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LightSail 2 engineers continue to test for success

Posted by Jason Davis

18-04-2016 6:00 CDT

Topics: LightSail

It's been a busy two months of testing for The Planetary Society's LightSail 2 spacecraft.

Engineers spun the CubeSat like a record and shined flashlights in its electronic eyes in order to make sure everything goes according to plan when the solar sail heads into space. More trials are on the horizon, including a trip to a special magnetic cage at Utah State University's Space Dynamics Laboratory.

Here's a video to catch you up on some of the tests recently performed at Ecliptic Enterprises Corporation in Pasadena, California. Included in the montage are experiments on the momentum wheel, gyroscopes, deployment motor and sun sensors.

The Planetary Society

SciTech - LightSail 2 engineers test for success

Most of those tests were relatively straightforward: Does the momentum wheel spin at the commanded rate? Do the gyroscopes record the correct orientation of the spacecraft? Are the sun sensors able to track a light source?

But now, an even bigger challenge awaits. In order for LightSail to raise its orbit by a kilometer each day, the spacecraft must "tack" its solar sails broadside against the sun's rays for half of each orbit. During the other half, LightSail must be rotated 90 degrees to face the solar photons edge-on. Here's a visual refresher on how that works:

LightSail orients itself using an attitude control system, which consists of magnetometers, torque rods and a momentum wheel.

The magnetometers read the direction and strength of Earth's natural magnetic field as the spacecraft zips around the planet. The torque rods are three, golden cylinders (one each for the X, Y and Z axes) that electrically charge to generate a magnetic field, torquing against Earth's field to rotate the spacecraft. And the momentum wheel turns the spacecraft on a single axis (many spacecraft have three of these—one per axis). 

So, in order to solar sail, we first stabilize the spacecraft using the torque rods. Then, the momentum wheel, which has more muscle, gives us the 90-degree swings into and out of the sun's rays each orbit.

Testing LightSail 2

Ecliptic Enterprises Corporation

Testing LightSail 2
Alex Diaz, an engineer for Ecliptic Enterprises Corporation, performs tests on the LightSail 2 flight unit.

But how do we make sure that's all going to work?

In early May, LightSail will travel to Utah State University's Space Dynamics Laboratory. There, the CubeSat will be placed into a Helmholtz cage (named after a German physicist).

It's difficult to calibrate a magnetometer on Earth because we are constantly being bombarded by magnetic interference from electronic devices. LightSail's own electronics, contribute to these distortions. A Helmholtz cage creates its own magnetic field, isolating its contents from outside interference. That means the team can simulate the same magnetic field profiles LightSail will see in orbit.

Ecliptic's Alex Diaz, as well as Barbara Plante of Boreal Space, will oversee the Utah trials. There are three main tests: First, Diaz and Plante will see if LightSail's magnetometers correctly read the fields generated by the Helmholtz cage. Next, they'll put LightSail on an air bearing—basically, a floating platform suspended by jets of air. The Helmholtz cage will generate a magnetic field, and LightSail will use its torque rods to swivel the way it will in space. Finally, Diaz and Plante will test LightSail's momentum wheel, commanding the spacecraft to make its 90-degree tacking maneuvers.

If all goes well, the tests shouldn't last more than a few days, paving the way for a day-in-the-life test back at Cal Poly San Luis Obispo, where the solar sails will be deployed for the last time before launch.

 
See other posts from April 2016

 

Or read more blog entries about: LightSail

Comments:

Messy: 04/18/2016 02:33 CDT

http://mobile.nytimes.com/images/100000004323364/2016/04/13/science/alpha-centauri-breakthrough-starshot-yuri-milner-stephen-hawking.html

Messy: 04/18/2016 02:36 CDT

the above link is about what Lightsail 2 is leading to, and I think that these people should be contacted and asked to chip in to the Lightsail 3 mission

Bob Ware: 04/22/2016 02:02 CDT

The LightSail 2 Flight Test will hopefully show that the problems learned on LS-1 have been understood and fixed. LS-2 will Flight Test its own objectives and from those we will learn. Will FL-2 be a success? I think so. Flying an LS-3 mission to pass in front of Luna then come back should be done. That success will show the world that we are on the right track for planetary exploration and star flight vehicles with our current technology level. A LS-4 Flight Test of the same nature as LS-3 should go to Mars and return. The return purpose further demonstrates the control capability of the spacecraft. Since there is not a LS-3 or LS-4 in the pipe line we should seriously consider doing it. What we accomplish will be beneficial for others in the knowledge gain to apply this to their plans. In the interim production and leasing or sale of such spacecraft to parties for space exploration can generate funding to support us (TPS) in this area of space exploration.

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