NASA SLS/Orion/Payloads

[DAL59]

Just now, sevenperforce said:

Costs about twice as much dV.

If they spiral out.  Why not just do a bunch of periapsis kicks?  It would take a long time though.

[sevenperforce]

4 minutes ago, DAL59 said:

If they spiral out.  Why not just do a bunch of periapsis kicks?  It would take a long time though.

Ions give much lower thrust IRL than in KSP. You'd be looking at hundreds or even thousands of periapsis kicks.

[Bill Phil]

1 hour ago, sevenperforce said:

Ions give much lower thrust IRL than in KSP. You'd be looking at hundreds or even thousands of periapsis kicks.

And that's only if your periapsis is on the day side...

If it can send the station to the Moon then it can put the station and a transfer stage into LEO.

[tater]

https://www.nasaspaceflight.com/2018/04/em-1-update-progress-still-behind-schedule/

Still looking at 2020 (even if they claim late 2019).

[DAL59]

2 hours ago, sevenperforce said:

Ions give much lower thrust IRL than in KSP. You'd be looking at hundreds or even thousands of periapsis kicks.

 

45 minutes ago, Bill Phil said:

And that's only if your periapsis is on the day side...

If it can send the station to the Moon then it can put the station and a transfer stage into LEO.

1000*90*2=180,000 minutes = 125 days.  

The question is, are ion engines infinitely restartable?

Edited April 3, 2018 by DAL59

[sevenperforce]

1 hour ago, Bill Phil said:

And that's only if your periapsis is on the day side...

If it can send the station to the Moon then it can put the station and a transfer stage into LEO.

Well, it IS the transfer stage.

39 minutes ago, DAL59 said:

1000*90*2=180,000 minutes = 125 days.  

The question is, are ion engines infinitely restartable?

No. Deep Space 1's single ion thruster ran for 10,000 hours but only restarted 34 times.

[DAL59]

4 hours ago, sevenperforce said:

but only restarted 34 times.

Was that an actual limit they encountered, or did they just test it that many times?

[sevenperforce]

53 minutes ago, DAL59 said:

Was that an actual limit they encountered, or did they just test it that many times?

That was just the number of restarts in the mission.

[PB666]

10 hours ago, sevenperforce said:

That was just the number of restarts in the mission.

They are not restartable an infinite number of times because there is not an infinite amount of fuel, solar panels do not have a infinite life, and eventually the dV imparted on the craft places its source of power (sun) at great distance from those solar panels .

[wumpus]

18 hours ago, DAL59 said:

If they spiral out.  Why not just do a bunch of periapsis kicks?  It would take a long time though.

PB666 posted his calculations on this forum.  You can cut the fuel needed in half if you are willing to increase the time needed by two orders of magnitude, although the first 10% and 20% add far less time to the voyage (the spreadsheet claims that burning 270 degrees instead of 360 degrees is slightly faster, but thanks to the units this may be a copying error).  In practice, I'm reasonably sure it makes more sense to bring the fuel and cut the thrust needed from the ion thrusters.  It should be certainly easier to double the Isp (and thus use half the fuel) instead of increasing the thrust by two orders of magnitude (thus making the same trip with half the fuel in the same time by Pe-kicks).

 

[_Augustus_]

Apparently pieces of SLS' SRBs may strike the main engines during launch and cause a RUD. Does NASA know this is a problem? Yes. Will they actually do anything about it? Probably not.

https://www.nasaspaceflight.com/2018/04/em-1-update-progress-still-behind-schedule/

InB4 EM-1 RUD

Edited April 4, 2018 by _Augustus_

[sevenperforce]

10 minutes ago, _Augustus_ said:

Apparently pieces of SLS' SRBs may strike the main engines during launch and cause a RUD. Does NASA know this is a problem? Yes. Will they actually do anything about it? Probably not.

https://www.nasaspaceflight.com/2018/04/em-1-update-progress-still-behind-schedule/

InB4 EM-1 RUD

At least there will be a gorram LES this time.

[DAL59]

32 minutes ago, sevenperforce said:

At least there will be a gorram LES this time.

The first launch is unmanned though.  If it exploded, it would be 8 billion dollars wasted.  Oh wait, the SLS is 8 billion wasted anyway... 

6 hours ago, PB666 said:

solar panels do not have a infinite life

They would last long enough to get to the moon though.

