In today’s world, technology has advanced to such an extent that even ordinary citizens can now dream of travelling into space. However, alongside the rise of space tourism, the challenges and risks have also increased. One of the greatest dangers in space is posed by unknown objects, tiny but fast-moving particles that can collide with spacecraft or damage an astronaut’s spacesuit during a spacewalk. Scientists warn that if larger such objects were to reach Earth, they could cause serious destruction. For this reason, major space agencies around the world are working continuously to identify, understand and assess the risks posed by objects approaching our planet. PRL’s small device making a big impact In this global effort, the Physical Research Laboratory (PRL) in Ahmedabad has achieved a significant breakthrough by developing and sending a small but highly sophisticated instrument into space. This small square-shaped device has set new benchmarks in space science. Known as the Cosmic Dust Experiment Instrument (DEX), it is a unique piece of equipment that is not commercially available anywhere in the world. As a result, PRL scientists designed and built the instrument entirely in-house. After earning recognition among the limited number of global institutions capable of developing such technology, PRL scientists are now analysing the data generated by DEX. The findings have yielded several crucial insights. Professor Jayesh Pabari, who leads the project, explained in detail how this data can be used for human safety and future space missions. Only 4 institutions worldwide have this capability Professor Pabari said, “This is India’s first cosmic dust experiment. Only about four research groups across the world are working in this field, and PRL is one of them. The United States has deployed around four detectors to different planets. Germany, Japan and Russia have also conducted work in this area. However, active research groups currently exist only in the US, Germany and India.” The solar system was formed nearly 4.6 billion years ago. After its formation, several fragments remained, known as pristine objects. These are mainly concentrated in two regions: the asteroid belt and the Kuiper belt. These belts contain tens of billions of particles, all orbiting the Sun. Over millions of years, some of these particles travel towards different planets.
Particles travel millions of kilometres to reach Earth The Sun lies at the centre of the solar system. Mercury is the closest planet, followed by Venus, Earth and Mars. The asteroid belt lies between Mars and Jupiter, beyond which are Saturn, Uranus and Neptune. Smaller particles tend to move outward from the asteroid belt, while larger ones drift inward. These particles first pass near Mars and, if they survive, move towards Earth. If they are pulled by Earth’s gravity but fail to enter the atmosphere, they continue towards Venus, then Mercury, and finally towards the Sun. As they move closer to the Sun, temperatures rise sharply, causing many particles to burn up completely. DEX operates 350 kilometres above Earth To study such particles passing near Earth, PRL developed the Cosmic Dust Experiment Instrument. DEX orbits at an altitude of 350 kilometres above the Earth’s surface. Particles that have travelled millions of kilometres collide with the instrument. Using specialised sensors, DEX collects data from these collisions in binary form. This data includes the particle’s unique dust signature and background information about the detector’s space environment. The collected data is filtered and analysed, producing two types of information: scientific data and technological data. Professor Pabari explained, ‘We conducted observations for several months, followed by an intensive study over 22 consecutive days. The particle size ranges between approximately 230 and 260 micrometres. Target plates are installed beneath and around the instrument to allow particle collisions.’ Dust particles move at extreme speeds Dust particles travelling through space move at extremely high speeds, between 10 and 20 kilometres per second, equivalent to 36,000 to 72,000 kilometres per hour. When a particle strikes the target plate, it generates plasma, electrons and ions, for a fraction of a second. This plasma is captured by an electrostatic analyser mounted on the instrument and sent for electronic processing. During this process, the signals are digitised. Scientists study three key parameters: the number of particles, the rise time of the signal, and peak voltage. According to PRL’s findings, on average, one particle strikes the detector every 1,000 seconds. Thousands of tonnes of space dust reach Earth annually Particles originating from the asteroid belt are believed to date back to the formation of the solar system, while those from the Kuiper belt differ in composition. DEX helps identify where these particles come from and what materials they contain. Noble gases trapped during their journey through space can also be detected. In 1992, scientists estimated that between 20,000 and 40,000 tonnes of dust reach Earth annually—equivalent to around 2,000 dumper trucks of material. Of this, 50 to 150 tonnes arrive daily from the asteroid belt. Most particles burn up in the atmosphere, appearing as shooting stars. Those that survive land on Earth or in oceans. The rate of particles passing through a square metre per second is known as flux. PRL joins the Global Scientific Elite Professor Pabari stated that the data analysed so far matches global expectations. When compared with results from similar instruments used by other international institutions, PRL’s data has proven equally accurate. This confirms that the instrument is functioning precisely as intended. The last such study was conducted in 2007–08. While it is assumed that dust particles reach Earth at a uniform speed, regular measurements are essential for confirmation. PRL’s experiment provides strong evidence supporting this assumption and shows that dust particles remain intact up to an altitude of 350 kilometres. Plans to extend research to Mars and Venus PRL is now preparing to deploy this technology on future missions to Mars and Venus, with proposals already submitted. On Mars, cosmic dust is believed to form the meteor layer, yet no detailed analysis has been conducted so far. Studying these particles could reveal vital information about Martian atmospheric layers. Similarly, research on Venus could shed light on the presence of dust particles in its upper atmosphere and the condition of its meteor layer, opening new frontiers in planetary science.
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