Author Topic: Deep Space Gateway Power/Propulsion RFI  (Read 65418 times)

Offline envy887

  • Senior Member
  • *****
  • Posts: 8144
  • Liked: 6801
  • Likes Given: 2965
Re: Deep Space Gateway Power/Propulsion RFI
« Reply #100 on: 02/28/2018 05:09 pm »
On a related note, isn't it also very difficult to bring a SEP craft to lunar orbit Moon using only its own power? Switching the PPE to a commercial launch brings many new issues.

Either Falcon Heavy or Delta IV Heavy can put a 10 tonne PPE through TLI. It would only need to do LOI with SEP, which is quite feasible.

Offline Proponent

  • Senior Member
  • *****
  • Posts: 7277
  • Liked: 2782
  • Likes Given: 1462
Re: Deep Space Gateway Power/Propulsion RFI
« Reply #101 on: 02/28/2018 06:16 pm »
On a related note, isn't it also very difficult to bring a SEP craft to lunar orbit Moon using only its own power? Switching the PPE to a commercial launch brings many new issues.

It's certainly slower than using chemical propulsion as far as lunar-orbit insertion, but there's no rush.  SMART-1 went as far as GTO on chemical propulsion and from there went electric.
« Last Edit: 03/01/2018 02:39 pm by Proponent »

Offline speedevil

  • Senior Member
  • *****
  • Posts: 4406
  • Fife
  • Liked: 2762
  • Likes Given: 3369
Re: Deep Space Gateway Power/Propulsion RFI
« Reply #102 on: 03/02/2018 11:51 am »
On a related note, isn't it also very difficult to bring a SEP craft to lunar orbit Moon using only its own power? Switching the PPE to a commercial launch brings many new issues.

It's certainly slower than using chemical propulsion as far as lunar-orbit insertion, but there's no rush.  SMART-1 went as far as GTO on chemical propulsion and from there went electric.
Quote
Forty-two minutes after launch SMART-1 was placed into a geostationary transfer orbit, 742 x 36 016 km, inclined at 7° to the Equator.

Quote
The last firing of the EP before lunar capture was a thrust arc around the third lunar resonance, and ended on 14 October 2004. Apart from a 4 hour correction burn on 25 October, the EP remained inactive until lunar capture.
Up to 26 October, and the 289th engine pulse, the SMART-1 EP system had cumulated a total on time of nearly 3650 hours, consumed about 59 kg of xenon and imparted to the spacecraft a velocity increment of approximately 2735 ms-1 (9850 kmh-1).


Offline blasphemer

  • Full Member
  • *
  • Posts: 186
  • Slovakia
  • Liked: 140
  • Likes Given: 1081
Re: Deep Space Gateway Power/Propulsion RFI
« Reply #103 on: 03/03/2018 01:11 pm »
Much like the terrible idea of "Lagrange Gateways" that's been floated for years, now NASA pushes an even worse idea.

Why are "Lagrange Gateways" a terrible idea?

Offline UltraViolet9

  • Full Member
  • *
  • Posts: 148
  • Undisclosed
  • Liked: 243
  • Likes Given: 19
Re: Deep Space Gateway Power/Propulsion RFI
« Reply #104 on: 03/03/2018 07:46 pm »
Why are "Lagrange Gateways" a terrible idea?

In the abstract, they are not.

If you want to park a large, expensive telescope a good distance from Earth and repair or upgrade it, a crew-tended habitat at a Lagrange Point is not a bad idea.

If you want to very efficiently (and very slowly) move lots of stuff long distances across the solar system, moving that stuff through Lagrange Points is about as efficient as you can get.  (Wiki "Interplanetary Transport Network".)

But for the foreseeable future, a Lagrange Gateway is a hammer in search of a nail. 

We don't have large, expensive, serviceable/upgradeable telescopes at Lagrange Points yet.  (JWST will be an exception in a couple or few years, hopefully, but it's not designed to be serviceable/upgradeable.)

And we're not trying to move lots of stuff very slowly but efficiently to Mars or anywhere else in the solar system yet.

All the other rationalizations for Lagrange Gateways or its cousin in DSG/LOP-G are specious.

Yes, you could get some deep space ops experience at such a gateway station before attempting a crewed Mars mission.  But such gateways are only crew tended for weeks to a few months.  You really need a year or so to properly simulate a Mars transit.

