Even with six months' notice, we can't stop an incoming asteroid.
- At an international space conference, attendees took part in an exercise that imagined an asteroid crashing into Earth.
- With the object first spotted six months before impact, attendees concluded that there was insufficient time for a meaningful response.
- There are an estimated 25,000 near-Earth objects potentially threatening our planet.
The asteroid 2021 PDC was first spotted on April 19, 2021 by the Pan-STARRS project at the University of Hawaii. By May 2, astronomers were 100% certain it was going to strike Earth somewhere in Europe or northern Africa. On October 20, 2021, the asteroid plowed into Europe, taking countless lives.
There was absolutely nothing anyone could do to deflect it from its deadly course. Experts could only warn a panicking population to get out of the way as soon as possible, if it was possible.
The above scenario is the result of a recently concluded NASA thought experiment.
The question the agency sought to answer was this: If we discovered a potentially deadly asteroid destined to hit Earth in six months, was there anything we could do to prevent a horrifying catastrophe? The disturbing answer is "no," not with currently available technology.
While Europe can breathe easy for now, the simulation conducted by NASA/JPL's Center for Near Earth Object Studies and presented at the 7th IAA Planetary Defense Conference is troubling. Space agencies spot "near-Earth objects" (NEOs) all the time. Many are larger than 140 meters in size, which means they're potentially deadly.
Credit: ImageBank4U / Adobe Stock
"The level [at] which we're finding the 140-meter and larger asteroids remains pretty stable, at about 500 a year. Our projection of the number of these objects out there is about 25,000, and we've only found a little over one-third of those so far, maybe 38% or so," NASA's Planetary Defense Office Lindley Johnson tells Space.com.
With our current technology, spotting an NEO comes down to whether we just happen to have a telescope pointing in its direction. To remove humanity's blind spot, NASA is developing the NEO Surveyor spacecraft, which they plan to deploy in 2025. The project is being supported by the Planetary Society, the same organization that deployed Earth's first light sails. According to the Planetary Society, NEO Surveyor will be able to detect 90 percent of NEOs of 140 meters or larger, a vast improvement.
How to move an asteroid
The DART spacecraft will attempt to deflect an asteroid.Credit: NASA
The NASA/JPL exercise made clear that six months is just not enough time with our current technology to prepare and launch a mission in time to nudge an NEO off its course. (Small course adjustments become significant over great distances, which is why "nudging" an asteroid is a potential strategy.)
What would such a mission look like? Hollywood aside — remember Armageddon?— we know of no good way to redirect an NEO headed our way. Experts believe that shooting laser beams at an incoming rock, exciting as it might look, is not a realistic possibility. Targeted nuclear blasts might work, but forget about landing Bruce Willis, Ben Affleck, and Liv Tyler on an asteroid to set off a course-altering bomb, especially just a month after its discovery (as was the case in the movie).
Another thing that might work is crashing a spacecraft into an NEO hard enough to shift its course. That's the idea behind NASA's Double Asteroid Redirection Test (DART). This mission will shoot a spacecraft at the (non-threatening) asteroid Dimorphos in the fall of 2022 in the hope of changing its trajectory.
The deadly asteroid's journey
The asteroid "2021 PDC" hit Europe in NASA's simulation.Credit: NASA/JPL
The harrowing "tabletop exercise," as NASA/JPL called it, took place across four days at the conference:
- Day 1, "April 19" — The asteroid named "2021 PDC" is discovered 35 million miles away. Scientists calculate it has a 1-in-20 chance of striking Earth.
- Day 2, "May 2" — Now certain that 2021 PDC will hit Earth, space mission designers attempt to dream up a response. They conclude that with less than six months to impact, there's not enough time to realistically mount a mission to disrupt the NEO's course.
- Day 3, "June 30" — Images from the world's four largest telescopes reveal the area in Europe that will be hit. Space-based infrared measurements narrow the object's size to between 35 and 700 meters. This would pack a similar punch as a 1.2-megaton nuclear bomb.
