NASA SLS/Orion/Payloads

[PB666]

not bury, it does not seem to me that anyone is seriously planning to build or launch it. If you want to launch something you don't announce that you are going to have a half-fit group to study it.

If DSG is supposed to be a cryogenics depot as stated, where is the launch vehicle that is going to bring fuel to refill it. You see any bulk liquid hydrogen or oxygen carriers out there. Certainly we are not go to have a cryogenic refueling station that is loaded with 4000 kg of fuel at a time? And frankly I don't think they have the cryogenic storage worked out either.

[tater]

1 hour ago, PB666 said:

not bury, it does not seem to me that anyone is seriously planning to build or launch it. If you want to launch something you don't announce that you are going to have a half-fit group to study it.

If DSG is supposed to be a cryogenics depot as stated, where is the launch vehicle that is going to bring fuel to refill it. You see any bulk liquid hydrogen or oxygen carriers out there. Certainly we are not go to have a cryogenic refueling station that is loaded with 4000 kg of fuel at a time? And frankly I don't think they have the cryogenic storage worked out either.

Yeah, a prop depot in NRO seems incredibly unlikely for lack of any way to get props there, and low launch cadence means boiloff is exacerbated (since the LH₂ has to sit there for a year between trips, lol, maybe 2).

[Canopus]

You wouldn‘t need a giant cryogenic tank if the fuel for one landing arrives as co manifest payload with the Orion and Crew, as outlined in the boeing proposal for the exploration gateway plattform. On the other hand the ACES could fill the role of both tanker and depot if you attach one to the DSG. 

[Canopus]

https://arstechnica.com/science/2017/12/nasa-is-trying-to-make-the-space-launch-system-rocket-more-affordable/

[_Augustus_]

8 hours ago, Canopus said:

https://arstechnica.com/science/2017/12/nasa-is-trying-to-make-the-space-launch-system-rocket-more-affordable/

Good luck with that.

[DAL59]

NASA just announced it plans to reach alpha centauri by 2069.  

Good luck with that.  

[RAJ JAR]

On 19/12/2017 at 2:19 AM, PB666 said:

Vasmir has never been tested in any circumstance that it was required to accomplish something other than showing it can blast ions and consume lots and lots and lots of power.

They are working on that. The important thing here is that it is real, it is still being tested and it is getting closer to being tested in space someday. It is similar to how other space electric propulsions are tested before they are tested in space. 

 

Back on topic: Is there an option to expand the DSG if there is a desire and need for it? Will the DSG be a modular design? 

[PB666]

55 minutes ago, RAJ JAR said:

They are working on that. The important thing here is that it is real, it is still being tested and it is getting closer to being tested in space someday. It is similar to how other space electric propulsions are tested before they are tested in space. 

You don't understand really how badly VASIMR performs compared to other lighter electric propulsions.

Take a look at this page. " The pre-prototype HiPEP produced 670 mN of thrust at a power level of 39.3 kW using 7.0 mg/s of fuel giving a specific impulse of 9620 s.^[2][4] Downrated to 24.4 kW, the HiPEP used 5.6 mg/s of fuel giving a specific impulse of 8270 s and 460 mN of thrust. "  and this page. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20040139476.pdf

After reading those compare that stats with VASIMR. http://spacenews.com/vasimr-hoax/

Thrust = 2 * power * efficiency / V_exhaust  Accleration = Thrust/Mass

 

[Mitchz95]

5 hours ago, DAL59 said:

NASA just announced it plans to reach alpha centauri by 2069.  

Good luck with that.  

Er, source?

[Bill Phil]

47 minutes ago, PB666 said:

After reading those compare that stats with VASIMR. http://spacenews.com/vasimr-hoax/

This article has... many flaws. The largest one is arguably the age. It's nearly six and a half years old, hardly usable to counter current VASIMR developments, which are meeting NASA requirements. Another issue is that he assumes that the only purpose is for Mars missions, and then attacks that particular use.

