Will we recognize alien life if we find it?

Searching for life out there

Photo: Astronomy.com

In searching for life on other planets, including on planets orbiting other stars (exoplanets), we are faced with some serious problems.

In the case of exoplanets, we are forced to observe from a great distance. Even at the speed of the Parker Solar Probe, the fastest moving spacecraft we have ever made, it would take us around 6,500 years to reach the nearest star. Looking at exoplanets for signs of life is being done using our telescopes, on the ground and in space. For the planets and moons in our Solar System, we can land spacecraft on them or orbit around them.

In many cases, it isn't out of the question that at some point in the next few years, space-suited feet will be walking on them. The exceptions will be where the conditions are just too extreme, such as on Venus or in orbit around Jupiter. This brings us to the biggest question. What are we looking for?

If we receive signals from distant worlds that are obviously produced by intelligent beings, or when we land on a planet and we see things crawling around, or fossils of possible extinct things that once crawled around, we have an answer. However, the search for alien life is likely to be more complicated than that.

Using what we see around us on our own world will be a help, but we have to be very careful not to adhere too closely to what we see here as an indicator of what extraterrestrial life, or evidence of it, will be like.

Since life appeared here on Earth around four billion years ago, it has gone through a long series of extinctions, where large numbers of species vanished. Those events were caused by environmental disruptions due to tectonic and volcanic activity, and the odd asteroid impact, After things recovered following the extinction, the survivors expanded and diversified to fill the ecological void, only to encounter the next extinction.

An example is some 250 million years ago, at the end of the Permian Period, more than 90% of animal species were wiped out, making room for the age of the dinosaurs to begin. That age ended around 65 million years ago, at the end of the Cretaceous Period, in an extinction where around 75% of species were wiped out.

The survivors of extinctions were not always the smartest. They were often just lucky. That led to humans, and all other living things, sharing this planet, the result of many throws of the genetic dice.

Other worlds will have their own throws of the dice, so there is little chance beings on those worlds will be like those living here, or that any intelligent creatures will look anything like us, or share our ideas and attitudes. Beings living in water would know little about fire and would have real problems with electricity and related technologies.

How then are we to search for extraterrestrial life?

One idea being followed is to look for things that living things introduce into their environments. In the case of our world, the answer is oxygen. This highly reactive gas does not occur naturally, and moreover, will react with minerals, and vanish quickly if not kept topped up.

The oxygen we breathe is a by-product of photosynthesis in plants. Finding oxygen, or other highly reactive gases such as chlorine in the atmosphere of a planet, would be a strong indicator of life being present.

Life as we know it is made up of complicated molecules. As far as we know, only living things make such molecules and as we live and die, those molecules find their way into the environment.

We know, for example, soil samples from the Moon contain no large molecules, whereas a sample of soil from our world would be loaded with them. We are searching for such molecules in the atmospheres of exoplanets, the soils of Mars and hopefully soon, in the under-ice oceans of Europa and Enceladus.

Of course, knowing life exists might not mean we will recognize that life when we see it. Have you ever seen a sea cucumber?

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• After sunset, Venus shines low in the southwest with Saturn close by. Jupiter lies high in the southeast and Mars rises in the northeast.

• The Moon will reach last quarter on Jan 21.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.

A close encounter with the Sun

Studying the sun

Photo: Pixabay

In December, the Parker Solar Probe spacecraft made the closest controlled approach to the sun of any manmade object.

Moving at 192 kilometres a second, it was also the fastest. It got to within 6.5 million kilometres of the solar surface (the photosphere). That is very close.

Our planet orbits the sun at a distance that varies little from 150 million kilometres. At our distance a square metre of non-reflective material located above the atmosphere will collect about 1,400 Watts of solar energy. At its point of closest approach, the Parker Solar Probe had to deal with about 745,000 Watts of energy per square metre.

Designing a shield to protect the spacecraft from this amount of heat was a major engineering challenge. Getting the spacecraft to the sun was another. The Earth is moving around the sun at roughly 30 kilometres per second. If we want to fall toward the sun, we will have to launch the spacecraft at that speed in the opposite direction, cancelling out that 30 km/s. Unfortunately, we have no launcher capable of that, so getting to the sun involved launching the spacecraft towards Venus, which we can do. Multiple swings by that world put the probe onto a path taking it close to the sun.

The effort was worth it for two reasons. Firstly the sun is the only star close enough for easy study, and secondly, our growing dependence on technology for our daily lives and our highest-ever degree of exploitation of our planet is making us more and more vulnerable to the Sun's bad behaviour. We need to address this issue.

