I work on a small team (10 people) that has about the same number of engineers, technicians and and scientists. I'm an software engineer with a science background, just under 2 years out of undergrad, and the most junior except for one tech. The team needs to decide whether a particular metric is suitable for a report we're putting together. A couple people have done some work on this, but it's been largely unfocused and not very fruitful. My job as I understood it was to implement the algorithm for others to do experiments on.
After a recent progress meeting (during which very little progress was shown), the team's manager asked me privately to take responsibility for the work getting done, but not in so many words. He also implied, but did not state, that I could give tasks to others. The work involved for this is probably on the order of hundreds of man-hours; I can't work full time on this project.
It feels as though I have been given (a large) responsibility without the power to make it happen. I think I'm capable of designing a test plan for this problem, but I'm uncomfortable about how to communicate about it and get the other team members to do their part of it. It's possible the manager expects me to send it to him to ok, and then he will tell everyone else, but generally speaking he's very laid back and uninterested in anything except results.
Question: How do I make a plan which involves the efforts of several people without an official way to set tasking? What's the best way to introduce something like this to my more experienced coworkers?