Collecting the most important and interesting science news for the second week of May 2018, including North Korea’s mountain of a nuclear problem, volcano Kilauea continues to wreak havoc on Hawaii’s Big Island, NASA’s carbon monitoring activities are quietly killed and research points to the use of light-sails to spearhead a new age of space exploration.
North Korea’s mountainous nuclear problem
North Korea’s pledge to denuclearise was met with relief in the international community but said relief was tempered with some suspicion. Why, after being so bullish for so long, would Kim Jong-Un suddenly decide to play along with international demands to denuclearise? The University of Berkley this week (10.05.18) released details of a possible motivation for the change in attitude. International researchers have discovered using radar imagery, the damage that was done by North Korea’s largest underground nuclear test to date held on September 3rd, 2017.
The explosion which occurred under North Korea’s Mt. Mantap at the Punggye-ri nuclear test site in the country’s north, rocked the area like a 5.2-magnitude earthquake. Before and after radar imaging from multiple sources indicate the detonation, with a yield of 120-330 megatonnes, has pushed the mountain’s surface out by up to 11 feet whilst shortening it by approximately 20 inches. The researchers modelled the event and approximated the detonation occurred 400-600 beneath the mile-high summit of the mountain and it triggered a second seismic event 8 and a half minutes later 2300 feet south of the blast.
The research highlights the importance of using satellite radar imaging, the SAR (synthetic aperture radar) in addition to seismic data to more precisely analyse the effects of nuclear testing both in North Korea and around the world.
Douglas Dreger one of the project’s lead researchers and professor of Earth and planetary science from the University of California discussed the events that followed the blast: The explosion occurred more than a quarter mile (450 meters) below the summit of Mt. Mantap, vaporizing granite rock within a cavity about 160 feet (50 meters) across – the size of a football stadium – and damaging a volume of rock about 1,000 feet (300 meters) across. The blast likely raised the mountain six feet (2 meters) and pushed it outward up to 11 feet (3-4 meters), though within minutes, hours or days the rock above the cavity collapsed to form a depression. Eight and a half minutes after the bomb blast, a nearby underground cavity collapsed, producing the 4.5-magnitude aftershock with the characteristics of an implosion. Subsequently, a much larger volume of fractured rock, perhaps 1 mile (1-2 kilometres) across, compacted, causing the mountain to subside to about 1.5 feet (0.5 meters) lower than before the blast.
“There may be continuing post-explosion compaction at the mountain. It takes time for these aseismic processes to occur,” Dreger added.
Geologists had already believed the site was under enormous pressure due to its use as a nuclear testing site, with previous satellite imaging revealing landslides down the side of the mountain and the collapse of internal spaces within the base of the mountain. The collapse of these spaces poses an environmental hazard as it could see the release of radioactive material into the atmosphere.
Volcanic eruptions continue to cause havoc on Hawaii’s Big Island
Fissures continued to erupt on the Big Island of Hawaii over the weekend, with a 16th and 17th fissure opening in Puna on Saturday morning (12.05.18). Residents in high-risk areas are being urged to prepare for a quick evacuation by authorities joining over 1700 citizens that have already been relocated at short notice.
Kilauea, one of the world’s most active volcanoes, flared up on April 30th when the base of the lava reservoir under its summit collapsed. On May 3rd, volcanic activity triggered a magnitude 6.9 event creating large fissures which sprayed sulphur dioxide into the atmosphere and lava flows on land. Whilst the lava flows have destroyed over 350 buildings, including 23 homes, it’s the highly toxic sulphur dioxide that poses the most prescient danger.
At the moment it is difficult to pinpoint when the volcanic events will actually cease as the lava lake at Halemaʻumaʻu has continued falling with the total drop currently estimate to be over 300 metres. Fears grow that if the lava lake continues to fall it will reach the island’s water table and triggering a steam blast and a repeat of the 1942 explosive event at Mauna Loa.
You can follow developing events with frequent updates here...