Yes, you could joystick some lunar rovers from such a gateway station.  But such gateways will only reduce the comm time delay from Earth by a few seconds.  Might as well keep your controllers in Pasadena or Houston.

Yes, you could stage some crewed lunar excursions from such a gateway station.  But you're going out of your way to do so.  If you want to go to the Moon, then go to the Moon.

Yes, you could stage crewed Mars missions from such a gateway station, especially if they rely on electric propulsion.  But there's no particular advantage versus staging from a high Earth orbit and then just passing through the same Lagrange point.  And there's no particular need for a "staging station" at either location.  If you want to go to Mars, then go to Mars.

DSG/LOP-G really grows out of the shortcomings of Orion/SLS. 

Orion doesn't have the delta-V to return from lower lunar orbits, so crewed lunar missions must stage out of a higher orbit.

And SLS doesn't have anywhere near the launch rate to support a traditional crewed Mars mission architecture like DRM 5.0, so NASA will have to rely on an unproven, high-power electric transit stage (the Deep Space Transport) to get to Mars with fewer launches.  The PPE on DSG/LOP-G is a step towards the DST's power/propulsion element.

In a more muscular, better coordinated, and much more efficient civil space program, a Lagrange Gateway would make some sense.

But we're using it's kissing cousin in DSG/LOP-G as a point solution band-aid to keep a deficient exploration architecture from falling apart.

We'd be much better off starting off with more and efficient capable launchers and transit vehicles and only inserting Lagrange stations or other waypoints when there's a unique need or clear advantage to doing so.

EDIT:  One more thought... opportunity cost is important to these considerations.  If a gateway costs, say, a billion dollars to put in place, it doesn't have to be perfectly justified.  You won't forgo much in the way of lunar or Mars missions to have that additional capability.

But with the first element (PPE) of DSG/LOP-G coming in at over $2.5 billion, we're looking at a gateway that will cost low tens of billions of dollars to field.  That money could buy a lot of lunar missions much sooner.  It's a very expensive and lengthy detour without a clear rationale (other than to help keep an Orion/SLS architecture from falling apart).  We can and should do better.
« Last Edit: 03/03/2018 08:24 pm by UltraViolet9 »

Offline ncb1397

  • Senior Member
  • *****
  • Posts: 3497
  • Liked: 2310
  • Likes Given: 29
Re: Deep Space Gateway Power/Propulsion RFI
« Reply #105 on: 03/03/2018 08:21 pm »
Looks like in the budget proposal from a couple weeks back the Deep Space Gateway has been renamed the "Lunar Orbital Platform", the propulsion module now has funding attached to it ($504 million next year, $2.7 billion over five years), and the targeted launch date is actually being moved up to 2022. It is also now is planned for launch on a commercial vehicle instead of on the EM-2 SLS flight.

The funding line is for the whole station, not just the propulsion module. It looks to be about half the mass of skylab with them planning to spend under a third as much(<$5 billion).
« Last Edit: 03/03/2018 08:58 pm by ncb1397 »

Offline bodhiandphysics

  • Member
  • Posts: 18
  • Canada
  • Liked: 45
  • Likes Given: 3
Re: Deep Space Gateway Power/Propulsion RFI
« Reply #106 on: 03/03/2018 10:28 pm »
Much like the terrible idea of "Lagrange Gateways" that's been floated for years, now NASA pushes an even worse idea.

Why are "Lagrange Gateways" a terrible idea?

To understand why they might be a terrible idea you have to understand why they may be a good idea.  If you're interested in going to Mars, it's probably a good idea to reuse some of that expensive hardware for multiple missions.  One obvious component to reuse is the transfer vehicle that gets you from earth orbit to Mars orbit.  This creates a problem, though in that this vehicle will need a lot of delta-v.  From a Mars Transfer Orbit (MTO) to low mars orbit (LMO) takes 2.5 km/s of delta-v so 5 both ways.  Early Mars ideas staged in LEO, but to get to a MTO from LEO requires 4 km/s of delta-v, so the whole mission would require an absolutely absurd 13 km/s of delta-v.  By contrast staging in a high earth orbit (and Lagrange Point is just a certain high earth orbit with an orbital period of 28 days) could lower this down to about 7 km/s of delta-v, which is manageable, particularly with a combination of chemical and electric propulsion, like the DSG would use.  Staging in a high orbit, however requires a large rocket to bring the various components, which happens to create a perfect role for the SLS (though presumably multiple Vulcan or Falcon Heavies could also be used).

