You must be thinking of FS9. FS9 has two chief limitations insofar as "space" travel was concerned
1) a cylindrical globe (flat north/south, but curved east/west) versus FSX's true spherical globe, and
2) an altitude limit of FL999. In FSX its far higher - well above the Karman line of 62 miles/100km - a figure of 100,000,000' rings a bell, but have never been curious enough to try.
Nevertheless, FSX is still hampered in simulating hypersonic travel with a limit of approx. 2,600 kts or Mach 4. That not only limits you in accurately simulating some of the high speed X-15 missions (Mach 6.7), but certainly limits anything involving even low earth orbit (LEO) - typically speeds of 7-8 km/s. Speeds in space are not measured in Mach numbers, but for perspective, that would be an atmospheric equivalent of over Mach 20. So FSX barely can do a 1/4 of that speed.
So .... if FSX is no where near being able to simulate LEO, there's no hope to have a craft reach the much higher speeds yet for translunar injection (TLI) - needed to escape earth's gravitational pull in order to travel to the moon.
So ... there's no way something like Apollo could be simulated in FSX. Frankly, it surprises me that a payware product could be marketed with any kind of seriousness - but, alas, predation on the unwary is not uncommon in this hobby.
As a big NASA fan, I've been simulating high-speed flight on all the sim platforms since FS98, and most of the commercial space sim products out there. At this point, my recommendation would be thus:
1) FSX is good for some of the X-15 flights. Most were either high-speed or high altitude, and on some of the altitude flights, speeds were below Mach 5 - so that would be realistic in the sim.
2) Kerbal is infantile. Great for kids, maybe as a teaching aid in school, but if you're a hard-core simmer, or at least interested in the "flavor" of 60s aeronautics exploration, stay away, and save your money.
3) Orbiter (
http://orbit.medphys.ucl.ac.uk/) - this right here. In my view, it's the most realistic space sim available, and without question, the broadest in terms of reach (manned, unmanned, freaky sci-fi weirdness - something for everyone). Open (not as in source, but extremely "moddable") and FREE - it's one of the most underrated gems in the any sim community. It will rock your world. And for Apollo fans, you have either NASSP (hard) or AMSO (almost hard) projects to simulate realistically, everything from launch to maneuvering to lunar landing to exploring to splashdown....
Sorry that I can't affirm your purchase - I'd cut my losses, bin it, and use the platform best suited for it. Dr. Schweiger, for the decade and a half he has given to create something in some sense bigger than FSX, deserves to be mentioned here.
cheers,
dl