Author Topic: VASIMR Engine  (Read 126214 times)

Offline ChrisWilson68

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Re: VASIMR Engine
« Reply #40 on: 12/03/2014 09:33 AM »
Has Franklin Chang Diaz asked other aerospace companies to test VASIMR? Does he have enough money to make a small spacecraft to test the VX-200?. If NASA can not give funding, I think Franklin should ask Elon Musk or ask other aerospace companies for funding e.g. ESA for funding or international funding.

No other aerospace company is interested in funding VASIMR.  Except for SpaceX, other aerospace companies fall into one of two categories:

1. They have money to spend but take decisions based largely on making money.
2. They might be interested in spending money for reasons other than making money, but have almost no money of their own and are desperately seeking investors.

There's no money to be made from VASIMR, so category 1 companies won't spend money on it, and category 2 companies don't have any money to spend.

SpaceX is the anomaly.  But Elon's statements seem to indicate a lack of interest in VASIMR.  He seems committed to chemical propulsion for colonizing Mars.

As to the ESA or any other non-US government: they are generally only interested in spending money at home, where they can justify their existence by saying they are creating jobs.  There's no way they'd want to fund a foreign country's private company's R&D.

Offline truth is life

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Re: VASIMR Engine
« Reply #41 on: 12/10/2014 01:19 PM »
As to the ESA or any other non-US government: they are generally only interested in spending money at home, where they can justify their existence by saying they are creating jobs.  There's no way they'd want to fund a foreign country's private company's R&D.
To be fair, they could be interested in technology transfer, but that would require moving Ad Astra to whatever country is paying for it, in essence.

Offline Star One

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Re: VASIMR Engine
« Reply #42 on: 12/10/2014 04:59 PM »
Is there any way the technology could be varied so that it could be used in atmosphere as well as outside it?

Online Stormbringer

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Re: VASIMR Engine
« Reply #43 on: 12/10/2014 05:42 PM »
if i understand it properly it's strong suite is efficiency not raw power. it cannot make it out of a gravity well.
When antigravity is outlawed only outlaws will have antigravity.

Offline Star One

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Re: VASIMR Engine
« Reply #44 on: 12/10/2014 07:17 PM »
if i understand it properly it's strong suite is efficiency not raw power. it cannot make it out of a gravity well.
So it couldn't be used for a purely terrestrial vehicle then. Just wondered if this was another avenue open to them.

Offline Asteroza

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Re: VASIMR Engine
« Reply #45 on: 12/10/2014 10:03 PM »
As to the ESA or any other non-US government: they are generally only interested in spending money at home, where they can justify their existence by saying they are creating jobs.  There's no way they'd want to fund a foreign country's private company's R&D.
To be fair, they could be interested in technology transfer, but that would require moving Ad Astra to whatever country is paying for it, in essence.

That would involve ITAR and US State Department/DoD clearance to export, as it's probably (still) classified as a controlled item.

Offline truth is life

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Re: VASIMR Engine
« Reply #46 on: 12/10/2014 10:55 PM »
That would involve ITAR and US State Department/DoD clearance to export, as it's probably (still) classified as a controlled item.

This is also true, and I can't figure out why I forgot to mention it. Logically, it wouldn't be a big deal because all of the theory is known, anyone who wants could probably develop it themselves (though it would take a while), and it's not really particularly useful for any military uses that I'm aware of, but these things rarely seem to have much to do with logic.

Offline nadreck

Re: VASIMR Engine
« Reply #47 on: 12/10/2014 11:37 PM »
That would involve ITAR and US State Department/DoD clearance to export, as it's probably (still) classified as a controlled item.

This is also true, and I can't figure out why I forgot to mention it. Logically, it wouldn't be a big deal because all of the theory is known, anyone who wants could probably develop it themselves (though it would take a while), and it's not really particularly useful for any military uses that I'm aware of, but these things rarely seem to have much to do with logic.
IMNSHO, especially at altitude, something like a VASIMIR engine could be weaponized
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Online Stormbringer

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Re: VASIMR Engine
« Reply #48 on: 12/11/2014 12:38 AM »
it's plasma so if the VASIMR can be weaponized then this is a better candidate for a pew pew type weapon:

BELLA Table Top plasma accelerator

http://www.sciencedaily.com/releases/2014/12/141208135641.htm

4.25 Giga electron volts in about 6 inches.

When antigravity is outlawed only outlaws will have antigravity.

Offline A_M_Swallow

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Re: VASIMR Engine
« Reply #49 on: 12/11/2014 01:32 AM »
if i understand it properly it's strong suite is efficiency not raw power. it cannot make it out of a gravity well.
So it couldn't be used for a purely terrestrial vehicle then. Just wondered if this was another avenue open to them.

No.  These sort of thrusters only work in a vacuum.

