In the previous article, we looked at Juno’s mission overview from launch in 2011, Orbit Capture in 2016 to its plunge at 50km/s into Jupiter scheduled on February 20, 2018.
Here we will focus on the currently anticipated event Juno’s J – O – I.
If you missed the mission trailer, make sure you watch it now. If you have seen it, make sure you watch it again, because it is just amazing.
J – O – I
The Jupiter Orbit Insertion Phase started on July 1st, 4 days before insertion burn, and ends about 2.5 hours after the start of the insertion burn. The burn (insertion maneuver), which will start July 5th 0318 UTC occurs at the spacecraft’s closest approach to Jupiter (Perijove) and slows it enough to be captured by the giant planet’s gravity into a 53.5-day orbit.
How fast is too fast?
To allow Jupiter to capture Juno into an orbit, the velocity has to be less than Jupiter’s escape velocity of 59.5 km/sec (37mi/sec); at which an object can no longer make an orbit. Jupiter is a massive planet. Earth’s escape velocity is just 11.2km.sec (7mi/sec).
When Juno is at Perijove, the velocity will be 129,000 miles/hr Juno would travel right past Jupiter and miss it completely.
First Two Capture Orbits (Orbit 1 and Orbit 2)
Burn occurs 18,000km (11,000 miles) away from Jupiter. It will last for 35 minutes. Juno’s closest altitude will be 4487km (2,788 miles) from Jupiter. When successful, Juno should pass over the south pole and travel away from Jupiter and come back to Perijove 53.5 days later. Furthest point from Jupiter (Apojove) will be around 5 million miles away (8 million km) where Juno will start falling back toward Jupiter reaching Perijove again (Perijove 1) and completing Orbit 1, Capture Orbit, 53.5 days later on Aug 27th.
Orbit 2 will identical to Orbit 1 ending at Perijove on Oct. 19th. The next orbits will only be 14-day orbits during which Juno will start doing science.
Times below are listed in “Earth Receive Time” and Universal Time (UTC) as confirmation of the Jupiter Orbit Insertion (JOI) events arrives on Earth. The one-way light travel time from Jupiter to Earth is approximately 48 minutes.
July 5 at 1:13 a.m…..Status tones start
July 5 at 1:16 a.m…..Start initial precession to JOI attitude
July 5 at 1:37 a.m…..End initial precession to JOI attitude
July 5 at 2:28 a.m….Start fast precession to JOI attitude
July 5 at 2:41 a.m….Switch to toroidal low-gain antenna
July 5 at 2:45 a.m….Begin nutation damping
July 5 at 2:50 a.m….Start final transition to JOI attitude
July 5 at 2:53 a.m….Juno in JOI attitude
July 5 at 2:56 a.m….Spin up from 2 to 5 rpm
July 5 at 3:01 a.m….Juno spinning at 5 rpm
July 5 at 3:18 a.m….Start JOI burn
July 5 at 3:53 a.m….End JOI burn
July 5 at 3:55 a.m….Begin spinning down from 5 to 2 rpm
July 6 at 4:00 a.m….Juno spinning at 2 rpm
July 6 at 4:07 a.m….Start precession from JOI to solar-pointing attitude
July 6 at 4:11 a.m….Switch to medium-gain antenna; end status tones
July 6 at 4:16 a.m….End precession to solar-pointing attitude
July 6 at 4:36 a.m….Ground begins receiving detailed telemetry from Juno
Aug. 27…………….First perijove (with science instruments activated)
Oct. 19…………….Period reduction maneuver (from 53.5-day to 14-day orbit)
Feb. 20, 2018……….Nominal end of mission
Here you can watch with us live the events as they happen on NASA TV.
Tuesday, July 5 – Orbit Insertion Day (Early Morning)
(July 4) 4:00 p.m. UT — Pre-orbit insertion briefing at JPL
(July 5) 02:30 a.m. PT — Orbit insertion and NASA TV commentary begin
(July 5) 10:00 p.m. PT — Post-orbit insertion briefing at JPL
Follow the event here for updates and more Juno news.