Sail in View

by Paul Gilster on June 10, 2015

The main post for today will be online around 1230 EDT (1630 UTC), but first I have to publish this image from LightSail, along with Jason Davis’ description. Nice work!


“The Planetary Society’s LightSail test mission successfully completed its primary objective of deploying a solar sail in low-Earth orbit, mission managers said today [June 9]. During a ground station pass over Cal Poly San Luis Obispo that began at 1:26 p.m. EDT (17:26 UTC), the final pieces of an image showcasing LightSail’s deployed solar sails were received on Earth. The image confirms the sails have unfurled, which was the final milestone of a shakedown mission designed to pave the way for a full-fledged solar sail flight in 2016.”

A second image may include a view of the Earth, according to Davis. What may happen next is a further tensioning, or ‘walking out,’ of the sail booms, which should further flatten the sail. Davis notes, too, that the ‘fish-eye’ lens of the camera produces a bit of distortion in the image.

Addendum: Bill Nye’s statement on LightSail’s success.

“I’m very proud to say that our LightSail test mission was a success. We saw again that space is hard. It’s a test flight, and sure enough our little spacecraft tested us. I’ve got to congratulate our remarkable team. They solved some unexpected big problems up there with nothing but short radio signals sent from down here. This LightSail test taught us a lot, just as we hoped it would, and so we’re ready to do some real solar sailing with LightSail’s 2016 mission. Let me finish by reminding everyone that this mission and next year’s flight are funded entirely by our supporters and especially our members— people of Earth, who want to participate in space exploration. We’re changing the way humankind explores space. Today is a big day for The Society and for space explorers everywhere.”


Alex Tolley June 10, 2015 at 12:08

Can anyone confirm that the altitude is: “LightSail is circling Earth in an orbit ranging in altitude between 220 miles and 435 miles each time around the planet. “


I am assuming that it is the low perigee that is causing sufficient drag to cause re-entry.

Also, is the reduced tumbling due to ground control or drag from the sail? It seemed to me that the telemetry indicated reduced tumbling at the same time as teh sail was unfurling, but that may just be due to the intermittent communications with Lightsail-1.

I am most impressed that the Planetary Society made this such an open mission, risking the consequences of another failure. While this wasn’t a perfect mission, it was still a great success and bodes well for next year’s mission. The image of the [almost fully] deployed sail is priceless.

Ron S June 10, 2015 at 15:06

Alex, there is no propulsion. It is all due to conservation of angular momentum, like a spinning skater whose spin slows when the arms are extended. That is, in LightSail’s case, if the plane of the sail deployment is normal to the spin axis. But there are 3 dimensions of spin to be considered. Thus the concerns about the 3 axes of tumbling rate increasing the risk of sail fouling or mechanism failure by the multi-dimensional torque during deployment.

James M Essig June 10, 2015 at 16:30

Beautiful image! I will have to renew my Planetary Society membership. Looking forward the “full-fledged solar sail flight in 2016″.

Alex Tolley June 10, 2015 at 16:33

@Ron. Thank you. I got a better understanding of this listening to today’s press conference. I gather the solar panels contributed to the increased tumbling rate, but how exactly wasn’t explained.

I have been scouring the web to understand more about Lightsail-1, even educating myself to read the TLE data so that I could understand the orbit better.

ljk June 11, 2015 at 14:53

A very partial glimpse of the planet Earth from LightSail:

The satellite is still tumbling, though not as much before the sails were unfurled. However, ground stations are having trouble getting decent data.

ljk June 11, 2015 at 15:23

LightSail A Success: Planetary Society Reviews Data and Plans for 2016 Mission

By Talia Landman

It’s not a true space mission without a little bit of drama, and The Planetary Society had just that. Unforeseen software glitches, spacecraft falling silent, and periods of no contact with Earth had The Planetary Society and their fans sitting on the edge of their seats. The LightSail mission team and supporters spent 19 days following the solar sailing spacecraft, LightSail A, as it circled in low-Earth orbit, days numbered, before deploying its Mylar solar sails on Sunday, June 7.

The successful deployment of LightSail’s solar sails marked a milestone for the non-profit space interest group as they work toward a LightSail primary mission in 2016. The Planetary Society held a LightSail mission press conference Wednesday, June 8, to discuss the outcomes of their first (and last) test flight and what to expect when the second mission launches next summer.

LightSail is a CubeSat spacecraft designed to test solar sailing technology. The idea behind solar sailing is to use energy from our Sun to propel a spacecraft throughout the Solar System. The Planetary Society agrees that solar sailing is a much more cost efficient method for space travel, rather than the traditional chemical fuel methods used today.

The Planetary Society’s citizen-funded LightSail mission is designed with the goal of opening up space exploration and the testing of new technologies at an affordable cost. LightSail demonstrates the viability of solar sailing for small spacecrafts, such as CubeSats, that are used by many universities and research groups. The cost of flying these small satellites can be a challenge, but the successful completion of LightSail’s first mission puts humanity one step closer to changing that.

Full article here:

ljk June 14, 2015 at 12:44
ljk June 14, 2015 at 23:33

Bill Nye – the Science Guy – got a look at LightSail before it burns up in Earth’s atmosphere:

ljk June 19, 2015 at 10:37

Engineers Stumble on a Whole New Method of Laser-Based Spacecraft Propulsion


June 17, 2015 // 05:00 AM EST

A team of Chinese physicists has developed a new variety of light-based propulsion system with the ability to harness much greater forces than a conventional solar sail.

The key, according to the Nankai University-based group, is in swapping out the mirrored sail—which captures photonic energy as radiation pressure in much the same way a regular air-sail captures wind energy—for a pure-black graphene sponge. Rather than reflect off of the sail, light is absorbed by the sponge, which converts that energy into propulsion.

The group’s work is published this week in Nature Photonics.

Full article here:

Alex Tolley June 19, 2015 at 12:44

@ljk – this approach may on;y last for a very short time as propulsion. I believe the laser stimulates electron emission that causes the sail to be propelled. The sail will quickly build up a charge reducing its efficiency.

Paradoxically, if the sail did build up a +ve charge, it could act as an electric sail instead, by repelling solar protons.

It is also worth while checking out the idea of painting the sail with material that can be ablated off by a beam. For short bursts, a sail is reported to be able to accelerate with high g instead of the usual tiny g. The Benford’s have worked on this and I think they have a paper published.

ljk June 22, 2015 at 9:48

A gallery of data and images of LightSail from those who tracked the solar sail satellite from Earth:

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