Simulating the velocities and thermal of a rentry is kinda hard to do on the ground.
They have several further experimental tiles for future flights planned.
From Wayne Hales blog:
So why is all of this important? Exactly at this time there is a large effort by many companies and government agencies to develop hypersonic aircraft. NASA has even sponsored a couple of test flights. The problem, as it is for all types of aircraft flight, is drag and heating. When the boundary layer over the wings or in the engine is laminar, there is low drag and low heating; and when the boundary layer is turbulent, drag and heating increase dramatically. All boundary layers can be "tripped" or transition from laminar to turbulent flow.
In some of these experimental aircraft the engines [called SCRAM jets for Supersonic Combustion Ram jet engines] have only operated for a fraction of a second or a very few seconds. Why? Because the designers do not know how to cool them; they don't understand when or whether the boundary layer inside the engine is turbulent or laminar.
In some of these experimental aircraft, the engine begins to melt as soon as it is turned on; hence the extremely short operating times.
This is no good for a hypersonic passenger aircraft which might carry a hundred people from New York to Tokyo in a couple of hours.
Why do we not understand this phenomenon? Because it cannot be recreated in a wind tunnel or other experimental apparatus. The wind tunnels that have long enough flow durations to study this phenomenon run only up to about Mach 6. These hypersonic engines need to perform at Mach 8 or 10 or 12. There are "wind tunnels" that operate at high Mach numbers but only for fractions of a second; not long enough to understand the way in which a boundary layer works.
No aircraft fly that fast, missiles can achieve it briefly, but there is one platform that spends a serious amount of time flying through the atmosphere at speeds above Mach 6:
http://blogs.nasa.gov/cm/blog/waynehale ... 16008.html