Glue and Glue-like anchoring (strictly no harpoons, move along!!)

[Andersenman]

Hello, fellow forumnauts,

From the 67P thread:

What would you suggest? Superglue?

Pros:

• Specifically, Cyanoacrylate binds with water, which the comet is known to have plenty of.
  
• Glue is somewhat agnostic to ground structure. It can stick to hard rock as well as coagulate dust into anchoring clumps.
  
• Can engage a large contact area.
  
• Can be combined with other anchoring technology (glue lance/harpoon/screw)
  
• May employ local resources both chemically (like the superglue example) and physically (eg. simple melting and freezing)
  
• Able to create bonds without requiring a (counter-) force, initially or permanently
  

Cons:

• Substances unstable over longer periods of time
  
• Are there glues working at these temperatures?
  
• Out-gassing, soil contamination (at least near the anchor points)
  
• Mechanical reliability solely dependent on soil wetted by the glue and the material in immediate contact
  
• Not instant
  
• Single-use only
  
• Once set, difficult/impossible to adjust. (You can tighten a screw simply by turning it more, you can't squeeze more glue from a set nozzle)
  

Modern glues have long evolved from their starch and egg yolk ancestors. May I hear your educated and/or wild guesses on application of glue or glue-like technology in spaceflight, please? Specifically, for landing and anchoring, as crazy as it may sound at first, but anything that fits 'after craft or person have left the protection of both homely atmosphere and something with 1g to stand on' I'd be very interested to hear your thoughts and knowledge about.

Many thanks

A.

Edited November 14, 2014 by Andersenman

[Camacha]

Glue is great, until your target is covered by a thin layer of dust. Then it becomes useless real quick.

[Tommygun]

Yes the dust will kill the glue.

But maybe if you have several dozen kilometers of thin strong line..........I'm thinking space cowboys and comets.

[Andersenman]

Yes, I am aware of the dust issue. A simple kitchen experiment, trying to glue something to a pile of flour, should demonstrate. Flour screens liquids from penetrating deeper because when it gets wet, the starch activates and expands into a gel, creating a barrier. However, I don't (yet) have reason to expect mineral dust to behave like starch, and with a wetting agent (say, soap) any prevalent Lotus effect should be overcome, if the glue or its solvent isn't already capable enough. But feel free to educate me otherwise.

[magnemoe]

Yes the dust will kill the glue.

But maybe if you have several dozen kilometers of thin strong line..........I'm thinking space cowboys and comets.

The line idea is pretty smart for smaller bodies, think a KSP class E up to some hundred meters who make them a bit large to bag, probably be smarter to do it more like a net you close on top.

[LaytheAerospace]

A potential problem I see is we don't know just how strong the comet's surface is. Doesn't matter how good your glue is if the thing it's stuck to just flakes off under modest pressure. Stakes (or harpoons) work very well to tie things down to something with a weak surface, which is why we use them to secure things to loose dirt on Earth.

[Sky_walker]

Cons:

• Substances unstable over longer periods of time
  
• Not instant
  

It will not work for the reasons above. You can't replace harpoons with something that is not instant and we can tell from right on that won't survive 10 years in vacuum.

[Technical Ben]

The line idea is pretty smart for smaller bodies, think a KSP class E up to some hundred meters who make them a bit large to bag, probably be smarter to do it more like a net you close on top.

With a slow enough approach, a multiple set of long lines and weights could "clamp" the craft to the asteroid... I'd say look at biology and how it does it. They kind of have with the thruster/drill/harpoon idea. It's just the strength of each, the size of the tool (penetration into the ground was not deep enough for such a dusty landing site) etc seem to have let the poor lander down.

Perhaps a harpoon/drill/rod that expands once into the ground?

[Camacha]

Perhaps a harpoon/drill/rod that expands once into the ground?

The Philea ones already do.

[Andersenman]

Guys, guys, guys, hold it.

Thanks for your input so far, but please keep in mind that I wasn't implying glue to be an outright replacement for anything, have already acknowledged and addressed the issue with surface dust/flakiness, and, while purely "macro-" mechanical means of attachment or anchoring alternatives are interesting to hear about, wasn't planning to have the subject changed to those. In this thread I would prefer to keep it to any substance or preparation, or in-situ generation and/or utilisation thereof, with the purpose of creating a viable anchor or attachment point in space or other extra-terrestrial environment by means of changing from a liquid to a solid by undergoing phase change and/or chemical reaction, their practical application, and solutions to make these substances or means of timely preparation spaceworthy. In other words: I listed the cons to learn thoughts for solutions, not to have my thread answered with what I already know.

Many thanks

A.

[Moar Boosters]

I expect they might use a design like this for future missions to unpredictable environments.

http://www.wired.com/2014/02/nasas-super-ball-bot-revolutionize-robotics/

I don't think the concept existed when Philae was designed, but it appears to offer many advantages over a traditional design. The most obvious being it's easily movable on terrain unsuitable for wheels. Obviously there's a big risk of it getting snagged on something....... but that's something they should be able to reduce using test-environments on earth.

If it contained experiments that require anchoring, I expect it's design could entail multiple anchoring methods and use whichever is deemed most suitable. Dust it a big problem for glue, but if the lander was able to move around and find a suitable surface..... maybe use a small can of gas to blow it clean..... I'm sure it could be viable.

Edited November 14, 2014 by Moar Boosters

[GregA]

Use an explosive to fire a nail or piton into the rock or regolith. vent the explosive so it provides all the needed forces to set the nail. Small light and fail safe.