There are other ways however of skinning this cat.  You can use aerobraking in mars and earth orbit to lower the delta v, but this makes it harder to build the vehicle and to reuse the vehicle (and also makes the mission much more dangerous). You can use ISRU on mars surface If you just want to go to Mars, the above architecture might be too complicated. Mars Direct doesn't stage at all!  It just lofts stuff to Mars and uses sacrificial aerobraking and Mars ISRU to make the numbers work. 

The advantage of staging in LOE, however, is that its easier to use reusable rockets to lift payload, and so the cost of payload in LOE might be orders of magnitude cheaper than in a higher orbit.  This is the basis of Spacex's mars plan which is based on aerobraking both in mars and earth orbit, as well as using ISRU extremely aggressively.  It's incredibly ambitious, but does give the advantage of amazing capability if it works. 

So staging at Lagrange point is fine and dandy!  A Langrange station might still be a dumb idea.  Why not just build the whole thing directly? Why use the intermediate step of the DSG?  The answer is that you need to test... to which the reply is  test in LOE which is going to be much cheaper than testing in a high orbit.  Here lies the second advantage of the Lagrange Gateway.  It's quite possible that during all the testing for the Mars mission, the political winds will change and the mission will be cancelled. If we're building the DSG, at least we get a moon mission out of all the mess.  Moon missions aren't bad? 

Of course, the DSG makes it much more likely that all we'll get is a moon mission.  And a) its a dumb moon mission, and b) we've already been to the moon!
 

Offline jongoff

  • Recovering Rocket Plumber/Space Entrepreneur
  • Senior Member
  • *****
  • Posts: 6807
  • Lafayette/Broomfield, CO
  • Liked: 3987
  • Likes Given: 1684
Re: Deep Space Gateway Power/Propulsion RFI
« Reply #107 on: 03/04/2018 02:56 am »
Orion does not have enough propulsive capability to enter and return from LLO.

Yes, that's true. It does have enough delta-V to leave LLO though. An EUS designed to last the three day journey to the Moon could do LLO insertion with Orion (as well as an LM on a separate mission).

Yeah, but that would make too much sense.

~Jon

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 39271
  • Minnesota
  • Liked: 25240
  • Likes Given: 12115
Re: Deep Space Gateway Power/Propulsion RFI
« Reply #108 on: 03/04/2018 03:01 am »
It’s a shame the PPE won’t have enough power to send it somewhere interesting, like Mars or an asteroid. 250kW should do it.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Steven Pietrobon

  • Member
  • Senior Member
  • *****
  • Posts: 39218
  • Adelaide, Australia
    • Steven Pietrobon's Space Archive
  • Liked: 32738
  • Likes Given: 8196
Re: Deep Space Gateway Power/Propulsion RFI
« Reply #109 on: 03/04/2018 04:59 am »
Orion doesn't have the delta-V to return from lower lunar orbits, ...

Yes it does. Orion has a delta-V of 1.2 km/s. That's sufficient for TEI from LLO. Of course, another rocket would need to place Orion in LLO for this to work.

Quote
And SLS doesn't have anywhere near the launch rate to support a traditional crewed Mars mission architecture like DRM 5.0, so NASA will have to rely on an unproven, high-power electric transit stage (the Deep Space Transport) to get to Mars with fewer launches.

Have you actually compared the number of SLS launches for both architectures? You can do a Mars mission from LEO using only three SLS Block II launches (first launch carries Orion, Hab and Lander/MAV in re-entry fairing, second and third launches refuel SLS upper stage for TMI). NASA's gateway plan requires a lot more launches than that.

Quote
b) we've already been to the moon!

We've also been to LEO, but we still keep going there. That's because its worthwhile to do so. Same with the Moon.
« Last Edit: 03/04/2018 04:59 am by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline UltraViolet9

  • Full Member
  • *
  • Posts: 148
  • Undisclosed
  • Liked: 243
  • Likes Given: 19
Re: Deep Space Gateway Power/Propulsion RFI
« Reply #110 on: 03/04/2018 06:58 am »
Of course, another rocket would need to place Orion in LLO for this to work.