NASA monitoring of atmospheric carbon quietly ceased
Science reported on May 9th that the Trump administration had quietly cut funding to NASA’s Carbon Monitoring System (CMS). The project had helped create models of carbon flow across the globe and it’s cancellation seriously threatens the monitoring of carbon emissions countries agreed to under the Paris climate accord. Kelly Sims Gallagher, director of Tufts University’s Center for International Environment and Resource Policy in Medford, Massachusetts told Science “If you cannot measure emissions reductions, you cannot be confident that countries are adhering to the agreement,” she says. Cancelling the CMS “is a grave mistake,”
The move is the latest in a long line of attacks on NASA’s Earth science mission, with a series of proposed budget cuts and the cancellation of the Orbiting Carbon Observatory 3 (OCO-3) being other recent striking examples of the White House’s stance of NASA’s goals in this area.
Climate scientists now hope that Europe can take over where it seems the US is poised to jump off in this area of research. Currently, there is only one European carbon monitoring satellite, but more are planned for the near future.
“CMS is an obvious target for the Trump administration because of its association with climate treaties and its work to help foreign nations understand their emissions, ” Phil Duffy, president of the Woods Hole Research Center in Falmouth, Massachusetts told Science “The topic of climate mitigation and carbon monitoring is maybe not the highest priority now in the United States. But it is almost everywhere else.”
Light sails: the future of space exploration?
Dreams of journeying to neighbouring star system Alpha Centauri have long been held by physicists and astronomers but the practicalities of such a mission have made it seem an impossibility. Any such journey would require a probe to carry enough propulsive material to carry it 4.37 light years, approximately 25.6 trillion miles. And fuel has mass, making the craft much heavier, meaning they require more fuel… and so on. Clearly, even the most advanced modern space vessel would not be near efficient enough to make a journey to a neighbouring star system. And certainly not within a human lifetime.
Scientists speculated that by using an alternative source, such as radiation from the Sun or an earth-based source we coold negate the use of huge reserves of fuel. The radiation could be utilised by mirror-like collectors or sails attached to the vessel. This technology has already been used by the Japanese mission IKAROS (Interplanetary Kite-craft Accelerated by Radiation of the Sun) launched in 2010.
This week saw the publication of two papers which may bring an inter-star system light-sail mission closer to reality. On 10th May Scientific American reported on advancements in the ‘Breakthrough Starshot Initiative’ which intend to send tens of thousands of tiny space probes named ‘starchips’ to our the nearest star system. Space.com explains the launch procedure
“Many Starchips would be launched at a time, propelled by a 100-gigawatt laser blast from a ground-based light-beamer array. This is about the same amount of energy required to launch a space shuttle. The probes would be accelerated to 20 percent of the speed of light in about two minutes (an acceleration of 60,000 times that of the Earth’s gravity). This velocity would get the probe past the orbit of Pluto in three days and to the nearest star in 20 years.”
One of the drawbacks to the initiative has been the material needed to construct the sail, which is required to be 10 square metres with a mass of 1 gram. To put this into context, this means a thickness of approximately 100 atoms. A challenge for modern material science to say the least.
The paper published on May 7th in the online journal Nature Materials suggests a potential roadmap for such materials suggesting materials such as crystalline silicon and molybdenum disulfide. As far as finding a sail that reflects as much light as possible while staying low in mass, the scientists recommended sails with hexagonal lattices of holes to reduce their weight. The researchers also noted that controlling the microscopic structure of the sail—such as by using alternating layers of material, each only nanometers (billionths of a meter) thick—could boost its reflectivity and reduce its absorptivity.
Another paper released on May 2nd reveals that the China Academy of Launch Vehicle Technology (CALT), the rocket development arm of the Chinese space programme, has designed a graphene-based composite film that may well fit the requirements of a working light-sail. The design is similar to the solar-sail used in the aforementioned IKAROS mission but the solar cells in that material will be replaced with a strong conductive graphene film. The European Space Agency is currently also researching the possibility of a graphene-based material that fits the requires of a light-sail.