- Day 4, "October 14" — Six days before impact, the asteroid is just 6.3 million km from Earth. Finally, the Goldstone Solar System Radar has been able to assess the size of 2021 PDC. Scientists calculate the blast from the asteroid will be primarily confined to the border region between Germany, Czechia, Austria, Slovenia, and Croatia. Disaster response experts develop plans for addressing the human toll.
"Each time we participate in an exercise of this nature," says Johnson, "we learn more about who the key players are in a disaster event, and who needs to know what information, and when."
Practically speaking, little can be done to hurry technological development along other than budgeting more money toward that goal. Maybe we should have Bruce Willis on call, just in case.
A recent study of Iceland's Krafla volcanic caldera suggests hidden magma pools may be lurking under many of the world's volcanic systems.
- The study analyzed magma collected from a 2009 incident in which geothermal drillers encountered magma that geophysical surveys failed to detect.
- Currently, magma imaging technology can't accurately detect magma pools under a certain size.
- Hidden magma pools pose safety concerns because magma from other sources might combine with the hidden magma, which could trigger unexpectedly explosive eruptions.
In 2009, scientists with the Deep Drilling Project were drilling a mile-deep borehole into Iceland's Krafla volcanic caldera when magma suddenly began creeping into the hole. The team had known, based on geophysical surveys, that a large magma body lay about two miles below the surface. But the surveys had failed to warn of molten rock at these shallower depths.
It was a concerning oversight. After all, Krafla is one of the world's most closely monitored volcanic systems, so if volcanologists can't detect shallow magma there, what does that suggest about risk assessments at other volcanoes?
A new study published in Geology explores the potential threats of such hidden magma pools, or "covert silicic magma." The researchers used the 2009 Krafla incident to assess how hidden magma pools form and whether they might pose previously unknown eruptions risks.
The devil's in the magma
To better understand the origins of hidden magma pools, the researchers took magma samples from the 2009 Krafla incident and compared them to seven other recorded eruptions within the Krafla caldera involving rhyolite, a silica-rich type of volcanic rock that's especially explosive.
At first, the team thought the hidden magma pool formed during relatively passive eruptions during the 1980s. But the analysis revealed the samples to be "essentially indistinguishable" from rocks ejected by Krafla's most recent explosive eruption: a mixed hydrothermal-magmatic event that occurred in 1724.
Credit: Rooyakkers et al
Still, the researchers couldn't determine exactly how the magma pool formed or has behaved since then, nor could they determine the size of the pool. That's mostly because modern magma-detecting instruments, such as seismic tomography, can't accurately identify magma pools smaller than about 1 cubic kilometer.
How could these relatively small magma pools pose major threats? One reason centers on composition. For example, the drillers involved in the Krafla incident struck rhyolitic magma, which is more explosive than basalt, the type of magma that dominates the Krafla caldera.
As basalt ascends toward the surface, it could potentially combine with and "mobilize" the rhyolitic magma, causing a violent eruption that offers "little warning," the researchers wrote.
"So the concern in this case would be that you have a shallow rhyolitic magma that you don't know about, so it hasn't been considered in hazards planning," study author Shane Rooyakkers said in a press release published by The Geological Society of America. "If it's hit by new magma moving up, you might have a much more explosive eruption than you were anticipating."
To better understand and forecast such eruptions, the researchers called for improving magma-detection strategies, such as using extremely dense geophone arrays, which use soundwaves to monitor the earth for seismic events.
If magma-detection technology improves, scientists might someday be able to install sensors around previously hidden magma pools, which could provide warnings of upcoming eruptions. But for now, volcanologists still have much to learn about hidden magma pools, and their prevalence around the globe.
Satellite imagery can help better predict volcanic eruptions by monitoring changes in surface temperature near volcanoes.
