Returns on investment on peer-to-peer (P2P) lending sites (a similar funding method) have been in the 10% range.

FORBES: Are You Looking for a Small Business Loan in the Right Places?

In the 1990s America's Supreme Court deemed it the responsibility of federal judges to insist that expert witnesses testify about the reliability of a forensic-scientific method only if the method in question has been tested so that the range of its error rate is known.

ECONOMIST: Fingerprint evidence

Add in the effects of chance (what is known as the Monte Carlo simulation method), and you end up with what should be a plausible range of timescales and costs.

ECONOMIST: Tuberculosis

Conveniently, more modern spacecraft than the Pioneers include separate range-finding hardware, which can be used to test the accuracy of the Doppler method.

ECONOMIST: A space oddity