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Category: space

The relationship between mental imagery and vision is a long-standing problem in neuroscience. Currently, it is not known whether differences between the activity evoked during vision and reinstated during imagery reflect different codes for seen and mental images. To address this problem, we modeled mental imagery in the human brain as feedback in a hierarchical generative network. Such networks synthesize images by feeding abstract representations from higher to lower levels of the network hierarchy. When higher processing levels are less sensitive to stimulus variation than lower processing levels, as in the human brain, activity in low-level visual areas should encode variation in mental images with less precision than seen images. To test this prediction, we conducted an fMRI experiment in which subjects imagined and then viewed hundreds of spatially varying naturalistic stimuli. To analyze these data, we developed imagery-encoding models. These models accurately predicted brain responses to imagined stimuli and enabled accurate decoding of their position and content. They also allowed us to compare, for every voxel, tuning to seen and imagined spatial frequencies, as well as the location and size of receptive fields in visual and imagined space. We confirmed our prediction, showing that, in low-level visual areas, imagined spatial frequencies in individual voxels are reduced relative to seen spatial frequencies and that receptive fields in imagined space are larger than in visual space. These findings reveal distinct codes for seen and mental images and link mental imagery to the computational abilities of generative networks.

Keywords: encoding models; fMRI; generative network; mental imagery; receptive fields; vision.

Copyright © 2020 Elsevier Inc. All rights reserved.

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Mars in 4 K.

A world first. New footage from Mars rendered in stunning 4K resolution. We also talk about the cameras on board the Martian rovers and how we made the video.

The cameras on board the rovers were the height of technology when the respective missions launched.

A question often asked is:
‘Why don’t we actually have live video from Mars?’

Although the cameras are high quality, the rate at which the rovers can send data back to earth is the biggest challenge. Curiosity can only send data directly back to earth at 32 kilo-bits per second.

Instead, when the rover can connect to the Mars Reconnaissance Orbiter, we get more favourable speeds of 2 Megabytes per second.

However, this link is only available for about 8 minutes each Sol, or Martian day.

As you would expect, sending HD video at these speeds would take a long long time. As nothing really moves on Mars, it makes more sense to take and send back images.

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But now, all the Arab world’s universities must be ready to run with the baton that Hope is handing to them. Currently, the overwhelming majority of the young people who watched the launch on their smartphones and decided on a career in space science will have to study abroad, because the Arab world largely lacks the capacity to educate them in astrophysics or space science.

The United Arab Emirates’ Mars probe is a stunning and historic effort, but it needs to be transformational, too.

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A new study identified 37 recently active volcanic structures on Venus. The study provides some of the best evidence yet that Venus is still a geologically active planet. A research paper on the work, which was conducted by researchers at the University of Maryland and the Institute of Geophysics at ETH Zurich, Switzerland, was published in the journal Nature Geoscience on July 20, 2020.

“This is the first time we are able to point to specific structures and say ‘Look, this is not an ancient volcano but one that is active today, dormant perhaps, but not dead,’” said Laurent Montési, a professor of geology at UMD and co-author of the . “This study significantly changes the view of Venus from a mostly inactive planet to one whose interior is still churning and can feed many .”

Scientists have known for some time that Venus has a younger surface than like Mars and Mercury, which have cold interiors. Evidence of a warm interior and dots the surface of the planet in the form of ring-like structures known as , which form when plumes of hot material deep inside the planet rise through the mantle layer and crust. This is similar to the way mantle plumes formed the volcanic Hawaiian Islands.

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Once Upon a Time I Lived on Mars: Space, Exploration, and Life on Earth by Kate Greene St. Martin’s Press, 2020 hardcover, 240 pp. ISBN 978−1−250−15947−2 US$27.

While the robotic missions launching to Mars this year have a wide range of science goals, they are widely seen as precursors for eventual human missions to the Red Planet. NASA’s Mars 2020 mission includes an experiment called MOXIE that will demonstrate a way to produce oxygen from the carbon dioxide in the Martian atmosphere, a capability that will be essential for future human expeditions. NASA’s fiscal year 2021 budget proposal included a request to start work on a Mars Ice Mapper mission, an orbiter that would search for subsurface ice deposits that could be resources for future human expeditions.

Much of the planning for future Mars missions is focused on various capabilities needed to safely transport humans to the surface of Mars and bring them back. But beyond technologies like in situ resource utilization and supersonic retropropulsion are more mundane, but no less essential, matters: How will the crew eat? How will they deal with boredom on the long mission? How will they get along with one another in a confined space?

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SANTA BARBARA, CALIFORNIA — NASA scientist Philip Lubin is working on perfecting laser technology that could propel a light spacecraft to Mars in as little as three days.

In order for spacecraft to achieve faster speeds, Lubin proposes using an electromagnetic propulsion system that uses light and radiation, rather than the current fuel-based rocket propulsion system.

Photonic propulsion is a theoretical system that uses the energy and momentum from photons to move objects through space. According to Wired, when photons from a laser array reflect off an object, their energy is translated into a push that’s capable of moving objects like a spacecraft.

The system would currently work best with robotic spacecraft. According to Lubin, a robotic probe with a thin reflective sail could travel to Mars in three days. On the other hand, a manned shuttle could reach Mars in a month using the laser-based system. He estimates that lasers could accelerate spacecraft to 30 percent the speed of light, which was previously unheard of.

Using photonic propulsion, interstellar travel may be possible and sending a probe to Earth’s closest star, Alpha Centauri, could take as little as 15 years, reported Space.com.

In comparison, our current technology takes four to eight months to get to Mars. It took 37 years for the Voyager 1 spacecraft to reach the edge of our solar system.

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The United Arab Emirates’ first interplanetary mission successfully took off from the southern tip of Japan on July 20th, sending up a car-sized probe bound for the planet Mars. The spacecraft, called Hope, will now spend the next seven months traveling through deep space, before inserting itself into Mars’ orbit in February.

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