On 26 November 2018, the NASA InSight lander successfully set down on Mars in the Elysium Planitia region. Seventy Martian days later, the mission’s seismometer SEIS began recording the planet’s vibrations. A team of researchers and engineers at ETH Zurich, led by ETH Professor Domenico Giardini, had delivered the SEIS control electronics and is responsible for the Marsquake Service. The latter is in charge of the daily interpretation of the data transmitted from Mars, in collaboration with the Swiss Seismological Service at ETH Zurich. Now, the journal Nature Geoscience published a series of articles on the results of the mission in the first months of operation on Mars.
As reported in these articles, InSight recorded 174 events until the end of September 2019. Since then, the measurements have continued leading to more than 450 observed marsquakes as of today, which have not yet been analysed in detail. This accounts for one event a day on average.
The data allows researchers observing how seismic waves travel through the planet and unveiling its internal characteristics—similar to how x-rays are used in medical tomography. Before InSight landed, researchers had developed a wide range of possible models to represent the internal structure of the red planet. The recorded marsquakes, already after few months, enable refining the understanding of the structure of the planet and to reduce the uncertainties.
Interpreting marsquake data is challenging
Marsquakes are similar to the seismic events we see on Earth, although they are generally of smaller magnitude. The 174 registered marsquakes can be categorized in two families: One includes 24 low-frequency events with magnitudes between 3 and 4, as documented in the papers, with waves propagating through the Martian mantle. A second family of marsquakes comprises 150 events with smaller magnitudes, shallower hypocentral depth and high frequency waves trapped in the Martian crust.
“Marsquakes have characteristics already observed on the Moon during the Apollo era, with a long signal duration (10 to 20 minutes) due to the scattering properties of the Martian crust,” explains ETH Professor Giardini. In general, however, he says, interpreting marsquake data is very challenging and in most cases, it is only possible to identify the distance but not the direction from which the waves are arriving.
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InSight landed on a thin, sandy layer
InSight opens a new era for planetary seismology. The SEIS performance exceeded so far expectations, considering the harsh conditions on Mars, characterized by temperatures ranging from minus 80 to 0 degrees Celsius every day and by strong wind oscillations. Indeed wind shakes the InSight lander and its instrumentation during the day leading to a high level of ambient noise. However, at sunset, the winds calm down allowing recording the quietest seismic data ever collected in the solar system. As a result, most seismic events detected on Mars by SEIS occurred in the quiet night hours. The challenging environment also requires to carefully distinguishing between seismic events and signals originating from movements of the lander, other instruments or atmospheric-induced perturbances.
The hammering by the HP3 instrument (another InSight experiment) and the close passage of whirlwinds (dust devils), recorded by SEIS, allow to map the physical properties of the shallow soil layers just below the station. We now know that SEIS landed on a thin, sandy layer reaching a few meters deep, in the middle of a 20 meter-wide ancient impact crater. At greater depths, the Martian crust has properties comparable to Earth’s crystalline massifs but appears to be more fractured. The propagation of the seismic waves suggest that the upper mantle has a stronger attenuation compared to the lower mantle.
Credit: ETH Zurich
Seismic activity also induced by tectonic stress
InSight landed in a rather quiet region of Mars, as no events near the station have been recorded up to now. The three biggest events were located in the Cerberus Fossae region about 1’500 km away. It is a tectonic graben system, caused by the weight of the Elysium Mons, the biggest volcano in the Elysium Planitia area. This provides strong evidence that seismic activity on Mars is not only a consequence of the cooling and therewith the shrinking of the planet but also induced by tectonic stress. The total seismic energy released on Mars lies between the one of Earth and of the Moon.
SEIS, complementary to other InSight measurements, also meaningfully contributed data to better understand the meteorological processes on Mars. The instrument’s sensitivity to both wind and atmospheric pressure allowed identifying meteorological phenomena characteristic of Mars, including the many dust devils that pass by the spacecraft every afternoon.
More information:
W. Bruce Banerdt et al. Initial results from the InSight mission on Mars, Nature Geoscience (2020). DOI: 10.1038/s41561-020-0544-yD. Giardini et al. The seismicity of Mars, Nature Geoscience (2020). DOI: 10.1038/s41561-020-0539-8
P. Lognonné et al. Constraints on the shallow elastic and anelastic structure of Mars from InSight seismic data, Nature Geoscience (2020). DOI: 10.1038/s41561-020-0536-y
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NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