Quote

Existing ion thrusters routinely achieve 70 percent efficiency and have operated successfully both on the test stand and in space for thousands of hours. In contrast, after 30 years of research, the VASIMR has only obtained about 50 percent efficiency in test stand burns of a few seconds’ duration, and that is only at high specific impulse. When the specific impulse is reduced, the efficiency drops in direct proportion. This means that the VASIMR’s much chanted (but always doubtful) claim that it could offer significant mission benefit by trading specific impulse for thrust is simply false. In contrast, this capability has been demonstrated by the ion-drive that propelled Dawn spacecraft on its way to an asteroid. Finally, if it is to be used in space, VASIMR will require practical high temperature superconducting magnets, which do not exist.

None of the claims he makes are cited. Nothing is here to back up any of the claims made, at any point in the article (and this extends to other claims Zubrin makes). While it is certainly true that current ion engines have achieved high efficiency and long test times, he does not cite his data for the performance of the VASIMR. And then he goes further to not provide any reason, let alone a citation, for why VASIMR would require "high temperature superconducting magnets." This article is not an effective argument against VASIMR. For one thing, Zubrin is very likely to be biased against it due to his belief that we have the technology to go to Mars now. The only issue with that is, well, the fact that going to Mars is not NASA's job. It would be great, but nothing regarding Mars missions is being planned beyond the occasional Design Reference Mission. Even SLS can not support a proper Mars campaign. Further, the article is outdated, and, as such, does not have the benefit of the newest data. As of this year, Ad Astra is on track to meet NASA's requirements for development. Near the end of the article Zubrin states that the true problem is, essentially, the opportunity cost of not embarking on a Mars mission as soon as possible, and then claims that this is not occurring because the country is waiting for VASIMR to be developed. That is not the case. Mars missions are not occurring because they are high cost and high risk. VASIMR will not change that. It only serves as the transfer vehicle propulsion system. However, this will cost large sums of money, along with whatever hardware required to land on the red planet and later return to the transfer vehicle.

On a less grounded note, it is often remarked that new technologies are often less efficient than their old counterparts when initially developed and introduced. Beyond that, so many examples of technology that are now common have ancestors that were terribly inefficient (see: mechanical television, electric lighting, air conditioning, and many more). While it is certainly possible that VASIMR may prove to be a dead end, it is also possible that it will be useful for some in-space applications.

NASA is paying pennies for VASIMR, and if it pays off, then NASA will benefit. If it doesn't, well, NASA has made worse trades in the past.

I'd complain much more vocally about how Boeing is throttling SLS (straight from the mouths of MSFC engineers). 

You (and many others) are free to dislike, be skeptical of, and disregard VASIMR. However, do not use this article as justification. It is outdated, it does not cite its claims, and makes assumptions that are not grounded, among other issues. 

[PB666]

1 hour ago, Bill Phil said:

This article has... many flaws. The largest one is arguably the age. It's nearly six and a half years old, hardly usable to counter current VASIMR developments, which are meeting NASA requirements. Another issue is that he assumes that the only purpose is for Mars missions, and then attacks that particular use.

None of the claims he makes are cited. Nothing is here to back up any of the claims made, at any point in the article (and this extends to other claims Zubrin makes). While it is certainly true that current ion engines have achieved high efficiency and long test times, he does not cite his data for the performance of the VASIMR. And then he goes further to not provide any reason, let alone a citation, for why VASIMR would require "high temperature superconducting magnets." This article is not an effective argument against VASIMR. For one thing, Zubrin is very likely to be biased against it due to his belief that we have the technology to go to Mars now. The only issue with that is, well, the fact that going to Mars is not NASA's job. It would be great, but nothing regarding Mars missions is being planned beyond the occasional Design Reference Mission. Even SLS can not support a proper Mars campaign. Further, the article is outdated, and, as such, does not have the benefit of the newest data. As of this year, Ad Astra is on track to meet NASA's requirements for development. Near the end of the article Zubrin states that the true problem is, essentially, the opportunity cost of not embarking on a Mars mission as soon as possible, and then claims that this is not occurring because the country is waiting for VASIMR to be developed. That is not the case. Mars missions are not occurring because they are high cost and high risk. VASIMR will not change that. It only serves as the transfer vehicle propulsion system. However, this will cost large sums of money, along with whatever hardware required to land on the red planet and later return to the transfer vehicle.

