ESA successfully unfurls solar sail from cubesat

The European Space Agency (ESA) has successfully unfurled a solar sail from a cubesat in order to test using that sail to help de-orbit that cubesat more quickly.

The sail was deployed from a package measuring 3.93 by 3.93 by 3.93 inches (10 by 10 by 10 centimeters). The unfurling process was captured by an integrated camera onboard the Ion satellite carrier, which is operated by the Italian company D-Orbit.

The satellite will eventually burn up in the atmosphere, providing a quicker, residue-free method of disposal, according to ESA.

A short video of that unfurling can be viewed here.

This flight was intended as a proof of concept. Thus, ESA like many similar NASA test projects will now close the project down, which is dubbed ADEO, having no specific plans to do anything with what was learned. Private cubesat companies, however, might adopt this solar sail deployment technology, but I suspect less for de-orbit purposes but instead as a method of maneuvering their satellite in orbit.

LightSail-2 completes three-plus year mission, burning up in atmosphere

LightSail-2 sail deployed
LightSail-2, shortly after deployment in 2019.

LightSail-2, an experimental solar sail built by the Planetary Society, finally ended its mission this week, with the test sail burning up in the atmosphere upon re-entry.

LightSail 2 was launched aboard a SpaceX Falcon Heavy rocket in June 2019, settling into an initial orbit at an altitude of around 720 km (450 miles). At that height, the Earth’s atmosphere is still thick enough to create drag, which would threaten to eventually pull the spacecraft down.

But that’s where the plucky little satellite’s special ability came in. Although it’s only the size of a shoebox, LightSail 2 unfurled a big reflective sheet, called a solar sail, about the size of a boxing ring. The idea is that photons from sunlight strike this sail and generate tiny amounts of thrust, allowing the craft to change its orbit.

And LightSail 2 demonstrated this concept beautifully. In three and a half years, the spacecraft completed around 18,000 orbits and traveled 8 million km (5 million miles), adjusting its orbit continuously to keep itself aloft. But all good things must come to an end, and sometime on November 17, drag finally won the tug-of-war and pulled the spacecraft back to Earth.

LightSail-2 was the third time a light sail had been flown in space, with the first, Ikaros, deployed by the Japanese in 2010 and flown in solar orbit through 2012. That mission was successful in using sunlight to accelerate the sail. This was followed by LightSail-1 in 2015. That mission has some communications problems, but eventually succeeded in its main engineering mission by testing the sail deployment system.

LightSail deploys its solar sails

Though full confirmation will not come until later tonight, telemetry from LightSail suggests that its solar sails have successfully begun deployment.

Telemetry received on the ground showed motor counts climbing to the halfway point before LightSail traveled out of range. Power levels were consistent with ground-based deployment tests, and the spacecraft’s cameras were on. “All indications are that the solar sail deployment was proceeding nominally,” wrote mission manager David Spencer in an email update.

They will have to wait until the cubesat comes back in range at 2:46 am (Eastern) to see if the deployment completed successfully, as well as download images.

LightSail deployment scheduled for Tuesday

Assuming all goes well with the orbital preparations today, LightSail will perform its test deployment on Tuesday at 11:44 am.

If successful, this deployment will achieve several significant engineering firsts, the most important of which will be to have demonstrated that a cubesat can be used for such a task. Proving that fact will increase their commercial usefulness for future space endeavors.

Solar sail experiment stymied by software crash

The Planetary Society’s LightSail solar sail test mission, launched as a secondary payload on last week’s Atlas 5 X-37B launch, has fallen silent because of a software problem.

The communications problem occurred before the mission could achieve its main engineering goal of testing the deployment of the solar sail. They still hope to regain communications, but time is limited as the cubesat is in a low orbit that will decade relatively quickly.

Sunjammer, NASA’s next solar sail experiment.

Sunjammer, NASA’s next solar sail experiment.

Though the article headline focuses on the addition of space weather instruments to this solar sail, the article says very little about those instruments. One, Swan, is described as a “wind instrument”, which probably means it would study the solar wind. The other instrument would study the Earth’s magnetic field. Both instruments are needed to track the effect of the Sun on local space weather, since the one satellite we have to do this, Ace, is now more than a decade past its expiration date.

Nanosail-D has sailed home, burning up in the atmosphere on September 17

The solar sail Nanosail-D has sailed home, burning up in the atmosphere on September 17.

The flight phase of the mission successfully demonstrated a deorbit capability that could potentially be used to bring down decommissioned satellites and space debris by re-entering and totally burning up in the Earth’s atmosphere. The team continues to analyze the orbital data to determine how future satellites can use this new technology.

The concept being tested appears to use a solar sail as a navigating tool for guiding defunct satellites back into the atmosphere.

Using a solar sail to deflect an earth-destroying asteroid

solar sail mission to Apophis

In a paper published today on the Los Alamos astro-ph preprint website, two Chinese scientists have proposed using a solar sail for deflecting any asteroid that happens to be aimed at the earth. The diagram to the right is their simulated mission to impact the asteroid Apophis, which will pass close to the earth in 2029 and — depending on whether that flyby puts it through a very small 600 meter-wide mathematical “keyhole” — could then return in 2036 on a collision course.

The idea is to use the sail to slow the spacecraft down enough so that it starts to fall towards the sun. The sail is then used to maneuver it into a retrograde orbit. When it impacts the asteroid the impact will therefore be similar to a head-on collision, thereby imputing the most energy in the least amount of time with the least amount of rocket fuel. In their Apophis simulation, a mission, weighing only 10 kilograms (about 22 pounds), launched around 2025, and hitting the asteroid in this manner in 2026, would deflect its flyby in 2029 enough to guarantee it will not fly through the “keyhole” and therefore eliminate any chance of it hitting the earth in 2036.

Obviously many questions must be answered before such a mission should fly.
» Read more