The screen shot and block quote below are from Oribal ATK's Mission Update: Minotaur IV ORS-5 Launch. ORS-5 or "SensorSat" is a technology demonstration for a class of satellites that will sit in LEO and keep an eye on the GEO belt for any "debris" which I suspect means pranksats or worse. ORS-5 will sit in a 600 x 600 km equatorial LEO.
The graphic suggests that after stage 5 (Orion 38) burnout and payload separation, the velocity will be 7.05 km/s and the altitude 600 km and that checks out; the sidereal rotation speed of the Earth-Fixed frame at this altitude is another 0.51 km/s. That means the speed of the orbit in inertial coordinates is 7.05 + 0.51 = 7.56 km/s.
Orbital ATK's Minotaur IV space launch vehicle will launch the ORS-5 mission for the U.S. Air Force as a part of the Orbital/Suborbital Program-3 (OSP-3) contract. ORS-5, also known as SensorSat, is designed to scan for other satellites and debris to aid the U.S. military’s tracking of objects in geosynchronous orbit. For the ORS-5 launch, the Minotaur IV will use two Orion 38 upper stage motors. The final Orion 38 motor burn will reduce the angle of the ORS-5 satellite’s orbit, redirecting the spacecraft to equatorial orbit.
If I understand correctly, "The final Orion 38 motor burn" does not suggest that the solid fuel motor can burn twice, but that both the 4th and 5th stages are Orion 38 motors, and "the final burn" really means the 5th stage, or the burn of "the final Orion 38 motor".
I'm curious what "angle" means in last sentence, and guessing that it means inclination. For such a light satellite (something like 110 - 140 kg) would the standard thrust of the Orion 38 happen to provide just the right amount of delta-v to change the inclination to equatorial? Since the table shows the velocity unchanged during the 5th stage burn, it seems all of the thrust should be perpendicular to the direction of motion and purely for inclination change.
Question: Could someone help to estimate the change in inclination angle that an Orion 38 can provide this satellite, starting with the specs in English units :-( and see if it's even in the right ballpark for this launch?
Approximate mass of the payload:
Approximate mass of the Orion 38:
- Oribal ATK: ~875 kg
below: Image of Orion 38 motor from Orbital ATK's Propulsion Products Catalog.
below: Orion 38 motor specifications from Orbital ATK's Propulsion Products Catalog.
below: ORS-5 during assembly from Orbital ATK tweet.