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Comment by DCKing | Hacker News Reader

The most expensive element you can currently send to Mars is platinum [1], which would equate to a value of roughly €10 million. All other things you could send either decay quickly (plutonium) or otherwise devalue over time (micro sd cards) or fluctuate too heavily to depend upon (microSD cards filled with Bitcoin private keys, LSD).

I wonder what would happen if a space agency went to Mars and dropped a minted coin valued €50 billion (or something) by the US Treasury/European Central Bank/National Bank of China and see who could retrieve it the quickest. That should be an interesting competition.

[1]: http://what-if.xkcd.com/108/

(Edited because for wrong terminology)

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> The most expensive rare earth element you can currently send to Mars is platinum

Platinum is not a rare earth element. REE is a specific term which describes the lanthanides, scandium and yttrium. Platinum instead belongs to the imaginatively named platinum group.

> The most expensive rare earth element you can currently send to Mars is platinum (...)

> All other things you could send either decay quickly (platinum) (...)

I don't understand. Did you mean platinum in both places? In that case, I got confused by the "other". Or did you mean something other than platinum in one of the cases? Or am I just failing to comprehend? :)

Based on the xkcd link I'm sure he meant plutonium decays quickly.

So out of curiosity:

Wolfram has the weight of a MicroSD card at half a gram.

So 300kg of those cards would work out to about 600,000 of them.

Let's say they're 8 gig cards. The largest BTC private key size is 512 bytes, so you could fit about 15.62 million of those large keys on a single card, or 9.36 trillion individual keys in the entire lot.

Now for sake of sheer bloody-mindedness, let's assume each of those wallets have 1BTC to their name. (Nevermind this is impossible since there will never be that many bitcoins)

3 quadrillion 718 trillion 728 billion dollars.

That's the entire GDP of the world, about 44 times over.

Damn.

You could fit every bitcoin currently minted on one single card, and have a card worth about 5.5 billion USD.

(5.5bn in .5g. That's a pretty crazy value to weight ratio)

The maximum amount of BTC that can be created is only around 21 million.

Cryptocurrency stuff might be needlessly complex for a reward mechanism.

Just put a secret on the weight (stamp it on the tungsten or something) and promise the one who reads it some sum that was deposited on a bank account before launch.

It should survive entry and impact.

This should be really interesting to do with public key cryptography.

Generate an RSA private key and corresponding 32+ kbit RSA public key. Send off the private key to Mars, and afterwards publish the public key. Award €50 billion to the party which can prove possession of the private key and give a demonstration of how it was obtained.

Anyone claiming the price has either:

- Gone to Mars and returned with the private key

- Broken the prime factorization problem from a theoretical perspective

- Built a practical quantum computer and thereby broken the prime factorization problem practically

Admittedly, the first and last would be big advancements for humandkind, but the second one would probably mostly give some really nasty problems.

That sounds excellent, though 50 billion is a bit too much. Say 10 billion?

You could send stuff to Jupiter's moons, to asteroids or to Mercury as well.

It would need to have some kind of a passive beacon to aid retrieval and prove that it is there. On Mars dust is a problem so a retroreflector might not hold up for long.

Ah, I falsely remembered hearing quotes on a sample return mission to be $20 billion, and was factoring in estimation errors and profit incentives.

Mars should be the first goal, I think. IANAP, but I think Jupiter's moons and Mercury are very substantially harder to collect samples from when compared to Mars. For Mercury it would be very difficult to escape the Sun's gravity well and get enough momentum to return to Earth orbit. Jupiter is also much further away than Mars and has a huge gravity well to escape from too. I'd wager that sample return missions are possible to them practically even given unlimited budget.

You'd likely read the data in situ and just beam the info back. That's orders of magnitude easier than sending anything back here.

Gold and platinum are each a smidgen more dense than tungsten, so if you're willing to splash out for one of those metals you'd even have a bit of volume left over for a really tiny science experiment.

As a note, there is only 13.3 Million BTC in existence, which comes to ~$5 Billion USD market cap.

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