Emily LakdawallaDec 04, 2015

Timeline for Akatsuki's second attempt at orbit insertion

This is it: Akatsuki's final chance at Venus orbit insertion. The rocket firing should begin on December 7 at 08:51 Japan time (December 6 23:51 UT / 15:51 PST) and last for 20 minutes. If for some reason the first rocket firing doesn't work, they'll turn the spacecraft about and try again with the opposite set of thrusters. We'll know right away if the rocket firing was successful, but it will take a couple of days of radio tracking to be sure that Akatsuki's modified path is one that will remain in a closed loop around Venus.

I don't currently know of any online webcast related to this arrival attempt -- I will update this post if I have any recommended places to view the event other than Akatsuki's official Twitter account. Just a few minutes ago, they posted an update that they are now only 430,000 kilometers from Venus -- similar to the Earth-Moon distance. So close...

Akatsuki attempting orbit insertion
Akatsuki attempting orbit insertion Image: Go Miyazaki

You can read Ralph Lorenz' excellent story for the details on how we got here. A Japanese fan website has posted an incredibly detailed slide presentation on the upcoming orbit insertion and science plans, in Japanese of course. I found a diagram describing the orbit insertion and a timeline and ran text through Google Translate and read some tweets by a helpful space fan and can provide the following, hopefully correct, information.

  • Sunday, December 6 (Japan time): Akatsuki turns to orbit insertion attitude.
  • Dec 7 04:30 JST / Dec 6 19:30 UT / Dec 6 11:30 PST: Usuda Deep Space Center begins tracking Akatsuki.
  • Dec 7 08:22 JST / Dec 6 23:22 UT / Dec 6 15:22 PST: Akatsuki enters Venus' penumbra.
  • Dec 7 08:51 JST / Dec 6 23:51 UT / Dec 6 15:51 PST: Akatsuki fires one set of RCS thrusters for about 20 minutes to enter Venus orbit.
  • After the firing, Akatsuki will automatically rotate to prepare for a second attempt at orbit insertion with its opposite set of RCS thrusters. Akatsuki will wait for instruction from Earth to find out if the second attempt is needed.
  • Dec 7 12:00 JST / Dec 7 03:00 UT / Dec 6 19:00 PST: JAXA will hold a press briefing from Sagamihara. At the press briefing, they will only be able to say whether or not the attitude control system functioned as commanded. It will take until December 9 to confirm that the spacecraft successfully entered Venus orbit. Another press briefing is scheduled for that day.
  • December 7, afternoon (Japan time): Canberra Deep Space Network begins tracking Akatsuki.

Here's the translated diagram -- you can see how small a change in trajectory the orbit insertion makes, at least initially:

Akatsuki orbit insertion trajectory
Akatsuki orbit insertion trajectory Image: JAXA / translated by Emily Lakdawalla

 Everybody cross your fingers for a successful arrival for Akatsuki at Venus!

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