NASA Juno space probe entered Jupiter’s orbit and is in perfect condition.
It was most important moment during Juno’s mission which lasts since 2011 and impressive show of JPL abilities for developing and operating deep space probes. After performing two deep space maneuvers and orbit corrections on June 16, 2016 (first two burns of main engine of Juno during whole mission) and sending “ji4040” command on June 30, 2016, via 70 m dish from DSN facility in Goldstone, Colorado Juno was set to be switched to autopilot mode to perform maneuver of insertion into Jupiter’s orbit. Date of final maneuver was set for today. Culmination moment of the approach was scheduled for 03:18 when switching on propulsion of the probe was planned. LEROS-1b engine fueled with hydrazine and nitrogen tetroxide was planned to burn for 35 minutes to reduce speed of the probe with its 645 N thrust to 1950 km/h. But to perform successful JOI (Jupiter’s Orbit Insertion) first preparation were performed two weeks before final day. First, probe opened cover which was protecting main engine nozzle and enabled auto-restart option of LEROS-1b. Seven days later Juno opened valves which were cutting fuel from main engine. Next day later propulsion system was pressurized and on June 30, 2016, scientific instruments installed inside Juno were shut down to avoid any computer anomaly during orbit insertion; on June 30 it also received command to turn on autopilot during further insertion maneuver. On July 1, Juno started Jupiter Orbit Insertion command sequence. Jet Propulsion Laboratory Mission Control Center and specialists in Lockheed Martin Mission Control in Denver started to prepare for today’s maneuver; in spite of fact that it was performed autonomously by probe, progress of the insertion was monitored via DSN stations in Goldstone, Colorado and in Canberra, Australia with utilization of 70 m dish antennas supported by 34 m dish antennas. Today, over two hours before T=0, communication was switched to Medium Gain Antenna instead main one. At T-125′ first maneuver was performed. Probe turned for 15° from the sun; around 02:20 Juno performed second course change again to toward deeper to the Jupiter orbit. At T-37′ communication was switched to Low Gain Antenna (Medium and Low gain antennas are installed on the edge of the dish of main antenna). At T-33′ nutation damping process started which eliminated all the wobble of the probe which could possibly effect on probe during insertion. Last corrections were performed 28 minutes before burn; six minute later number of rotations per minute of probe was temporarily increased from 2 to 5. Punctually at 03:18 GMT LEROS-1b started and provide 645 N of thrust for 35 minutes. At 03:43 GMT valves stopped flow hydrazine and N2O4 to engine. Two minutes later probe returned to its normal rotation speed with 2 RPM. Next at T+49′ probe started to turn to sun-pointed attitude after 103 minutes (during this time solar panels were not providing power) and four minutes later switched to Medium Gain Antenna again. First telemetry data were sent at T+58′. Third burn of the Juno’s propulsion during whole mission finished with success.
Juno mission on Jupiter’s orbit covers performing various experiments and measurements which will improve knowledge on atmosphere, magnetosphere and magnetic field of Jupiter. Research on atmosphere will help in understanding process of its forming and level of ammonia and water. It will also improve knowledge of its structure, density and temperature, clouds structure and their altitude. Probe will measure structure of magnetosphere and gravity of Jupiter; gathered data will help in better understanding Dynamo theory (theory in physics which explains process of generating magnetic field by celestial body).
Juno will finish its mission during 37th orbit on 20th February 2018. It will perform deorbit burn and will be destroyed in Jupiter’s atmosphere around 34° North latitude.
On picture above: Jupiter seen by Juno camera on June 21, 2016, from distance of 10900000 km.