Context: In August, The Chinese military launched a rocket that carried a hypersonic glide vehicle, which flew through low-orbit space before cruising down towards its target.

Note: Hypersonic speeds are 5 or more times the speed of sound.

• India’s DRDO too tested a hypersonic vehicle in September last year. “The exact details on technology used by China in this particular test are not known through media sources. But most of the hypersonic vehicles primarily use the scramjet technology. 

Background

• China tested a nuclear-capable hypersonic missile in August that circled the globe before speeding towards its target, demonstrating an advanced space capability that caught US intelligence by surprise.
• Five people familiar with the test said the Chinese military launched a rocket that carried a hypersonic glide vehicle which flew through low-orbit space before cruising down towards its target.
• The missile missed its target by about two-dozen miles, according to three people briefed on the intelligence. 
• But two said the test showed that China had made astounding progress on hypersonic weapons and was far more advanced than US officials realised.

Significance of this test

• The test has raised new questions about why the US often underestimated China’s military modernisation.
• Hypersonic glide vehicle armed with a nuclear warhead could help China “negate” US missile defence systems which are designed to destroy incoming ballistic missiles.

Note: Hypersonic glide vehicles fly at lower trajectories and can manoeuvre in flight, which makes them hard to track and destroy.

• Although US, Russia and China are all developing hypersonic weapons, including glide vehicles that are launched into space on a rocket but orbit the earth under their own momentum. 
• They fly at five times the speed of sound, slower than a ballistic missile. But they do not follow the fixed parabolic trajectory of a ballistic missile and are manoeuvrable, making them harder to track.

Key Concerns

• It would be “destabilising” if China fully developed and deployed such a weapon.
• Mounting concern about China’s nuclear capabilities comes as Beijing continues to build up its conventional military forces and engages in increasingly assertive military activity near Taiwan.
• Tensions between the US and China have risen as the Biden administration has taken a tough tack on Beijing, which has accused Washington of being overly hostile.

Implications for India

• “This test by China certainly needs to be watched closely by the world, especially India considering relations with China in the recent past,”. 
• Such capabilities also highlight the threat for our space assets along with the surface assets.  The offence system operating at these speeds would mean requirement to develop defence systems at these speeds.
• India too is working on hypersonic technologies. As far as space assets are concerned, India has already proved its capabilities through the test of ASAT.
• Hypersonic technology has been developed and tested by both DRDO and ISRO. 
• Last September, DRDO successfully flight-tested the Hypersonic Technology Demonstrator Vehicle (HSTDV), with a capability to travel at 6 times the speed of sound. 

Additional Information
About Hypersonic Technology Demonstrator Vehicle

• HSTDV is a scramjet vehicle with a capability to travel at six times the speed of sound.
• The scramjets are a variant of a category of jet engines called the air-breathing engines.
• Hypersonic speeds are those which are five times or more than the speed of sound.

Its development in India

• The Defence Research and Development Organisation started this initiative in the early 2010s.
• The Indian Space Research Organisation has worked on the development of the technology and has successfully tested a system in 2016.
• DRDO has conducted a test of indigenously developed Hypersonic Technology Demonstrator Vehicle (HSTDV) in June 2019.

Advantages

• It can be used for launching satellites at low cost.
• This test augurs well for the development of air-breathing in technologies in India.

Ramjet Engines

• It is a form of airbreathing jet engine that uses the engine’s forward motion to compress incoming air without a centrifugal compressor.
• A ramjet-powered vehicle, requires an assisted take-off like a rocket, to accelerate it to a speed where it begins to produce thrust.
• It works most efficiently at supersonic speeds around Mach 3 (3,700 km/h).

Scramjet Engines

• Scramjet is a variant of a ramjet airbreathing jet engine
• Here, the airflow through the engine remains supersonic, or greater than the speed of sound.
• Scramjet relies on high vehicle speed to compress the incoming air forcefully before combustion.

The scramjet is composed of three basic components

• A converging inlet, where incoming air is compressed.
• A combustor, where gaseous fuel is burned with atmospheric oxygen to produce heat.
• A diverging nozzle, where the heated air is accelerated to produce thrust.