NASA wants to catch, return asteroid

[Solman]

 So the primary purpose is to develop a Hall thruster SEP based asteroid redirection system?
A system that would bring all its propellant from Earth?
That would therefore have to have a high exhaust velocity and therefore low thrust?
All to change the velocity of a million pounds or so by a couple hundred m/s?
I've been reading about asteroid mining since a 1977 article on the subject and while I've seen mass drivers and steam tea kettles (John Lewis - "Mining the Sky") i.e. solar thermal rockets using asteroid's own water; I've never seen Hall thruster SEP proposed as a practical mining concept.
 Develop a system that uses the asteroid itself as the source of propellant and you can use lower Isp and have greater thrust giving you a much more robust ability to redirect and a much bigger target list.
This can be as simple as solar powered resistojets using water from electrically heating regolith to solar concentrator mirrors focussing onto fiber optic cables that are stuck inside the bag - I saw a show a few years age in which a meteorite was blasted by the AFRL solar concentrator. The hydrates became steam that blew it apart. For that matter forget the bag and use this alone as a thruster to redirect perhaps.
Point being that it would be so much better to develop a robust redirection capability that would have utility for practical mining operations IMO.

[Hop_David]

So the primary purpose is to develop a Hall thruster SEP based asteroid redirection system?
A system that would bring all its propellant from Earth?
That would therefore have to have a high exhaust velocity and therefore low thrust?
All to change the velocity of a million pounds or so by a couple hundred m/s?
I've been reading about asteroid mining since a 1977 article on the subject and while I've seen mass drivers and steam tea kettles (John Lewis - "Mining the Sky") i.e. solar thermal rockets using asteroid's own water; I've never seen Hall thruster SEP proposed as a practical mining concept.
 Develop a system that uses the asteroid itself as the source of propellant and you can use lower Isp and have greater thrust giving you a much more robust ability to redirect and a much bigger target list.

You'd need to set up a mining and transportation infrastructure on the asteroid to mine and deliver propellant to the rocket engines.

You'd either need humans there or robots autonomous enough to function well even with a light lag of tens of minutes.

This can be as simple as solar powered resistojets using water from electrically heating regolith to solar concentrator mirrors focussing onto fiber optic cables that are stuck inside the bag - I saw a show a few years age in which a meteorite was blasted by the AFRL solar concentrator. The hydrates became steam that blew it apart. For that matter forget the bag and use this alone as a thruster to redirect perhaps.

If it's so easy you should set up a demo model and pitch it to DSI and PR.

[KelvinZero]

I've been reading about asteroid mining since a 1977 article on the subject and while I've seen mass drivers and steam tea kettles (John Lewis - "Mining the Sky") i.e. solar thermal rockets using asteroid's own water; I've never seen Hall thruster SEP proposed as a practical mining concept.

A lot of stuff written about space is bollocks, and it wasnt any better in the 70s. I would put a thousand times more faith in the technology that has actually visited asteroids. Besides, I see this SEP tug more as a general tool. We can use it for moving a space station to an EML2 postion for example.

If you want to know why mass drivers and steam kettles make for lousy propulsion start a thread somewhere, but I vaguely recall that we have already gone over this several times.

Yeah at some point I would love to see us exploit asteroids for ISRU, but for now a fairly efficient way to collect them (so that we have real samples to begin research into ISRU) is more than I hoped for.

[Solman]

@ Hop David:
Your remark that a mining infrastructure needs to be set up on the asteroid is baffling. h A robotic arm holding a fiber optic cable from a solar concentrator up to the exposed surface of an asteroid in a bag is an infrastructure of sorts I suppose, but why do you see this as a problem?
A statement like if its so easy you do it is hardly helpful or illuminating and borderline abusive. Given your past comments on this site it is surprising and not in a good way.
Failure to use the asteroid itself for propellant will mean many more years to return an asteroid and no progress toward actual practical mining systems.
Minimally useful stunt vs. beginning of asteroid mining.

[Solman]

I've been reading about asteroid mining since a 1977 article on the subject and while I've seen mass drivers and steam tea kettles (John Lewis - "Mining the Sky") i.e. solar thermal rockets using asteroid's own water; I've never seen Hall thruster SEP proposed as a practical mining concept.