On a less grounded note, it is often remarked that new technologies are often less efficient than their old counterparts when initially developed and introduced. Beyond that, so many examples of technology that are now common have ancestors that were terribly inefficient (see: mechanical television, electric lighting, air conditioning, and many more). While it is certainly possible that VASIMR may prove to be a dead end, it is also possible that it will be useful for some in-space applications.

NASA is paying pennies for VASIMR, and if it pays off, then NASA will benefit. If it doesn't, well, NASA has made worse trades in the past.

I'd complain much more vocally about how Boeing is throttling SLS (straight from the mouths of MSFC engineers). 

You (and many others) are free to dislike, be skeptical of, and disregard VASIMR. However, do not use this article as justification. It is outdated, it does not cite its claims, and makes assumptions that are not grounded, among other issues. 

I was being lazy, I did not want to have to give the math involved. VASIMR has not changed all that much in 6 years, its still heavy, it still cannot outperform lighter technology that is older than it is.

My personal reason, even looking at the most recent specs, VASIMR still underperforms HiPEP with regard to Thrust to weight ratio, with regard to efficiency. HiPEP is scalable from as low as you want (for example using capacitors). IN FACT if you wanted the most stable system have twice as many HiPEP as you can power and alternate their use so that they run cooler and run them at the highest possible ISP, that achieves the best efficiency, per weight. 

Reason #1 Its not about how much KW you can use, its about how much acceleration you can produce per amount of fuel and per kilowatt. The 39 days to mars justifies VASIMR for the sole reason that if you have the power to burn from LEO to Escape velocity (3212 m/s) you only need 400 more dV to reach Mars, but in 100 to 150 days. So VASIMR is something you add to the craft to make it get there in 39 days once you have burned to or almost to escape velocity. The problem is that you could almost do the same with conventional power given the extra added weight of VASIMR and the power supply. But the craft is already going to have solar panels, so just plop a few lightweight HiPEP on the backside and maybe a few more panels and use waste electricity to shorten the trip time. We are talking about the difference between 20kg of thruster versus a couple of tons. Its a no brainer, go with HiPEP.

Reason #2 I could not care less if humans went to Mars, if you want to send some joker there to die on Mars, thats fine 100 day trip aint going to kill him half as fast as living on Mars will. VASIMR will not get them back home. My only thing is get a sample return mission going, and that sample return mission is probably going to come on a conventional ION drive system that can shuttle materials back and forth from Earth.

Reason #3 is that it will not pay off, as already stated you have a technology that is a fraction of the weight, you can have multiple redundancies and in the end if one breaks you flip on the next one for the cost of one VASIMR. There is no scenario were VASIMR can pay off because you have this already

Thrust = 2 * 0.8 * KW / 95000   or Thrust = 2 * 0.72 * KW /54000  This equation is tyrannical and VASIMR does not change or alter the equation, it never can, that's that. The best VASIMR can do is get efficiency in the 80 to 90 range.  The most you can ever get is 100% efficiency. Power comes at the expense of something, and that something we do not have. We do not have a nuclear reactor and as far as I know, NASA is not planning one. Second there is no situation were radiative cooling and the reactor is going to produce 200kw of power unless the nuclear reactor exceeds 1 Megawatt, in which case the ship needs to be able to cool 800 MW of radiative heat, this involves mass also. For HiPEP we can have a system, light weight, essentially flat, small enough to run on solar power small enough and light enough to cool itself. 

Another example of this is the Cannae drive, everyone talked about how it was going to change the world being 10 time more efficient than a photon drive.

T_{Photon drive} = 2 * Power /3E8 =  0.000007 N/kw versus T_cannae = 2 * Power/3E7 = 0.00007N/KW <----- not changing fundementally the thrust issue with electric propulsion systems.

