Author Topic: NASA examines options and flight paths for SLS EM-2 mission  (Read 31171 times)

Offline sdsds

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #40 on: 12/09/2016 05:43 am »
In the multi-translunar injection mission profile that now seems to be the plan of record for EM-2 has anything been said about the inclinations of the orbits with respect to the plane of the Moon's orbit around the Earth?

Looking closely at the diagram that accompanied the Dec 1 announcement (https://www.nasa.gov/feature/nasa-s-first-flight-with-crew-will-mark-important-step-on-journey-to-mars) it may intentionally show an "over/under" trajectory rather than a coplanar one.

Getting some velocity in the z-axis direction would let Orion pass over more polar regions of the Moon. And it can do that without compromising the "free return" property of the trajectory, so it doesn't reduce crew safety.
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Offline sdsds

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #41 on: 12/09/2016 10:27 am »
I'll trust your judgement about what is an option for EM-2.

But note that for Apollo all TLI impulse was provided while in LEO reached from KSC. For EM-2 only the SLS portion of the TLI impulse must be provided in that kind of orbit.

I'm not saying NASA plans to take advantage of the first Orion apogee (71333 km) to perform a maneuver. I have no idea what NASA plans. But I think Orion could do that and get itself onto a translunar trajectory out of the plane into which SLS delivered it.

And then there's yet another possibility. The Chinese have published (in the the AIAA  Journal of Guidance, Control, and Dynamics) some research on what they call, "Multi Segment Lunar Free-Return Trajectories." In their scheme each trajectory segment is a free return. But they perform a maneuver days after TLI. (It's sort of like where some Apollo flights departed from free return.) I believe that approach might reduce the delta-t and perilune distance penalties.

LOL. Maybe I should write NASA a letter and tell them how to plan this mission!
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Offline Proponent

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #42 on: 12/09/2016 11:44 am »
Sorry, sdsds, shortly after I made the post which I suspect your post immediately above addresses, I decided it fit better here (we seem to be discussing something similar in two places at once).  If I had realized you'd already replied, I'd have left my post where it was.

I'll trust your judgement about what is an option for EM-2.

Please don't -- I'm just guessing!

Quote
But note that for Apollo all TLI impulse was provided while in LEO reached from KSC. For EM-2 only the SLS portion of the TLI impulse must be provided in that kind of orbit.

That's true -- with such a high apogee, Orion could make a substantial plane change with low delta-V.  NASA might still worry about the increased trip time.

Quote
And then there's yet another possibility. The Chinese have published (in the the AIAA  Journal of Guidance, Control, and Dynamics) some research on what they call, "Multi Segment Lunar Free-Return Trajectories." In their scheme each trajectory segment is a free return. But they perform a maneuver days after TLI. (It's sort of like where some Apollo flights departed from free return.) I believe that approach might reduce the delta-t and perilune distance penalties.

Thanks!  Google Scholar turns up a link the full text of the paper, which I hope to read shortly.
« Last Edit: 12/09/2016 12:02 pm by Proponent »

Offline Khadgars

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #43 on: 12/09/2016 03:01 pm »
Please feel free to move this to another thread, but I didn't see any chatter in regards to the PM article below (I know they are not held in high esteem here).

http://www.popularmechanics.com/space/moon-mars/a24206/orion-nasa-space-plan/

It seems to cover material from EM-2 onward that I haven't seen here (perhaps in L2).
« Last Edit: 12/09/2016 03:02 pm by Khadgars »
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Offline sdsds

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #44 on: 12/10/2016 08:33 pm »
It looks like Popular Mechanics is reporting the ideas laid out by the Advanced Concepts Office at Marshall as being the "plan of record." Not sure if that's true... but we can hope!

Or is Popular Mechanics saying something different than what Smitherman said?

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160012094.pdf
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Offline redliox

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #45 on: 12/11/2016 02:31 pm »
It looks like Popular Mechanics is reporting the ideas laid out by the Advanced Concepts Office at Marshall as being the "plan of record." Not sure if that's true... but we can hope!

Or is Popular Mechanics saying something different than what Smitherman said?

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160012094.pdf

Looking at the hab options considered they favor something sized like the SLS tankage at 8+ meter diameters.
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Offline A_M_Swallow

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #46 on: 12/11/2016 05:47 pm »
It looks like Popular Mechanics is reporting the ideas laid out by the Advanced Concepts Office at Marshall as being the "plan of record." Not sure if that's true... but we can hope!

