Editorial 1 : ISRO has a problem: many rockets, but too few satellites to launch
Context
In June, S. Somanath, Chairman of the Indian Space Research Organisation (ISRO) and Secretary of the Department of Space, said ISRO’s launch vehicle capability was three-times the demand.
Launch vehicles
- India currently has four launch vehicles: the Small Satellite Launch Vehicle (SSLV), the Polar Satellite Launch Vehicle (PSLV), the Geosynchronous Satellite Launch Vehicle (GSLV), and the Launch Vehicle Mark-III (LVM-3).
- These rockets can launch satellites weighing up to four tonnes to the geosynchronous orbit.
- India also relies on foreign launch vehicles, like Europe’s Ariane V and SpaceX’s Falcon 9, when a satellite weighs more than four tonnes.
- At present, the country operates a fleet of satellites with applications in communications, remote sensing, positioning, navigation and timing (PNT), meteorology, disaster management, space-based internet, scientific missions, and experimental missions.
- It also needs launch vehicles for space missions like Chandrayaan 3 and Aditya L1.
- All this makes it look like there are more applications and satellites than there are launch vehicles.
Demand-driven model
- The Indian space programme used to follow a supply-driven model: ISRO would build and launch satellites and then look for customers who needed the services provided by the satellites.
- When the Indian government reformed the space sector in 2019-2020, it changed this to a demand-driven model.
- Here, a satellite needs to be built and launched only if there is already demand for it.
- There needs to be a demand for space-based internet in a country already filled with affordable fibre and mobile-based internet services, so a company will launch a constellation of satellites into orbit to provide that service.
The question arises: Who will educate the customer, ISRO or the industry?
- Without such educated customers, demand at the scale ISRO expects will not be created.
- The customers here are not only consumers of space-based internet.
- These are other companies, government institutions, defence enterprises, and ordinary people including farmers, bankers, etc. So the ‘amount’ of education required is very great.
- QThe other area from which demand is likely to arise is human spaceflight. This includes human-rated launch vehicles that carry humans and supplies into orbit and to destinations like an orbiting space station or the moon. There could in future be demand for space tourism as well.
Launch capability limitations
- India’s launch vehicles are also not powerful enough to undertake certain missions, like Chandrayaan 4.
- China used its Long March 5 launch vehicle to launch its Chang’e 4 and Chang’e 5 missions in a single launch.
- India’s LVM-3 has less than one-third of Long March 5’s capability (28% to be more precise) and will need two LVM-3 launches to launch all the components of Chandrayaan 4.
- ISRO will be upgrading the LVM-3 with a semi-cryogenic engine to boost its payload capacity to six tonnes to the geostationary transfer orbit (GTO).
- The organisation will also need a new launch vehicle — already dubbed the Next Generation Launch Vehicle (NGLV), a.k.a. Project Soorya — to carry 10 tonnes to GTO.
- India will also need one more successful flight of the SSLV to be confident about its ability to launch smaller satellites.
- Smaller satellites are usually experimental and university-built. More success in this domain will encourage space companies to build larger satellites, eventually leading to a demand for launch vehicles.
Launch vehicle economics
- All these launch vehicles will need satellites to launch. The heavier vehicles can fulfil some national goals like lunar exploration and a space station while ISRO can use the smaller satellites for technology and capability demonstration. However, the latter will constitute only a small number of launches.
- Satellites have a defined mission life. As they get old, they will need to be replaced with newer satellites.
- This will also create a demand for launch vehicles. However, mission operators like their satellites to live longer and have been improving their lifetimes with software and hardware upgrades. This complicates estimates of the number and frequency of launch vehicles that will be needed.
- Launch vehicles are improving as well. In a single launch, the PSLV can deliver multiple satellites in multiple orbits.
- Rocket stages are becoming reusable, which reduces the cost of building the rocket and increases profitability.
- ISRO has been building its Reusable Launch Vehicle and vertical landing technologies to make reusable landing stages. It is also making an effort to replace toxic fuels for rocket engines with green alternatives.
Private sector vs government
- The richer the ecosystem, the greater the demand. The Indian government wants the private sector to create demand among customers and to build and launch satellites.
- It wants them to look for services to offer customers in India and abroad. It also wants revenue by providing launch services of its own. Finally, the government wants to upskill workers and give them jobs.
