VASIMR based spaceship for heliosphere

[EarthlingX]

Original discussion started here:
viewtopic.php?f=6&t=19538
where we strayed into discussion of hypothetical MPD interplanetary spaceship.

I propose name 'Space.com Heliosphere Explorer' (SHE). (edit 2009.08.31, abbreviation)

There are still many open questions, for which i hope, we can find answers together.

- Use Altair for the lander, make it very Single Stage To Surface and Single Stage To Orbit, fix what's missing (evolve) for atmosphere landing a bit later.
- 660 m3 (2xBA 330) would be enough for 6 people, if we stay close. If working modular, we can always plug in more a bit later. There will probably also be some pressurized space in other modules, but BA 330 k***s a*s.
- Hyperion (http://www.hyperionpowergeneration.com/product.html) for power generation, we could add more, if (when) we need them.
- 670 N thrust (2x VX-13000) 2x 13 MW 20t engine per one generator.
- Argon tank goes to LEO empty, refills in the orbit. Assuming 80% fuel/structure ratio gives 80t Argon.

7 modules, 660 m3 space = 140t + 80t Argon, how much ?
1. 1x SSTO Altair = 5 G$ ?
2. 2x BA 330 = 200 M$
3. 1x Hyperion = 30 M$
4. 1x Argon tank = ?
5. 2x VX-13000 = ?
6. 80t Argon = ?
7. 220t to LEO, assuming 4k$/kg = 880 M$

I guestimate, based on previous discussion and available data, that this could be under 10 G$ or very close.

(edit 2009.08.28, changed VF-?? to VX-?? based on Ad Astra Rocket press release: http://www.adastrarocket.com/Release241008.pdf)
(edit 2009.09.01, found cause of VF-??/VX-?? confusion)
(VASIMR Performance Measurements at Powers Exceeding 50 kW and Lunar
Robotic Mission Applications, 6.Summary)

Design of the VF-200, a flight-ready engine to follow VX-200 ....

http://www.adastrarocket.com/ISGLP_JPSquire2008.pdf

 

[TC_sc]

I don't know about strayed since going anywhere in Orion other then the moon or LEO is nonsense

I think this topic is too limiting since there are other engines capable of doing the job as well or better. VASIMR is just getting a kick to the front of the line since it can operate nonnuclear, at least for testing, boosting ISS and lunar missions. Anything past that might preferably be nuclear. Okay, and since a functioning engine is ready for installation on ISS

 

[EarthlingX]

I don't know about strayed since going anywhere in Orion other then the moon or LEO is nonsense

True but it was misleading as at least couple of people mentioned

I think this topic is too limiting since there are other engines capable of doing the job as well or better. VASIMR is just getting a kick to the front of the line since it can operate nonnuclear, at least for testing, boosting ISS and lunar missions.
Anything past that might preferably be nuclear. Okay, and since a functioning engine is ready for installation on ISS

I was considering 'Magneto Plasma Dynamic thruster engine ...' but it's not so catchy Do you know of any ?

Concerning nuclear, i think that politically Hyperion Power Module (HPM) has some chances, but very much doubt so about NERVA or project Orion nuclear. SHE-1 is at the moment rather green, i hope :roll:

I just managed to pull this out of wikipedia, i hope i'm less off than before
http://en.wikipedia.org/wiki/Rocket_equation
Isp = 5000
Ve = Isp g0 = 5000 s * 10 m/s^2 = 50km/s
dV = ve ln (m1/m2) = 50km/s * ln(220t/140t) = 50 km/s * 0.45 = 22,6 km/s :roll:

 

[neutrino78x]

I would not think that VASIMR to mars would require a nuke. Could be wrong on that...as far as choice of nukes, I would suggest the SAFE 400, since it is designed to work in space, as opposed to the hyperion device, which is designed to be buried underground and hooked up to a steam turbine. If this vehicle is designed to go the heliopause, I agree that it definitely would have to be powered by a nuclear reactor!!! As I have said before, I support nuclear in space where needed, not as a first choice, and this is an example of where it would be needed, if you are sending humans for this mission. (if robotic, an RTG might be sufficient, and is proven to withstand reentry etc.)

--Brian

 

[neutrino78x]

I don't know about strayed since going anywhere in Orion other then the moon or LEO is nonsense

Isn't Orion just the ascent vehicle? That is to say, if you were going to Moon, most of your time would be spent in the Altair module? :?:

Either way, as a former submariner, personal experience tells me that many people can handle close quarters like that just fine for months at a time.

Let us not get into what Robert Zubrin calls "battlestar galactica mode" where we have to wait until we have a huge ship with artificial gravity etc before we go to Mars.

--Brian

 

[docm]

What we need is Galactica Lite; a hab, small reactor, VASIMR or MPD power, lander/return vehicle etc. and a gas generating hab launched to the surface long before the people. Get there in 3-4 months and you minimize the risk of microgravity, radiation, solar activity, micrometeoroids etc.

