Science News
Headlines
. Rats have an imagination, new research suggests
. Has the lost planet, Theia, been found?
. What James Webb Space Telescope tells us about the Crab Nebula
. Ingenuity Helicopter ends its Mars mission
. New study warns of an imminent spike in planetary warming
Read more details on some of these topics below.

Rats have an imagination, new research suggests
As humans, we live in our thoughts: from pondering what to make for dinner to daydreaming about climbing Mount Everest. Now, researchers at HHMI's Janelia Research Campus have found that animals also possess an imagination.
A team from the Lee and Harris labs developed a novel system combining virtual reality and a brain-machine interface to probe the rat's inner thoughts. They found that, like humans, animals can think about places and objects that aren't right in front of them, using their thoughts to imagine walking to a location. Or even imagine moving a remote object to a specific spot.
Like humans, when rodents experience places and events, specific neural activity patterns are activated in the hippocampus. This is an area of the brain responsible for spatial memory. The new study finds rats can voluntarily generate these same activity patterns. They can recall remote locations distant from their current position.
This ability to imagine locations away from one's current position is fundamental to remembering past events and imagining possible future scenarios. Therefore, the new work shows that animals, like humans, possess a form of imagination, according to the study's authors.
How did they find this out? The system uses a brain-machine interface (BMI), which provides a direct connection between brain activity and an external device. The team's system studied the rat's hippocampus, a complex brain structure which has a major role in learning and memory. The hippocampus stores mental maps of the world. For instance, it has locations which are involved in recalling past events and imagining future scenarios. So when a memory about some place or an event is recalled, specific locations in the hippocampus get activated. This activity pattern shows up as electrical signals that can be recorded by the external device.
This thought process is something humans experience regularly. For example, when your father asks you if you are ready to go to school in the morning, you will run through a mental check-list of things like school uniform, homework, today's timetabel, lunch-box, etc. But no one knew whether animals could voluntarily control this activity.
The BMI produces a connection between the electrical activity in the rat's hippocampus and its position in a 360-degree virtual reality (VR) arena. The BMI allows the researchers to test whether a rat can activate hippocampal activity by just thinking about a location in the arena without physically going there -- essentially, detecting if the animal is able to imagine going to the location.
Once they developed their system, the researchers had to create the "thought dictionary" that would allow them to decode the rat's brain signals. This dictionary compiles what activity patterns look like when the rat experiences something -- in this case, places in the VR arena. As the rat walks on a spherical treadmill, its movements are translated on the 360-degree screen. The rat is rewarded when it navigates to its goal.
At the same time, the BMI system records the rat's hippocampal activity. The researchers can see which neurons are activated when the rat navigates the arena to reach each goal. These signals provide the basis for a real-time hippocampal BMI, with the brain's hippocampal activity translated into actions on the screen.
Next, the researchers disconnect the treadmill and reward the rat for reproducing the hippocampal activity pattern associated with a goal location. In this task, the BMI translates the animal's brain activity into motion on the virtual reality screen. Essentially, the animal uses its thoughts to navigate to the reward by first thinking about where they need to go to get the reward.
In the second task, the rat moves an object to a location by thoughts alone. The rat is fixed in a virtual place but "moves" an object to a goal in the VR space by controlling its hippocampal activity. This is like how a student in a classroom imagines taking their favourite football to the games field while still sitting in class! The researchers then changed the location of the goal, requiring the animal to produce activity patterns associated with the new location.
The team found that rats can precisely and flexibly control their hippocampal activity, in the same way humans likely do. The animals are also able to sustain this hippocampal activity, holding their thoughts on a given location for many seconds -- a timeframe similar to the one at which humans relive past events or imagine new scenarios.
The research also shows that BMI can be used to probe hippocampal activity, providing a novel system for studying this important brain region. BMI is increasingly used in prosthetics (artificial limbs). So this new work also opens up the possibility of designing novel prosthetic devices based on the same principles, according to the authors.