A lot of stuff written about space is bollocks, and it wasnt any better in the 70s. I would put a thousand times more faith in the technology that has actually visited asteroids. Besides, I see this SEP tug more as a general tool. We can use it for moving a space station to an EML2 postion for example.

If you want to know why mass drivers and steam kettles make for lousy propulsion start a thread somewhere, but I vaguely recall that we have already gone over this several times.

Yeah at some point I would love to see us exploit asteroids for ISRU, but for now a fairly efficient way to collect them (so that we have real samples to begin research into ISRU) is more than I hoped for.

We already have samples they're called meteorites.
The "lousy propulsion" as you call it produces orders of magnitude more thrust than the SEP you reference per IMLEO. It's efficiency is not particularly relevant anyway if you are using the asteroid itself for propellant. The system you call efficient is barely able to redirect anything and needs years to do so.
Asteroid derived propellant soon or put off to "eventually"?
John Lewis is on the PR team so I guess they might have a little more respect than your description of "bollocks"

[douglas100]

Failure to use the asteroid itself for propellant will mean many more years to return an asteroid and no progress toward actual practical mining systems.
Minimally useful stunt vs. beginning of asteroid mining.

Failure to use the asteroid itself for propellant for this mission is simple common sense. The point of this mission is to return a pristine undamaged asteroid to cislunar space not blast it with heat to extract an unknown and dubious amount of propulsive impulse. It is not about ISRU or solar concentrators or steam kettles. NASA is not in the business of asteroid mining.

The SEP proposal for this mission is the right way to do it, stunt or not. I will make a modest prediction: if this mission goes ahead, it will not use any form of solar concentrator propulsion.

[Hop_David]

@ Hop David:
Your remark that a mining infrastructure needs to be set up on the asteroid is baffling. h A robotic arm holding a fiber optic cable from a solar concentrator up to the exposed surface of an asteroid in a bag is an infrastructure of sorts I suppose, but why do you see this as a problem?

The devil is in the details. I can see a number of problems with this. But I have limited time. Please think about your scheme. Truly, you can see no problems?

A statement like if its so easy you do it is hardly helpful or illuminating and borderline abusive.

A devil's advocate is often helpful. If a critic imagines possible failure modes before they happen, he potentially saves a huge amount of time and effort.

An optimistic cheerleader who relies on handwavium is actually a hindrance.

Given your past comments on this site it is surprising and not in a good way.
Failure to use the asteroid itself for propellant will mean many more years to return an asteroid

Failure to use a propulsion system that is actually doable means we probably wouldn't retrieve an asteroid in this century.

and no progress toward actual practical mining systems.
Minimally useful stunt vs. beginning of asteroid mining.

For beginning of asteroid mining we would need several things:
Light lag less than tens of minutes.
Frequent launch windows
Short trip times.

We'd have all of the above is for a rock parked in high lunar orbit. None of it for a rock in heliocentric orbit that spends most of its time far from earth.

[KelvinZero]

We already have samples they're called meteorites.
The "lousy propulsion" as you call it produces orders of magnitude more thrust than the SEP you reference per IMLEO. It's efficiency is not particularly relevant anyway if you are using the asteroid itself for propellant. The system you call efficient is barely able to redirect anything and needs years to do so.
Asteroid derived propellant soon or put off to "eventually"?
John Lewis is on the PR team so I guess they might have a little more respect than your description of "bollocks"

Meteorites tell us a hell of a lot, but they get baked entering out atmosphere an those containing significant volatiles explode. There is a big gap in our knowledge here. For example, we dont even know if Phobos contains ice! From a science perspective that may be just a detail, from a HSF perpective its an abysmal lack.

My understanding was that PR was planning on eventually progressing from telescopes to SEP. You can use them as advocates for mass driver or kettle propulsion when they start pouring money into raising them to the same technological readiness as SEP.

To the degree you think mass drivers and kettles are reasonable, fine. If there is a clear business case, you don't need/shouldn't want NASA. Commercial interests have much more money than NASA, which is about 0.5% of whatever the federal government gathers from tax. The fraction of that 0.5% money that can be spared for the mission to give an actual purpose to the SLS+orion hardware is a tiny fraction of this.

