Emily Lakdawalla • Jul 10, 2015
Two more brief mission updates: Philae makes contact; Akatsuki to perform course correction
As a followup to yesterday's post about Dawn, Juno, and OSIRIS-REx, I have updates on two more missions. With this post, I hope to have cleared the decks so that I can focus on Pluto for the next week!
Philae makes contact
The Philae comet lander woke up from its long hibernation on June 14, 2015. Since then, there were seven sporadic contacts, and then nothing since June 24. Puzzled by the silence, on July 5 the Philae team tried commanding the CONSERT instrument -- which has components on both orbiter and lander -- to turn on and establish a link between the two. They detected no signal from the lander that day, which was quite disheartening. But they kept trying, and today's update from the lander control center reports that not only was Philae heard from, but the data received indicates that the July 9 commands to turn on CONSERT were received and correctly responded to by Philae.
The report says, "The data sent on 24 June did not suggest that the lander had experienced technical difficulties. Now, Philae’s internal temperature of zero degrees Celsius gives the team hope that the lander can charge its batteries; this would make scientific work possible regardless of the ‘time of day’ on the comet." There is no indication of any internal problem that would have prevented communication on previous days.
This ESA blog entry has a thorough summary of what might be causing the sporadic communications with the lander, and how it affects the mission. For the time being, "The mission teams are working on a short-term trajectory planning schedule, which is updated every Monday and Thursday morning." That will allow them to respond quickly to any change in Philae's status...but it must make it tough to do orbital science at the comet, which is quickly approaching perihelion.
Akatsuki to perform course correction
On December 7, Akatsuki is going to make a second attempt at Venus orbit insertion using only its attitude control jets; its main engine failed during its first orbit insertion event back on Deceber 6, 2010. JAXA announced yesterday that Akatsuki will be performing three trajectory correction maneuvers this month in order to target the best science orbit at Venus that it is capable of achieving:
AKATSUKI to perform fourth orbit control to Venus
The AKATSUKI will perform an orbit control for the fourth time (DV4: Delta Velocity 4) from July 17, targeting to be injected into the Venus orbit again in December 2015. The control will be divided into three performances.
The orbit control this time aims at correcting AKATSUKI’s orbit to one that is advantageous to its observations after being injected into the Venus orbit. We will use four attitude control engines on the upper part of the explorer this time to take this opportunity to also verify their performance for re-entry in December.
The Japanese language version of the update includes a link to a PDF that contains a table of the planned maneuver dates: July 17, 24, and 31. I wish the best of luck to the Akatsuki team!
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