Offline Star One

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Re: VASIMR Engine
« Reply #50 on: 12/11/2014 06:38 AM »

if i understand it properly it's strong suite is efficiency not raw power. it cannot make it out of a gravity well.
So it couldn't be used for a purely terrestrial vehicle then. Just wondered if this was another avenue open to them.

No.  These sort of thrusters only work in a vacuum.

Thank you for that clarification on the matter.

Offline rusty

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Re: VASIMR Engine
« Reply #51 on: 12/13/2014 08:22 AM »
...
There's no money to be made from VASIMR ...
As to the ESA or any other non-US government: they are generally only interested in spending money at home, where they can justify their existence by saying they are creating jobs.  There's no way they'd want to fund a foreign country's private company's R&D.
Near-term, it's primary use would be as a lunar tug and only profitable as a separate company with a COTS-like arrangement. Since Little-O srcubbed the Moon, that's a non-option for years. Another option could be hurling asteroids toward Earth for Doomsday or scientific "prestige" reasons, but that's understandably a terrible route.

Offline Raj2014

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Re: VASIMR Engine
« Reply #52 on: 12/13/2014 10:11 AM »
Has Franklin Chang Diaz asked other aerospace companies to test VASIMR? Does he have enough money to make a small spacecraft to test the VX-200?. If NASA can not give funding, I think Franklin should ask Elon Musk or ask other aerospace companies for funding e.g. ESA for funding or international funding.

No other aerospace company is interested in funding VASIMR.  Except for SpaceX, other aerospace companies fall into one of two categories:

1. They have money to spend but take decisions based largely on making money.
2. They might be interested in spending money for reasons other than making money, but have almost no money of their own and are desperately seeking investors.

There's no money to be made from VASIMR, so category 1 companies won't spend money on it, and category 2 companies don't have any money to spend.

SpaceX is the anomaly.  But Elon's statements seem to indicate a lack of interest in VASIMR.  He seems committed to chemical propulsion for colonizing Mars.

As to the ESA or any other non-US government: they are generally only interested in spending money at home, where they can justify their existence by saying they are creating jobs.  There's no way they'd want to fund a foreign country's private company's R&D.

One of the ideas for VASIMR is to use it to collect space debris. They could make money this way and test the engine. Also the engine could be used for robotic probes. Other than waiting to test on the ISS, could they build a small spacecraft to test the engine in Space, to see how well it is in a real space environment. I know they have tested in a vacuum at their facility. Also NASA is going to get an increase in their budget, maybe they could give some of it to Adastra, if there is enough money.   

Offline alexterrell

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Re: VASIMR Engine
« Reply #53 on: 12/13/2014 04:27 PM »


SpaceX is the anomaly.  But Elon's statements seem to indicate a lack of interest in VASIMR.  He seems committed to chemical propulsion for colonizing Mars.


I have a spreadsheet of numbers somewhere - but they basically showed very little benefit in using electric propulsion to get from High Earth Orbit (e.g. Earth-Moon L1) to Mars, because SEP cannot use the Oberth effect and cannot use aero-capture at Mars.

Using these effects, a minimum delta-V from HEO to Mars Aeocapture entry is only 700m/s. Getting from LEO to HEO is the major delta-V challenge (about 4km/s). A SEP could be useful here provided it can handle the Van Allen radiation environment. It could be used to lift all the mission mass to HEO, apart from crew. And it could be reusable - a genuine space tug.

I assume SpaceX reckon their launch cost will be low enough that they won't need this. Just launch from LEO and keep it simple. Zubrin would agree. VASIMR will just complicate things, even if it does reduce in orbit mass. And complexity = cost.

Two other potential benefits of SEP:
- If using to haul water from LEO to HEO, you then have lots of power to electrolyse your fuel on demand.
- If going all the way to Mars, you have a lot of power in Mars orbit. So you could look at laser beamed power for your surface operations.

Offline HailColumbia

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Re: VASIMR Engine
« Reply #54 on: 12/13/2014 04:35 PM »


I have a spreadsheet of numbers somewhere - but they basically showed very little benefit in using electric propulsion to get from High Earth Orbit (e.g. Earth-Moon L1) to Mars, because SEP cannot use the Oberth effect and cannot use aero-capture at Mars.


Why can't you aerocapture with VASIMR?  I think you would want a small chemical engine to circularize your orbit. Doesn't areocapture mostly come down to hitting a planets atmosphere at the correct angle? Seems like VASIMR should be able to do that.
-Steve

Offline Hanelyp

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Re: VASIMR Engine
« Reply #55 on: 12/13/2014 05:48 PM »
The trick with aerocapture and solar electric propulsion is getting the featherweight solar collectors to survive the aerocapture maneuver.

Offline MP99

Re: VASIMR Engine
« Reply #56 on: 12/13/2014 07:02 PM »


SpaceX is the anomaly.  But Elon's statements seem to indicate a lack of interest in VASIMR.  He seems committed to chemical propulsion for colonizing Mars.