Bigelow had this (bottom) as a lunar ship concept - might have some merit for long duration missions too. That their habs can include water blankets for shielding and have many layers of Kevlar and Vectran for micrometeoroid protection is sauce for the goose.

NASA actually did hypervelocity impact testing on the TransHab tech before it was shut down and the patents sold to Bigelow. The results were so good it was proposed that the aluminum modules of the ISS be retro-fitted with TransHab-style materials for debris protection.

Bigelow then made changes of his own that appear in this patent;

Orbital debris shield
United States Patent 7204460

http://www.freepatentsonline.com/7204460.html
and
http://www.freepatentsonline.com/y2005/0284986.html

 

[EarthlingX]

I don't know about strayed since going anywhere in Orion other then the moon or LEO is nonsense

Isn't Orion just the ascent vehicle? That is to say, if you were going to Moon, most of your time would be spent in the Altair module? :?:

Orion, i think, they meet in Moon orbit, but go there each on it's own trashable EDS.

Either way, as a former submariner, personal experience tells me that many people can handle close quarters like that just fine for months at a time.

I agree, same thing with yachts (maybe not exactly) and small sail boats. I did some submarining too, but i guess, my sub was much much smaller than the one where you served. I would prefer to avoid details, it's a national secret :roll:

Let us not get into what Robert Zubrin calls "battlestar galactica mode" where we have to wait until we have a huge ship with artificial gravity etc before we go to Mars.
--Brian

I m trying very much to avoid this, but 100 m3 per person is rather comfy, space-wise, there will still be a need for all sorts of instrumentation and gadgetry, so at the end it will be probably closer to 50 m3 per person. I can live with that.
I m more into some kind of Ford-T for a solar system or at least to the asteroid belt at the beginning.

This is a very interesting thing. It looks it will ruin my calculations so far (specific energy), but if it can fly, no problemo, welcome
(SAFE 400)
http://adsabs.harvard.edu/abs/2002AIPC..608..578P

SHE-1 is still missing crew provisions and supplies, such details as oxygen, food, spare parts and cat, but i hope that adding another 20t module for that can do for some time.

 

[EarthlingX]

What we need is Galactica Lite; a hab, small reactor, VASIMR or MPD power, lander/return vehicle etc. and a gas generating hab launched to the surface long before the people. Get there in 3-4 months and you minimize the risk of microgravity, radiation, solar activity, micrometeoroids etc.

Exactly. My guesculator shows SHE-1 has enough fuel for almost 9 months of thrust or about 2 months to Mars on optimal thrust. I was thinking to add another HPM to allow engines to do some serious kicking which would bring transit closer to 1 month, i guess. :roll:
I still have to plug in that alternative generator, see what comes out.

Bigelow had this as a lunar ship concept - might have some merit for long duration missions too. That their habs can include water blankets for shielding and have many layers of Kevlar and Vectran for micrometeoroid protection is sauce for the goose.

Thank you for this picture, it really helps the perspective. I also deleted my 'if' remark about radiation in the first post.

 

[EarthlingX]

Just noticed, SHE-1 needs something like Node-1 on ISS for docking, maybe 2 nodes like that.

I'm also reposting this link here, because it shows possibility of lowering cost of the lander:
(2009 U.S. Commercial Space Transportation Developments and Concepts:
Vehicles, Technologies, and Spaceports January 2009)
http://www.faa.gov/about/office_org/hea ... 202009.pdf

Another link to tech behind Liquid Metal Stirling and Brayton Cycle generators. I think they are both kind of a heat engine.
(Heat Engine Projects.) http://www.redrok.com/engine.htm

Link on Wikipedia to get specific energy for SAFE-400
http://en.wikipedia.org/wiki/Safe_Affor ... ion_Engine

It shows 83 kW/t or 83 W/kg and that means 1,6 MWe per 20t module.
Yea, i thought it was too good to be true (HPM = 26 MWe/20t)

So, to get amount of HPM juice, we would need 16 SAFE-6400 ( 6,4 MWt).

We can drop one VX-13000, get only 8 or better 10 SAFE-6400, so there's a little bit of a margin.

140t - 1x20t + 10x20t + 2x20t (docking and supply node) = 360t empty.
Add 80t for fuel and 440t. Not funny anymore.

Pluging this numbers into a rocket equation above gives delta V = 10 km/s, which is just enough to get to Mars, without aerobraking aerobics.

Access to LEO goes from 880 M$ to 1,8 G$.

This is a serious wake up call.

Oh, and we are now at 330N thrust, which translates to more time if nothing else.

I will check if i can find specific energy info for
Liquid Metal Stirling http://www.grc.nasa.gov/WWW/TECB/fsp_li ... st_rig.htm
nope, still in the lab,

technology readiness level (TRL) 6 by the end of FY 2012.

