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The seismicity of Mars

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Mars is shaking. Credit: NASA/JPL – Caltech

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  

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Marsquakes are similar to the 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 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 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.

The seismicity of Mars
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.


Explore further

First direct seismic measurements of Mars reveal a geologically active planet


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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The seismicity of Mars (2020, February 24)
retrieved 25 February 2020
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An SUV-sized asteroid zoom by Earth in close shave flyby in this time-lapse video

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Asteroid 2023 BU zipped past Earth Thursday night (Jan. 26) to the delight of amateur astronomers worldwide. For skywatchers without access to a telescope or those who had their view hampered by bad weather, luckily the Italy-based Virtual Telescope Project was there to observe the event and livestream the whole thing for free.

The Virtual Telescope is a robotic telescope operated by Italian amateur astronomer Gianluca Masi near Rome, Italy. As 2023 BU hurtled toward Earth, the telescope was able to track the rock through a gap in the clouds when it was about 13,670 miles (22,000 kilometers) from the closest point on Earth’s surface (about the altitude of the GPS navigation satellite constellation) and 22,990 miles (37,000 km) from the Virtual Telescope.

Masi, who shared an hour-long webcast of the observations on the Virtual Telescope website, wasn’t able to capture the closest approach as clouds rolled in, however. Nonetheless, the Virtual Telescope Project was able to get a good look at the car-sized rock, seen in time-lapse above.

 

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The Italy-based Virtual Telescope captured asteroid 2023 BU shortly before its closest approach to Earth. (Image credit: The Virtual Telescope Project)

The rock, discovered less than a week ago on Saturday (Jan. 21), passed above the southern tip of South America at 7:27 p.m. EST on Thursday Jan. 26 (0027 GMT on Jan. 27), at a distance of only 2,240 miles (3,600 km) at its closest point to Earth’s surface.

This close approach makes 2023 BU the fourth nearest asteroid ever observed from Earth, with the exception of five space rocks that were detected before diving into Earth’s atmosphere.

Only 11.5 to 28 feet wide (3.5 to 8.5 meters), 2023 BU posed no danger to the planet. If the trajectories of the two bodies had intersected, the asteroid would mostly have burned up in the atmosphere with only small fragments possibly falling to the ground as meteorites.

In the videos and images shared by Masi, the asteroid is seen as a small bright dot in the center of the frame, while the longer, brighter lines are the surrounding stars. In reality, of course, it was the asteroid that was moving with respect to Earth, traveling at a speed of 21,000 mph (33,800 km/h) with respect to Earth. As Masi’s computerized telescope tracked its positionthe rock appeared stationary in the images while rendering the stars as these moving streaks.

Related stories:

The gravitational kick that 2023 BU received during its encounter with Earth will alter the shape of its orbit around the sun. Previously, the space rock followed a rather circular orbit, completing one lap around the sun in 359 days. From now on, BU 2023 will travel through the inner solar system on a more elliptical path, venturing half way toward Mars at the farthest point of its orbit. This alteration will add 66 days to BU 2023’s orbital period.

The asteroid was discovered by famed Crimea-based astronomer and astrophotographer Gennadiy Borisov, the same man who in 2018 found the first interstellar comet, which now bears his name, Borisov.

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Green comet zooming our way, last visited 50,000 years ago

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This photo provided by Dan Bartlett shows comet C/2022 E3 (ZTF) on Dec. 19, 2022. It last visited during Neanderthal times, according to NASA. It is expected to come within 26 million miles (42 million kilometers) of Earth on Feb. 1, 2023, before speeding away again, unlikely to return for millions of years. Credit: Dan Bartlett via AP

A comet is streaking back our way after 50,000 years.

The dirty snowball last visited during Neanderthal times, according to NASA. It will come within 26 million miles (42 million kilometers) of Earth Wednesday before speeding away again, unlikely to return for millions of years.

So do look up, contrary to the title of the killer- movie “Don’t Look Up.”

Discovered less than a year ago, this harmless green comet already is visible in the northern night sky with binoculars and small telescopes, and possibly the naked eye in the darkest corners of the Northern Hemisphere. It’s expected to brighten as it draws closer and rises higher over the horizon through the end of January, best seen in the predawn hours. By Feb. 10, it will be near Mars, a good landmark.

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Skygazers in the Southern Hemisphere will have to wait until next month for a glimpse.

While plenty of comets have graced the sky over the past year, “this one seems probably a little bit bigger and therefore a little bit brighter and it’s coming a little bit closer to the Earth’s orbit,” said NASA’s comet and asteroid-tracking guru, Paul Chodas.

Green from all the carbon in the gas cloud, or coma, surrounding the nucleus, this long-period comet was discovered last March by astronomers using the Zwicky Transient Facility, a wide field camera at Caltech’s Palomar Observatory. That explains its official, cumbersome name: comet C/2022 E3 (ZTF).

On Wednesday, it will hurtle between the orbits of Earth and Mars at a relative speed of 128,500 mph (207,000 kilometers). Its nucleus is thought to be about a mile (1.6 kilometers) across, with its tails extending millions of miles (kilometers).

The comet isn’t expected to be nearly as bright as Neowise in 2020, or Hale-Bopp and Hyakutake in the mid to late 1990s.

