What "weed need" is a space mission!

[diep]

Originally Posted by xilman

Your duration assumptions are wildly wrong.

Current plans are for the probes to travel at 0.05 to 0.2c. Flight time is therefore 20 to 80 years. Results return at the speed of light so add another four years.

As I noted, large amounts of stuff has been shown to work perfectly for decades without any maintenance.

That's probes with nuclear batteries from which we know how long they last. They won't make it that much longer.

I hear wildly ideas through each other. First i hear something about solar parachutes and then suddenly something about lasers. Well let's forget about the lasers for now. Our lasers aren't powerful enough.

Then i hear something about weight. You do realize you need some power to ship back signals from Proxima Centauri to here?

[diep]

Originally Posted by xilman

The actual probes should not cost very much each. A few grams of graphene for a square-metre sail and a wafer-sized chip. In thousand-off quantities they might cost a million USD each, for a total cost of a billion.

The launch facility will be expensive, no doubt, but again economies of scale come into play. A phased-array of numerous lasers uses relatively cheap mass-produced components. A few billion USD should cover the manufacturing and installation.

Development costs are much less easily estimated. I'd guess something in the range 1-10 billion USD.


If I'm anywhere near the right ballpark, a mission cost of, say, 20 billion USD will cover it. This is more than an order of magnitude lower than your estimate. To put things in perspective, the Apollo project cost close to 100 billion USD in 2010 dollars.

Everything in space, first square the price and then the only question is whether it needs to get squared again.

To make some good pictures you need to equip each probe with a bunch of sensors and a good camera. You only get 1 shot at it with such mission so you want to equip it with really a lot of sensors.

You definitely need to ship something that's quickly 500 kilo or so. That would be something totally unprotected. We just gamble in such case nothing in space will hit it (as you ship a 1000 anyway).

How large does the sun parachute need to be in that case?

New Horizons launch mass was 478 kilo - yet that's without parachute.

[diep]

Originally Posted by xilman

....
Development costs are much less easily estimated. I'd guess something in the range 1-10 billion USD.

Well on development costs. Here i have a different opinion than how it currently works. I simply assume next:

a) spacecraft get ever more advanced and need to get more advanced
b) software you don't build with the same 2 persons that hacked together the spacecraft...

If we look how New Horizons was rushed together by just 2 persons that's not how it should go.

I'm in favour of a nonstop development team that develops great software and hardware solutions for future missions so that components are ready that can get used that work well and have been tested well.

First of all it reduces launch weight. Right now that mission we discuss probably needs to get hacked together by 2 persons within 1 year - before no more funding is there.

Either something gets funded now or not at all - and when it does get funded - you usually have little time to build something and deliver it.

That's dead wrong approach simply. A much better approach is not easy to find. Yet you simply want the best software guy to develop the software and the best hardware guy to develop the hardware. Right now that's not how it happens.

[xilman]

Originally Posted by diep

Everything in space, first square the price and then the only question is whether it needs to get squared again.

To make some good pictures you need to equip each probe with a bunch of sensors and a good camera. You only get 1 shot at it with such mission so you want to equip it with really a lot of sensors.

You definitely need to ship something that's quickly 500 kilo or so. That would be something totally unprotected. We just gamble in such case nothing in space will hit it (as you ship a 1000 anyway).

How large does the sun parachute need to be in that case?

New Horizons launch mass was 478 kilo - yet that's without parachute.

Once more: your assumptions are wildly inaccurate.

Each probe has a mass of under a kilogram. You are out by three orders of magnitude.

You don't launch one probe. You fire off a thousand or so. Who cares if even a hundred of them fail to work on arrival?

You don't get one shot. You get a thousand shots.

Not all probes need to be identical and carry a complete set of instruments. A hundred, say could be optimised for observing magnetic fields, another hundred for optical imaging, another hundred for measuring dust properties, another hundred for measuring the thermal properties of the planetary and stellar atmospheres another hundred for measuring the chemical compostition of the same. Let's see, I'm up to five hundred probes so far. Another five hundred still to be allocated.

A multi-megapixel camera and optics weigh a gram or less costs a few dollars at present.

The "sun parachute" (actually a light sail) is about a metre across.

The light sail is also the communications antenna. Communication back to the solar system is by laser. Diode lasers are also dirt cheap and very low mass.

New Horizons used almost totally different technology, rendering your comparison not particularly useful.

Please read https://breakthroughinitiatives.org/Initiative/3 and related material to bring yourself up to date on the proposals and technology I'm discussing. You appear still to be thinking about 1980's systems. I'm thinking about 2020-technolgy.

[chalsall]

Originally Posted by xilman

Not all probes need to be identical and carry a complete set of instruments. A hundred, say could be optimised for observing magnetic fields, another hundred for optical imaging, another hundred for measuring dust properties, another hundred for measuring the thermal properties of the planetary and stellar atmospheres another hundred for measuring the chemical compostition of the same. Let's see, I'm up to five hundred probes so far. Another five hundred still to be allocated.

Indeed. And even without guidance, they will all take different hyperbolic trajectories.

Should be a good and informative time.

[diep]

Originally Posted by xilman

Once more: your assumptions are wildly inaccurate.

Each probe has a mass of under a kilogram. You are out by three orders of magnitude.

You don't launch one probe. You fire off a thousand or so. Who cares if even a hundred of them fail to work on arrival?

You don't get one shot. You get a thousand shots.

Not all probes need to be identical and carry a complete set of instruments. A hundred, say could be optimised for observing magnetic fields, another hundred for optical imaging, another hundred for measuring dust properties, another hundred for measuring the thermal properties of the planetary and stellar atmospheres another hundred for measuring the chemical compostition of the same. Let's see, I'm up to five hundred probes so far. Another five hundred still to be allocated.

A multi-megapixel camera and optics weigh a gram or less costs a few dollars at present.

The "sun parachute" (actually a light sail) is about a metre across.

The light sail is also the communications antenna. Communication back to the solar system is by laser. Diode lasers are also dirt cheap and very low mass.

New Horizons used almost totally different technology, rendering your comparison not particularly useful.

Please read https://breakthroughinitiatives.org/Initiative/3 and related material to bring yourself up to date on the proposals and technology I'm discussing. You appear still to be thinking about 1980's systems. I'm thinking about 2020-technolgy.

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.

[chalsall]

Originally Posted by diep

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.

Just in case you are not aware, known life (including us) is carbon technology....

[diep]

Originally Posted by chalsall

Just in case you are not aware, known life (including us) is carbon technology....

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.

[chalsall]

Originally Posted by diep

structures in space that use carbon technology, such as hubble - they have a limited life - they keep shrinking.

Please support that statement with documentation.

[diep]

You can simply look it up at the hubble pages from NASA.

[chalsall]

Originally Posted by diep

You can simply look it up at the hubble pages from NASA.

You made the claim sir. Support it.