Answers to Last issue's Do You Know?
1. Could there be materials on other planets that we do not have on Earth?
Ans: A very few space vehicles have actually explored comets and meteors. In earlier issues of Jantar Mantar, we talked about the Rosetta space probe built by the European Space Agency (launched in March 2004) which studied the comet 67P/Churyumov–Gerasimenko. Its lander module called Philae actually landed on it. At the end of its mission, Rosetta also landed on the comet. Both Rosetta and Philae made several measurements, including of free oxygen and organic compounds on 67P. They found sixteen organic compounds, four of which were seen for the first time on a comet, and also an amino acid, glycine, which is one of the building blocks of proteins.
However, such space-craft are not the only way to see what is inside comets. Meteoroids are fragments of comets or asteroids. Sometimes they fall to earth, attracted by its gravity. Mostly they burn up due to friction as they enter earth's atmosphere and are seen as meteors streaking through the sky. Sometimes, they actually reach the earth as meteorites and then you can analyse their composition to see what they are made of.
Chemical analysis has so far identified around 300 minerals in these chunks of debris from deep space, including around 40 that have only ever been seen in meteorites. One of the most intriguing materials so far was found in the Allende meteorite, which exploded over Mexico in Feb, 1969. It is the largest (of the rare) carbonaceous chondrite ever found on Earth. An extensive search for pieces was conducted and over 2 tons of meteorite were recovered. Because of the amount of material found, it is one of the best studied meteorites ever. It was dated to be the same age as our solar system, with large amounts of calcium and aluminium.
After analysing samples from the debris, scientists in 2012 announced the discovery of a material that has not only never been seen on Earth, but wasn’t even known to be possible. Named ‘panguite’ – after the giant Pan Gu who created the Earth in Chinese mythology – it consists of a bizarre mix of elements, including titanium, zirconium and scandium.
Scientists also found new forms of the elements calcium, barium and neodymium in the meteorite. They were believed to come from some source outside the Solar System, probably due to shockwaves from a supernova explosion. It also contained the rare isotope Aluminum 26. Elements such as krypton, xenon, nitrogen and some other elements whose forms are also unknown in the Solar System were also found. All these were introduced as fine "dust" from nearby stars, and a cross section of the rock actually shows these grains clearly (see picture).
A detailed study in 2020 has even identified iron and lithium-containing protein of extraterrestrial origin, the first such discovery in meteorites.

2. We know that photosynthesis (using sunlight to make food) occurs in plants. Can an animal photosynthesise as well?
Ans: There are indeed some animals that photosynthesise, but most of them do so by forming partnerships. Corals are the classic example. They’re a collection of hundreds and thousands of soft-bodied animals that resemble sea anemones. They life in rocky reefs called coral reefs. Special algae called dinoflagellates live in compartments within their cells. These residents, or endo-symbionts, can photosynthesise and they provide the corals with nutrients.
Some sea anemones, clams, sponges, and worms also have photosynthetic endosymbionts, and also the spotted salamander.
Photosynthesis takes place within tiny structures called chloroplasts inside the cells of plants. The Elysia sea slugs eat algae and and then co-opt their chloroplasts for themselves! The stolen chloroplasts are stored along the slug’s digestive tract, provide it with energy, and allow it to “live as a plant“ This association is vital to the slug, which cannot reach adulthood without it.
But such partnerships are very complicated. The host needs to “pay” its symbionts in nutrients. They need ways of persuading the symbionts to release their manufactured nutrients, rather than hoarding it for themselves. They need to control the symbionts’ growth, and they need to transfer their partners to the next generation (corals do it by releasing the symbionts into the surrounding water).
Recently, an insect called pea aphid was found to have pigments called carotenoids that can produce ATP molecules (energy produced in photosynthesis is stored in ATP). They found out, curiously, that the aphids could do this because of a gene they stole from fungi!
Another insect, the Oriental hornet, uses a different pigment called xanthopterin to convert light to electrical energy. Both insects could be using their ability as a back-up generator, to provide energy when supplies are low or demand is high. But both cases are controversial, and the details of what the pigments are actually doing are unclear. And neither example is true photosynthesis, which also involves transforming carbon dioxide into sugars and other such compounds. Storing solar energy is just part of the full conversion process.
But is all this really useful? Is this something that humans want to try? Photosynthesis is a useless ability without some way of exposing yourself to as much of the Sun’s energy as possible. That requires a large surface area, relative to their volume. Plants achieve that with large, horizontal, light-capturing surfaces – leaves. The food pyramid then ensures that animals eat these plants and get their food from secondary sources. Life has its own way of organising itself.

3. We speak of "five senses", but is there a scientific notion of senses, and how many there are?
Ans: There are five basic human senses you must be familiar with: touch, sight, hearing, smell and taste. There are sense organs for each sense that collect and send information to the brain which decodes the information and helps us to understand the world around us. Even these senses are not independent: how often have you expected something to taste a certain way because it smelled a certain way?!
However, But there are other senses as well. These lesser-known senses include spatial awareness and balance. First consider the senses that relate to the position of our bodies. Even with eyes closed, you can touch your elbow with a finger. You somehow know where the end of the finger is, and where the elbow is located. This sense of spatial awareness is called proprioception.
Proprioception works due to receptors in our muscles known as spindles, which tell the brain about the current length and stretch of the muscles. Again, even with eyes closed, if someone tilts you forward or sideways, you will still have a good idea of your position. The sense organ responsible for this is the fluid-filled vestibular system in your inner ear, which helps us keep balance. For example, you can read while walking. You can even focus on the letters if you are running so this sense has the ability to compensate for our motion as well.
There are also many senses that tell us about the inner state of our bodies. The most obvious of these are hunger and thirst, inner body pain (nociception), and the need to empty the bladder or bowel. Less obvious and less available to conscious awareness are incoming signals about blood pressure, the pH level of the cerebrospinal fluid, plus many more.
Even senses like touch have different responses to different types of touch. Recently the Nobel prize was awarded to scientists who studied the response to pressure and temperature (thermoception). Pain, and even itching sensations, trigger different responses.
Some scientists include even more abilities as senses:
. sense of colour, sense of moods associated with colour, sense of temperature.
. sensitivity to gravity, air and wind pressure, and motion.
. hormonal sense, such as pheromones, hunger for food, water or air.
. pain, mental distress, sense of self, including friendship, companionship and power, psychic capacity.

4. Can we build a ship made of ice?
Ans: During World War II, there was a British project called Habakkuk which tried to build an aircraft out of ice. An aircraft carrier is a ship that carries aircraft to far away places from where it can be flown. Why did such a project exist? During the war, there were severe shortages of steel and aluminium!
The team building the prototype in Canada strengthened the ice by adding wood pulp to create a substance called pykrete, named after inventor Geoffrey Pyke. But they soon found that it needed an expensive refrigeration system, which required vast amounts of steel! So it was not a good idea. Today, global warming and warmer oceans with melting ice make it an even worse idea.
Today pykrete is used to create ice domes and ice roads. It can be three times stronger than pure ice. So, you can in principle build such a ship, but do you really want to?

5. I read about large amount of plastic waste found in oceans, but how does plastic get into the ocean?
Ans: See the graphic on this page.
Sources and picture credits: Wikipedia, BBC, Sensory Trust, Science focus, National Ocean Service, USA, Boomerang Alliance, Australia