[tater]

8?

LOL.

I'm unsure what the numbers are for EM-1, but I remember that by the time EM-2 flies (including that flight), SLS and Orion combined will have cost ~40 B$.

 

[DAL59]

6 hours ago, tater said:

I'm unsure what the numbers are for EM-1, but I remember that by the time EM-2 flies (including that flight), SLS and Orion combined will have cost ~40 B$.

 

40 B would be enough for a 4 person, manned mars mission.

Sigh.

[Bill Phil]

35 minutes ago, DAL59 said:

40 B would be enough for a 4 person, manned mars mission.

Sigh.

No. No it is not. 40 billion wouldn't even begin a moon base program, let alone a Mars program. 

40 billion is remarkably cheap for Super heavy development, being something like half the Saturn V's cost to develop. And if BFR can get it cheaper, then that's great.

Most realistic estimates for Mars missions put the program at about 400+ billion, for flags and footprints. Basic stuff. 

[tater]

Just now, Bill Phil said:

Most realistic estimates for Mars missions put the program at about 400+ billion, for flags and footprints. Basic stuff. 

Unless you're Zubrin, who apparently didn't even know what ACES was.

[PB666]

13 minutes ago, tater said:

Unless you're Zubrin, who apparently didn't even know what ACES was.

Who is Zubrin?  But seriously why do we mention his name here, h'is is nothing more than a blowhard.

[lugge]

20 hours ago, PB666 said:

They are not restartable an infinite number of times because there is not an infinite amount of fuel, solar panels do not have a infinite life, and eventually the dV imparted on the craft places its source of power (sun) at great distance from those solar panels .

Completely correct answer, and completely useless.
Are you a mathematician? ;-)

[DAL59]

16 hours ago, Bill Phil said:

Most realistic estimates for Mars missions put the program at about 400+ billion, for flags and footprints. Basic stuff. 

You could do a manned mars mission with three sls launches.

https://www.nasa.gov/pdf/376589main_04 - Mars Direct Power Point-7-30-09.pdf

Also, building several BFRs will not cost 400 billion.  We know this because SpaceX does not have 400 billion dollars.  

Zubrin FTW

16 hours ago, Bill Phil said:

40 billion wouldn't even begin a moon base program

Nope. 10 billion.

https://www.popularmechanics.com/space/moon-mars/news/a20102/we-could-have-a-moon-base-for-10-billion/

[tater]

20 minutes ago, DAL59 said:

You could do a manned mars mission with three sls launches.

https://www.nasa.gov/pdf/376589main_04 - Mars Direct Power Point-7-30-09.pdf

Also, building several BFRs will not cost 400 billion.  We know this because SpaceX does not have 400 billion dollars.  

Zubrin FTW

That ancient PDF again. No.

In no particular order:

1. Ares != SLS. All the payload masses are wrong. This needs block 2, which is unlikely to exist, IMO, and will take billions more to develop.

2. Assuming SLS was magically Ares, they'd need to launch 2 in one launch window. They can't even launch 2 in one year, much less days apart.

3. The ECLSS is not ready, the life support we are currently using needs constant repair.

4. NASA is not doing Mars Direct---nor will they ever---they would do something closer to their DRMs, which are influenced by MD, but involve more redundancy.

5. ISRU isn't a thing yet. It needs to be built, then tested before NASA stakes billions and lives on it.

NASA is not going to Mars for 10 B$. This project would have to basically assume all the SLS/Orion/DSG costs for a decade. That's 25 billion just to keep the lights on, right there, before they even launch a Mars vehicle (all of which would have to be built, then tested before the 1st one is ever sent to Mars).

 

20 minutes ago, DAL59 said:

 

Nope. 10 billion.

https://www.popularmechanics.com/space/moon-mars/news/a20102/we-could-have-a-moon-base-for-10-billion/

Popular mechanics is certainly an excellent source, lol.

[DAL59]

40 minutes ago, tater said:

. ISRU isn't a thing yet. It needs to be built, then tested before NASA stakes billions and lives on it.

The sabatier reaction is old.  Just send one on the next launch window.  They should have put one on the 2020 rover.

41 minutes ago, tater said:

NASA is not doing Mars Direct---nor will they ever---they would do something closer to their DRMs, which are influenced by MD, but involve more redundancy.

