Long term absentees Heremaia (neck) and Westerman (shoulder) have been joined on the sidelines this week by centre Kirk Yeaman, who has had surgery on a foot injury this week.
Centre Tony Martin has been cleared after suffering a head injury in the win at St Helens last Friday, while Aspinwall is waiting the results of tests to see whether he can feature against the Vikings, who picked up their first win in Super League last Sunday.
Head Coach Peter Gentle told the club’s official website: “We’re looking forward to getting Aaron back but we won’t be taking any undue risks with him.
“The important thing for us is not to rush him back too soon, particularly with a neck injury, so we’ll take our guidance from our specialists and take the appropriate course of action.
“As for Joe, it’s long road to recovery unfortunately but he has taken it well and in his stride so far.
“It’s unfortunate to lose a player for such a long period of time and hard for them to cope with it when they’ve worked so hard in pre-season, but he’s a bright young man, he’s working extremely well on his rehab and looks to be a touch ahead of schedule already which is pleasing.”
Meanwhile, young hooker James Cunningham is likely to face a spell on the sidelines after suffering an ankle injury in Hull Under 20’s match last weekend.