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LightSail Team Prepares for Sail Deployment

Posted by Jason Davis

30-05-2015 23:08 CDT

Topics: mission status, LightSail

Update, June 1: Tomorrow's solar sail deployment has been rescheduled to Wednesday to allow for additional image capture and downlink testing. A timeline will be posted as soon as it is confirmed.

LightSail is almost ready for its moment in the sun.

This afternoon, mission managers gave the go-ahead for a manual solar sail deployment as early as Tuesday, June 2 at 11:44 a.m. EDT (15:44 UTC), providing the spacecraft completes an arduous set of Monday preparations. Since waking up Saturday after eight days of silence, the spacecraft has been busy sending telemetry back to Earth, snapping test images and preparing itself for sail deployment.

LightSail 1 in the clean room

The Planetary Society

LightSail 1 in the clean room
The LightSail 1 spacecraft sits in a Cal Poly clean room prior to a scrubbed day-in-the-life test on Aug. 20, 2014.

LightSail completed 12 ground station passes over Cal Poly and Georgia Tech Sunday, sending home 102 data packets. The team started the day with a ground-commanded reboot to reset a file overload vulnerability believed to have silenced the spacecraft two days after launch. On a subsequent ground pass, engineers attempted to upload a software patch designed to fix the problem once and for all, but were unable to maintain two-way communications. LightSail’s tumble rate has increased since it entered orbit May 20. It can receive certain commands and transmit data to the ground, but the data link is not stable enough for the team to log in and make software changes.

Because the primary goal of the test mission is sail deployment, the plan to apply the patch has been shelved. As a workaround, LightSail will be rebooted at least once per day to reset the contents of beacon.csv, the spreadsheet-like file that stores the spacecraft’s automated data chirps. Several successful reboots have already been completed.

Doppler shifts contained within LightSail's chirps have allowed engineers at Cal Poly and Georgia Tech to refine the spacecraft's position. It is now believed to be one of five ULTRASat spacecraft bunched together on the fleet’s orbital path. Our Mission Control Center page has been updated for the first time since launch day. It now shows the position of ULTRASat 8, believed to be a close match for LightSail. You can view all ten ULTRASat two-line element sets in the radio tracking section.

Also on Sunday, LightSail’s cameras were commanded to capture a series of test images. Telemetry indicated a power draw consistent with camera operation, and memory allocation counters for the cameras incremented as expected. On Monday, the team will attempt to download one of the images. It isn’t expected to show much—just a dark scene from the spacecraft’s innards. Only a partial download may be necessary to validate the camera is working before proceeding with the sail deployment sequence.

If the spacecraft continues to operate as expected through Monday, sail deployment could be scheduled for Tuesday morning. The deployment will be triggered during one of the first sunlit ground station passes of the day, when there are several subsequent passes over Cal Poly and Georgia Tech available. That currently works out to 11:44 a.m. EDT (15:44 UTC). A final go/no-go decision is expected Monday night.

See other posts from May 2015


Or read more blog entries about: mission status, LightSail


dougforworldsexplr: 06/01/2015 12:31 CDT

I am glad the Planetary Society is in contact with Lightsail1 again. As a Christian I think that God could have showed His goodness in sending a cosmic ray or something in answer to Christian or other prayers for resumption of Lightsail operations but the resumption of Lightsail contact is also due to the robustness of the Planetary Society's design of it and the production and testing of it at the California university and the the persistence of the Planetary Society to restore contact with it. I hope that contact can be maintained and resumed more fully to allow a successful deployment of the solar sails on this coming Tuesday or shortly afterward and some good video documentation. Go Lightsail! I hope this will also help a successful mission more in space where solar sailing can be better demonstrated next year.

flyingkiwiguy: 06/01/2015 09:13 CDT

A teapot in orbit seemed to have helped the communication.

Wizard: 06/01/2015 09:47 CDT

I am excited about this light sail test. Learned and processed data from this test and near future flights will enable scientists and engineers of future generations to design and build larger light sails tethered to starships carrying human astronauts to the far reaches of our solar system and beyond. Man is the great explorer. Space is our only limit left to explore. I envy our descendants who will take this next giant step to the stars.

TimM: 06/01/2015 11:08 CDT

I am actually glad this does not look too easy. Exploration... space, the brain, the oceans, DNA... takes real work. Great job Planetary and all who are doing the hard stuff.

Tim R: 06/01/2015 02:52 CDT

Your spacecraft is rotating rapidly, about 2 rpm. Is there concern that the deployment will place stresses on pivot and joints of the mechanism? While there seems to be this as a real concern, this is also a great example of how you will be using conservation of angular momentum to despin, slow down, your vehicle; great EPO thread. Once deployed and the spin rate slowed, will your torque rod or momentum wheels be capable of controlling or to some degree adjusted your attitude? Lastly, once deployed, isn't there a risk that LS-1 could retain a point of rotation that leaves the craft hidden behind its sail? Isnt' there some intention to furl and then unfurl the sail? Good luck!

Laura M: 06/01/2015 06:18 CDT

Yay!!!!! Little ET phoned home! So exciting!

AnnSewItGoes: 06/02/2015 08:24 CDT

I'm enjoying your updates on LightSail. Also, I'm sharing them with my Civil Air Patrol Squadron, Sugar Valley Comp Squadron in NC.

Bob Ware: 06/02/2015 03:51 CDT

This is great news! So what is the update? It's Tuesday 4:53 PM EDT.

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