UT: It’s Alive! NanoSail-D Comes Back to Life

[bystander]

It’s Alive! NanoSail-D Suddenly and Spontaneously Comes Back to Life
Universe Today | Nancy Atkinson | 2011 Jan 19

Artist concept of Nanosail-D. Is it alive? [i](Credit: NASA)[/i]

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A small solar sail that was thought to be a lost cause has “spontaneously” come back to life. The NanoSail-D — a NASA-designed solar sail cubesat that launched in December but suddenly went silent without confirmation of its deployment — unexpectedly ejected from its host satellite on Wednesday, Jan. 19 at 11:30 a.m. EST. Engineers at Marshall Space Flight Center confirmed that the NanoSail-D nanosatellite ejected from Fast Affordable Scientific and Technology Satellite, FASTSAT, when they looked at onboard FASTSAT telemetry. The ejection of NanoSail-D also has been confirmed by ground-based satellite tracking.

Now NASA is asking for help from ham radio operators to listen for the signal to verify NanoSail-D is operating. And knowing the status of the solar sail is time critical.

“This is great news for our team. We’re anxious to hear the beacon which tells us that NanoSail-D is healthy and operating as planned,” said Dean Alhorn, NanoSail-D principal investigator and aerospace engineer at the Marshall Center. “The science team is hopeful to see that NanoSail-D is operational and will be able to unfurl its solar sail.”

If you are a ham operator, This information should be sent to the NanoSail-D dashboard at: http://nanosaild.engr.scu.edu/dashboard.htm. The NanoSail-D beacon signal can be found at 437.270 MHz.

NanoSail-D was designed to test the potential for solar sails in atmospheric braking. On December 6, 2010, it was schedule to eject from the FASTSAT, and initially it looked as though it did. But later, ground controllers were unable to confirm if the solar sail had ejected or deployed. Further analysis showed no evidence of NanoSail-D in low-Earth orbit, leading the team to believe NanoSail-D remained inside FASTSAT.

Now, with this latest news that the loaf-of-bread-sized satellite has ejected on its own, the NanoSail-D science team is hopeful the nanosatellite is healthy and can complete its solar sail mission. But the sequence of events are time critical.

After ejection, a timer within NanoSail-D begins a three-day countdown as the satellite orbits the Earth. Once the timer reaches zero, four booms will quickly deploy and the NanoSail-D sail will start to unfold to a 100-square-foot polymer sail. Within five seconds the sail fully unfurls.

“We knew that the door opened and it was possible that NanoSail-D could eject on its own,” said Mark Boudreaux, FASTSAT project manager at the Marshall Center. “What a pleasant surprise this morning when our flight operations team confirmed that NanoSail-D is now a free flyer.”

If the deployment is successful, NanoSail-D will stay in low-Earth orbit between 70 and 120 days, depending on atmospheric conditions. NanoSail-D is designed to demonstrate deployment of a compact solar sail boom system that could lead to further development of this alternative solar sail propulsion technology and FASTSAT’s ability to eject a nano-satellite from a micro-satellite — while avoiding re-contact with the FASTSAT satellite bus.

Source: Marshall Space Flight Center

[bystander]

Solar Sail Stunner
NASA Science News | Dr. Tony Phillips | 2011 Jan 24

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In an unexpected reversal of fortune, NASA's NanoSail-D spacecraft has unfurled a gleaming sheet of space-age fabric 650 km above Earth, becoming the first-ever solar sail to circle our planet.

"We're solar sailing!" says NanoSail-D principal investigator Dean Alhorn of the Marshall Space Flight Center in Huntsville, AL. "This is a momentous achievement."

NanoSail-D spent the previous month and a half stuck inside its mothership, the Fast, Affordable, Science and Technology SATellite (FASTSAT). FASTSAT was launched in November 2010 with NanoSail-D and five other experiments onboard. High above Earth, a spring was supposed to push the breadbox-sized probe into an orbit of its own with room to unfurl a sail. But when the big moment arrived, NanoSail-D got stuck.