(Future NASA Multi-kilowatt Free Piston Stirling Applications)

This paper describes the preliminary work that will be performed toward development of a nuclear-fission-powered nominal 30 kW Stirling power system for use on the lunar surface with a specific power goal of about 140 W/kg for the Stirling power conversion system.

http://sri.auburn.edu/papers/2006/futur ... irling.pdf

 

[EarthlingX]

There is another annoying detail, cooling. All above mentioned generators create a lot of heat which we must dump. In space it's a bit more tricky, because there's no medium to transport heat, so the only way to get rid off it is through infrared radiation which translates into big radiators which also add mass.

I guess this is equation that can tell us the size of radiators:
(Stefan–Boltzmann law)
http://en.wikipedia.org/wiki/Stefan%E2% ... tzmann_law

 

[rmchung]

I'm interested in figuring out if the ISS really can be a transport to Mars without blowing the NASA budget. Using VASIMR could be a key to making it feasible. Here are my rough calculations, assumptions, and projections:

VASIMR thrust: 1 N per 100 KW
Total thrust: 200 N (via 100 VX-200's or 20 VX-1000's?)
Current ISS mass: 400 metric tons (?)
Total mass: 500 metric tons (add consumables, O2 and H2 for Mars descent/return vehicle, redundant life support)
Solar array power: 450 MW at Earth, 200 MW at Mars
Delta V: 6000 m/sec after 180 days
Time to Mars: 10 months?
Orbit Mars: 6 months?
Time to return: 10 months?

VASIMR cost: ?
Solar array cost: US$5 billion (Solaren's 15 year revenue for 200 MW space power system, so it must include construction and launch costs)

I assume there will be a separate launch of the Mars lander vehicle, it would be sent unmanned and unfuelled. Fuel and crew would be transferred in Mars orbit.

Any feedback welcome, especially any help in calculating transit times.

 

[EarthlingX]

I'm interested in figuring out if the ISS really can be a transport to Mars without blowing the NASA budget. Using VASIMR could be a key to making it feasible. Here are my rough calculations, assumptions, and projections:

VASIMR thrust: 1 N per 100 KW
Total thrust: 200 N (via 100 VX-200's or 20 VX-1000's?)
Current ISS mass: 400 metric tons (?)
Total mass: 500 metric tons (add consumables, O2 and H2 for Mars descent/return vehicle, redundant life support)
Solar array power: 450 MW at Earth, 200 MW at Mars
Delta V: 6000 m/sec after 180 days
Time to Mars: 10 months?
Orbit Mars: 6 months?
Time to return: 10 months?

VASIMR cost: ?
Solar array cost: US$5 billion (Solaren's 15 year revenue for 200 MW space power system, so it must include construction and launch costs)

I assume there will be a separate launch of the Mars lander vehicle, it would be sent unmanned and unfuelled. Fuel and crew would be transferred in Mars orbit.

Any feedback welcome, especially any help in calculating transit times.

from wiki (http://en.wikipedia.org/wiki/VASIMR) :

Based on data released from previous VX-100 testing,[7] we can expect that the VF-200 engine (to be installed on ISS) will have a system efficiency of 60-65% and thrust level of 5N.

5N per 200 kW = 2.5N per 100 kW
2x VX-10000 then push with 500 N or not ? (check bellow)

Here is probably better calculation (wiki VASIMR discussion) :

For any given amount of power, the maximum thrust that can be generated is defined by T = 2 * P / Ve, where P is power, T is the thrust, and Ve is the exhaust velocity. Ve can be calculated from the specific impulse, Is, where Ve = Is * g

Assuming 60 % efficiency for VX-10000
10000 kW * 0,6 / (1000s * 9,81 m/s^2) = 610 N
Isp 5000s = 122 N
Isp 10000s = 61 N

Maybe instead of 20 VX-1000 take 2 VX-10000, they should be each under 20t. Correct ?
(Ad Astra Rocket uses VX-??, on wikipedia it's mixed with VF-??, i m fixing previous posts, edit 2009.08.28)

With such small delta V (Mars from LEO is about 6 km/s) you will have to climb there, not jump. In other words, there is not enough dV for braking maneuver, so you will probably follow some fuzzy orbit or interplanetary transport network and that means a lot of time.
I m putting this two links here for a reference:
http://en.wikipedia.org/wiki/Hohmann
http://en.wikipedia.org/wiki/Interplanetary_spaceflight

You also brought question what is kW/t for solar ? Could we use it instead of RTG ? It might simplify cooling problem ...
Checking NASA ISS page at http://www.nasa.gov/pdf/167128main_Facts.pdf tells me:

At Assembly Complete, a maximum 110 kW of power, including 30 kW of long-term average power for applications, is/will be available.

