By Girish Linganna
Jan 6: SO, INDIA HAS STARTED THE NEW YEAR literally with a bang, as India’s space agency, the Indian Space Research Organisation (ISRO) successfully launched a rocket carrying an observatory as part of an ambitious space exploration project to investigate the polarization of high-intensity X-ray sources and study celestial objects like black holes—an area in space where matter has collapsed in on itself with gravitational pull so strong that even light cannot escape it.
XPoSat, or X-ray Polarimeter Satellite, launched from the Sriharikota spaceport at 09:10 local time (03:40 GMT) on Monday, January 1, 2024, is only the second mission of this nature in the world after NASA launched a similar mission which produced unprecedented results. Built at an approximate cost of Rs 250 million ($30 million; £23.5 million), XPoSat is expected to have a lifespan of around five years.
ISRO wrote in a post on X (formerly Twitter) on Monday, “2024 lifted off majestically. XPoSat health is normal. Power generation has commenced,” while ISRO chief S Somanath said the PSLV-C58 vehicle had placed the satellite into its intended orbit, which he described as “excellent”. “We have an exciting time ahead,” he said after the launch.
The goal of the mission is to measure the polarization of X-rays in the energy range of 8-30 KeV. It involves conducting extended observations of cosmic X-ray sources—such celestial objects as black holes, neutron stars and active galaxies that emit X-rays from their surroundings due to intense gravitational forces or other energetic processes—in the energy range of 8-30 KeV, focusing on their spectral and temporal characteristics over a long period of time.
X-rays and visible light are parts of the electromagnetic spectrum but their wavelengths and energies differ. X-rays have shorter wavelengths, of around 0.01 to 10 nanometres (where 1 nanometre is one-billionth of a metre), corresponding to energies of 100-100,000 electron-volt (eV). Electromagnetic radiation is created when an electric field and a magnetic field vibrate perpendicular to each other. The polarization of electromagnetic radiation refers to the orientation of these two fields as the radiation moves through space.
On the contrary, visible light has longer wavelengths in the 380-750 nanometre range and less energy. The difference in wavelength and energy makes X-rays suitable for penetrating materials and viewing the universe’s extreme conditions, while visible light is key to our daily visual experience. Visible light is the spectrum of light that human eyes can detect and interpret, which helps us see colours and shapes around us.
XPoSat is designed to carry out its observations from a low-Earth orbit (LEO) and is carrying 2 scientific payloads. With the help of these two payloads, XpoSat can simultaneously investigate the time, characteristics of light and alignment aspects of intense X-ray sources.
THE TWO PAYLOADS
1. The main payload, POLIX (Polarimeter Instrument in X-rays), is designed to measure the polarization parameters, including the degree and angle, within the 8-30 Kilo-electron Volt (keV) range of medium X-ray energy from celestial sources
2. The XSPECT (X-ray Spectroscopy and Timing) payload will measure spectroscopic data on energy levels ranging from 0.8 to 15 Kilo-electron Volts. (‘Spectroscopy’ is a detailed analysis of energy levels using techniques involving the interaction of matter with electromagnetic radiation)
WHAT EXACTLY IS A BLACK HOLE?
Black holes are born from the explosive ‘death’ of certain large stars. Some of them are really huge—of a size billions of times the mass of our Sun. The name, ‘Black’, comes from the fact that nothing—not even light—can escape its gravity. They are massive in size, with very strong gravitational forces. Things with mass attract each other. And the more mass, the more gravity! Despite the speed of light travels fast, it is not fast enough to outpace a black hole’s gravitational pull.
But why are they called ‘holes”? The term is misleading! Although their appearance may seem like holes in space because of the absence of light, a black hole is not empty. It is, in fact, a huge amount of matter condensed into a single point—known as a ‘singularity’.
So, how does such a huge mass gather together at one point in space? Imagine a large star. Big stars burn up their fuel really fast because of their higher gravity, which makes their core denser and hotter. A lot more nuclear reactions can occur, speeding up the burning process. The huge pile of ashes that build up in the centre of the star are actually iron, which does not facilitate nuclear burning. Neither does it give off extra heat. It keeps sitting there and growing bigger. These two opposing forces fight against each other.?One caused by the remaining fuel left to burn; and the other the gravity of the iron that draws everything inward.
In the end, that star runs out of heat even as this pressure holds up its centre. The gravity keeps growing bigger, but the pressure remains… Until, finally, it’s gravity that wins out and everything just starts collapsing! At this very point, two things happen: Some part of the star is ejected into space causing light shows that we call supernovae. The remaining part condenses into one singularity.
DO BLACK HOLES AFFECT EARTH?
WHILE IT IS NOT VERY LIKELY that a black hole could have a direct impact on Earth, its gravitational pull could affect our planet indirectly. But, if a black hole were actually to move close to our solar system, it could disrupt the orbits of planets and alter the gravitational pull of our Sun, which could potentially cause changes in Earth’s rotation—or even orbit.
Theoretically, a black hole could also pass close enough to our solar system causing intense cosmic radiation that would bombard Earth. Such an event would cause widespread damage to Earth’s atmosphere and biosphere, although the probability of such an event happening in the foreseeable future is extremely low.
ARE BLACK HOLES NECESSARY?
ALTHOUGH THERE ARE POTENTIAL RISKS, black holes are essential to the functioning of the universe. Their role in galaxy formation is vital; they also help regulate the movement of matter in space. In the absence of black holes, galaxies would not form and the universe, as humans know it, would not exist!
Studying the characteristics of black holes is essential for scientists for a better understanding of the fundamental workings of the universe. While black holes are incredibly fascinating objects, they are extremely unlikely to impact Earth directly due to the vast distances that separate them from us.
However, it is vital that scientists and astrophysicists continue to study them to understand better their impact on the universe. That black holes ‘gobble up’ celestial bodies such as stars, moons and planets by moving around in space is a fallacy. The chances that our Earth will be pulled into a black hole are next to impossible since no black holes exist in close proximity to our solar system.
(The author of this article is a Defence, Aerospace & Political Analyst based in Bengaluru. He is also Director of ADD Engineering Components, India, Pvt. Ltd, a subsidiary of ADD Engineering GmbH, Germany. You can reach out to him at: girishlinganna@gmail.com)