Of course.  Enter and return.

Quote
You can do a Mars mission from LEO using only three SLS Block II launches (first launch carries Orion, Hab and Lander/MAV in re-entry fairing, second and third launches refuel SLS upper stage for TMI).

DRM 5.0 assumes three Mars surface missions over a decade.  On that timeframe, the program could stockpile for one, but not several.

And even with stockpiling, the launch cadence for refueling could not be pulled off with the planned workforce and ground infrastructure.

Quote
NASA's gateway plan requires a lot more launches than that.

But it spaces out the launches, which is what SLS's extremely low launch cadence requires.

It's arse-backwards.  The launcher is driving the architecture instead of the other way around.

(And putting electric propulsion at an unproven order of magnitude on the critical path, to boot.)

Offline MATTBLAK

  • Elite Veteran & 'J.A.F.A'
  • Senior Member
  • *****
  • Posts: 5362
  • 'Space Cadets' Let us; UNITE!! (crickets chirping)
  • New Zealand
  • Liked: 2239
  • Likes Given: 3883
Re: Deep Space Gateway Power/Propulsion RFI
« Reply #111 on: 03/04/2018 07:14 am »
Orion doesn't have the delta-V to return from lower lunar orbits, ...

Yes it does. Orion has a delta-V of 1.2 km/s. That's sufficient for TEI from LLO. Of course, another rocket would need to place Orion in LLO for this to work.

Quote
And SLS doesn't have anywhere near the launch rate to support a traditional crewed Mars mission architecture like DRM 5.0, so NASA will have to rely on an unproven, high-power electric transit stage (the Deep Space Transport) to get to Mars with fewer launches.

Have you actually compared the number of SLS launches for both architectures? You can do a Mars mission from LEO using only three SLS Block II launches (first launch carries Orion, Hab and Lander/MAV in re-entry fairing, second and third launches refuel SLS upper stage for TMI). NASA's gateway plan requires a lot more launches than that.

Quote
b) we've already been to the moon!

We've also been to LEO, but we still keep going there. That's because its worthwhile to do so. Same with the Moon.
Would that EDS also brake the group of spacecraft into Martian orbit, and return them later to Earth? Or would there have to be a Earth Return Stage(s), waiting there for them to send the Orion and Habitat back?
« Last Edit: 03/04/2018 07:14 am by MATTBLAK »
"Those who can't, Blog".   'Space Cadets' of the World - Let us UNITE!! (crickets chirping)

Offline Proponent

  • Senior Member
  • *****
  • Posts: 7277
  • Liked: 2782
  • Likes Given: 1462
Re: Deep Space Gateway Power/Propulsion RFI
« Reply #112 on: 03/04/2018 03:08 pm »
But we're using it's kissing cousin in DSG/LOP-G as a point solution band-aid to keep a deficient exploration architecture from falling apart.

I like your entire post.  If I may generalize, what NASA and other space agencies like about LOP-G is that it's something they may actually be able to do within the political and financial constraints imposed upon them.  It suits the needs of space agencies, but it has little to do with exploring space.

If LOP-G really is the key to going to the moon or Mars, why does it not appear in the multitude of studies of lunar and martian architectures by NASA and others (e.g., ESAS in 2005 or the relatively recent Evolvable Mars Campaign)?

EDIT:  Deleted extraneous "of lunar architectures" after the closing parenthesis.  Added bolding and missing "of" in final sentence.
« Last Edit: 04/18/2018 12:50 pm by Proponent »

Offline A_M_Swallow

  • Elite Veteran
  • Senior Member
  • *****
  • Posts: 8906
  • South coast of England
  • Liked: 500
  • Likes Given: 223
Re: Deep Space Gateway Power/Propulsion RFI
« Reply #113 on: 03/04/2018 04:21 pm »
Orion doesn't have the delta-V to return from lower lunar orbits, ...

Yes it does. Orion has a delta-V of 1.2 km/s. That's sufficient for TEI from LLO. Of course, another rocket would need to place Orion in LLO for this to work.
{snip}

A depot in LLO could refuel the Orion's service module.