What NASA is proposing to develop is essentially this:
http://www.nasaspaceflight.com/2012/01/aerojet-solar-electric-propulsion-enabler-exploration-gateway/

It is a sensible general purpose tool for HSF that may fit inside their tiny budget.

[Chris Bergin]

Nice linkage there Kelvin (usually people wait for space.com - or whoever - to do something and then link it with a "OMG! Why hasn't anyone reported SEP in relation to BEO before this article!!" .........and that makes me sob! )

I also have a request in with Aerojet to follow that up per EM-2

PS We have several threads on this now. I'll probably convert this one into a general discussion thread.

For those who don't browse, the latest thread is this one:
http://forum.nasaspaceflight.com/index.php?topic=31758.0

[A_M_Swallow]

I've been reading about asteroid mining since a 1977 article on the subject and while I've seen mass drivers and steam tea kettles (John Lewis - "Mining the Sky") i.e. solar thermal rockets using asteroid's own water; I've never seen Hall thruster SEP proposed as a practical mining concept.

A lot of stuff written about space is bollocks, and it wasnt any better in the 70s. I would put a thousand times more faith in the technology that has actually visited asteroids. Besides, I see this SEP tug more as a general tool. We can use it for moving a space station to an EML2 postion for example.

If you want to know why mass drivers and steam kettles make for lousy propulsion start a thread somewhere, but I vaguely recall that we have already gone over this several times.

Yeah at some point I would love to see us exploit asteroids for ISRU, but for now a fairly efficient way to collect them (so that we have real samples to begin research into ISRU) is more than I hoped for.

We already have samples they're called meteorites.
The "lousy propulsion" as you call it produces orders of magnitude more thrust than the SEP you reference per IMLEO. It's efficiency is not particularly relevant anyway if you are using the asteroid itself for propellant. The system you call efficient is barely able to redirect anything and needs years to do so.
Asteroid derived propellant soon or put off to "eventually"?
John Lewis is on the PR team so I guess they might have a little more respect than your description of "bollocks"

Using the asteroid as propellant in a solar thermal thruster sounds like a great way for space miners to save a lot of money.  Unfortunately we will have to demonstrate STP in space first.

To demonstrate the system we need to say produce a 'cubesat' STP able to propel a 1 kg payload from LEO to GEO.

In the case of this asteroid we need to bring all of it back, to find out what volatilities it contains.  Since in future we will not be using pure fuels the STP will have to be designed to deal with propellants containing these volatilities.

[JohnFornaro]

... devil's advocate is often helpful...

For beginning of asteroid mining we would need several things:
Light lag less than tens of minutes.
Frequent launch windows
Short trip times.

...something more than one hundred tons of water baked out of rock which we dragged to lunar orbit, every ten years or so...

[JohnFornaro]

For those who don't browse ...

Why would I do that? Makes my blood pressure rise....

<smilie></smilie>

[DougL]

Excuse me if this has already been explained, but I'm trying to understand the phrase, which Gerstenmaier uses repeatedly (and now the press and legislators are dutifully repeating), of "deep retrograde orbit". What exactly is that? I'm familiar with "distant retrograde orbits" (DROs), which are somewhat lopsided orbits in cislunar space, roughly centered on the Moon, in the X-Y plane. but "deep lunar orbit" is something that doesn't have any evident astrodynamic heritage. These "deep lunar orbits" are supposed to be highly stable, which DROs are also. Are these one and the same?

[RigelFive]

Like uhhhhh....  isn't the NASA Deep Impact mission pretty much long forgotten by the general public by now? 

Just to get a minute of excitement requires an explosion or possibly seven minutes of terror landing like MSL.  This sounds like there won't be any big thrilling moments coming up when something / someone lands on an asteroid.

These asteroid mission concepts are potentially so boring, they wouldn't even be covered on NASATV.

We could of had a NASA mission to construct a Death Star and perhaps explode asteroids 1980s style.... BUT NOOOOOO!

[JohnFornaro]

We could of had a NASA mission to construct a Death Star and perhaps explode asteroids 1980s style.... BUT NOOOOOO!

LOL

[R7]

These asteroid mission concepts are potentially so boring, they wouldn't even be covered on NASATV.

Hire Ridley Scott to direct the mission coverage. In the promo video the moment of unzipping the asteroid just begs for angry facehugger attack scene.