Green comet zooming our way, last visited 50,000 years ago
This photo provided by Dan Bartlett shows comet C/2022 E3 (ZTF) on Dec. 19, 2022. It last visited during Neanderthal times, according to NASA. It is expected to come within 26 million miles (42 million kilometers) of Earth on Feb. 1, 2023, before speeding away again, unlikely to return for millions of years. Credit: Dan Bartlett via AP

But “it will be bright by virtue of its close Earth passage … which allows scientists to do more experiments and the public to be able to see a beautiful comet,” University of Hawaii astronomer Karen Meech said in an email.

Scientists are confident in their orbital calculations putting the comet’s last swing through the ‘s planetary neighborhood at 50,000 years ago. But they don’t know how close it came to Earth or whether it was even visible to the Neanderthals, said Chodas, director of the Center for Near Earth Object Studies at NASA’s Jet Propulsion Laboratory in California.

When it returns, though, is tougher to judge.

Every time the comet skirts the sun and planets, their gravitational tugs alter the iceball’s path ever so slightly, leading to major course changes over time. Another wild card: jets of dust and gas streaming off the comet as it heats up near the sun.

“We don’t really know exactly how much they are pushing this comet around,” Chodas said.

The comet—a time capsule from the emerging solar system 4.5 billion years ago—came from what’s known as the Oort Cloud well beyond Pluto. This deep-freeze haven for comets is believed to stretch more than one-quarter of the way to the next star.

While comet ZTF originated in our solar system, we can’t be sure it will stay there, Chodas said. If it gets booted out of the solar system, it will never return, he added.

Don’t fret if you miss it.

“In the comet business, you just wait for the next one because there are dozens of these,” Chodas said. “And the next one might be bigger, might be brighter, might be closer.”

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Green comet zooming our way, last visited 50,000 years ago (2023, January 27)
retrieved 27 January 2023
from https://phys.org/news/2023-01-green-comet-years.html

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University of Guelph students are in the race to grow food in space

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Growing food in space is a complex challenge, but students at the University of Guelph have a pretty good idea of how to go about it.

The team, Canada GOOSE — which stands for Growth Options for Outer Space Environments — is among five teams across Canada, including the University of Waterloo, competing in the multi-year competition from the Canadian Space Agency (CSA) known as the Deep Space Food Challenge.

The team is currently on the second phase of the competition and hosted representatives from CSA on Thursday to showcase their idea.

The teams have been instructed to develop new technologies that would be able to produce food in space, but that could also be used for production here on Earth.

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The Canada GOOSE team uses a hydroponic-like, high-density system to produce several kinds of fruits, vegetables and mushrooms.

Ajwal Dsouza is a first year PhD student, who is part of the University of Guelph’s Canada GOOSE team. He believes this technology can be used to grow food and educate communities outside the lab. (Carmen Groleau/CBC)

“We have a multi-tier system growing a variety of plants, but the whole environment is being controlled so, air circulation, temperature, CO2 level, also light levels with the LEDs. So basically giving the best conditions for the plants to grow,” explained Serge Levesque, a second-year PhD student.

Rosemary Brockett, a second year masters student, explained the crops were developed and grown to produce as little waste as possible.

A row of different vegetables grown inside a unit.
The Canada GOOSE team uses a hydroponic-like system in their growth chamber to produce different fruits and vegetables, as well as mushrooms. (Carmen Groleau/CBC)

“We can’t have any kind of waste in space or in remote areas so we’re growing them all using fabric wicks,” she said.

“The fabric pulls up the water to the plants and then we have 3D-printed holders that support the plants and the fabric.”

Brockett said they can grow root vegetables like turnips and carrots; dwarf tomatoes and peppers; leafy greens like cabbage, lettuce and bok choy; smaller trays have herbs, radish microgreens and sprouts.

Levesque said they also grow mushrooms because they play a key role in the unit’s ecosystem.

“Plants photosynthesize and release oxygen and mushrooms need oxygen to release CO2, so it allows us to use CO2 more efficiently,” he said, adding the inedible parts of other vegetables can be used to help grow the mushrooms; a way to re-use and eliminate waste.

A group of people wearing blue lab coats gather around a small greenhouse in a lab.
Representatives with the Canadian Space Agency were at the University of Guelph on Thursday, as students who are part of the school’s Canada GOOSE team competing in the Deep Space Food Challenge. (Carmen Groleau/CBC)

Tech can help feed, educate Earthlings

The Canadian grand prize won’t be announced until Spring 2024, but no matter the results, the students see applications for their technology closer to home.

First-year PhD student Ajwal Dsouza says it could be a useful education tool for youth, for example.

“Imagine putting this system up in a school or a university and educate people about the technological advancements happening but also [encourage] younger generations to study this,” and can also imagine applications in addressing food insecurity in other more remote parts of the world, like Canada’s northern communities.

“A system like this can be economically feasible. You can use it in remote areas where there is food insecurity using limited resources,” he said.

“We can grow food in places where the weather is not good, like Canada’s north or in a desert, where there’s limited resources. This can help people grow food in tough conditions,” said Dsouza.

The Canada GOOSE team will find out if they enter the third stage of the competition in March.

 

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