Missions to and Sample Returns from Nearby Interstellar Objects
arxiv.org
arxiv.org
One point that I haven't seen discussed in similar papers was the need to deal with uncertainty in the object's trajectory. You have to be able to do targeting (i.e. carry a big enough telescope) and do course correction on-route (i.e. carry enough fuel).
I'm all for nuclear rockets, but it's a bit hard to believe that people will accept a flying nuclear reactor when you remember the controversy over Cassini's comparatively puny RTG.
From a technical standpoint, both Cassini and Galileo did Earth gravity assists. The argument was that an error in navigation could cause them to hit Earth on such a flyby. While RTGs were designed to remain contained on launch failure they wouldn't survive such a high-speed reentry. Another (much less realistic) fear I heard was that the plutonium in their RTGs could ignite fusion in the cores of Jupiter or Saturn when the probes were dumped into their atmospheres.
Neither of these two concerns apply to Mars rovers.
No way we will see something like this without military involvement. Thinking about the huge amount of money to be invested.
Actually, wouldn't it be a blast if we found signs that someone had done just that already?
Imagine you were making a sail-propelled probe, with the intent of slowing the probe so it was captured by the target system. So the probe would have two sails. The first would be deployed after launch, to catch the initial laser beam, then later solar winds, to accelerate to system escape velocity.
You'd then detach that sail, and cruise. Later, you'd deploy a second sail to start braking on your way into the target system, to slow to capture velocity.
The first thing the inhabitants of the target system would see would be the first, discarded, sail as it tumbled through their system and accelerated back out ...
Why? Just accelerate towards the target as long as possible and then flip around. Assuming a columnar source (e.g. from a laser) and non-columnar target (e.g. from our sun), this could be done with minimal (if any) cost in time to arrival.
Carrying two solar sails is expensive. If it’s not, I’m not sure one would be using solar sails at all.
1) The characteristics of a good laser-propelled acceleration sail would be different to those of a good solar-powered braking sail.
2) Flipping around while attached to a deployed solar sail would be hard. In my head I'm imagining something like looping a paraglider (https://www.youtube.com/watch?v=-oEeTtQIEjs) but much harder. It'd have to be autonomous (no fly-by-wire at those ranges), and for recovery purposes I'd want to have a spare sail anyway that it could deploy in the case the primary got tangled.
That’s got to be more difficult than spinning around because any mistakes will be amplified over the vast distances, whereas a slight trajectory problem once you’ve arrived is much less of an issue and is correctable with onboard guidance. If you screw up the detach procedure.... you can’t steer to correct.
Assuming two different methods of acceleration (laser on departure, solar on arrival), why not construct the sail in such a way that the probe goes through the sail? It could pull the sail in, and mechanically route it’s connections to the rear of the craft. If there are material or structural difference needed, it could be incorporated into the design and two opposing surfaces.
Missions to (and Sample Returns from) Nearby Interstellar Objects
However, the 'correct' parse would be: "(Missions to and Sample Returns from) Nearby Interstellar Objects", i.e. the two nouns 'missions' and 'returns' (with 'sample' as its specifier) are linked by conjunction because only words of the the same type (noun, verb etc.) can by linked by conjunctions (or disjunctions, for that matter).
Missions (Plural Noun) To (Preposition) And (Conjunction) Sample (Verb)
Where they should have
Sample Returns (Compound Plural Noun)
My grammatical terms are probably all wrong, but you get the gist. It reads fine to me, but it can be hard to see these hiccups once you've read it the "correct" way. Edit: Also I think the unusually-placed preposition is pushing them that way.
So in expanded form:
"Missions to Nearby Interstellar Objects and Sample Returns from Nearby Interstellar Objects"
So "Collecting Samples from Nearby Interstellar Objects" would have been enough to do the job.
"Missions and Sample Returns to and from Nearby Interstellar Objects" is probably what I would have made from that, but no idea if that is allowed or comprehensible.
English is not my native tongue and I noticed that I don't understand capitalization as well as I thought. Why do you do that now? Just because it is a title? And why not for to/and/from? Are prepositions exempt?
A mathematician or experienced computer programmer would, of course, reach for parentheses instead of commas.
A headline writer uses nothing. Brevity and attention capture are their goals, not clarity of content.