Space Debris and Sri Lanka: Facts over Fiction

Everyone’s heard of the space debris heading to the Indian Ocean mid November – but beyond a few reports, there’s a dearth of information on this event. Roar decided to investigate further and get the facts straight. We reached out to Nicholas Moskovitz, an astronomer at the Lowell Observatory in Arizona, to shed some light on this event and separate fact from fiction.

Moskovitz, a leading astronomer who collects data on small bodies in the Solar System, primarily the Main Belt and near-Earth asteroids, joined us via Skype on the 28th of October to help us better understand this phenomenon.

What Is It?

According to Moskovitz, the object was first detected in 2013 by the Catalina Sky Survey (CSS), a project based near Tucson that searches the sky for comets and asteroids, particularly those that could potentially impact Earth. Fast forward to October 3, 2015 and the folks at CSS detected the same object heading to Earth on a spiraling and chaotic trajectory. Moskovitz explained to us that CSS was able to connect the two observations using still images of the fast moving objects taken both in 2013 and 2015. “Granted that we have enough images, we can connect them via a trajectory line and figure out how to predict the future trajectory, as well as connect it to the past,” he said, adding that “we were able to determine that the objects observed by CSS in 2013 and 2015 were one and the same object by comparing their paths using this technique.”

The object has been identified as being “artificial” (or man-made), an observation based by studying its orbit. According to Moskovitz, the orbit has a diverting character which indicates that it has a very low mass in comparison to it’s size, which is estimated to be about 1-2 meters across. The orbital diversion is due to radiation pressure from the sun, from which it can be reasonably inferred that the piece of debris is most likely an aluminium shell of sorts. “This would not be the case if the object was a small scale asteroid,” Moskovitz notes. This radiation pressure is the same phenomenon that is exploited to drive solar sail type spacecrafts, which are currently in an experimental stage.  

Is There Cause for Concern?

The answer is a no.

For that matter, Moskovitz noted that he would be “very surprised if it hits the Earth. Almost all of the material will burn up in the atmosphere causing a brightness comparable to a full moon.”

The best estimate for the trajectory indicates that the piece of debris is heading 50-100 km off the Southern tip of Sri Lanka.

The current best estimate for time and date of impact is 6.20 UTC (11.50 am Sri Lanka time) on the 13th of November. Moskovitz noted that these estimates would be refined over the next few days. Despite the event taking place during midday local time, those who wish to can witness the event off the Southern coast.

“This is the first time humans have predicted where and when some space debris would hit the Earth. Something we put up decades ago is coming back to us, and that really captures the imagination and is pretty cool,” he added.

Witnessing The Event

Peter Jenniskens of SETI, an expert on meteors and other small bodies, is expected to charter a flight to rise above the cloud cover over the Southern coast of Sri Lanka to witness this event. It is reported that he will be carrying certain specialized instruments in order to make scientific measurements while on the aircraft. Rising above the cloud cover would give this team the advantage of making more refined measurements.

Given the brightness of the event, Moskovitz said that amateur photographers and astronomers may be able to make their own observations from the ground while on the Southern coast, even without any specialized equipment.  

The Science

According to Moskovitz, “these objects have decaying orbits that spiral inwards, which is one of the reasons why it’s hard to predict their descent through the atmosphere.”

“We were fortunate when it came to this particular object since it’s trajectory showed less drag,” he explained. “Using the Discovery Channel Telescope (DCT), a 4.3 meter telescope at the Lowell Observatory (editor’s note: Pluto was discovered at Lowell!), we were able to take multiple images of the object moving through the atmosphere.”   

Moskovitz also noted that they use advanced Charged Coupled Devices (CCD sensors) to capture the images. Essentially, CCDs are what you find in your smartphone camera, except that the CCDs that Moskovitz uses are far more sensitive and accurate than those found in phone cameras. “CCDs have been a transformational piece of technology since they were first introduced in the 90s. Their use has since become economical. We are still riding this wave, and most advances in astronomy tend to be technology driven,” Moskovitz explained.

When we asked Moskovitz why this study was important, he noted that “apart from being really cool, this is a controlled experiment for us. We get to study, for the first time, how such debris behaves in the atmosphere.” He added that this data can also be used to model trajectories of other debris, as well as assist in understanding how meteors and asteroids behave in our atmosphere. “These studies also have relevance to asteroid impact threat assessment related studies and we plan to study this event as best we can,” Moskovitz explained.

According to Moskovitz, he initially wanted to study the object using a special spectral technique which would have allowed him to make a better prediction of the composition. His team had planned to use the Southern Astrophysical Research Telescope in Chile but said that “we were weathered out on the two days we were there. We had winds of about 70 km/h with 90% humidity and 100% cloud cover. Overall bad conditions for observing the object.” The window for this observation has since passed and Moskovitz is exploring alternatives.

“We also studied the brightness variation over time, which seems flat,” he said. This would tell him two things: either the object is roughly spherical or it’s rotating too fast for the instruments to pick up.

The Future

Optical sky survey projects have taken on an exciting dimension during the last couple of years. According to Moskovitz, we are now able to study large portions of the sky using advanced CCD arrays, powerful software and modest telescopes, which have been yielding amazing results such as this event. CSS and Pan-STARRS are great examples of this approach. He notes that in the next 5-10 years a project called the LSST would be coming online, which would essentially photograph the entire sky every four days and generate petabytes of data. By the looks of it, we will soon be moving into an era where astronomy and big data would collide, leading to new discoveries, especially where small bodies in the Solar System such as satellites, meteors, asteroids and comets are concerned.  

Who can predict what we would be able to learn next? We at Roar are pretty excited about the discoveries this event will bring and how it will help change the future of astronomy.   

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