24/2023 04:03 pm by Spaceguy5 »

Tags:
 

Advertisement NovaTech
Advertisement Northrop Grumman
Advertisement
Advertisement Margaritaville Beach Resort South Padre Island
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
1