Join Donate

Emily LakdawallaJune 7, 2010

IKAROS update: Rotation rate inexplicably increasing

JAXA's end-of-Sunday update on IKAROS' status gives more details about an issue they are working on the spacecraft. The spacecraft itself is in perfect health, but its dynamics are different from what was expected. Here's the content of the update, which I edited from the Google translation and another version helpfully posted to unmannedspaceflight.com by user "akibow."

IKAROS is standing by after completion of the first-stage deployment, with the sails deployed about five meters. At present, the spin rate is increasing very slowly. This is worrisome to the IKAROS team, although the spacecraft is presently in no danger from the increased spin rate. The concern is that the team cannot explain the cause of the spin-up.

Engineers are working some possible explanations. For example, it could be caused by sunlight pressure on the tilted, folded blades -- that is, the spacecraft, which now has four long blades spanning 10 meters (as in the picture below), may be acting like a pinwheel. Alternatively, it could be caused by outgassing from the sail material. Other possibilities are also being explored. The team is pausing deployment to watch the spacecraft's behavior to attempt to discern the cause of the spin-up before meeting again to determine whether to proceed with the final deployment.

The reported spin rate of 7.4 rotations per minute is the same for the end of the day Sunday as it was for the end of the day Friday, so the rate of increase is clearly much smaller than 0.1 rotation per minute per day, for what that's worth.

IKAROS first stage deployment complete

ISAS / JAXA

IKAROS first stage deployment complete
Artist's concept of the IKAROS solar sail mission with the first stage of sail deployment complete.

Read more: IKAROS, mission status

You are here:
Headshot of Emily Lakdawalla (2017, alternate)
Emily Lakdawalla

Senior Editor and Planetary Evangelist for The Planetary Society
Read more articles by Emily Lakdawalla

Comments & Sharing
MER
Let's Change the World

Become a member of The Planetary Society and together we will create the future of space exploration.

Join Today

Emily Lakdwalla
The Planetary Fund

Support enables our dedicated journalists to research deeply and bring you original space exploration articles.

Donate