. Has the lost planet, Theia, been found?
Theia is an ancient planet body. Scientists believe that Theia's collision with Earth has given rise to the Moon. In a recent study, scientists at the California Institute of Technology say that two massive, iron-rich structures lying close to Earth’s core are the last remains of Theia.
If validated, the discovery could revolutionize our understanding of Earth’s history and lunar origins. It will finally prove that Theia existed and is still there: not in bits and pieces in space, but actually inside the Earth, deep in its mantle. What has this to do with the Moon?
For years, the origins of the Moon have puzzled scientists. The dominant theory, known as the giant impact hypothesis, says that the Moon formed from the remains of a massive collision between Earth and a mysterious lost planet roughly the size of Mars, aptly named Theia (after the Greek goddess of divine light).
According to the giant impact hypothesis, Theia orbited the Sun, nearly along the orbit of the proto-Earth (meaning, the Earth that existed before the collision). Due to the gravitational influence of Jupiter and/or Venus, Theia moved away from that orbit an collided with Earth. Scientists propose the Moon was formed from matter that was ejected following this devastating impact. 
Evidence for this theory come from lunar rock samples brought back to Earth by astronauts on the Apollo Space mission who landed on the moon. They were found to have very similar compositions to Earth’s crust. This seems to support the Theia-impact hypothesis. However, remnants of this ancient planet have never been found.
Now, researchers from CalTech, USA, say that they have located strange “blobs” near the center of the Earth. These structures were first discovered in the 1980s. They are continent- sized blobs, one beneath Africa and another under the Pacific Ocean. When there is an earthquake, seismic waves are generated which pass through the Earth and get detected in seismic stations. These structures cause seismic waves to slow down when passing through, so scientists realised that they are made up of material different from the surrounding mantle. It turns out that the difference is due to their high iron content.
For decades, the origin of these two dense regions has remained a mystery. Working with a multidisciplinary team, Dr. Yuan of CalTech used advanced seismic analysis and geochemical modeling to simulate on a computer what the chemical composition of Theia could have been and what its impact with Earth might have looked like. They found that such a collision would not have had the material mix uniformly with the Earth, but remain as separate blobs, just like what is seen. The blobs being heavy (since they are made of iron), would sink deep down towards Earth's core.
These findings may help us understand better the origins of planets formation of the first continents, and the origin of the very oldest surviving terrestrial minerals.

. What James Webb Space Telescope tells us about the Crab Nebula
The James Webb Space Telescope (JWST) of NASA, USA, is a telescope stationed in space! It is placed in orbit outside Earth's atmosphere so that it can conduct infrared astronomy. (The Earth's atmosphere blocks a lot of infra-red light; see figure). Its high-resolution and high-sensitivity instruments allow it to view objects too old, distant, or faint for the older Hubble Space Telescope. This enables it to observe the first stars and the formation of the first galaxies.
The James Webb Space Telescope has captured mind- blowing images of the Crab Nebula. It is one of the closest stars in our Milky Way galaxy which is a supernova remnant, that is, the star that remains after a supernova explosion. It can be seen on a clear night with binoculars in the Taurus constellation. At the center of the nebula lies the Crab Pulsar, a neutron star just 30 kilometres wide spinning at a rate of 30 times per second! This amazing behaviour is shown by 100s of pulsar stars which have been observed in the sky, because they emit pulses of radiation (in all wavemengths from gamma rays to radio waves).
Over the years, the Crab Nebula is been studied to gain more knowledge on supernovae, black holes and other mysteries. Webb can accurately determine the composition of the ejected material, particularly the content of iron and nickel, which may reveal what type of explosion produced the Crab Nebula. How does it do this? By comparison with pictures from the older Hubble telescope.
The Hubble telescope takes pictures in visible light, while Webb takes pictures in infra-red light. The figure shows images of the Crab Nebula taken by these two telescopes. At first glance, the general shape of the supernova remnant is similar to the image from NASA’s Hubble Space Telescope. In Webb’s infrared observation, a crisp, cage-like structure of fluffy gaseous filaments are shown in red-orange. In the central regions, emission from dust grains (yellow-white and green) is mapped out by Webb for the first time.
The inner workings of the Crab Nebula become more prominent and are seen in greater detail in the infrared light captured by Webb. In particular, Webb highlights what is known as synchrotron radiation: emission produced from charged particles, like electrons, moving around magnetic field lines at relativistic speeds. The radiation appears here as milky smoke-like material throughout the majority of the Crab Nebula’s interior.
This feature is a product of the nebula’s pulsar, a rapidly rotating neutron star. The pulsar’s strong magnetic field accelerates charged particles to extremely high speeds and causes them to emit radiation as they wind around magnetic field lines. Though emitted across the electromagnetic spectrum, the synchrotron radiation is seen in unprecedented detail with Webb’s NIRCam instrument.
How wonderful that we can learn all this about a star that is 6500 light years away from us! (One light year is the distance travelled by light in one year, that is 9.5x10^{12} km.) 

