What "weed need" is a space mission!

[xilman]

Originally Posted by diep

For optics you'll need something that's like 8 inches at least in diameter, probably 10 would be better. Doesn't weigh that much though. Optics are optics simply.

For communications using the light sail seems suspected to me.

I'm not so sure using carbon technology is a good idea for something that has to get dead old. In space all carbon structures have the habit to shrink and vanish.

Lots of those 2020s technologies still need to get tested out and majority won't work.

Where do you get the figure of 8 to 10 inches (I prefer 20 to 25 cm but there again I'm British and more accustomed to SI units) for the size of the optics? My entire phone is only a fraction of that size and manages to take entirely adequate pictures as well as performing all its other functions.

A light sail, by definition is a reflector of light. Suitably curved it could focus a comms laser beam from earth on to the probe for software updates. It could also act as the transmitter antenna in the reverse direction, though I suspect that just pointing a laser back at the solar system will be better.

You are thinking about carbon fibre which does indeed tend to shrink. However, it's not the carbon at fault but the resin which holds the fibre together. It slowly evaporates in the hard vacuum.

The proposed structural material is essentially pure carbon, graphite for the probe body and graphene for the sail. Silica has also been proposed for the former. Even nicer, in many ways, would be a diamond structure but artificial diamonds circa 10-20 cm in diameter are not currently possible.

I fully agree that making square-metre scale sheets of graphene has not yet been demonstrated in the public literature. That is definitely some 2020-technology which needs to be demonstrated. I see absolutely no reason why it should not be possible within the next few years.

[only_human]

Custom developed diamond device technology is proceeding:

Under an operating microscope, doctors will cleanly chop through both spinal cords—with a $200,000 diamond nanoblade, so thin that it is measured in angstroms, provided by the University of Texas.

DOCTOR READY TO PERFORM FIRST HUMAN HEAD TRANSPLANT

[xilman]

Originally Posted by diep

We get protected by earth from the sun there. structures in space that use carbon technology, such as hubble - they have a limited life - they keep shrinking.

Hubble has been in orbit for something over 26 years now. It is still working and the shrinkage you allege has not yet caused it to fail. A trip of 4 light years at 0.2c takes twenty years.

Before you comment, I'm well aware that Hubble has been serviced. Such servicing was of the optical and ancillary equipment, not the structural components.

[LaurV]

Originally Posted by only_human

DOCTOR READY TO PERFORM FIRST HUMAN HEAD TRANSPLANT

Didn't click it yet (busy here!) but wondering: is that a head transplant, or a body transplant? If you take the heart out of a guy (whose body is damaged) and put it inside other guy's chest (whose heart was damaged), that is a heart transplant, which makes the second guy function, using "spare parts" from the first. But if you take the brain out of a guy X (with a damaged body) and place it inside the scull of other guy Y (whose brain is damaged), is that a brain transplant, or a body transplant? Because when (and if) the "functioning" guy wakes up, he is X, in a new body. And not Y with a new brain. All the knowledge, memories, logic, un-logic, whatever, is from the X guy....

[only_human]

Originally Posted by LaurV

Didn't click it yet (busy here!) but wondering: is that a head transplant, or a body transplant?..

Head transplant onto a donor body ... as you say it could be called a body transplant but when you move a plant into a bigger pot we call that a plant transplant instead of a pot transplant. This ethically challenged procedure will be moving a head into a bigger pot.
The Audacious Plan to Save This Man’s Life by Transplanting His Head

Spiridonov’s head would float across the operating theater to the donor body on a customized crane, hanging by Velcro straps. Surgeons would align the spinal stumps and bind the two ends together, using peg to fuse Spiridonov’s spinal cells with the donor’s. The surgeons would also implant an electrical paddle near the fusion site, because studies have shown that bursts of electricity help establish communication across a severed spinal cord.

At the same time, another team of surgeons would begin the long, messy process of attaching a head to a body. With the hour ticking down, establishing blood flow to Spiridonov’s brain would take priority. After that, surgeons would install the spinal bones, trachea, and esophagus, then attach the color-coded muscles. One vital step would involve connecting the nerves that carry signals from the brain to the heart and to the muscles that pump the lungs, so Spiridonov’s new body could breathe and regulate its heartbeat.

Thirty-six hours after entering surgery, the new Spiridonov would roll out the door, sitting upright.

[diep]

Originally Posted by xilman

Hubble has been in orbit for something over 26 years now. It is still working and the shrinkage you allege has not yet caused it to fail. A trip of 4 light years at 0.2c takes twenty years.

Before you comment, I'm well aware that Hubble has been serviced. Such servicing was of the optical and ancillary equipment, not the structural components.

Hubble has been designed such that it could survive some decades of shrinkage.