- A recent study used data collected by NASA satellites to conduct a statistical analysis of surface temperatures near volcanoes that erupted from 2002 to 2019.
- The results showed that surface temperatures near volcanoes gradually increased in the months and years prior to eruptions.
- The method was able to detect potential eruptions that were not anticipated by other volcano monitoring methods, such as eruptions in Japan in 2014 and Chile in 2015.
How can modern technology help warn us of impending volcanic eruptions?
One promising answer may lie in satellite imagery. In a recent study published in Nature Geoscience, researchers used infrared data collected by NASA satellites to study the conditions near volcanoes in the months and years before they erupted.
The results revealed a pattern: Prior to eruptions, an unusually large amount of heat had been escaping through soil near volcanoes. This diffusion of subterranean heat — which is a byproduct of "large-scale thermal unrest" — could potentially represent a warning sign of future eruptions.
Conceptual model of large-scale thermal unrestCredit: Girona et al.
For the study, the researchers conducted a statistical analysis of changes in surface temperature near volcanoes, using data collected over 16.5 years by NASA's Terra and Aqua satellites. The results showed that eruptions tended to occur around the time when surface temperatures near the volcanoes peaked.
Eruptions were preceded by "subtle but significant long-term (years), large-scale (tens of square kilometres) increases in their radiant heat flux (up to ~1 °C in median radiant temperature)," the researchers wrote. After eruptions, surface temperatures reliably decreased, though the cool-down period took longer for bigger eruptions.
"Volcanoes can experience thermal unrest for several years before eruption," the researchers wrote. "This thermal unrest is dominated by a large-scale phenomenon operating over extensive areas of volcanic edifices, can be an early indicator of volcanic reactivation, can increase prior to different types of eruption and can be tracked through a statistical analysis of little-processed (that is, radiance or radiant temperature) satellite-based remote sensing data with high temporal resolution."
Temporal variations of target volcanoesCredit: Girona et al.
Although using satellites to monitor thermal unrest wouldn't enable scientists to make hyper-specific eruption predictions (like predicting the exact day), it could significantly improve prediction efforts. Seismologists and volcanologists currently use a range of techniques to forecast eruptions, including monitoring for gas emissions, ground deformation, and changes to nearby water channels, to name a few.
Still, none of these techniques have proven completely reliable, both because of the science and the practical barriers (e.g. funding) standing in the way of large-scale monitoring. In 2014, for example, Japan's Mount Ontake suddenly erupted, killing 63 people. It was the nation's deadliest eruption in nearly a century.
In the study, the researchers found that surface temperatures near Mount Ontake had been increasing in the two years prior to the eruption. To date, no other monitoring method has detected "well-defined" warning signs for the 2014 disaster, the researchers noted.
The researchers hope satellite-based infrared monitoring techniques, combined with existing methods, can improve prediction efforts for volcanic eruptions. Volcanic eruptions have killed about 2,000 people since 2000.
"Our findings can open new horizons to better constrain magma–hydrothermal interaction processes, especially when integrated with other datasets, allowing us to explore the thermal budget of volcanoes and anticipate eruptions that are very difficult to forecast through other geophysical/geochemical methods."
The chariot survived ancient eruptions and modern-day looters to become a part of the world heritage site.
- Archeologists recently discovered a first-of-its-kind chariot in Pompeii.
- The ceremonial chariot is decorated with bronze and tin medallions, while the sides sport bronzesheets and red-and-black paintings.
- Given looting activity in the area, it's lucky the 2,000-year-old treasure wasn't lost to the world heritage site.
In 79 CE, near the Bay of Naples, Mt. Vesuvius erupted. Geologically, this was business as usual for the volatile volcano, but for the nearby cities of Pompeii and Herculaneum, it proved a cataclysmic event.
