The 31-year-old was forced to return from the test series against India because of the recurrence of a back injury which has afflicted him for much of his career.
Clarke, who has been in brilliant form with the bat over the last year, is scheduled to play in the Indian Premier League (IPL) before going to England for the June 6-23 Champions Trophy.
The first of back-to-back Ashes test series then starts at Trent Bridge on July 10 and Clarke is desperate not to miss it.
"I hope not, right now I'm not really in a position to say because I don't know what the scans say," Clarke told reporters at Sydney airport.
"I need to have the X-rays, listen to the experts and then make a plan, but from my point of view I'm always pretty positive so I think it's very unlikely I'll miss the Champions Trophy and the Ashes.
"I'll listen to the experts once I've had my scans and do as I'm told."
Clarke said he was a little stiff after spending 12 hours on an aeroplane but had given no thought as to whether he would play in the IPL.
"Right now it's about having the scans and waiting to see what the results say," he said.
"I think I need to wait on the results, listen to the experts and then make a plan from there."
The second Ashes series of the year begins at the Gabba in Brisbane on Nov. 21.