The problem they are having with Rosetta is that they designed it to land on a surface that is mostly water ice. If Rosetta had been launched after Deep Impact it would have informed their design choices. They would have known the surface of comets has no water ice, and is made of carbonaceous chondrite. They were working with the best information they had at the time,

[Kryten]

The problem is the harpoons never fired at all, and neither did the thruster. The screws alone would not be sufficent in any material.

[Armchair Rocket Scientist]

Yes, I am aware of the dust issue. A simple kitchen experiment, trying to glue something to a pile of flour, should demonstrate. Flour screens liquids from penetrating deeper because when it gets wet, the starch activates and expands into a gel, creating a barrier. However, I don't (yet) have reason to expect mineral dust to behave like starch, and with a wetting agent (say, soap) any prevalent Lotus effect should be overcome, if the glue or its solvent isn't already capable enough. But feel free to educate me otherwise.

Okay. Buy some sand - as fine as possible - from your local hardware store and perform the same experiment. It will be a bit different from actual regolith because the grains will be rounded, but should still be a decent analog for determining whether glue will stick to the surface in a useful way.

[Tweeker]

I'd worry about contamination. It would be hard to get a clean sample from the surface after then glue had set and out-gassed

[Aningaaq]

Not really glue but people have been looking at gecko feet for robots stability recently. http://www.washingtonpost.com/news/speaking-of-science/wp/2014/08/12/new-research-investigates-the-physics-of-sticky-gecko-feet/

[Nuke]

im having a hard time finding any information about the workings of the harpoons, i personally would have stuck it in a shotgun shell and fired it with a solenoid. im rather curious what they used.

powder actuated pitons might have been a better idea, thinking foot long rods of metal fired into the surface at diverging angles, this would also set off a powerful anti-recoil charge to keep the probe on the ground.

you still want to use glue, take a laser and bore a hole a several cm deep, just a couple mm across. then insert a thin metal tube capped at the end and full of tiny perforations, insert it into the hole and inject an epoxy resin (vacuum would draw it out of its reservoir and you just need to turn on a couple solenoid/servo valves to activate). the epoxy would be mixed when injected into the tube, and would harden pretty fast. the laser bore would not be a perfect cylendrical tap because of focusing concerns, and this is perfect for creating a good bond with the tube, epoxy, and the surface material. small lasers are getting really good at puncturing through various materials, i think the best bet would be to use a 1MW pulse laser, firing a high powered pulse for a tiny fraction of a second, you would need to recharge the capacitors from the solar panels after each pulse, and it might take days to complete the bore. such lasers have been made very portable, for example this one, which can punch through sheet metal.

[peadar1987]

Problem is epoxy needs to be very well mixed, and it also doesn't keep particularly well, particularly when there are extreme variations in temperature.

[heng]

Pros:

• Specifically, Cyanoacrylate binds with water, which the comet is known to have plenty of.
  

Cons:

• Mechanical reliability solely dependent on soil wetted by the glue and the material in immediate contact
  
• Single-use only
  

I would suggest using a different material, if I may. Instead of using cyano-acrylates, which bond with water, try using UV curing adhesives. You can just release a blob of the stuff, adjust as necessary - take your time, then switch on the lamp for bonding. Basically glueing the UV lamp directly to the surface:

######### -   surface
.#.#..#.. 
......... -   adhesive
========= -   glas
=^^^^^^^=
=|||||||= -   UV light/heat lamp

Pro:

- more time to adjust to optimal position

- bond can be released after use by using a heat lamp

- not reliant on water

The other Pros and Cons are the same.

[Nuke]

one problem that occurred to me is you are going to be releasing contaminants into the landing site, which might ruin your experiments. blobbing on adhesives might be a bad idea if you want soil samples.

[GregA]

Woah... If your target is made of nickle iron....

Just a big old magnet on the bottom of your probe.

[Deadpangod3]

Woah... If your target is made of nickle iron....

Just a big old magnet on the bottom of your probe.

that would require your target to have a magnetic field, which usually only planets have, since it is generated by a mantle and a solid core, which asteroids and comets dont have, and you wouldnt need a magnet on a planet since you have gravity.

Edited November 18, 2014 by Deadpangod3

[Oscilllator]

that would require your target to have a magnetic field, which usually only planets have, since it is generated by a mantle and a solid core, which asteroids and comets dont have, and you wouldnt need a magnet on a planet since you have gravity.

NoNo. The magnetism of a blob of Nickel/Iron is completely separate from the the earths magnetic field. Magnets by definition have their own magnetic field, they don't need an external one to work.

Back on topic though, nobody has mentioned a crucial drawback that is common to all glues - before they have time to set, they will evaporate! All glues are either based on polymerisation or the evaporation of a solvent such as water. Either way, an active component of the glue is quite volatile and as such will evaporate very quickly under the near-perfect vacuum of space. The most likely outcome of this is that the nozzle will be gummed up as soon as it is opened, and at best your glue will be very ineffective, having mostly evaporated before it had time to properly set.

[*Aqua*]

What about something simpler?

Before landing shoot a net at a big rock. The net then wraps around it and tigthens itself (maybe with help of a winch). Even if the lander weights only 3 grams on a comet, a whole boulder weights at least a few kilos serving as an anchor.

Pros

- easy mechanics

- proven design

- survives enviroment

- allows integrated sensors if there's an application for them

Cons

- propably size and mass

- needs a fairly complex aiming system (cameras, computers, actuators)

- needs a decent sized and shaped rock

Edited November 24, 2014 by *Aqua*