After the terrifying initial blast, the volcano spewed ash and rocks miles into the atmosphere. As this volcanic drift cooled, it began to snow onto the cities. It collapsed buildings under its weight and suffocated those unlucky enough to not flee. Then came the pyroclastic flows—massive waves of ash, gases, and lava fragments that washed over the cities at speeds of more than 100 miles per hour. All told, Vesuvius unleashed more than 100,000 times the energy of the two atomic bombs dropped during World War II on doomed towns nestled beneath it.
It seemed as though the cities weren't simply wiped off the map but practically from history itself, banished to a footnote in historical text. And so when explorers in the 1700s found the super-heated ash had preserved the city with taxidermic care, it was a miraculous discovery.
Today, Pompeii's fossilized slice-of-life gives historians an unprecedented view into a moment of history and culture. Bodies lie where they lived, traces of their clothes and other belongings still clinging to their forms. Frescos retain their imagery and vibrant colors. Fast food joints (called thermopolium) can be found with the jars still holding remnants of their menu items. Even the brain cells of a young man managed to survive the ages in vitrified conservation.
Each excavation teaches us something new about life in this Roman resort town, and Pompeii continues to surprise archeologists and historians well in the 21st century.
One dope Pompeian whip
Researchers carefully extract the chariot from the sedimentary rock encasing it.
Credit: Luigi Spina, Archaeological Park of Pompeii
In a recent discovery, researchers unearthed a first-of-its-kind chariot at Civita Giuliana, an excavation site north of Pompeii's ancient walls. In Roman times, the site served as a getaway for Rome's elite and wealthy citizens, a serene countryside brimming with villas and Mediterranean farms. So, it's understandable why such an exquisite chariot was found here.
"I was astounded," Eric Poehler, a professor at the University of Massachusetts Amherst, who specializes in Pompeii traffic, told NPR. "Many of the vehicles I'd written about before ... are your standard station wagon or vehicle for taking the kids to soccer. This is a Lamborghini. This is an outright fancy, fancy car."
Located in a double-level portico, the chariot is a far cry from anything Ben-Hur would have been seen cruising around in. It sports four iron wheels and a high seat complete with arm- and backrest. The sides are adorned with engraved bronze and wooden panels painted with red-and-black figures. And the rear bumps with a register of bronze and tin medallion depicting Eros-inspired scenes of satyrs, nymphs, and cupids. In short, this chariot is slab.
"It is an extraordinary discovery for the advancement of our knowledge of the ancient world," Massimo Osanna, the director of the archaeological park, said in a statement. "At Pompeii vehicles used for transport have been found in the past, […] but nothing like the Civita Giuliana chariot."
But unlike a Lamborghini—which serves only to show the owner has more money than sense—this chariot served a social and cultural role. Likely a pilentum, it would have been rolled out in times of ceremony, potentially during festivals, processions, or weddings.
While similar chariots have been uncovered in northern Greece, this is the first such chariot to be discovered in Italy. Its presence in Pompeii will further help historians understand the people who called the city home, as well as their relation to the Mediterranean world.
As Poehler added, "This is precisely the kind of find that one wants to find at Pompeii, the really well-articulated, very well-preserved moments in time. And it happens to be in this case an object that is relatively rare despite its ubiquity in the past."
It belongs in a museum (not the black market)
Bronze and tin medallions depict satyrs, nymphs and cupids.
Credit: Luigi Spina, Archaeological Park of Pompeii
Beyond its gilded appeal, the chariot is also special because it survived so we could learn from it. The area where the vehicle was found has been favored in recent years by looters, and illicit tunnels had been dug precariously close to the chariot's resting place. For this reason, the archeological park has teamed up with the Public Prosecutor's Office of Torre Annunziata to protect Pompeii's history and excavate its treasures before they become lost or stolen.
