A spaceman, a labourer and a blank canvas who turned up with barely a game to his name. These are the rookies ready to step in and fill the void for the Canberra Raiders as the premiership contenders prepare for a heavy travel toll in a revamped NRL season. Parkes Spacemen junior and NSW under 20s back-rower Darby Medlyn joins versatile forward Kai O'Donnell and teenage prop Ata Mariota in the fold for the Green Machine. The trio could soon find themselves banging down the door for a start after the club waved goodbye to Jack Murchie [New Zealand Warriors], Luke Bateman and JJ Collins [Queensland] over the past fortnight. Raiders recruitment guru Peter Mulholland says the rookies enter the fray with plenty of potential but concedes no second tier competition for them to bide their time in makes for a steep learning curve.