- However, private companies don’t want the government to be in the launch business. Instead, they want the government to be their customer and to provide rule of law and reliable regulations.
Conclusion
Thus, the Indian government will absorb the cost of the transition from supply-driven to demand-driven building of satellites and launch vehicles. But it isn’t yet educating its own Ministries and creating some of the anchor demand for satellites and launch vehicles.
Editorial 2 : 100 years of EEG: how does it work and what is its significance?
Context
This year marks the centenary of the first human EEG, produced by German physiologist Hans Berger.
About
- EEG measures electrical activity in the brain generated by neurons. In research, scientists use EEG for neuroscience, cognitive psychology, neurolinguistics etc
- The EEG is a marvel of physics and neurobiology that opens a simple window into the human brain.
- This window is often small and yet it reveals so much. But not least is the wonder that it reveals anything at all without having to break open the skull first.
What is an EEG?
- EEG stands for electroencephalography. ‘Electro’ pertains to electricity; ‘encephalo’ refers to the brain; and ‘graphy’ is a suffix meaning to show or to represent.
- Neurons in the brain perform various functions by moving electrically charged particles such as ions.
- The movement of these particles gives rise to electrical activity that a health worker can use an EEG test to visualise.
- Researchers have also been able to relate data obtained from an EEG with different levels and modes of brain activity, and used it to distinguish reliably between normal and abnormal states.
- EEG is not an uncommon diagnostic test in clinical settings. Among other applications, it is the reference standard — that is, the best test available — to diagnose epilepsy.
- An EEG test can also reveal the effects of anaesthesia, sleeping patterns, neurological activity during a coma, and availability of oxygen.
- EEG can also confirm brain death, one of the two legally recognised forms of death in India.
- In research, scientists use EEG for neuroscience, cognitive psychology, neurolinguistics, neuromarketing studies and to develop brain-computer interfaces.
What is volume conduction?
- EEG measures electrical activity in the brain generated by neurons.
- During an EEG test, a health worker will place electrodes on your scalp.
- There are many layers of skin, fluid, and bone between the electrodes and the neurons.
- When a neuron produces electrical activity, charged particles will move through all these media before reaching the electrodes, and will be reflected, refracted, scattered, etc. en route.
- Volume conduction refers to the movement of electrical activity through this three-dimensional volume.
- It also stands for the fact that the electrical activity is produced in one place whereas the detectors that detect it are located at some distance.
- The raw data collected by the electrodes will first need to be corrected for the effects of volume conduction, and then for noise in the data arising from faulty electrodes and incidental physiological activity. A clinician finally interprets the processed data.
How does an EEG test work?
- The neurons that make up the human brain are constantly exchanging atoms, molecules, proteins, etc. with their surroundings.
- Sometimes neurons will push ions out into the space between neurons.
- Since ions of the same charge repel each other, this ‘motion’ can push away other ions, which push away even other ions, and so on.
- When a large number of neurons start this cascade at the same time, a (relatively) big wave of electrical activity flows through the brain.
- The electrodes on the scalp are made of metal and track the changes in voltage as the waves move past them, creating an electroencephalogram.
- Four common points of reference are the nasion (the depression between the eyes, just above the bridge of the nose) and the inion (the crest at the back of the skull) going front to back, and from tragus to tragus going side to side.
- The tragus is the small flap-like projection on the outer ear; you push it in to shut your ears when there’s a loud noise.)
What does and doesn’t EEG show?
- The changes in voltage recorded at the electrodes are transmitted to a computer, which plots the readings on a graph with voltage on one axis and time passed on another.
- EEG is better than other diagnostic devices at tracking relatively rapid electrical activity in the brain, in the order of milliseconds.
- On the downside, it is biased towards electrical signals generated closer to the surface of the cortex, and significantly so towards currents generated by neurons’ dendrites and against those generated by the axons.
- To overcome these and other challenges, researchers have used EEG together with other tests, like magnetic resonance imaging (MRI), and have developed sophisticated data acquisition, processing, and reconstruction methods.
Conclusion
- Aside from its metrological and diagnostic abilities, an EEG setup is also relatively simple and cost-effective.
- The equipment involved doesn’t take up much space, doesn’t emit high-energy radiation or sounds, doesn’t confine patients to small spaces (like MRI), is non-invasive, and is portable (the invasive version of EEG is called electrocorticography, or ECoG).
