Orbital ATK returned in 2016 not only with Antares rocket. Today, Company performed launch of their Pegasus XL rocket with NASA payload.

Finally, after first not successful attempt of delivering to 500 km LEO orbit eight CYGNSS satellites, Pegasus XL managed to deliver payload to space. Problems with hydraulics, which appeared on Monday were followed with issues with software used for eight CYGNSS spacecrafts. Delay was increasing, but bad luck left Orbital ATK yesterday. Technicians managed to prepare, L-1011 Stargazer motherplane, Pegasus XL passed all test and satellites received software updates. Little mess with simple mission of delivering to LEO small satellites, but all in all, maybe problems with hydraulics gave opportunity to spot issues with satellite’s software ? One thing is sure – Pegasus XL proved to be useful launch vehicle during LEO missions with light payload.


On picture above: L-1011 just before take off.

Today launch was planned for 12:26 UTC but in case of Pegasus, launch means dropping rocket from Stargazer. L-1011 was prepared early in the morning along with Pegasus XL; in the meantime launch was postponed again, but this time only for ten minutes, due the risk of collision with other object in space. L-1011 and F-18 airplane with video operator on second seat were both waiting to finally move to Cape Canaveral’s Skid Strip. F-18 took off first at 12:34 UTC. L-1011 after receiving green light was still waiting. Finally at 12:37 UTC it took off, to and begun its flight to drop zone placed 160 km for east from Daytona Beach. F-18 started to chase it piloted by pilot Troy Asher with videographer Lori Losey onboard. At 12:45 UTC Stargazer started its maneuver to reach exact position toward south east direction. Nine minutes later crew of the L-1011 spotted some issues with air condition of Pegasus XL fairing covering payload with mass of 345.6 kg, but they were solved and did not affected on countdown. At 13:05 UTC L-1011 reached correct altitude for dropping – 11887 m. At 13:17 UTC self destruction system of Pegasus was armed; it was followed by arming release mechanism at 13:20 UTC and switching CYGNSS to internal power one minute later. At 13:23 UTC weather report was favorable and final “go” was given after consultations with mission control center at Cape Canaveral, Orbital ATK in Boulder Colorado and University of Michigan (manufacturer of all eight CYGNSS satellites). Three minutes later L-1011 started to turn towards south east direction. Pegasus XL was switched to internal power at 13:27 UTC. After another correction, launch was moved for two minutes. Finally at 13:37 UTC crew push button to release rocket. After few seconds of freefall, it started its first stage and begun flight with course at 118.7°. Next, it performed pitch maneuver (it raises its nose for 35°)and was continuing its flight with speed of 2400 km/h. At T+1′ it reached speed of 4000 km/h and altitude of 30 km. AT T+1’35” first stage was cut off and jettisoned on altitude of around 60 km. At T+2’15” payload fairing was splitted and adapter with CYGNSS satellites was exposed. At T+3′ rocket cut off second stage and started ballistic phase of flight. After over 3 minutes at T+3’55”, second stage was ignited and at 13:49 UTC rocket reached correct orbit of 510 km and inclination of 35°. After two minutes eight CYGNSS satellites were already separated after deploying in pairs at T+12’56”, T+13’26” and T+13’56”. Satellites deployed their solar wings ten minutes later. At 14:13 UTC L-1011 landed at Cape Canaveral.

On picture above: L-1011 motherplane.