The spacecraft was named after Eugene Parker, an American physicist who contributed hugely to our knowledge of how solar plasmas and magnetic fields interact. This might sound esoteric, but it is these interactions that cause solar flares and coronal mass ejections, both of which are extremely disruptive to us.

If you were to take a long iron bar, and put one end in a pile of ice cubes and the other in hot water, you would expect the temperature to vary gradually along its length, from cold at the icy end to hot at the hot water end. You would not expect the middle of the rod to glow red hot. Our understanding of the nature of heat, and simple common sense would rule that out. However, we have exactly that sort of problem with the sun.

The visible surface of the sun, the photosphere, has a temperature of about 6,000 C. Above that is a thin layer called the chromosphere, which can be a little hotter and above that is a layer extending all the way out to Earth and probably beyond, called the corona, which has a temperature of a million degrees or more.

Beyond the corona is the cold vacuum of space. One side of the corona is in contact with a medium with a temperature of 6,000 C and the other is exposed to cold space. Since heat only flows from warmer to colder things, where is the corona getting its heat? The only way the corona could be hotter than the substances with which it is in contact is if there is something generating heat within it.

In 1957, Parker proposed that whatever is heating the corona forces it to expand, driving a "solar wind". Back then, his idea was treated with derision. However, he was proven right.

Solar flares, coronal mass ejections and other explosive solar events are all driven by processes in that hot corona. Understanding what is going on there is not only a matter of scientific curiosity but could have enormous value in minimizing the disruption of our transportation, energy and communications infrastructure the sun causes.

Our growing dependence on instant world-wide communication is making us more vulnerable. It will take a while to digest the data coming back from the Parker Solar Probe, but we know it will teach us a lot about our star, especially what drives its bad behaviour and how to predict it.

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• After sunset, Venus shines low in the southwest with Saturn nearby. Jupiter shines high in the east. At the same time Mars is rising in the northeast.

• The moon will be full on Jan. 13.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.

Light from one of first galaxies to form after the beginning of the universe finally seen

A Christmas light galaxy

Photo: NASA, ESA, CSA, STScI, Chris Willott (National Research Council Canada), Lamiya Mowla (Wellesley College), Kartheik Iyer (Columbia University)

In this image from NASA's James Webb Space Telescope, thousands of glimmering galaxies are bound together by their own gravity, making up a massive cluster formally classified as MACS J1423. The largest, bright white oval is a supergiant elliptical galaxy. The galaxy cluster acts like a lens, magnifying and distorting the light of objects that lie well behind it, an effect known as gravitational lensing.

Once again the James Webb Space Telescope has come up with a stunning and intriguing image.

Taken with some major cosmic help, it shows one of the first galaxies to form after the beginning of the universe, almost 14 billion years ago. The image looks like a collection of old-style Christmas lights, where highly luminous stars of all colours are forming and starting to shine.

About 380,000 years after the Big Bang, the universe had cooled to the point where the primordial "quark soup" could condense into atoms. At this point the universe changed from an incredibly hot, opaque, glowing fog, to more or less the way it looks today.

At the point of transition we see the beginnings of the condensations of matter that were the embryos of the first galaxies. A mere 220,000 years later, we had galaxies, like the one above, described in this article from NASA.

This ability to look back in time is a consequence of the universe being so large that light from the more distant objects, despite travelling at almost 300,000 kilometres a second, can take billions of years to reach us.

That Christmas light galaxy is so far away its light is reaching us now. However, without a huge piece of cosmic help, the light from that and other objects that far away would be too faint for our telescopes. What makes it visible is a process known as gravitational lensing.

Imagine a bowling ball sitting in the middle of a trampoline, its weight stretching the fabric, forming a depression. If you roll marbles across the trampoline, passing over the edges of the depression, the marbles will have their paths bent inwards, towards a point behind the bowling ball. They have been focussed. The distorted fabric is acting like a crude lens.

Precisely in line between us and that distant galaxy there happens to be a cluster of galaxies. Just like the bowling ball, the colossal mass of the galaxy cluster is stretching the fabric of space-time. As in the case of the bowling ball and trampoline, the stretched space-time acts as a lens, fortuitously collecting and focussing light in our direction. Imagine a light collector millions of light years across, unimaginably larger than any telescope we can build.

Understandably, the "lens" is not perfect. However, thanks to Albert Einstein, and images of that galaxy cluster, it has been possible to largely correct for those imperfections, enabling us to look more than 13 billion years back in time.