Your numbers might be slightly off

Another question is: how much fuel ? Here might be the answer:
http://en.wikipedia.org/wiki/Specific_f ... 8thrust%29
(101972/1000) g/kN*s = 101,972 kg/N*s (edit 2009.09.02 - something is wrong with this)
Isp 5000 -> 20,3944 g/kN*s
Isp 10000 -> 10,1972 kg/N*s

I'm trying to avoid questions about radiation protection on ISS and structural integrity at this moment, but can't help myself mentioning it :roll:

I also noticed i had in mind wrong number for pressurized space on ISS.
It is 358 m3 (12,626 cubic feet) which translates into 1 BA 330 on SHE-1 :
http://www.nasa.gov/mission_pages/stati ... odate.html

 

[rmchung]

5N per 200 kW = 2.5N per 100 kW

2.5N per 100 kW is even better than the 1N per 100 kW assumed earlier.

Maybe instead of 20 VX-1000 take 2 VX-10000, they should be each under 20t. Correct ?

2 engines or 20, both approaches will get the job done. Losing 1 engine out of 2 is a big problem though, losing 1 engine out of 20 is not nearly so big a problem. Also, it may actually be cheaper to mass produce 20 engines than to produce 2 ultra reliable engines.

With such small delta V (Mars from LEO is about 6 km/s) you will have to climb there, not jump. In other words, there is not enough dV for braking maneuver, so you will probably follow some fuzzy orbit or interplanetary transport network and that means a lot of time.

Yes, it will months to move to GTO. Perhaps there would be a caretaker crew for the move from LEO to GTO, then the final crew joins at GTO. Your point about delta V is good, the peak delta V should be higher. There is some time allotted for braking, though trajectory calculations are far beyond me.

You also brought question what is kW/t for solar ? Could we use it instead of RTG ? It might simplify cooling problem ...
Checking NASA ISS page ...

At Assembly Complete, a maximum 110 kW of power, including 30 kW of long-term average power for applications, is/will be available.

The ISS solar panels would not be used for the VASIMR engines. There would be an additional power sat, essentially a cut down version of the power sat from Solaren, attached to the ISS. There's no need for the power beaming, just the thin film solar reflectors and the multi-junction solar cells. From what can be gleaned from the net, it would take 4 to 5 launches for the power sat, and around $5billion to build it, launch it, and assemble it. Falcon 9 can deliver 10 tons to LEO, so 30 to 40 tons for the power sat must be close. Solaren has made all their info private, but you can see a nice picture here: http://www.engadget.com/2009/04/15/solaren-corp-to-supply-california-with-space-based-solar-power/

I'm trying to avoid questions about radiation protection on ISS and structural integrity at this moment, but can't help myself mentioning it :roll:

Outbound, there will be a lot of consumables with considerable mass, along with fuel for the descent vehicle. Probably they could be arranged in the right places to act as a radiation shield. Inbound, there'd be a lot of trash equal to the amount of stuff consumed. Just use it for shielding, rather than jettisoning it.

I also noticed i had in mind wrong number for pressurized space on ISS.
It is 358 m3 (12,626 cubic feet) which translates into 1 BA 330 on SHE-1 :
http://www.nasa.gov/mission_pages/stati ... odate.html

I imagine if this idea is actually taken seriously, member nations of the ISS will send up additional modules and equipment to support their crew.

Now after reviewing things, the mass of the whole thing will probably be more tlike 600 or 700 tons.

 

[EarthlingX]

Just in short: 600t - 700t is just too much. It simply wont fly. Let's try and keep is as low as possible. Ford-T, ok ?
I think it makes no sense to try and tinker with ISS to make it do something it was not made for. One failure can be enough for a very very bad day. ISS has another role(s) which it can fulfill just fine.

Please check radiation shielding for BA 330. It looks rather 'simple' and effective. There is also an option to add water for shielding, but i left it out of calculations, because i haven't got that far yet.

I must say i like that Solaren idea. Were they not the people behind some sexy patent for PV that uses lenses over cells to concentrate light ? In SHE-1 configuration we are talking MW not kW. Without checking, just from memory, i think they used at least 3-4 launches to bring PV wings in the orbit. If we do same with RTG, we get MW. If you have any info on kW/t for Solaren PV it would be greatly appreciated. Just don't forget batteries and when you put those in the equation, you could get probably better off with fuel cells ........ Are you saying we get 200 MW in 40t (5 MW/t) ? Any non-password info on net ? (it's just too good :shock: )
It might be interesting though, because we will need something to compare with once we have power/cooling/fuel/propulsion block a bit settled. I will continue with RTG until we know more.
And here it is: (PG&E makes deal for space solar power)
http://www.msnbc.msn.com/id/30198977/

Boerman said Solaren's plan called for four or five heavy-lift launches that would put the elements of the power-generating facility in orbit. Those elements would dock automatically in space to create the satellite system. Boerman declined to describe the elements in detail but noted that each heavy-lift launch could put 25 tons of payload into orbit.