Or is Popular Mechanics saying something different than what Smitherman said?

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160012094.pdf

Looking at the hab options considered they favor something sized like the SLS tankage at 8+ meter diameters.

Since 8 metres diameter is too wide for rail tunnels it will have to be brought in by barge. The workshop will have to be near a river or the sea shore.

Offline Jim

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #47 on: 12/11/2016 06:19 pm »

Since 8 metres diameter is too wide for rail tunnels it will have to be brought in by barge. The workshop will have to be near a river or the sea shore.

Rail tunnels have no bearing on the matter.  The US does not use rail to transport payloads across the country

Offline TrevorMonty

The 8m has few issues with it compared to modular approach. Needs a dedicated SLS plus a propulsion module to deliver it to DRO after TLI.
That means one less crew mission. The  modules can share a Orion launch and use Orion to deliver them to DRO.
With modules, the crew start getting benefits from 1st module delivered which would be sooner and cheaper than 8m. Budget cuts could push 8m further out leaving crew missions stuck in Orion. If there are budget cuts after first module is delivered, crew will still be able to do 30-60 missions.


Offline okan170

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #49 on: 12/11/2016 06:45 pm »
Looking at the hab options considered they favor something sized like the SLS tankage at 8+ meter diameters.

With that in mind, perhaps the 7.2m version is the most likely, as it won't need the 10m PLF in order to fly without aerodynamic mods.  (Assuming the 8.4m fairing is the only one developed aside from the USA cap)

Offline sdsds

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #50 on: 12/11/2016 08:45 pm »
I hope the large hab is openly competed. Would the RFP likely be timed before or after completion of EM-2? That is, would any lessons learned from EM-2 need to be carried forward into the hab requirements?
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Offline Khadgars

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #51 on: 12/14/2016 03:04 pm »
I hope the large hab is openly competed. Would the RFP likely be timed before or after completion of EM-2? That is, would any lessons learned from EM-2 need to be carried forward into the hab requirements?

I would expect an RFP to likely go out sometime after EM-1 to be honest.  This of course, pending political winds.
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Offline wannamoonbase

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #52 on: 12/14/2016 06:55 pm »
I'm disappointed in the timidity in decision making.

Go for the Moon, get into orbit and show some marbles. 

It was possible in 1968, I would hope it's possible 50+ years later.
Wildly optimistic prediction, Superheavy recovery on IFT-4 or IFT-5

Offline TomH

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #53 on: 12/15/2016 01:59 am »
I'm disappointed in the timidity in decision making.

Go for the Moon, get into orbit and show some marbles. 

It was possible in 1968, I would hope it's possible 50+ years later.

I don't think that's a fair thing to say. In 1968, a budget surge had NASA at 4.5% of the federal budget, and most of that was for the manned deep space program. Today NASA is getting about 0.5% of the federal budget and the manned deep space program is only a fraction of that. It's easy for us to sit back and criticize, but these guys have to be very careful with the limited amount of money they are given.

Offline redliox

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #54 on: 12/15/2016 02:55 am »
I'm disappointed in the timidity in decision making.

Go for the Moon, get into orbit and show some marbles. 

It was possible in 1968, I would hope it's possible 50+ years later.

I don't think that's a fair thing to say. In 1968, a budget surge had NASA at 4.5% of the federal budget, and most of that was for the manned deep space program. Today NASA is getting about 0.5% of the federal budget and the manned deep space program is only a fraction of that. It's easy for us to sit back and criticize, but these guys have to be very careful with the limited amount of money they are given.

Sadly yes.  The Apollo effort amounted to an expensive political gesture; literally "Mooning" the Soviets.  And the point about the budget brings home a further point: NASA had access to nine times its current budgetary resources so it's little wonder both the '80s SEI or the 2000s Constellation efforts floundered.

For the foreseeable future NASA circling the moon is the best it can do although there are some options.
« Last Edit: 12/15/2016 02:56 am by redliox »
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Offline Proponent

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #55 on: 12/15/2016 01:09 pm »
I'm disappointed in the timidity in decision making.-2 f

Go for the Moon, get into orbit and show some marbles. 

It was possible in 1968, I would hope it's possible 50+ years later.