"We couldn't get out of FASTSAT," says Alhorn. "It was heart-wrenching—yet another failure in the long and troubled history of solar sails."

Team members began to give up hope as weeks went by and NanoSail-D remained stubbornly and inexplicably onboard. The mission seemed to be over before it even began.

And then came Jan. 17th. For reasons engineers still don't fully understand, NanoSail-D spontaneously ejected itself. When Alhorn walked into the control room and saw the telemetry on the screen, he says "I couldn't believe my eyes. Our spacecraft was flying free!"

The team quickly enlisted amateur radio enthusiasts Alan Sieg and Stan Sims at the Marshal Space Flight Center to try to pick up NanoSail-D's radio beacon.

"The timing could not have been better," says Sieg. "NanoSail-D was going to track right over Huntsville, and the chance to be the first ones to hear and decode the signal was irresistible."

Right before 5pm CST, they heard a faint signal. As the spacecraft soared overhead, the signal grew stronger and the operators were able to decode the first packet. NanoSail-D was alive and well.

"You could have scraped Dean off the ceiling. He was bouncing around like a new father," says Sieg.

The biggest moment, however, was still to come. NanoSail-D had to actually unfurl its sail. This happened on Jan. 20th at 9 pm CST.

Activated by an onboard timer, a wire burner cut the 50lb fishing line holding the spacecraft's panels closed; a second wire burner released the booms. Within seconds they unrolled, spreading a thin polymer sheet of reflective material into a 10 m2 sail.

Only one spacecraft has done anything like this before: Japan's IKAROS probe deployed a solar sail in interplanetary space and used it to fly by Venus in 2010. IKAROS is using the pressure of sunlight as its primary means of propulsion—a landmark achievement, which has encouraged JAXA to plan a follow-up solar sail mission to Jupiter later this decade.

NanoSail-D will remain closer to home. "Our mission is to circle Earth and investigate the possibility of using solar sails as a tool to de-orbit old satellites and space junk," explains Alhorn. "As the sail orbits our planet, it skims the top of our atmosphere and experiences aerodynamic drag. Eventually, this brings it down."

Indeed, mission planners expect NanoSail-D to return to Earth, meteor-style, in 70 to 120 days.

If this works, NanoSail-D could pave the way for a future clean-up of low-Earth orbit. Drag sails might become standard issue on future satellites. When a satellite's mission ends, it would deploy the sail and return to Earth via aerodynamic drag, harmlessly disintegrating in the atmosphere before it reaches the ground. Experts agree that something like this is required to prevent an exponential buildup of space junk around Earth.

Alhorn and colleagues will be monitoring NanoSail-D in the months ahead to see how its orbit decays. They'd also like to measure the pressure of sunlight on the sail, although atmospheric drag could overwhelm that effect.

No matter what happens next, NanoSail-D has already made history: It has demonstrated an elegant and inexpensive method for deploying sails and become the first sail to orbit Earth. Eventually, the team will diagnose the sail’s reluctance to leave FASTSAT—"and then we'll be batting a thousand," says Alhorn.

A follow-up story on Science@NASA will explain how sky watchers can track and photograph NanoSail-D before it returns to Earth. Stay tuned for "Solar Sail Flares."

http://asterisk.apod.com/vie ... 29&t=22736

[bystander]

Watch Out for Solar Sail Flares
NASA Science News | Dr. Tony Phillips | 2011 Feb 01

A camera in Finland caught NanoSail-D flaring on Jan. 30th. The streak of light was almost three times brighter than a 1st-magnitude star. Credit: Esko Lyytinen. [[url=http://www.spaceweather.com/submissions/large_image_popup.php?image_name=Esko-Lyytinen-20110130-173400_1296412631.jpg]details[/url]]

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A conjunction of the Moon and NanoSail-D over Buenos Aires, Argentina, photographed by Enzo De Bernardini on Jan. 27th. On this occasion, the sail was not visible to the unaided eye. De Bernardini used a 3-inch refracting telescope to capture the 7th-magnitude streak. [[url=http://www.spaceweather.com/submissions/large_image_popup.php?image_name=Enzo-De-Bernardini-NanoSail-D_20110127_1_1296121292.jpg]more[/url]]

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It's a calm and peaceful night. Stars twinkle in the velvety darkness overhead as a distant plane blinks silently on the horizon. You could almost hear a pin drop.

