The online really kills this one. Buying a ticket to space would be like buying a house The much nicer Ticketto dot space would still even be sketchy for a company that spent millions to put together a spacetravel program. Good Luck
ticketto*space - quite nice playful domain name imo, still hard to resell for significant profit
onlineticketto*space - too much, and lot of competition, so extremely hard to get any profit from it
(think of webticketto*space, yourticketto*space, myticketto*space, and dozens of variants one can create here)
With new gTLDs, keep the names as simple as possible