"The collaboration between the Public Prosecutor's Office of Torre Annunziata and the Archaeological Park of Pompeii has proved itself to be a formidable instrument, not only for bringing finds of exceptional historical and artistic value to light, but also for halting the criminal actions of individuals who for years have been the protagonists in a systematic looting of the priceless archaeological heritage preserved in the vast area of the Civita Giuliana villa, which is still largely buried and to which the recent exceptional findings bear witness," Nunzio Fragliasso, chief prosecutor of Torre Annunziata, said in his joint statement with Osanna.
Nor is everything that glitters historic gold. Even Pompeii's everyday ephemera can have an outsized impact on history. Pompeian citizens, for example, viewed street walls as a type of "public advertisement space" and so painted them thick with graffiti. As historians must often rely on the written works of the literate elite, this graffiti gives the ordinary Pompeians their voice back. One such charcoal tag even corrected the record of Vesuvius's eruption by two months, from August to October, contradicting the traditionally accepted date set by Pliny the Younger.
"Today, archaeologists try to understand ancient societies by studying the entire material record -- not just the beautiful or luxurious objects, but also the broken bits of cooking pottery, the animal bones thrown into the trash, the microscopic grains of pollen in the soil, and much more," Caitlín Barrett, associate professor at Cornell University, told CNN.
This ephemera is also at risk. Looters looking for eye-catching treasure and artwork will often destroy everyday objects in their pursuit. And after centuries encased in protective sedimentary rock, the city has again been exposed to the rains, winds, and human blunders that erode. The goal now isn't just to excavate fantastic treasures, but to preserve the world heritage site and learn from it for as long as time (and maybe Vesuvius) will allow.
In a joint briefing at the 101st American Meteorological Society Annual Meeting, NASA and NOAA revealed 2020's scorching climate data.
You may have noticed a trend in the last few years. At the beginning of every year, NASA and NOAA share their analyses of the previous year's climate data. And every year, their data reveal the previous year to be one of the hottest on record—with 2016 at the torrid top of 139 years of documentation. That's no coincidence. Climate change is happening, it's happening now, and it's human-caused.
That's the consensus of 97 percent of climate scientists, according to a 2014 report from the American Association for the Advancement of Science. That's the same percentage of physicians and cardiovascular scientists who agree that smoking causes lung cancer, and it's a consensus reached through decades worth of surveys and studies into the realities and causes of climate change.
Now, climate scientists have two more analyses to add to their overwhelming evidence. In a briefing at this year's 101st American Meteorological Society Annual Meeting, representatives for NASA and NOAA revealed their independent analyses of 2020's climate data. And the trend continues.
A dead heat
A graph showing the global mean temperatures from 1880–2020 (with the years 1951–1980 serving as the mean baseline).
Credit: NASA and NOAA
For its 2020 analysis, NASA gathered surface temperature measurements from more than 26,000 weather stations. This data was incorporated with data from satellites as well as sea-surface temperatures taken from ship and buoy instruments. Once tallied, NASA's data showed 2020 barely edged out 2016 as the warmest year on record, with average global temperatures 1.02°C (1.84°F) above the baseline mean (1951-1980).
In a separate analysis of the raw data, NOAA found 2020 to be slightly cooler than 2016. This distinction is the result of the different methodologies used in each—for example, NOAA uses a different baseline period (1901–2000) and does not infer temperatures in polar regions lacking observations. Together, these analyses put 2020 in a statistical dead heat with the sweltering 2016 and demonstrate the global-warming trend of the past four decades.
"The last seven years have been the warmest seven years on record, typifying the ongoing and dramatic warming trend," Gavin Schmidt, director of the NASA Goddard Institute for Space Studies, said in a release. "Whether one year is a record or not is not really that important—the important things are long-term trends. With these trends, and as the human impact on the climate increases, we have to expect that records will continue to be broken."
And they are. According to the analyses, 2020 was the warmest year on record for Asia and Europe, the second warmest for South America, the fourth warmest for Africa and Australia, and the tenth warmest for North America.