and

He said the agreement called for 800 gigawatt-hours of electricity to be provided during the first year of operation

That would be about 90 MW in 125t or 0,72 MW/t in Earth orbit. Please check my numbers.
This is way better than 0.083 MW/t for SAFE-400, even assuming half power at Mars and gives us little less than 30t for 20MW we are after for engines. Can it be ? :shock: :?
If it is, we get 40 MW in 60t (3x20t module, 6x10t) and that allows higher thrust than assumed.
We would still need to radiate 8MWt from engines, but nothing from power source. I guesculate that to be about 10000 m^2 radiator (assuming it can radiate in two directions) and would very much appreciate anyone doing more precise calculation.
It would also be very nice if we could use those 8MWt for some heat engine thingy, like Stirling or Brayton cycle engine.
It might be lighter than radiators and we get about 4MWe more, assuming 60% Stirling efficiency and 90% electric generator efficiency.

I have an idea how to approach calculation of time required with a little help of over simplification and wild assumption. I guess it shouldn't be off for too much. Let's put Earth and Mars in Earths space frame. Change circular orbits to parallel lines and what's left is a simple right-angled triangle. Not very accurate, but we also use g as Earth acceleration and don't compute Sun's, which i guess would be a little bigger. You can also put in difference of Earth and Mars orbital speed to make it a little more interesting

As to the number of engines, your objection makes sense. What do you think about 4x VX-5000 engines, around 10t each ? Too many engines bring another problems and complicate things unnecessarily. If Ad Astra Rocket builds such an engine and if they can sell it on international market (ITAR), i'm almost certain they will be mass produced.

I was considering resupply and docking, that's why i included 1 ISS Node-1 module. Add to it 2 PMA-s and you are very close to 20t i assumed for Node-1. Same ports can be used for docking lander. If we start with missions under 6 months, it's comparable with amount of supply for ISS in the same period and that is not really a killer. With 4 PMA-s (1,5t each) we can have permanently docked atmosphere lander, vacuum (SSTO) lander and two open ports for resupply. No need to start with everything at once.

 

[EarthlingX]

Space.com Heliosphere Explorer 1 (SHE-1) (edit 2009.08.30)
_____________________________________________________________________
1. Lander:
Start with Altair (Lunar lander), keep it in one piece (SSTO), apply COTS tricks to lower cost.
2. Habitation and logistics:
1x BA330, 1x ISS Node-1, 2x ISS PMA
3. Power source (20 MW or 20 000 kW for engines)
a.) use RTG
- RTG generator
- cooling radiators
b.) use PV
- PV cells
- batteries
4. VASIMR, fuel
- 20t argon fuel tank for 80t of argon
- 4x VX-5000
5. Supplies, instrumentation, science (edit 2009.08.31)
- 20t supplies for 6 people for 6 months
- 40t instrumentation, science, for first evaluation
____________________________________________________________________
1. = 20t
2. = 40t
3a. - using HPM (1MWe/t, text in reference speculates it could work in space, heat sink?) = 20t
3b. - using SAFE-6400 (0,083MWe/t, heat sink?) = 16 * (16 * SAFE-400) = 16 * 20t = 320t
3c. - using Solaren PV (0,72 MWe/t) = 60t (check above discussion)
- batteries or fuel cells ?
4. - 20t fuel tank + 80t fuel = 100t
- 4x VX-5000 = 4 * (25 * VX-200) = 4 * 10t = 40t
- heat sink = ?
5. 20t + 40t = 60t

(edit 2009.09.30, added equation)
http://en.wikipedia.org/wiki/Rocket_equation
Isp = 5000
Ve = Isp * g = 5000 s * 10 m/s^2 = 50km/s (edit 2009.08.31, changed g0 to g, added * multiplication symbol)
dV = Ve * ln (m1/m2)

Options:
(using rocket equation, Isp = 5000)
3a.) 20t + 40t + 20t + 100t + 40t + 60t = 280t, delta V = 16,8 km/s
3b.) 20t + 40t + 320t + 100t + 40t + 60t = 580t, delta V = 7,4 km/s
3c.) 20t + 40t + 60t + 100t + 40t + 60t = 320t, delta V = 14,4 km/s
(using rocket equation, Isp = 10000) (edit 2009.08.31, calculations for Isp 10000)
3a.) 280t full (m1), 200t empty (m2), delta V = 33647,22 m/s = 33,65 km/s
3b.) 580t full, 500t empty, delta V = 14,84 km/s
3c.) 320t full, 240t empty, delta V = 28,77 km/s
(using rocket equation, Isp = 30000) (edit 2009.09.01)
3a.) delta V = 99 km/s
3b.) delta V = 43 km/s
3c.) delta V = 84,7 km/s

Thrust assuming 60 % efficiency for 4x VX-5000 (edit 2009.09.01, expected efficiency around 80 %)
Isp 1000s = 20000 kW * 0,6 / (1000s * 9,81 m/s^2) = 1220 N (not in operational range of VASIMR)
Isp 5000s = 245 N
Isp 10000s = 122 N
Isp 30000s = 41 N

(edit 2009.08.30, added burn time)
Burn time, assuming 80t argon, using equation (fuel * Isp * g)/thrust, numbers are approximate :
Isp 1000s = 7 days (not in operational range of VASIMR)
Isp 5000s = 189 days
Isp 10000s = 758 days
Isp 30000s = 6646 days (18+ years)
_______________________________________________________________

We are missing info on heat sink (8 MWt for engines), batteries/fuel cells and radiation shielding mass. I am also avoiding cost discussion until we have stable hardware configuration.

