which has these general characteristics…

Crew: 6

Payload: 250,000 kg (550,000 lb)

Door dimensions: 440 x 640 cm (14.4 x 21 ft)

Length: 84 m (275.6 ft)

Wingspan: 88.4 m (290 ft 2 in)

Height: 18.1 m (59.3 ft)

Wing area: 905 m2 (9,743.7 sq ft))

Aspect ratio: 8.6

Cargo Volume: 1,300 m^3 (46,000 cu ft)

Empty weight: 285,000 kg (628,315 lb)

Max takeoff weight: 640,000 kg (1,323,000 lb)

Powerplant: 6 × ZMKB Progress D-18 turbofans, 229.5 kN (51,600 lbf) each

Takeoff run: 3,500 m (11,500 ft) with maximum payload

Performance

Maximum speed: 850 km/h (460 knots, 530 mph)

Cruise speed: 800 km/h (430 knots, 500 mph)

Range: ** With maximum fuel: 15,400 km (9,570 mi)

With maximum payload: 4,000 km (2,500 mi))

Service ceiling: 11,000 m (36,100 ft)

Wing loading: 662.9 kg/m² (135.5 lb/ft²)

Thrust/weight: 0.234

I note that the An-225 has interesting landing gear which enable it to operate from unpaved airstrips, such as grass. Also, other jet engines are available with greater thrust from GE and Rolls-Royce, up to 60,600 pounds force, which could be used to significantly upgrage the performance of either the An-225 or the StratoLaunch carrier aircraft.

The An-225 has a much smaller (though still huge) wingspan. Is Rutan thinking of using a greater wingspan in order to enable operating at higher altitudes and/or lower speeds? What gives?!?