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[Remcook]

Ok, so we found some nice planetary systems to explore and we have some nice propulsion technology to get there pretty fast. So you produce some nice probes in a large batch (all standardized).

What instruments would be on such a probe? and what could you already do by remote sensing?
"_____________________________

-Imager
-Radar (in case of thick clouds)
-1 small lander (for probing a planet from up close)
-magnetometer

[rob schwarz]

Would be a system that was accurate enough and powerful enough to send a signal back to Earth.

And a power system that would survive the long trip out. It might be possible to have most of the ship power-down during the majority of the journey but you would still need some power going all the time.

Niether seems to be techologically insurmountable problems.

[Remcook]

But besides the problems, how would you like to see such a probe?

[rob schwarz]

The probe would have to be fairly cheap or else its competing with my manned mission to Mars or the Moon. Probe would also take 8 years to have any turn-around, assuming it travelled at the speed of light to Alpha Centauri. Realistically speaking we're talking decades for it to get anywhere and even more decades to get back.

Government types have a hard time thinking in that kind of time frame.

[Remcook]

Sorry Rob, but I was not assuming this to be realistic. I just wondered that in a hundred years or so, when we hopefully have explored our own solar system and found a lot of others, we could send probes to these solar systems. I'm not asking if it's feasible, I'm just asking:

What does a standard interstellar probe need to make a good picture of other solar systems?

[rob schwarz]

We'd want details on all of the planets, and their orbits, and if the orbits are stable. We'd want to concentrate on any planets that are unique or Earth-like and go in for some close details on those.

Beyond that, its out of my league. I just hope they make it smart enough to not be distracted by a wookie, and to not self-distruct at the first blaster shot.

[TVYee1]

The agonizing problem is getting data back from so far away.  However long it is until we do a mission like this, that part of radio physics is unlikely to go away, so our instrument suite probably has to have a way to condense it's data stream enormously before transmission.  I'm not talking just compression, but using on board AI to analyze the data and just send back the results with a minimum sample of raw data for scientists back home to validate.  That means, no high resolution global maps, or hyperspectral images in the final data products, or even Synthetic Aperature Radar.  Neutron spectrometer for detecting water (actually hydrogen) is good due to it's low data rate and easy analysis on board.  I like the magnetometer too for similar reasons, although a magnetic field map would probably be too much data.    Charged particle counters (maybe mass specs) would be good, although you could argue about whether the data would be as scientifically interesting as some other choices.  Probably most useful on the interstellar portion of the journey.  On the lander, there are some nice X-ray differaction sensors made now that give great molecular species detection, plus they're really small.  Couple that with a residual gas analyzer and some type of life detection experiment and a still camera for a couple of hyperspectral snapshots of the surface and I think you've got the lander suite mostly done.  Add a standard weather station with temp, wind speed, pressure, and relative humidity.

On the orbiter, you probably want an IR camera too.  I guess a lot of the planetologists agree that IR can tell you more than visible as far as composition goes.  Maybe if your AI is smart enough, you can autonomously use the cameras to map out the place and then select a few shots of closeups to send back home if they are particularly interesting, like active geological sites or potential evidence of life or civilization.  Better include a good radio frequency scanner on board to listen for signals or for plasma physics.

I'd be tempted to dump all the imagers however, except for a simple, very small aperature visible camera, just for the mass savings.  I can only imagine how tight the weight constraint will be for this mission.

[Remcook]

Thanks a lot for all the info!

In the future I can imagine these satellites have supercomputers the size of matchboxes, so the on-board data processing won't be a problem. I can also imagine there being a communications network streching at least to Saturn for different exploration programs so that may help a little, using interferometry, to have better contact with a distant space probe.

Maybe if these probes are send -say- every ten years, data could be relayed to the closest other space probe. But then these probes would need huge receivers, but they need that anyway.

[String]

We'd need to compromise between high-tech wizadry and old fashioned strength.

Where ever we send it the thing is in for a very long journey with exposure to radiation, temperature extremes, micrometeorites and who knows what else.  IT'll need to be build like a battle tank !

Power source, assuming a star at the end will be solar but it will have to have RTGs or similar to power it en route (even then the half life of the RTGs arent going to provide power for say 20,000 years it'll take to get there) so we need something with an even longer half life.

As for probes, spectrometers, radar (mapping), thermal mapping and the usual stuff like that.  A nice capsule to send to the surface as a "we've been here" thing would be a nice touch.

Two way communications would be near impossible given the time to travel to the probe and back so it would need excellent software capable of adapting and learning itself.

A dish the size of something used on the DSN to send back data would be nice too


Anyway, just my thoughts.

[John Fraz]

step 1) Build a pilot SPS system. (Prerequisite, space industry, primary profitable venture; GEO telecommunications antennae farms from NEA materials)
 As an early project of that pilot SSPS, zap a starwisp probe on its way.
As the probe nears the target system, the first and a second SSPS array send phased microwave beams to flood the target system.
 Within 25 years from sending the first wisp on its way, you have detailed images of everything in the system. Down to a depth beneath the soils, you have rough compositions on everything the probe passes near.


As you said, we're not asuming that we're launching everything on Shuttles. Rather, we're positing some advancement, and space resources and better funding than space gets now.

Acrobat file
www.whidbey.com/forward/pdf/tp075.pdf
website
ffden-2.phys.uaf.edu/213.web.stuff/Scott%20Kircher/lightsails.html

[Remcook]

one word: WOW!

Never heard of that!

I understand that you can build larger dishes on earth to send the microwaves, but doesn't the rotation of the earth makes the microwaves not always available for the probe. Except when you have more dishes. Or one in orbit around the sun.

[String]

Yep, thats why the DSN has several dishes spread around the planet so there is always one pointed towards whatever target they pick.

On a sort of related SDC thread i dug up NASA/JPLs communication strategy for Mars and cutting a long article short their long term plans involve a relay at a Lagrange point meaning it will always be able to see earth and never blocked by the sun from a Mars perspective.

Ive got a feeling relays like this will be needed and will become the norm if we ever start serious space exploration robotically or manned.

[TVYee1]

Starwisp certainly rocks and Robert Forward is an engineering hero of mine.  The problem at this stage is figuring out any real engineering details for a device that is so far ahead of the current nanotechnology curve.  We're just figuring out how to make simple mechanisms on this scale right now.  Sensors of the type we're discussing are very hard to conceptualize on the nano scale.  I'm not saying we won't get there eventually, it's just hard to say if it'll be 50 years or 500, so although I like Starwisp as a concept, it's still too much fiction and not enough science for my taste.  Give me a "bulky" 10 gram CMOS camera instead.

The Starflight Handbook is a great read on the topic and goes into a lot of interesting "what if's" about the detailed technical challenges and possible solutions, including Starwisp.  The amazon link (if it pastes right) is below:

www.amazon.com/exec/obido...s&n=507846

[remcook]

I don't know if you can read this document, and I haven't read it myself (yet), but it seems interesting.

d'oh! add attachment

http://www.jpl.nasa.gov/csmad/journal/issue2/02.pdf