I'm still checking the list, please comment.
______________________________________
Here are some links for reference: (edit 2009.09.01, references)

I have some assumptions about size and mass of heat sinks, but no real data yet, using this page:
http://en.wikipedia.org/wiki/Thermal_radiation

(2009 U.S. Commercial Space Transportation Developments and Concepts:
Vehicles, Technologies, and Spaceports January 2009)
http://www.faa.gov/about/office_org/hea ... 202009.pdf

Reference Guide to the International Space Station :
http://www.nasa.gov/mission_pages/stati ... Guide.html

VASIMR article on Wikipedia with lots of links:
http://en.wikipedia.org/wiki/VASIMR

This document includes information about maximum possible Isp in 30 000s range.
I have received email from Ad Astra Rocket, confirming operational Isp range from 5000s - 30000s
(edit 2009.09.02)
(VASIMR Plasma Rocket Technology)
http://dma.ing.uniroma1.it/users/bruno/Petro.prn.pdf

About nuclear option:

Seven of the nuclear generators would provide 200 MW of power to enable 39 day one way trips to Mars.

(November 28, 2007 - Vasimr engines plus 200 MW of nuclear "batteries" = 39 days to Mars )
http://nextbigfuture.com/2007/11/vasimr ... clear.html

Hyperion Power Module information:
http://www.hyperionpowergeneration.com/product.html

Link on Wikipedia to get specific energy for SAFE-400
http://en.wikipedia.org/wiki/SAFE-400

Some past projections:
(Future NASA Multi-kilowatt Free Piston Stirling Applications)

This paper describes the preliminary work that will be performed toward development of a nuclear-fission-powered nominal 30 kW Stirling power system for use on the lunar surface with a specific power goal of about 140 W/kg for the Stirling power conversion system.

http://sri.auburn.edu/papers/2006/futur ... irling.pdf

Solar alternative:
(Stretched Lens Array SquareRigger (SLASR): A New Space Array for High-Power Missions)
http://www.stretchedlensarray.com/Paper ... WCPEC4.pdf

· Areal Power Density = 300 - 400 W/m2
· Specific Power = 300 W/kg - 500 W/kg
· Stowed Power = 80 - 120 kW/m3
· Scalable Array Power = 4 kW to 100’s of kW’s
· Super-Insulated Small Cell Circuit = High-Voltage (300-
600 V) Operation at Low Mass Penalty
· Super-Shielded Small Cell Circuit = Excellent Radiation
Hardness at Low Mass Penalty
· 85% Cell Area Savings = 66% to 75% Lower Array Cost
per Watt than One-Sun Array
· Modular, Scalable, & Mass-Producible at MW’s per Year
Using Existing Capacities

Orbital Data for the Planets & Dwarf Planets :
http://www.windows.ucar.edu/tour/link=/ ... table.html

Conceptual Mars mission using 3 VASIMR engines (SHE has 100):
http://www.youtube.com/watch?v=Zj53rVWK5z0

 

[rmchung]

He said the agreement called for 800 gigawatt-hours of electricity to be provided during the first year of operation

That would be about 90 MW in 125t or 0,72 MW/t in Earth orbit ...

It's actually double that, the 800 gigawatt-hours was only for the first year. It's 1700 gigawatt-hours after that. And the mass should be less, since there's no need for the DC to microwave conversion and the antenna to beam the power back to Earth. But there's no information on how much mass that would save, so it would be conservative to not account for that.

There's another possible advancement in shielding using nanoparticles, but there's no news other than this article a few years back: http://www.nanowerk.com/spotlight/spotid=2150. There's been tremendous progress in carbon nanotube knowledge in just the last year or two, so CNT based shielding might actually be more practical than boron nanotubes. But it probably would be a good idea for NASA to fund both kinds of nanoparticle shielding. Even small shields would be very useful for protecting microprocessors, FPGA's, memory chips, etc.

 

[neutrino78x]

What is this SHE-1 you guys are talking about? :?: :?:

Also, you can achieve megawatts with the SAFE-400, but you would have to have multiple SAFE-400 on your spacecraft. Unfortunately, there is not a multi-megawatt nuclear reactor that is portable and intended to be launched on a rocket. At least, not that I know of.

