"There are ten people on the crew," he says to Nerdanel of the first test of lightleapers for intergalactic travel. "Mandos agreed to resurrect them if they get stranded and can't get back and stop their hearts before they run out of supplies. Now, if they do it in a specific order, then we have a mechanism by which they can transit a nontrivial amount of data - there are 3628800 orders in which ten people can die, and we can ask Mandos about times of death -"
"Or we could just ask them once they're resurrected."
"That might take Years!!"
"If only we had a way to do resurrections ourselves."
"Not soon enough."
"I could give the crew a book of possible messages and the suicide order associated -"
"It'll upset them, they might not stick to it, it puts them in a terrible position if one person is suddenly unwilling to suicide -"
"It wouldn't upset me. It'd make it easier, really, knowing someone was learning something -"
"You're very unusual, love."
The lightleaper coordinates are set for an unthinkable distance away. The crew is not advised on any particular order for suicide, should it be necessary. It shouldn't be necessary. Tests of shorter hops have gone fine, trips to Endorë would be practically routine if not for the recent political complications. The math all checks out.
But if it fails, somehow, they will be very, very far away when it does.