I have a spreadsheet of numbers somewhere - but they basically showed very little benefit in using electric propulsion to get from High Earth Orbit (e.g. Earth-Moon L1) to Mars, because SEP cannot use the Oberth effect and cannot use aero-capture at Mars.

Using these effects, a minimum delta-V from HEO to Mars Aeocapture entry is only 700m/s. Getting from LEO to HEO is the major delta-V challenge (about 4km/s). A SEP could be useful here provided it can handle the Van Allen radiation environment. It could be used to lift all the mission mass to HEO, apart from crew. And it could be reusable - a genuine space tug.

Using a Weak Stability Boundary Transfer, Chemical can get you to EML2 in 3 months for ~3.2 km/s, but that's using Oberth assistance at TLI.

I think you need to recalculate the dV required for SEP to slog it's way out to EML when it can't take advantage of Oberth - I think you've under-estimated it quite a bit.

OTOH, I believe your 0.7 km/s from EML through TMI is low - you'll use about half that just leaving EML (the perigee lowering burn as you pass the Moon), so you can do an Oberth burn at earth. But the Oberth burn itself can be around 1 km/s (or some of the numbers appropriate for cargo mission do seem to be lower, as per your estimate).



I assume SpaceX reckon their launch cost will be low enough that they won't need this. Just launch from LEO and keep it simple. Zubrin would agree. VASIMR will just complicate things, even if it does reduce in orbit mass. And complexity = cost.

I agree re an "abundant chemical" architecture.

The Earth end works even better if you have a massive Mars Transfer Vehicle, do a small Oberth braking burn at LEO, then store the rest of the gravitational potential energy by positioning it at EML ready for the next mission.

It's worth mentioning for EML2 that 1-1.5 km/s of chemical burn with Oberth assist would need to be matched by at least 3-5 km/s by VASIMR in order to achieve the same interplanetary speeds.

cheers, Martin

Offline Alf Fass

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Re: VASIMR Engine
« Reply #57 on: 12/13/2014 10:37 PM »
G. Nordley has a table for delta V's and transit times to Mars here:

http://www.gdnordley.com/_files/Going_to_Mars.html

As can be seen, chemical propulsion can get you there in ~80 days with reasonable propellant mass ratios(this was demonstrated by New Horizons on its way to Pluto, about 80 days to reach Mars orbit).

To compete with this electric propulsion would need to be faster and/or cheaper, something that I think is unlikely to happen with a fission or fusion energy source.

The Adastra VASIMR concept suggests 39 days is possible, interestingly this article, http://www.fromquarkstoquasars.com/vasimr-impulse-engine/

admits:
Quote
Currently the VASIMR engines are operating over 60% efficiency; however, we have hit a wall on how to power the unit while in space.  To achieve the amounts of power required for such a powerful engine, we would need to design some form of nuclear reactor, fusion reactor, or matter-antimatter reactor as a supply of power in space.  Theoretically, you could use large solar panels as well; however, the weight for such panels would pose an issue at launch.


Which is Why concentrating a lot of Sunlight onto a small area of cooled PV cells is necessary, solar reflectors are theoretically able to be made as light as 0.02g/m2
Quote
At a thickness of 20 nm, lithium has an areal density of 0.011 g/m2. A high-performance sail could be made of lithium alone at 20 nm (no emission layer). It would have to be fabricated in space and not used to approach the sun. In the limit, a sail craft might be constructed with a total areal density of around 0.02 g/m2, giving it a lightness number of 67 and ac of about 400 mm/s2. Magnesium and beryllium are also potential materials for high-performance sails. These 3 metals can be alloyed with each other and with aluminium.[2]
http://en.wikipedia.org/wiki/Solar_sail#Materials

Such a lightweight reflector, able to concentrate a GW(!) at an AU from the Sun might be built weighing only 20kg, I think it possible its parabolic shape could be retained at ship accelerations of up to around 0.05g by the pressure of the Sunlight and by slowly rotating of the reflector.

When my information changes, I alter my conclusions. What do you do, sir?
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Offline alexterrell

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Re: VASIMR Engine
« Reply #58 on: 12/13/2014 10:47 PM »
The trick with aerocapture and solar electric propulsion is getting the featherweight solar collectors to survive the aerocapture maneuver.

I suppose you could abandon the VASIMR its solar panels, and aerocapture the rest of the craft.

Seems a bit of a waste.

Offline HailColumbia

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Re: VASIMR Engine
« Reply #59 on: 12/14/2014 12:13 AM »
The trick with aerocapture and solar electric propulsion is getting the featherweight solar collectors to survive the aerocapture maneuver.

I suppose you could abandon the VASIMR its solar panels, and aerocapture the rest of the craft.

Seems a bit of a waste.

Wouldn't retractable panels solve this problem?  Given the surface area needed for something like VASIMR you have to build panels that fold out anyway. Why not just tuck them in and box them up before you hit the martian atmosphere?
-Steve

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