. Ingenuity Helicopter ends its Mars mission
Mars has a thin atmosphere made up mostly of carbon dioxide, argon, nitrogen, and a small amount of oxygen and water vapour. Scientists always wondered whether it would be possible for a plane to fly in this very thin atmosphere. When the Mars 2020 programme was approved by NASA, USA, in July 2014, a helicopter flight demonstration was neither included nor budgeted for. 
First tests on Earth were done to simulate the very low pressure of the atmosphere of Mars. A large chamber was filled with carbon dioxide to about 0.60% (about 1⁄160) of standard atmospheric pressure at sea level on Earth. This is like a helicopter flying at 34 km altitude in the atmosphere of Earth. In order to simulate the much-reduced gravity field of Mars (38% of Earth's), a line was attached to pull upwards during flight tests. A "wind-wall" consisting of almost 900 computer fans was used to provide wind in the chamber. After all these tests and simulations, the helicopter Ingenuity was designed.
Ingenuity is an autonomous (self-driving) NASA helicopter that operated on Mars from 2021 to 2024 as part of the Mars 2020 mission. Ingenuity was designed to be a technology demonstrator by JPL to assess whether such a vehicle could fly safely. Before it was built, launched and landed, scientists and managers expressed hope that helicopters could provide better mapping and guidance that would give future mission controllers more information to help with travel routes, planning, and hazard avoidance.
The helicopter underwent extensive flight-dynamics and environment testing, and was mounted on the underside of the Perseverance rover in August 2019. The rover was launched on July 30, 2020, and successfully landed on Mars on February 18, 2021. 
Ingenuity made its first flight on April 19, 2021, demonstrating that flight is possible in the extremely thin atmosphere of Mars, and becoming the first aircraft to conduct a powered and controlled extra-terrestrial flight. Because radio signals take between five and 20 minutes to travel between Earth and Mars, depending on the planets' positions, it could not be controlled directly in real time but flew autonomously to execute flight plans designed and sent to it in advance by JPL.
Originally intended to make only five flights, Ingenuity completed 72 flights in nearly three years. The five planned flights were part of a 30-sol technology demonstration. This was just to prove its airworthiness with each flight lasting up to 90 seconds at altitudes ranging from 3–5 m.
Following this demonstration, JPL designed a series of operational flights to explore how aerial scouts could help explore Mars and other worlds. In this operational role, Ingenuity scouted areas of interest for the Perseverance rover, improved navigational techniques, and explored the limits of its flight envelope. Ingenuity's performance and resilience in the harsh Martian environment greatly exceeded expectations, allowing it to perform far more flights than were initially planned.
Unfortunately, on January 18, 2024, Ingenuity's rotor blades were damaged while landing on its 72nd flight, permanently grounding the helicopter. NASA announced the end of its mission one week later. Ingenuity had flown for a total of two hours, eight minutes and 48 seconds over 1,004 days, covering more than 17 kilometres on a planet no human being has set foot on.

Sources: ScienceDaily https://www.sciencedaily.com, The Brief https://thedebrief.org, NASA https://www.nasa.gov, Wikipedia