The Strategic Technologies Center hosted the webinar titled ‘Nuclear Electromagnetic Pulse and Satellites in Low Earth Orbit’ by Dr. D.V.Giri on 1 May 2023 at 1500 Hrs. Dr. Cherian Samuel, Research Fellow at the Centre for Strategic Technologies Centre, MP-IDSA, moderated the session.

Dr. Giri began his talk by sharing his connection with India despite residing in the US for almost five decades. He mentioned that he had trained a group of Indian engineers in satellite technology and had also served as a professor at the Indian Institute of Science. He began his career amidst the increased tensions between the United States and the Soviet Union and the looming threat of a nuclear Electro-Magnetic Pulse (EMP). He shared a brief timeline of how the research on EMP began in 1945 with the Trinity Test, the first detonation of a nuclear weapon. During the test, Nobel Laureate physicist Enrico Fermi tried to calculate the possible electromagnetic fields to be produced from nuclear explosions, also considered the birth of the High Power Magnetic Field (HPEM).

Later, during 1945-1962, the major powers conducted a series of atmospheric nuclear tests, culminating in the first human-caused EMP in 1962 when the 1.4 megaton Starfish Prime thermonuclear weapon detonated 400 km above Pacific Ocean. After the Limited Test Ban Treaty (LTBT) of 1963 forbade nuclear weapons testing or any other nuclear detonations in the atmosphere, underwater, or outer space, countries began to carry out nuclear tests underground.

Furthermore, Dr. Giri elucidated the growing significance of EMP’s impact as manifested in the first Nuclear Electromagnetics Meeting (NEM) in 1978. To bring the challenging problem of EMP engineering to the attention of the general electrical engineering community, the Antennas and Propagation Society and the Electromagnetic Compatibility of the Institute of Electrical and Electronics Engineers (IEEE) jointly sponsored the special issue concerning some of the more fundamental aspects of the EMP technology. However, with the fall of the Berlin Wall and the dissolution of the USSR, the importance of high-altitude electromagnetic pulse (HEMP) began to fade. Subsequently, given the growing potency and weaponization of EMP and related tools, the US formed Congressional Committees on EMP in the early 2000s.

Moving ahead, Dr. Giri explained the three components of the EMP: E1, E2, and E3. The E1 component has a rise-time measured in the range of a fraction of a billionth to a few billionths of a second. This is extremely fast that produces an intense pulse immediately following an explosion. Electromagnetic shock disrupts electronics-based control systems, sensors, communication systems, computers, and similar devices. The middle-time component E2 lasts from 1 microsecond to 1 second, which is far more geographically widespread in character and somewhat lower in amplitude, making it a lesser threat. The final major component of EMP is a subsequent, slower-rising, longer-duration pulse (lasting 1 second to several minutes), E3, that creates disruptive currents in long electricity transmission lines, damaging the electric supply.

Elaborating further, Dr. Giri elucidated other consequences of HEMP causing ‘orbital debris’ and producing X-rays and Gamma (γ) rays. Dr. Giri explained how X-rays and Gamma rays generated by a space detonation could impact a satellite but won’t reach the ground. He also said that EMP could cause damage to solar panels and optical components and burnout of a satellite.

Micro debris, also known as small debris, is challenging to identify. On the other hand, medium debris, referred to as “risk objects,” cannot be monitored and can potentially cause catastrophic destruction. In contrast, large debris is routinely traced and cataloged. Dr. Giri introduced the audience to Haystack Radar, which has been used to monitor orbital debris. The radar is considered the most powerful in the world and can detect 1 cm of objects orbiting at 1000 km altitude.

Dr. Giri also explored the decades of nuclear electromagnetic pulse (NEMP) simulator development. The purpose of a NEMP simulator is to replicate the effects of EMP in a controlled environment to test the resilience of electronic devices and systems against such an event. It can also be used to evaluate the effectiveness of various protective measures and mitigation strategies. Dr. Giri talked about one of the largest NEMP generators in the world, ATLAS-1, better known as Trestle, designed to test the radiation hardening of strategic aircraft systems against EMP pulses from nuclear warfare. Other major electronic systems that went through NEMP simulations were the B1 Bomber, F-5 Tigers fighter jets, and Air Force One.

Furthermore, Dr. Giri shared the list of above-ground explosions before the LTBT of 1963 came into effect. The table detailed the location, altitude, and yield of the explosions during the period. Elaborating further, he underscored the major satellite subsystems in jeopardy following a NEMP, including- power systems; altitude control system electronics; communication systems; surveillance systems; information processing systems, and thermal controlling systems.

According to Dr. Giri, the worst case of a NEMP is the exposure of Low Earth Orbit (LEO) satellites to direct X-ray radiation. On the other hand, Medium Earth Orbit satellites (MEO) and Geostationary Earth Orbit (GEO) satellites are unlikely to be damaged because of large distances from the bursting point. Also, MEO and GEO satellites are designed to operate in harsh environments. To mitigate the impact of NEMP, Dr. Giri emphasised the importance of keeping critical electronics within the satellite safe and the significance of building protections in the design of the systems. Unfortunately, in most cases, Dr. Giri observed that systems go through retrofitting, adding new technology or feature to older systems. He also shared his impression that the Rafale fighter jets brought by India are not tested for EMPs; however, he also shared his optimism about DRDO’s ground-based facility to test EMPs on electronic systems. He further mentioned that EMPs are discouraged from being used against satellites because all major nations have their satellites in orbit, providing a built-in deterrent. Dr. Giri concluded the talk by accentuating the importance of studying the survivability of space and ground-based components of ISRO’s assets and the significance of R&D efforts in assessing the NEMP effects to reduce the uncertainties.

In the Q&A session that followed the talk, Dr. Giri explained to Gp. Cpt. (Retd.) Ajey Lele that the system testing process is intricate and involves step-by-step testing before integration when queried about Elon Musk’s 49 satellites that were destroyed by a solar flare. He also said that international agreements and treaties make the use of NEMP unlikely unless a country goes rogue.

The report was prepared by Mr. Rohit Kumar Sharma, Research Analyst, Strategic Technologies Centre.