Radiation is the reason the general public doesn't want to luanch nuclear reactors. There are people who are not the types who would protest the use of RTGs, but still hesitate to launch a nuclear reactor on a rocket...at least the RTG is designed, and proven able, to survive an explosion of the rocket.

The ideal way to do nuclear fueled ships would be to make the reactor on the ground, without the fuel rods, and somehow have a way to manufacture the fuel rods in space and insert them in the reactor while it is far from Earth. Then there is no possible danger. But that assumes a level of infrastructure in space far beyond what we have right now...

--Brian

 

[Bill_Wright]

Folks,
How did we get to the heliosphere to all of the talk about Mars and human-rated landers? It seems to me that a very long term artificial comet might be the best bet to check out the "bubble" that the Sun has blown into the galactic environment. We would need a low thrust, high run-time engine to be able to change trajectories, and also lots of computing power to get assists from the gravity of various planets and bodies. We should probably build a few and even check out the Oort Cloud and Kuiper Belt as the one-shot New Horizons mission could produce fluky data based upon such a small sample. This is one of those projects that I can see building hundreds of probes and really doing a good inventory of the Solar System. I'd like to see:
1) the shape of the Sun's magnetic field, especially as we go through different Solar cycles
2) how much gas and dust is in our system, the density, and what it is made of (spectroscope or GC/MS)
3) radioactivity levels at various points in the system
4) a laser-based communication system to be able to download lots and lots of data
5) a highly programmable and well protected computer on board
6) a very long term power and heat source (RTG+)
7) a scope with hgih-quality optics and a good detector
8) a cloud chamber with a really good high speed camera
9) at least a few way out of the plane of ecliptic of the Sun

Who knows, besides the inventory we also might be able to settle some of these gravity questions that have come up with the four probes that have passed or are nearing the heliopause. The serendipity factor always comes into play when you try something new. Also, just think of all of the high-paying jobs that would be created!

Peace to all on Planet Earth,
Bill

 

[EarthlingX]

There's another possible advancement in shielding using nanoparticles, but there's no news other than this article a few years back: http://www.nanowerk.com/spotlight/spotid=2150. There's been tremendous progress in carbon nanotube knowledge in just the last year or two, so CNT based shielding might actually be more practical than boron nanotubes. But it probably would be a good idea for NASA to fund both kinds of nanoparticle shielding. Even small shields would be very useful for protecting microprocessors, FPGA's, memory chips, etc.

Here are two working links.
http://www.nanowerk.com/spotlight/spotid=2150.php
http://www.nanowerk.com/spotlight/spotid=1040.php

I wonder if it is possible to mix nanotech, cloaking tech meta materials and magnetic plasma shielding ? hm... :?:

Any news from NASA ?
(Multifunctional Carbon Nanotube/Polyethylene Complex Composites for Space Radiation Shielding - 2004)
http://sbir.nasa.gov/SBIR/abstracts/04/ ... -9315.html

Looks like boron nanotubes could be used for radiation shielding in RTG, if nothing else
(Nanotechnology in space - 2007)
http://www.rsphysse.anu.edu.au/nanotube ... space2.htm

Scientists have known about the ability of boron 10 to capture neutrons since the 1930s and use it as a radiation shield in geiger counters as well as a shielding layer in nuclear reactors.

"I have communicated with researchers at NASA about the possible application of our boron nanotubes in space missions" says Chen. "Several years ago they asked me to prepare boron nanotube samples for tests on the space station. We also have discussed the possible use of 10BN nanotubes. Currently we are conducting radiation tests on the nanotubes at the Australian Nuclear Science and Technology Organization."

What happened ?

 

[EarthlingX]

What is this SHE-1 you guys are talking about? :?: :?:

Space.com Heliosphere Explorer Mark 1

Also, you can achieve megawatts with the SAFE-400, but you would have to have multiple SAFE-400 on your spacecraft. Unfortunately, there is not a multi-megawatt nuclear reactor that is portable and intended to be launched on a rocket. At least, not that I know of.

Yes, we are slightly in the dream land. But that doesn't need to stop us (edit 2009.08.31, added SAFE-6400/SAFE-400 ratio to SHE-1 config)

Radiation is the reason the general public doesn't want to luanch nuclear reactors. There are people who are not the types who would protest the use of RTGs, but still hesitate to launch a nuclear reactor on a rocket...at least the RTG is designed, and proven able, to survive an explosion of the rocket.

The ideal way to do nuclear fueled ships would be to make the reactor on the ground, without the fuel rods, and somehow have a way to manufacture the fuel rods in space and insert them in the reactor while it is far from Earth. Then there is no possible danger. But that assumes a level of infrastructure in space far beyond what we have right now...