The evidence we have collected so far suggests that the first galaxies formed surprisingly early in the history of the universe. There were functioning galaxies a mere 500,000 years after the Big Bang. As yet we cannot explain this. Understandably we are trying hard to figure out what is going on.

As that quark soup cooled after the Big Bang, the first atoms to form were the ones most able to tolerate the intense heat and density. There were hydrogen and helium.

Nothing was left over for other atoms to form as the cooling continued. Without all the other elements, planets and life as we know it is impossible. However, these two elements are enough to make stars, and back then, star formation was very vigorous, producing extremely bright, supergiant stars.

These lived short, active lives and exploded, distributing the waste products of their energy production: all the other elements. These first stars started to build up the concentration of ingredients necessary for making planets, us, and any other living things who almost certainly share the universe with us.

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• After sunset, Venus shines low in the southwest with Saturn nearby. Jupiter shines high in the southeast. At the same time Mars is rising in the northeast. Mercury lies in the southeast just before dawn.

• The Moon will reach its first quarter on Jan. 6.

Here's to 2025 being scientifically exciting but otherwise quiet and peaceful. Happy New Year.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.

Astronomy from a logging road

Listening to space

Photo: Pixabay

There are some astronomy projects that are better done far away from observatories, or any other form of human activity.

The enormous amount of interference from our power lines, electric motors and most of all, digital devices can totally obliterate the signals being sought. Years ago, an ionospheric physicist friend and I worked on such a project. We wanted to observe the waves launched onto the field lines of the Earth's magnetic field by the rubbing of the solar wind over its outer surface, the magnetopause.

Since the magnetic field lines dive down to the North Magnetic Pole, which lies under the Canadian Arctic, we just needed a quiet, deserted Canadian location for our equipment. We finally selected the Algonquin Provincial Park, in Ontario.

It was a hot, clear, summer's day in Ottawa when we loaded the equipment into the car for a drive of some 250 kilometres. There were two possible routes to the Algonquin Park. One, Ontario's Highway 17, runs just south of the Ottawa River, which is more direct but less scenic, and Quebec's Highway 148, longer, but more scenic and running north of the Ottawa River.

We chose the Quebec option. We crossed back into Ontario at L'Isle aux Allumettes, passed through the town of Pembroke, and continued into the park. Now we were on a dirt road with, thanks to heavy logging traffic, severe washboard surfaces on every hill and bend. There is a major radio observatory and an important power line in the park. We had to avoid both.

After crossing the Barron River Canyon we turned right onto a narrow, dirt road and headed up it for two or three kilometres. It was a strip of dirt with dense forest either side. We found a place where we could pull off the road with a chance of being able to get back onto it, and set up our experiment.

The detector consisted of a very long length of electrical cable with ten cores in it, connected so that when laid on the ground in a loop, some 15 metres across, it formed a ten-turn coil. We threaded it on the ground among the trees, helped by countless black flies. In the car we had a sensitive audio amplifier and a battery powered tape recorder. We had no digital devices because of the interference issue. Screening them would be more work than using an old tape recorder and digitizing things later. By the time we had the stuff up and running it was dark.

The bugs had gone home, so we did not need to swelter in the car as an alternative to being eaten alive. Air conditioning was not an option because running the car would create interference. We listened to the signals as they came in, while recording them.

The rubbing of the solar wind makes waves in the field lines, rather like a bow making waves in a violin string. These waves then travel along the field lines, down to the ground, and some of them passed through our loop, being converted into electrical currents which we amplified and recorded. They sounded like feeding time at an alien cosmic zoo.

There were rising and falling whistles and tweaks, various hissing noises and assorted clicks, and under all of it, the inevitable, although faint hum from distant power lines.

In a completely dark environment, the clear, night sky looks grey. I will never forget the experience of standing by the car, surrounded by the black silhouettes of high trees, with that strip of grey sky, sprinkled with stars, while listening to those sounds from space.

Space is filled with interacting magnetic fields. Imagine what we might pick up if we could put a nice big coil somewhere out beyond the edges of the Solar System, in interstellar space. One day it will happen.

In the meantime, since this is my last column before Christmas, I wish you all a merry Christmas and a happy New Year.

•••

• After sunset, Venus shines low in the southwest.

• Saturn lies in the south and Jupiter is rising in the northeast. Mars rises about three hours later. • Mercury lies in the southeast just before dawn.

• The Moon will be new on Dec. 30.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.