Temat 9: Sanjay Limaye and Akatsuki 6 - 8 December 2015

Live from Sagamihara: Akatsuki in Orbit, The Planetary Society
Posted by Sanjay Limaye

December 8
One day after closest approach, Akatsuki is now speeding away from Venus at 4.09 kilometers per second and is 180,000 kilometers from the planet. I am still thinking about the higher-than-expected delta-V achieved yesterday. One possible answer is that closest approach could have been a little bit nearer to Venus than the planned 550 km distance. This would induce extra velocity due to more bending of the trajectory and result in a larger change in velocity than what would result from the actual thrust for the planned miss-distance. The apoapsis distance will now determine the orbit period which is of some concern due to the time Akatsuki will spend in eclipse and need to draw upon the battery power.
In the press conference yesterday, we learned that the amount of fuel used for orbit insertion was close to what was expected. The insertion sequence occurred while the spacecraft was in shadow cast by the planet. Battery capacity, charging and discharging rates will be checked out in the coming days. The fuel left after the orbit insertion burn will also determine operations. Once the orbit is determined in the next day or so, the team will streamline the command generation process.
more: Blog by Sanjay Limaye on The Planetary Society

A Blog by Nadia Drake
Now Orbiting Cloud-Shrouded Venus, Akatsuki Sends New Images
POSTED WED, 12/9/2015

It’s not every day you hear about a troubled spacecraft making a desperate attempt to cling to a planet — for the second time. After missing its first chance to orbit Venus, Japan’s Akatsuki spacecraft circled the sun for five long years, waiting for the right time to try again. That moment came on Dec. 7, a half-decade to the day after a broken nozzle sent Akatsuki hurtling toward the sun instead of falling into the gravitational clutches of Earth’s sister planet. But with its large, main engine crippled, the spacecraft needed another way to slip into orbit. That responsibility went to four smaller thrusters that are normally used to adjust where the spacecraft is pointing; for 20 minutes they fired, nudging Akatsuki onto a course for capture as it skimmed the Venusian cloud tops.
And then the team commanding the spacecraft, at the Japan Aerospace Exploration Agency, waited. Shifts in the radio waves Akatsuki uses to communicate with Earth would indicate whether the spacecraft had changed course. If it hadn’t, there was a small window in which the team could try again, using an alternate set of thrusters. And if that didn’t work? Well, no one wanted to think about that. The third time might be the charm on Earth, but in space, getting even a second chance is exceedingly rare.
An hour later, scientists shared the exciting news: “It is in orbit!!” reported Sanjay Limaye, of the University of Wisconsin-Madison, who was with the team in Sagamihara, Japan. The question was, which orbit? Was it stable? Could the team talk with the spacecraft? Is Akatsuki healthy?
more: Phenomena, National Geographic