--Brian

I would prefer to avoid 'nuclear space' discussion, because it can get very lengthy and off topic. Here is an example where it was topic (as you know :
viewtopic.php?f=15&t=19313

 

[EarthlingX]

Folks,
How did we get to the heliosphere to all of the talk about Mars and human-rated landers? It seems to me that a very long term artificial comet might be the best bet to check out the "bubble" that the Sun has blown into the galactic environment. We would need a low thrust, high run-time engine to be able to change trajectories, and also lots of computing power to get assists from the gravity of various planets and bodies. We should probably build a few and even check out the Oort Cloud and Kuiper Belt as the one-shot New Horizons mission could produce fluky data based upon such a small sample. This is one of those projects that I can see building hundreds of probes and really doing a good inventory of the Solar System. I'd like to see:
1) the shape of the Sun's magnetic field, especially as we go through different Solar cycles
2) how much gas and dust is in our system, the density, and what it is made of (spectroscope or GC/MS)
3) radioactivity levels at various points in the system
4) a laser-based communication system to be able to download lots and lots of data
5) a highly programmable and well protected computer on board
6) a very long term power and heat source (RTG+)
7) a scope with hgih-quality optics and a good detector
8) a cloud chamber with a really good high speed camera
9) at least a few way out of the plane of ecliptic of the Sun

Who knows, besides the inventory we also might be able to settle some of these gravity questions that have come up with the four probes that have passed or are nearing the heliopause. The serendipity factor always comes into play when you try something new. Also, just think of all of the high-paying jobs that would be created!

Peace to all on Planet Earth,
Bill

Yes Bill, we need a low thrust, high run-time engine. Check SHE-1 config and see if you like. (edit 2009.08.31, added burn time)
You can check how we got here at the beginning of this thread, where is a link to where this discussion started.

(edit 2009.08.31, added science, instrumentation, gadgetry, mass estimate to SHE-1 config, peace Bill We will add a cat (Felis catus) a little bit later

 

[neutrino78x]

So I've got a question, if you have several megawatts of power for VASIMR, does that give you a 1 G thrust? 1 G would be 9.81 meters per second right, aka 9.8 N, but I thought vasimr could only do small fractions of a newton.

Also, I would definitely like to see all kinds of missions to the outer solar system. Various Kuiper belt objects, the oort cloud, etc. I would like to see people land on some of these targets too!! Maybe a nuclear powered base in the Jupiter system to reduce speed of light delay in radio communications out there.

 

[EarthlingX]

So I've got a question, if you have several megawatts of power for VASIMR, does that give you a 1 G thrust? 1 G would be 9.81 meters per second right, aka 9.8 N, but I thought vasimr could only do small fractions of a newton.

SHE-1 has 20 MW power for it's engines in the last configuration. I can put power numbers in list too, just thought it's already a bit crowded
There is a difference between g and G. G means Giga or billion (1000 000 000) of something and g stands for average Earths gravitational acceleration. Newton (N) is a measure of force, like kgf or lbf and 1 kg of mass accelerated by g gives you mass * g of force (m*a=F) or 1kg * 9.81 m/s^2 = 9,81 N. I use 1 to 10 conversion in the name of simplification. There will be necessary more exact calculations, but it's good enough for getting the overall picture.
Force of thrust depends on working regime of engines, which is represented by Isp (specific impulse) and you can see calculated different values for different working regimes or different Isp.
(edit 2009.08.31, added more colors on SHE-1 config)

Also, I would definitely like to see all kinds of missions to the outer solar system. Various Kuiper belt objects, the oort cloud, etc. I would like to see people land on some of these targets too!! Maybe a nuclear powered base in the Jupiter system to reduce speed of light delay in radio communications out there.

Yes, me too Those two configurations, RTG and solar, can be used for different mission objectives. If you want to explore inner Solar system, that is Mercury, Venus, Mars, NEOs, asteroids, you would go all solar. You could probably get into Jupiters magnetic field also, with a little help of gravitational slingshots and similar aerobics
If you go full nuclear and run engines in very high Isp, this baby can visit Saturn, Uranus, Neptun, maybe even peek into Kuipers belt

 

[jakethesnake]

I am a huge fan of VASIMR; I'm eagerly awaiting the test results on the second stage ramp-up to 200kW.

I'm a little worried at this point, they were supposed to start testing the second stage at the end of July and so far not a peep? :?:

Hope everything is good, Go Ad Astra Go!

 

[EarthlingX]

jakethesnake i have my eye on your thread
VASIMR Updates
(edit 2007.01.27, fixed link)

Here are some assumptions about heat sink:
using equations from http://en.wikipedia.org/wiki/Thermal_radiation and a lot of aspirins:
A = P / (e * o * T^4)
where
A = area
P = power = 1MWt (t stands for thermal)
e = emissivity = 1 for black body
o = Stefan-Boltzmann constant = 5,6704 * 10^-8 * J * s^-1 * m^-2 * K^-4
T = temperature = 700K
__________________________________________________________
= 73,4 m^2 (approximately)

It's not that scary