All told, 2020 was 1.19°C (2.14°F) above averages from the late-19th century, a period that provides a rough approximate for pre-industrial conditions. This temperature is closing in on the Paris Climate Agreement's preferred goal of limiting global warming to 1.5°C of those pre-industrial conditions.
2020's hotspot was—the Arctic?
A map of global mean temperatures in 2020 shows an scorching year for the Arctic.
(Photo: NASA and NOAA)
Heatwaves have become more common all over the world, but a region that really endured the heat in 2020 was the Arctic.
"The big story this year is Siberia; it was a hotspot," Russell Vose, chief of the analysis and synthesis branch of NOAA's National Centers for Environmental Information, said during the briefing. "In May, some places were 18°F above the average. There was a town in Siberia […] that reported a high temperature of 104°F. If that gets verified by the World Metrological Organization, it will the first there's been a weather station in the Arctic with a temperature above 100°F."
The Arctic is warming at three times the global mean, thanks to a phenomenon known as Arctic Amplification. As the Arctic warms, it loses its sea ice, and this creates a feedback loop. The more Arctic sea ice loss, the more heat introduced into the oceans; the more heat introduced, the more sea ice loss. And the longer this trend continues, the more devastating the effects.
For example, since the 1980s, there's been a 50 percent decline in sea ice, and this loss has exposed more of the ocean to the sun's rays. That energy then gets trapped in the ocean as heat. As the ocean heat content rises, it threatens rising sea levels and the sustainability of natural ecosystems. In 2020 alone, 255 zeta joules of heat above the baseline were introduced into Earth's oceans. In (admittedly) dramatic terms, that's the equivalent of introducing 5 to 6 Hiroshima atom bombs worth of energy every second of every day.
Looking beyond the Arctic, the average snow cover for the Northern Hemisphere was also the lowest on record. Like the Arctic sea ices, such snow cover helps regulate Earth's surface temperatures. Its melt off in the spring and summer also provides the freshwater ecosystems rely on to survive and farmers need to grow crops, especially in the Western United States.
Natural disasters get a man-made bump
A map of 2020's billion-dollar weather and climate disasters, which totaled approximately $95 billion in losses.
Credit: NASA and NOAA
2020 was also a record-breaking year for natural disasters. In the U.S. alone, there were 22 billion-dollar disasters, the most ever recorded. Combined, they resulted in a total of $95 billion in losses. The western wildfires alone consumed more than 10 million acres and destroyed large portions of Oregon, Colorado, and California.
The year also witnessed a record-setting Atlantic Hurricane season with more than 30 named storms, 13 of which were hurricanes. Typically, the World Meteorological Organization names storms from an annual list of 21 selected names—one for each letter of the alphabet, minus Q, U, X, Y, and Z. For only the second time in history, the Organization had to resort to naming storms after Greek letters because they ran out of alphabet.
For the record, there's a consensus about the record
Such records are a dramatic reminder of climate change's ongoing effect on our planet. They make for an eye-catching headline, sure. But those headlines can sometimes mask the fact that these years are part of decade-long trends, trends providing a preview of what a climate-changed world will be like.
And in case there was any question as to whether these trends were the result of natural processes or man-made conditions, Schmidt and Vose did not mince words.
As Schmidt said in the briefing: "Many, many things have caused the climate to change in the past: asteroids, wobbles in the Earth's orbit, moving continents. But when we look at the 20th century, we can see very clearly what has been happening. We know the continents have not moved very much, we know the orbit has not changed very much, we know when there were volcanoes, we know what the sun is doing, and we know what we've been doing."
He continued, "When we do an attribution by driver of climate change over the 20th century, what we find is that the overwhelming cause of the warming is the increase of greenhouse gases. When you add in all of the things humans have done, all of the trends over this period are attributable to human activity."
The data are in; the consensus is in. The only thing left is to figure out how to prevent the worst of climate change before it's too late. As bad as 2020 was, it was only a preview of what could come.