Yet there is a limit to it when the motors no longer can compensate for it.

No service mission would help in the end. Yet from my viewpoint i wonder already for a long time why they didn't design it such that it could get serviced by robots.

A robot of a few kilo's, maybe even lighter, is a lot cheaper to launch to low orbit than a human being with a space suit, survival gear and so on.

[diep]

Note that telescope apertures usually work in inches just like your plumbing tubing does.

Even though the inches that plumbers use are total outdated as nowadays improved production techniques take care the thickness of the pipes has improved a lot.

My telescope here is 10 inch.

Yet the entire math regarding the rest is in millimeters :)

[diep]

Graphene type structures are highly poisenous.

I'm not so sure we soon will see industry grade materials that are easy to proces from graphene as there is only some industrial purposes to it.

Right now in a lab they have like 1 atom thick layer material or something and largest size ever produced you still need a microsope - would be amazed if it's above 1 square inch by now.

That'll take decades.

In space using graphene i'm not so sure that would be a good idea - yet i'm no material expert in that sense. The carbon structures in space all shrink.

After graphene has been produced on earth it still needs to be tested in space of course.

Why can't the parachute be from some other material?

If you want to use it as a laster disk i assume aluminium is a good material?
Highly reflective!

Yet something travelling that far away i assume such parabolic sphere needs to be pretty large. Maybe diameter 10 meters would be enough?

[diep]

Note that i remember that pluto photos from recently were taken with a camera with 10 inch lenses - yet i do that from memories from some time ago - so you might want to dive into that one.

If you don't like the quality of those pictures, your probe to other stars will need to carry larger camera's with it.

Probably you want it to have at least 2 camera's as getting back pictures is most important.

Quite probably you want better camera's as well - which basically means larger enlargements - so that means wider apertures - as you are going to take pictures from further away most likely from planets.

[diep]

As for shipping probes out to discover outside our system - please realize i'm a fan of that.

Yet it'll require a better approach than past missions. Spending billions for probes that get hacked together by 2 men within a year time - without KNOWING it works ok - i call that amateuristic work.

A professional probe to discover far far away systems - it'll require some testing and tests - as well as maybe more than we were used to have. Like having its own autonomeous robots that can move outside to repair and inspect - remove dirt and so on. Can be very tiny robots and maybe some service robot that can do welding / 3d printing of materials to repair small damages.

If you ship something - please ship something professional :)

[xilman]

Originally Posted by diep

Graphene type structures are highly poisenous.

Evidence please. This is the first I've heard of the claim --- an admission of ignorance on my part.

Anyway, what does it matter if they are poisonous? Hypergolic rocket fuels and Pu radioisotopes are highly poisonous too, but space missions use them regardless.

Originally Posted by diep

That'll take decades.

Why? Anyway, the project assumes a 20-year span for research and construction, so we have decades.

Originally Posted by diep

In space using graphene i'm not so sure that would be a good idea - yet i'm no material expert in that sense. The carbon structures in space all shrink.

Once more: you are talking about carbon fibre composites, where it is the binder which shrinks, not the carbon fibres themselves. Graphene sails and graphite (or diamond) structures are pure carbon and are extremely unlikely to shrink. If you have evidence to the contrary, please produce it.

It's far more likely that a graphite spacecraft structure will expand rather than shrink. Experience with graphite moderated reactors shows that the crystal structure is damaged by radiation in such a way that atomic-sized voids are created as carbon atoms are displaced by high energy radiation. Interstellar gas travelling at 0.2c is high energy radiation. Fortunately its density is so low that significant damage to the graphite crystal structure won't occur. Note that this is easy to test in the lab. Creating 0.2c proton and helium beams is easy. Heavier atoms too, but they are much less common in the ISM.

Originally Posted by diep

After graphene has been produced on earth it still needs to be tested in space of course.

Agreed. Easily enough to do, and on earth too. Vacuum chambers exist down here; they can be kitted out with UV radiation, heating and cooling, ionizing radiation, mechanical vibrations and so forth. This is old technology. It was used over fifty years ago in the Apollo project.

Originally Posted by diep

Why can't the parachute be from some other material?

It can. Graphene is very much lighter and stronger than other known materials.

Originally Posted by diep

If you want to use it as a laster disk i assume aluminium is a good material?
Highly reflective!

Aluminium is reflective but weak. Light-weight mirrors generally use a thin plastic, such as mylar, on which very thin layer of Al (or Au for infrared mirrors) has been deposited.

Originally Posted by diep

Yet something travelling that far away i assume such parabolic sphere needs to be pretty large. Maybe diameter 10 meters would be enough?

You can assume anything you like. Your views would be taken much more seriously if you first read and then understood the proposals before commenting on them. I've already provided you with the starting point for your investigations.