Author Topic: What would it take to change your mind on SLS/Orion?  (Read 12441 times)

Offline tdperk

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Re: What would it take to change your mind on SLS/Orion?
« Reply #80 on: 08/17/2017 08:48 PM »
What would it take to change my mind on SLS/Orion?

That it had capabilities which it provided less expensively going forward than other plausible options AND that it was not the product of the cost plus business model, such that it trapped it's operators (and passengers) in "Columbia type thinking".  Hat tip to Jim, not that he'll appreciate my use of the phrase.

https://forum.nasaspaceflight.com/index.php?topic=43527.msg1713733#msg1713733
« Last Edit: 08/17/2017 09:15 PM by tdperk »

Online oldAtlas_Eguy

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Re: What would it take to change your mind on SLS/Orion?
« Reply #81 on: 10/16/2017 05:09 PM »
What would it take to change my mind on SLS/Orion?

NASA developing a large 35-40mt BEO single element payload that cannot be broken down into 10-25mt elements.

There are other methods (LVs) much cheaper to get manned capsules and 15mt cargo payloads into a Lunar orbit which will exist (launch) prior to SLS-1B/Orion launch and as well even before SLS-1A/Orion launch.

NASA does not have such 35- 40mt payloads on its "radar" in the conceivable future out through 2030. Why such a large payload would change my mind? Anything smaller than 35mt BEO could be launched with Vulcan/ACES-DL (Distributed Launch). Even then if BO is not to tardy with its NG development a 3 stage NG with some DL capabilities could do the up to 40mt BEO. So a large BEO payload is not an assured thing for justification of SLS. And definitely not for Orion.

There is a likely case that a manned Dragon 2 Lunar flyby will occur before even EM-1. If D2 is BEO capable then what is the reason to have Orion? If there was a continuously manned BEO station or Lunar base then having two different systems would be of some reasoning. But there are other options than Orion for even that case that are much cheaper.

The closet thing for justification of the expense of an SLS (not Orion though) is the Europa Clipper and Europa Lander because of truncated mission time that SLS offers these programs. Such complex missions and a standing army of experts to support the mission causes a several year decrease in mission time does two things. Decrease the after launch mission expenses to almost in half and increases mission success because time in space for a probe is the biggest threat to success. A tremendous shortened mission time means a tremendous boost in probable mission success. At the moment the DV that SLS can offer these probe missions can not be duplicated by  other LVs existing or soon to exist that can be provided by SLS within the timeframe for EC. But EL (Europa Lander) with an unsure launch date which may be at the end of the 2020s, something else may come along that can get close to it or even exceed SLS.

In other words it would take a lot to change my mind about the SLS/Orion program. The program doesn't even challenge the technology existing for space Launch which could have gotten me to be a marginal proponent. It does not do other than some very minor tech upgrades of systems that have flown for more than 30 years. In some cases the exact same systems as flown 30+ years ago. NOTE such a system is Orion's heat shield which is an 50+ year old Apollo era design.

Offline Proponent

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Re: What would it take to change your mind on SLS/Orion?
« Reply #82 on: 10/16/2017 06:13 PM »
The closet thing for justification of the expense of an SLS (not Orion though) is the Europa Clipper and Europa Lander because of truncated mission time that SLS offers these programs. Such complex missions and a standing army of experts to support the mission causes a several year decrease in mission time does two things. Decrease the after launch mission expenses to almost in half and increases mission success because time in space for a probe is the biggest threat to success. A tremendous shortened mission time means a tremendous boost in probable mission success. At the moment the DV that SLS can offer these probe missions can not be duplicated by  other LVs existing or soon to exist that can be provided by SLS within the timeframe for EC

My understanding from reading Blackstar's posts is that the benefit of the faster trajectory is not in higher reliability but in less testing.  In other words, if the mission is longer, then the hardware is tested more extensively to bring it to the same reliability over the longer lifetime.  That additional testing is expensive, and its elimination results in a significant savings.  In fact, IIRC, the savings from reduced testing likely exceeds the savings from fewer years of operations to fund.

While the faster mission is undeniably a benefit, what's missing, as always in the case of SLS, is any analysis of whether the it is worth the additional cost of the launch vehicle.

Given the more onerous testing regime for longer missions, using SLS increases the risk of failure, because the launch vehicle will have little track record.  EC will be an extremely expensive test weight if it flies on the first EUS (though not as expensive as the alternative, namely the first Orion crew). 

Compare to Atlas V's long and nearly perfect record.

EDIT:  "launch vehicle" -> "the launch vehicle" in penultimate paragraph.
« Last Edit: 10/16/2017 08:26 PM by Proponent »

Offline Political Hack Wannabe

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Re: What would it take to change your mind on SLS/Orion?
« Reply #83 on: 10/16/2017 08:10 PM »
Very simply - show me how SLS actually enables space settlement. 

IMHO - if something in our human space program isn't about enabling settlement, we shouldn't be doing it.  And if we aren't settling space, no reasons to send humans. 
It's not democrats vs republicans, it's reality vs innumerate space cadet fantasy.

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