Offline TrevorMonty

Re: Deep Space Gateway Power/Propulsion RFI
« Reply #114 on: 03/04/2018 05:43 pm »
Orion doesn't have the delta-V to return from lower lunar orbits, ...

Yes it does. Orion has a delta-V of 1.2 km/s. That's sufficient for TEI from LLO. Of course, another rocket would need to place Orion in LLO for this to work.
{snip}

A depot in LLO could refuel the Orion's service module.
In theory yes, but adds another potential point of failure. Having crew stuck in LLO because of  refuelling failure is not good outcome.

Offline ncb1397

  • Senior Member
  • *****
  • Posts: 3497
  • Liked: 2310
  • Likes Given: 29
Re: Deep Space Gateway Power/Propulsion RFI
« Reply #115 on: 03/08/2018 01:45 am »
Orion doesn't have the delta-V to return from lower lunar orbits, ...

Yes it does. Orion has a delta-V of 1.2 km/s. That's sufficient for TEI from LLO. Of course, another rocket would need to place Orion in LLO for this to work.
{snip}

A depot in LLO could refuel the Orion's service module.
In theory yes, but adds another potential point of failure. Having crew stuck in LLO because of  refuelling failure is not good outcome.

You could always refuel in NRHO. Orion would use about 3300 kg of propellant to get into NRHO, be topped off to go to LLO and back (~1400-1500 m/s). It might be at a slight ~100 m/s deficit compared to a benchmark 100 km altitude circular orbit. Then it would just have to be fueled with about 2500 kg of propellant for the trip back to earth. Alternatively, it could be directed back to earth(TEI from LLO is about the same as LLO to NRHO(~750-800 m/s).

Or you could launch something else in the USA with a docking port to attach to the Orion. A lot of things would work to make up the modest 500 m/s deficit that Orion has to enter LLO and return to earth. A second SM with a docking port kit, a lunar descent stage equivalent in performence to th LEM descent module or even a ~8 mT chemical propulsion comsat with about 4200 kg of propellant(that it would need for GEO circularization - ~1.6 km/s, stationkeeping at 50 m/s per year anyway). The Block 1B is so overpowered for putting Orion alone into LLO that all kinds of not necessarily efficient schemes could work.

But what is the point with LLO really? It adds 1000 m/s of requirements on the Orion(vs NRHO), but subtracts 1000 m/s of requirements from the lander (vs staging at NRHO). The lander can be smaller and lighter compared to Orion that has to re-enter and support crew for longer durations and thus it could very well take less fuel to move the lander an extra 1 km/s vs move Orion an extra 1 km/s
« Last Edit: 03/08/2018 01:55 am by ncb1397 »

Offline TrevorMonty

Re: Deep Space Gateway Power/Propulsion RFI
« Reply #116 on: 03/08/2018 02:13 am »
Round trip for lander is 5.5km/s for NRO compared to 3.7km/s for LLO so extra 1.8km/s.  If DSG is already in place better to design lander to stage from.

Best to wait a few years and see what comes out of robotic exploration. With ISRU lunar refuelling lander only needs to be capable of 2.7km/s. Can be LH LOX as boil off is not an issue over a day.

The extra development costs of 5.5km/s lander compared to 2.7km/s would go long way to help pay for small ISRU plant.

Offline ncb1397

  • Senior Member
  • *****
  • Posts: 3497
  • Liked: 2310
  • Likes Given: 29
Re: Deep Space Gateway Power/Propulsion RFI
« Reply #117 on: 03/08/2018 02:51 am »
Round trip for lander is 5.5km/s for NRO compared to 3.7km/s for LLO so extra 1.8km/s.  If DSG is already in place better to design lander to stage from.

Best to wait a few years and see what comes out of robotic exploration. With ISRU lunar refuelling lander only needs to be capable of 2.7km/s. Can be LH LOX as boil off is not an issue over a day.

The extra development costs of 5.5km/s lander compared to 2.7km/s would go long way to help pay for small ISRU plant.