Thats not the point.  I'm saying they should- or more likely some private company.  Of course, the BFR doesn't need the MD architecture.  

43 minutes ago, tater said:

Assuming SLS was magically Ares, they'd need to launch 2 in one launch window. They can't even launch 2 in one year, much less days apart.

Send the backup ISRU a year in advance, stretching the total mission out to 6 years.

43 minutes ago, tater said:

The ECLSS is not ready, the life support we are currently using needs constant repair.

Does the ISS have enough spares currently aboard to last two years at the average failure rate?  Now that we have 3-d printers, it could be possible to make a modular, simple LSS designed to be repaired easily with printed parts.  

46 minutes ago, tater said:

1. Ares != SLS. All the payload masses are wrong. This needs block 2, which is unlikely to exist, IMO, and will take billions more to develop.

Launch a second SLS for a TMI stage.  Still less than 400 billion.  

Or use several FH or NG launches.  

Can you give any example of a mars mission costing 400 billion.  That's 200 SLS launches.  Or 4,000 FH launches.  

[tater]

3 minutes ago, DAL59 said:

The sabatier reaction is old.  Just send one on the next launch window.  They should have put one on the 2020 rover.

They didn't.

3 minutes ago, DAL59 said:

Thats not the point.  I'm saying they should- or more likely some private company.  Of course, the BFR doesn't need the MD architecture.  

Why should they? Why would a private company, where's the profit? This is the SLS/Orion/DSG thread. It means de facto NASA. Zubrin's numbers have never been realistic, just as his Moon Direct thing is also unrealistic.

3 minutes ago, DAL59 said:

Send the backup ISRU a year in advance, stretching the total mission out to 6 years.

You have to send anything 2 years in advance (because orbital mechanics).

His minimalistic mission architecture ain't happening.

[Bill Phil]

2 hours ago, DAL59 said:

You could do a manned mars mission with three sls launches.

https://www.nasa.gov/pdf/376589main_04 - Mars Direct Power Point-7-30-09.pdf

Also, building several BFRs will not cost 400 billion.  We know this because SpaceX does not have 400 billion dollars.  

Zubrin FTW

Nope. 10 billion.

https://www.popularmechanics.com/space/moon-mars/news/a20102/we-could-have-a-moon-base-for-10-billion/

Here's an interesting thing about space exploration: payloads cost more than launches. 

Curiosity cost a few billion, for less than a tonne of payload on the surface of Mars. We can expect manned hardware to be even more complex, so the cost would be higher. Using SLS will increase that cost even more. BFR might shave off a few billion. Maybe tens of billions, if we're lucky. But it will still be hundreds of billions of dollars for the program, consisting of maybe 6 landings, a la Apollo. Maybe even some around the same time? Would be cool, but unlikely.

I've talked to some NASA engineers working at MSFC. It'll take something like 7 SLS launches. At 3 billion per launch, plus 3 billion per payload, that's 42 billion. That's being generous (SLS will be more expensive, payloads too), but we only just got started. Adding in 15 years of paying off salaries and benefits for 10k people (about 250k per person, from what I can find), that's about 80 billion total. For the first mission, and an extra 42 per mission after that.

And that is guaranteed to be a gross underestimate. NASA has tens of thousands of contractor employees that work on NASA programs, and we've ignored the yearly SLS cost, the SLS development cost, and so on.

Edited April 5, 2018 by Bill Phil

[wumpus]

1 hour ago, Bill Phil said:

Here's an interesting thing about space exploration: payloads cost more than launches.

JPL must also charge some serious bucks to drive Curiosity and the other rovers all over Mars (even doing experiments and maintaining with stuck rovers isn't going to be much cheaper).

In the 1970s NASA would build at least two copies of various probes (like Voyager 1 & 2).  While building the first article was required a full-blown R&D budget, the cost of the second was a tiny percentage of the first.  Obviously you needed two launchers (at full cost) and ground control couldn't have been much cheaper (although I'm certain it made finding backups easier).  Eventually they decided that two launches was one too many (probably during the "everything launches from the Shuttle" era) and they stopped doing that (but somewhat revived the concept with the Mars rovers).

Reducing the cost of the payload is generally not seen as sexy as launching rockets, but Bigelow appears to be bringing at least some private megabucks in "dry mass" spacecraft.