Reason #4, Build to the power, and not power that needs to add mass just to cool itself. If it is not self cooling, leave it near a cooling tower on earth. The future is better solar panels, they can be lightened and they can produce more power, but they can be cooled simply by changing their angle to the sun. VASIMR is doing the exact opposite, it is building to the power we do not have in space. IF we go by current specs at 34 kw per 14tons to get a ship with 200 kw would require 100t just for solar panels, not intelligent. The only reason ever to use nuclear power in space is to travel beyond the asteroid belt, for missions to Jupiter this may be neccesary. That justifies nuclear power, but it does not justify VASIMR.

 

SLS can get beat when Space X proves itself with the heavy project, but they have to prove themselves.

 

Edited December 21, 2017 by PB666

[DDE]

3 hours ago, Mitchz95 said:

Er, source?

Several guys from JPL, not NASA. Ran a small presentation at a professional conference. Readily admit they have next to none of the tech, got some funding for a study.

Launch date set to 1969, hopefully the SLS will be ready by then.

Edited December 21, 2017 by DDE

[StarStreak2109]

5 hours ago, DDE said:

Several guys from JPL, not NASA. Ran a small presentation at a professional conference. Readily admit they have next to none of the tech, got some funding for a study.

Launch date set to 1969, hopefully the SLS will be ready by then.

Errr I guess you mean 2069?!

[DDE]

2 hours ago, StarStreak2109 said:

Errr I guess you mean 2069?!

That’s what I get for beating a dead horse.

[NSEP]

 

[RAJ JAR]

11 hours ago, PB666 said:

I was being lazy, I did not want to have to give the math involved. VASIMR has not changed all that much in 6 years, its still heavy, it still cannot outperform lighter technology that is older than it is.

My personal reason, even looking at the most recent specs, VASIMR still underperforms HiPEP with regard to Thrust to weight ratio, with regard to efficiency. HiPEP is scalable from as low as you want (for example using capacitors). IN FACT if you wanted the most stable system have twice as many HiPEP as you can power and alternate their use so that they run cooler and run them at the highest possible ISP, that achieves the best efficiency, per weight. 

Reason #1 Its not about how much KW you can use, its about how much acceleration you can produce per amount of fuel and per kilowatt. The 39 days to mars justifies VASIMR for the sole reason that if you have the power to burn from LEO to Escape velocity (3212 m/s) you only need 400 more dV to reach Mars, but in 100 to 150 days. So VASIMR is something you add to the craft to make it get there in 39 days once you have burned to or almost to escape velocity. The problem is that you could almost do the same with conventional power given the extra added weight of VASIMR and the power supply. But the craft is already going to have solar panels, so just plop a few lightweight HiPEP on the backside and maybe a few more panels and use waste electricity to shorten the trip time. We are talking about the difference between 20kg of thruster versus a couple of tons. Its a no brainer, go with HiPEP.

Reason #2 I could not care less if humans went to Mars, if you want to send some joker there to die on Mars, thats fine 100 day trip aint going to kill him half as fast as living on Mars will. VASIMR will not get them back home. My only thing is get a sample return mission going, and that sample return mission is probably going to come on a conventional ION drive system that can shuttle materials back and forth from Earth.

Reason #3 is that it will not pay off, as already stated you have a technology that is a fraction of the weight, you can have multiple redundancies and in the end if one breaks you flip on the next one for the cost of one VASIMR. There is no scenario were VASIMR can pay off because you have this already

Thrust = 2 * 0.8 * KW / 95000   or Thrust = 2 * 0.72 * KW /54000  This equation is tyrannical and VASIMR does not change or alter the equation, it never can, that's that. The best VASIMR can do is get efficiency in the 80 to 90 range.  The most you can ever get is 100% efficiency. Power comes at the expense of something, and that something we do not have. We do not have a nuclear reactor and as far as I know, NASA is not planning one. Second there is no situation were radiative cooling and the reactor is going to produce 200kw of power unless the nuclear reactor exceeds 1 Megawatt, in which case the ship needs to be able to cool 800 MW of radiative heat, this involves mass also. For HiPEP we can have a system, light weight, essentially flat, small enough to run on solar power small enough and light enough to cool itself. 