That is, until the flare.

High overhead, out of the darkness, a bright light surges into view. For 5 to 10 seconds it outshines the brightest stars in the sky, mimicking a supernova, perhaps even casting faint shadows at your feet. The silence is broken by your own excited shouts.

Could this happen to you?

"It could, if you happen to be outside when NanoSail-D flies by," says Dean Alhorn of the Marshall Space Flight Center in Huntsville, AL. "We think the spacecraft could produce this kind of display from time to time when sunlight glints off the reflective fabric of its solar sail."

On Jan. 21st, NanoSail-D unfurled a 10 m2 sail 650 km above Earth's surface, becoming the first solar sail to orbit our planet. For the next few months it will skim the top of the atmosphere, slowly descending in a test of 'drag sails' as a means of de-orbiting space junk. If all goes as planned, the spacecraft will disintegrate like a meteor in April or May of 2011, dispersing harmlessly more than 1100 km high.

Meanwhile, sky watchers should be alert for flares.

Many people have already seen Iridium flares--brilliant flashes of sunlight glinting off the flat antennas of Iridium communication satellites. Some Iridium flares are so bright, they can be seen in broad daylight. NanoSail-D could be even brighter.

"The surface area of our sail is six times greater than that of a single Iridium antenna," points out Alhorn. "Plus, we're closer to Earth. It all adds up to a much brighter flash."

As NanoSail-D gets closer to Earth, it could theoretically produce flashes of light 10 to 100 times (2.5 to 5 astronomical magnitudes) brighter than the planet Venus. That's the sort of thing you can see even through city lights.

In between flares, however, the sail is fairly dim. Internationally-recognized satellite tracking expert Ted Molczan describes what he and others have been seeing:

"NanoSail-D can be a challenging object to spot, but by no means impossible. At its faintest, it has been invisible even in large binoculars, but at its brightest, it has been seen easily with the un-aided eye. The great variation in brightness is due to its shape; it is a large, thin sheet of highly reflective material. Seen edge-on, it is faint, but seen face-on at a favorable sun-angle, it may rival the brightest stars."

NanoSail-D flyby predictions may be found in several places on the web: Heavens-Above, Spaceweather.com, and Calsky among others. These sites will tell you when the sail will soar overhead--but not when it will flare. The orientation of the sail isn't known precisely enough for that.

"Because it is impossible to predict exactly when NanoSail-D will be bright, observers can increase their chance of success by watching over a period of least several minutes," says Molczan. "A plot of its predicted path on a star chart, with annotations of the time at intervals of one minute or so, will help the observer stay focused on the satellite's approximate position as it moves across the sky. Observe with the unaided eye, or binoculars with a wide field of view, like 7x50s."

The brightest flares are likely to occur when the spacecraft is near the horizon. Former NanoSail-D principal investigator Mark Whorton (previously at NASA, now at Teledyne) explains why:

"Early in the mission NanoSail-D will be tumbling, so it really doesn't matter where it is in the sky. Flashes might occur almost anywhere along its path. But later in the mission it will be aerodynamically stabilized: the flat surface of the sail will face forward, much like the sail on a terrestrial sailing ship. That means you will see it edge on (dim) when it is directly overhead and face on (bright) when it is closer to the horizon."

So check the predictions, go outside and take a look. Says Alhorn, "You might see something worth shouting about."

NanoSail-D Photo Contest