Post TLI, the manuevers are the following:

Apollo route:
LOI: ~1000 m/s
Descent: ~1800 m/s
Ascent: ~1800 m/s
Total: ~4600 m/s

DSG/LOP route:
lunar powered flyby: ~180 m/s
NRHO insertion: ~250 m/s
NRHO -> polar LLO: ~750 m/s
Descent: ~1800 m/s
Ascent: ~1800 m/s
LLO -> NRHO: ~750 m/s
Total: ~5530 m/s

differential: ~930 m/s

most numbers from:
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150019648.pdf

Your numbers assume the lander just appears in LLO with the LLO staging orbit. It doesn't count that the vehicle has to be transported from Earth(for the foreseeable future).
« Last Edit: 03/08/2018 02:54 am by ncb1397 »

Offline Steven Pietrobon

  • Member
  • Senior Member
  • *****
  • Posts: 39218
  • Adelaide, Australia
    • Steven Pietrobon's Space Archive
  • Liked: 32738
  • Likes Given: 8196
Re: Deep Space Gateway Power/Propulsion RFI
« Reply #118 on: 03/08/2018 05:02 am »
Would that EDS also brake the group of spacecraft into Martian orbit, and return them later to Earth? Or would there have to be a Earth Return Stage(s), waiting there for them to send the Orion and Habitat back?

The EDS only does TMI. Aerobraking is used to go into Mars orbit. The Hab has a rocket stage for TEI.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Joseph Peterson

  • Full Member
  • ****
  • Posts: 752
  • Pittsburgh, PA
  • Liked: 578
  • Likes Given: 14356
Re: Deep Space Gateway Power/Propulsion RFI
« Reply #119 on: 03/08/2018 05:15 am »
Orion doesn't have the delta-V to return from lower lunar orbits, ...

Yes it does. Orion has a delta-V of 1.2 km/s. That's sufficient for TEI from LLO. Of course, another rocket would need to place Orion in LLO for this to work.
{snip}

A depot in LLO could refuel the Orion's service module.
In theory yes, but adds another potential point of failure. Having crew stuck in LLO because of  refuelling failure is not good outcome.

You could always refuel in NRHO. Orion would use about 3300 kg of propellant to get into NRHO, be topped off to go to LLO and back (~1400-1500 m/s). It might be at a slight ~100 m/s deficit compared to a benchmark 100 km altitude circular orbit. Then it would just have to be fueled with about 2500 kg of propellant for the trip back to earth. Alternatively, it could be directed back to earth(TEI from LLO is about the same as LLO to NRHO(~750-800 m/s).

Or you could launch something else in the USA with a docking port to attach to the Orion. A lot of things would work to make up the modest 500 m/s deficit that Orion has to enter LLO and return to earth. A second SM with a docking port kit, a lunar descent stage equivalent in performence to th LEM descent module or even a ~8 mT chemical propulsion comsat with about 4200 kg of propellant(that it would need for GEO circularization - ~1.6 km/s, stationkeeping at 50 m/s per year anyway). The Block 1B is so overpowered for putting Orion alone into LLO that all kinds of not necessarily efficient schemes could work.

But what is the point with LLO really? It adds 1000 m/s of requirements on the Orion(vs NRHO), but subtracts 1000 m/s of requirements from the lander (vs staging at NRHO). The lander can be smaller and lighter compared to Orion that has to re-enter and support crew for longer durations and thus it could very well take less fuel to move the lander an extra 1 km/s vs move Orion an extra 1 km/s

I fully agree that the Lunar lander can be smaller and lighter compared to Orion.  What I don't understand is why the capacities of Orion are anything other than the limitation of one specific component of the larger transportation network.  Most of the mass that we'll need to send can take the slow road to LLO on SEP for a ~ 90% reduction in propellant mass.  It currently appears to me that increasing the lander Dv requirement by ~33% is going to dramatically increase total propellant requirements, or require development and operation of two separate lander classes, and an LLO depot for cargo landers.

Tangentially related:

I am looking for the thread on ideal Earth orbit transfer points for SEP tugs and search results have failed so far.  If no such thread exists, can someone help me identify the homework that needs to be done to justify thread creation?  I'm really curious just how much TLI(or any other destination) Dv can be transferred from Earth LVs.  100 km 86° LLO appears to be the best compromise to use for proper exploration of the Lunar poles while allowing access to other points of interest.  Fixing the Earth orbit departure point(Please let it be my hypothesized EML1-synchronous elliptical parking orbit with a perigee between 6000-10,000 km.) is required so that I can move beyond speculation about overall architecture mass budgets.  While speculation is fun, I prefer to know what I'm talking about.

Tags:
 

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