Another example of this is the Cannae drive, everyone talked about how it was going to change the world being 10 time more efficient than a photon drive.

T_{Photon drive} = 2 * Power /3E8 =  0.000007 N/kw versus T_cannae = 2 * Power/3E7 = 0.00007N/KW <----- not changing fundementally the thrust issue with electric propulsion systems.

Reason #4, Build to the power, and not power that needs to add mass just to cool itself. If it is not self cooling, leave it near a cooling tower on earth. The future is better solar panels, they can be lightened and they can produce more power, but they can be cooled simply by changing their angle to the sun. VASIMR is doing the exact opposite, it is building to the power we do not have in space. IF we go by current specs at 34 kw per 14tons to get a ship with 200 kw would require 100t just for solar panels, not intelligent. The only reason ever to use nuclear power in space is to travel beyond the asteroid belt, for missions to Jupiter this may be neccesary. That justifies nuclear power, but it does not justify VASIMR.

 

SLS can get beat when Space X proves itself with the heavy project, but they have to prove themselves.

 

NASA is working on a nuclear reactor:

- https://www.nasa.gov/directorates/spacetech/feature/Powering_Up_NASA_Human_Reach_for_the_Red_Planet 

I have mixed thoughts about this. 

What I want to know is what are they going to do what the nuclear waste produced?  

[tater]

Reactors are a prerequisite for manned space past Earth orbit.

[DDE]

1 hour ago, tater said:

Reactors are a prerequisite for manned space past Earth orbit.

Apollo disagrees.

[Green Baron]

If H reacts with O .... a reactor isn't necessarily reacting nuclear

Seriously, in chemistry a lot of reactions take place in reactors :-)

But i disagree as well. Solar is much easier to handle, lighter to get up and more efficient.

Edited December 21, 2017 by Green Baron

[tater]

44 minutes ago, DDE said:

Apollo disagrees.

The moon is in Earth orbit.

Edited December 21, 2017 by tater

[DAL59]

16 hours ago, Bill Phil said:

Even SLS can not support a proper Mars campaign.

Why not?  It could in just three launches.  

[PB666]

3 hours ago, RAJ JAR said:

NASA is working on a nuclear reactor:

- https://www.nasa.gov/directorates/spacetech/feature/Powering_Up_NASA_Human_Reach_for_the_Red_Planet 

 

The power output of 20 of these reactors would not suffice to run  a ship and 1 VASIMR. The system is designed to run on the ground not in space.

Technically isn't a space reactor, its' a surface mounted colony support reactor.

3 hours ago, RAJ JAR said:

What I want to know is what are they going to do what the nuclear waste produced?  

Abandon in place.

Edited December 21, 2017 by PB666

[tater]

3 minutes ago, DAL59 said:

Why not?  It could in just three launches.  

No.

NASA DRM 5 has a single Mars mission using 7 Ares V (188 tons to LEO), plus a crew launch.

[DAL59]

1 minute ago, tater said:

No.

NASA DRM 5 has a single Mars mission using 7 Ares V (188 tons to LEO), plus a crew launch.

If you used Zubrin's plan.  One MAV launch, one backup MAV, and then lob the crew directly to Mars.    

[tater]

1 minute ago, DAL59 said:

If you used Zubrin's plan.  One MAV launch, one backup MAV, and then lob the crew directly to Mars.    

No one is using Zubrin's plan, sorry---unless Zubrin ponies up and builds it himself. Bezos wants to go to the Moon, so he's building huge rockets. Musk wants to go to Mars, so he's building huge rockets. If Zubrin wants manned Mars, he better stop whining, make a few billion $, and make huge rockets, because that's the only way his mission plan will happen.

The post-Mars Direct DRA/Ms are basically variants of Mars Direct, but with NASA concern regarding crew safety, etc. DRM 5 is as close to Zubrin as you're going to see out of NASA. The Lockheed Martin plan is much closer to what I could see NASA doing, and it requires literally sending 2 of everything. Looks to be what, 8-9 SLS launches for that one?