A Mysterious Light Has Been Blinking in Space Every 21 Minutes for 35 Years
Story by Jackie Appel •
A mysterious light has been blinking in space every 21 minutes for 35 years–and scientists have no idea what it is. What could it be?
Scientists have discovered a mysterious pulsating light—and they don’t know what it could be.
It pulses at a rate of about once every 21 minutes, and has been doing so since at least 1988.
It doesn’t nicely fit the description of any of the pulsating space objects we know of, so researchers are still trying to figure out what this object might be.
Some things in the universe shine with a constant, life-sustaining light. Some beam with the light of other sources. Some flash in a large explosion, never to be seen again. And some pulse. Like a ticking—or, rather, flashing—clock, some energy sources in the universe hit us with beam after beam of photons, lighting up and darkening on a very set schedule.
There’s actually a fair few types of objects that do this. But scientists recently discovered one particular source of flashing light has already proven especially puzzling. It blinks about once every 21 minutes, and according to archival data, it’s been doing that at least since 1988.
It’s called GPM J1839–10, and we don’t know what it is.
Usually, if you spot a pulsing object, your first instinct would be to identify it as a pulsar. Pulsars are rapidly rotating neutron stars with strong magnetic fields that generate radio jets at the magnetic poles. If their poles aren’t pointed directly at Earth, we will only see those radio jets when they spin around to hit us, causing an incredibly consistent pulse.
But in addition to the, well, pulsing, the key to identifying a pulsar is the timing. Pulsars spin incredibly fast—some hit us with their radio beams once a millisecond, and the longest pulse out way about once a minute. And they kind of can’t go slower than that. The rapid spin that makes them “blink” also powers the radio jets of the star. If they slow down, the jets die off completely (researchers actually call it the “pulsar death line”). So, the chances of us spotting a pulsar with a 21-minute pulse interval is incredibly small.
There are other options, but those don’t fit great either. It could be a magnetar (another kind of neutron star that is prone to bursts of activity), but they usually produce X-rays along with their radio bursts, and the last one we found with a pulse interval like this stopped emitting after about three years. GPM J1839–10 doesn’t seem to be producing X-rays, and it’s been emitting for three and a half decades.
Or, it could be what’s called a magnetized white dwarf. It’s also a long shot, as we’ve never seen a white dwarf give off super-bright radio emission (let alone bursts) before. But because white dwarfs are so much bigger in mass than neutron stars, they would take longer to spin around, and could achieve a rotation rate like the one observed from GPM J1839–10.
Researchers aren’t fully ready to give up on any of these ideas yet, no matter how long-shot they may be, largely because they don’t have a nicely fitting alternative. Further investigations will likely be needed to determine what exactly this thing is, and the observations needed to examine this things aren’t exactly easy to get.
It may be a while until we solve the mystery of GPM J1839–10. Until we do, it’ll just keep pulsing away, taunting scientists with the promise of answers to big questions.
Houston, we have a solution
The sun can repair solar cell defects in the vacuum of space
IMAGE: ANITA HO-BAILLIE AND SHI TANG WEAR PROTECTIVE GLOVES WHILE EXAMINING PEROVSKITE SOLAR CELL PROTOTYPES view more
CREDIT: UNIVERSITY OF SYDNEY
Australian researchers have demonstrated that perovskite solar cells damaged by proton radiation in low-earth orbit can recover up to 100% of their original efficiency via annealing in thermal vacuum.
This is achieved through careful design of the hole transport material (HTM), which is used to transport photo-generated positive charges to the electrode in the cell.
The multidisciplinary project is the first to use thermal admittance spectroscopy (TAS) and deep-level transient spectroscopy (DLTS) to study the defects in proton-irradiated and thermal-vacuum recovered perovskite solar cells (PSCs). It is also the first study to use ultrathin sapphire substrates with the high power-to-weight ratios suitable for commercial applications.
The results have been published in the journal Advanced Energy Materials and are available here.
Light-weight PSCs are a strong candidate for powering low-cost space hardware thanks to their low manufacturing cost, high efficiency and radiation hardness.
All previous proton irradiation studies of PSCs took place on heavier substrates thicker than 1mm. Here, to take advantage of high power-to-weight ratios, ultrathin radiation resistant and optically transparent sapphire substrates of 0.175mm were used by a team based at the University of Sydney. The project was led by Professor Anita Ho-Baillie, who is also an Associate Investigator with the ARC Centre of Excellence in Exciton Science.
The cells were exposed to rapid scanning pencil beam of seven mega-electron-volts (MeV) protons using the high energy heavy ion microprobe at the Centre for Accelerator Science (CAS) at ANSTO, mimicking the proton radiation exposure that the solar cell panels would undergo while orbiting the earth on a satellite in low-earth orbit (LEO) for tens to hundreds of years.
It was found that the type of cells featuring a popular HTM and a popular dopant within its HTM are less radiation tolerant than their rivals. The HTM in question is the compound 2,2',7,7'-Tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD), while the dopant is lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).
Through chemical analysis, the team found that fluorine diffusion from the LiTFSI induced by proton radiation introduces defects to the surface of the perovskite photo-absorber, which could lead to cell degradation and efficiency losses over time.
“Thanks to the support provided by Exciton Science, we were able to acquire the deep-level transient spectroscopy capability to study the defect behavior in the cells,” lead author Dr. Shi Tang said.
The team was able to ascertain that cells free of Spiro-OMeTAD and free of LiTFSI did not experience fluorine diffusion related damage, and degradation caused by proton-radiation could be reversed by heat treatment in vacuum. These radiation-resistant cells had either Poly[bis(4-phenyl) (2,5,6-trimethylphenyl) (PTAA) or a combination of PTAA and 2,7-Dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8BTBT) as the hole transport material, with tris(pentafluorophenyl)borane (TPFB) as the dopant.
“We hope that the insights generated by this work will help future efforts in developing low-cost light-weight solar cells for future space applications,” Professor Ho-Baillie said.
JOURNAL
Advanced Energy Materials
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Effect of Hole Transport Materials and Their Dopants on the Stability and Recoverability of Perovskite Solar Cells on Very Thin Substrates after 7 MeV Proton Irradiation
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