Suppose that before EM-2, SLS flies twice, once for EM-1 and once for Europa Clipper or something like that.  Now compare the flight experience of the relevant systems with that which had occurred by the time Apollo 8 flew, from the top of the stack downward:

SystemApollo 8EM-2
CM52
Heat shield @ hi speed21
SM51
CSM w/crew10
TLI stage71
Launch vehicle22

One could quibble with some of the numbers in the table (e.g., maybe EFT-1 counts as a high-speed heat-shield test, despite the facts that the manufacturing technique has since been changed and the entry speed was somewhat below full trans-lunar speed).  One could point out that, because the state of the art is more advanced now, maybe less flight testing is needed.  But on the whole, EM-2 looks pretty aggressive to me, especially since the NASA-industry team that built Apollo had lots of current experience building manned spacecraft, for more than today's NASA-industry team.  And the latest proposal for EM-2 still seems to include some kind of lunar orbit as an option, if preceding stages of the flight go well.

Basically, I'm just restating what redliox said about the budget being much less than Apollo's:  with less money, less testing is possible.

EDIT:  Fixed two typos -- and corrected spelling of "redliox"!
« Last Edit: 12/15/2016 03:47 pm by Proponent »

Offline redliox

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #56 on: 12/15/2016 03:07 pm »
Basically, I'm just restating what redilox said about the budget being much less than Apollo's:  with less money, less testing is possible.

Much appreciated  ;)

As far as EM-2 itself is concerned, it still seems possible.  If anything I just see the ESM as the weak point; both in schedule and for the fact it still limits Orion's performance.  It could suffice for some activities, but not directly with lunar landings (as in descending as far as low lunar orbit where that magic happens).  Just as the SLS is going to be upgraded, so should the SM for Orion, whether it be American or European-made.  However I wouldn't expect an upgraded SM until at least EM-5+ due to the budget.
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Offline Khadgars

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #57 on: 12/15/2016 04:13 pm »
Basically, I'm just restating what redilox said about the budget being much less than Apollo's:  with less money, less testing is possible.

Much appreciated  ;)

As far as EM-2 itself is concerned, it still seems possible.  If anything I just see the ESM as the weak point; both in schedule and for the fact it still limits Orion's performance.  It could suffice for some activities, but not directly with lunar landings (as in descending as far as low lunar orbit where that magic happens).  Just as the SLS is going to be upgraded, so should the SM for Orion, whether it be American or European-made.  However I wouldn't expect an upgraded SM until at least EM-5+ due to the budget.

I think that is certainly possible.  I also think is likely we'll see something similar to the 5 Seg boosters.  Instead of a whole new design, we'll end up with upgraded versions of the current boosters.  Both of which to happen towards end of 2020's.

Everyone loves to rag on the EM missions, but there is not a single entity currently bending hardware that comes even close to this type of exploration outside of NASA.  SpaceX may get into this game, but that is yet to be seen especially after the financial crunch they're experiencing from the recent failure.

Gods Speed to both of them...
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Offline PahTo

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #58 on: 12/15/2016 04:46 pm »

I think that is certainly possible.  I also think is likely we'll see something similar to the 5 Seg boosters.  Instead of a whole new design, we'll end up with upgraded versions of the current boosters.  Both of which to happen towards end of 2020's.

Everyone loves to rag on the EM missions, but there is not a single entity currently bending hardware that comes even close to this type of exploration outside of NASA.  SpaceX may get into this game, but that is yet to be seen especially after the financial crunch they're experiencing from the recent failure.

Gods Speed to both of them...

Concur with all.  I've maintained for years, since the earliest word of the 1B variant, that that would be the final edition of this LV.  We *may* see some type of "advanced booster" (read:  HTPB instead of PBAN, perhaps with some type of composite case, or elements of composite with steel case), but that's it.  At that (and not to be all negative) we'll likely only see TWO to six launches of this LV before the program ends.  This from an SLS supporter...
[edit, changed "four" to TWO]
« Last Edit: 12/15/2016 05:05 pm by PahTo »

Offline mike robel

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Re: NASA examines options and flight paths for SLS EM-2 mission
« Reply #59 on: 12/15/2016 05:03 pm »
The telling time will come, unless I missed it, of ATK being told to start making the 1sts set of SRBs after the current casings are exhausted.  Another indicator is the number of SSMEs they have available.  Will they last longer than he casings?

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