Context: 

Iran claimed that it had created a hypersonic missile called ‘Fattah,’ or ‘Conqueror’ in Farsi capable of travelling at 15 times the speed of sound.

Image Source: The Hindu

Key Points:

• The missile had a range of up to 1,400 kilometers (870 miles). 
• It is claimed the missile could pass through any regional missile defense system, though it offered no evidence to support the claim.

What is a hypersonic missile?

• Speed: A hypersonic missile is a weapon system which flies at least at the speed of Mach 5 i.e. five times the speed of sound and is manoeuvrable. 
• Manoeuvrability: Unlike ballistic missiles, hypersonic missiles do not follow a ballistic trajectory and can be manoeuvred to the intended target.
• Types: Hypersonic Glide Vehicles (HGV) and Hypersonic Cruise Missiles. 
  1. The HGV is launched from a rocket before gliding to the intended target. 
  2. The hypersonic cruise missile is powered by air breathing high speed engines or ‘scramjets’ after acquiring their target.

• Advantage: Hypersonic weapons can enable responsive, long range strike options against distant, defended or time critical threats (such as road mobile missiles) when other forces are unavailable, denied access or not preferred.

• Detectability:
  1. These missiles could challenge detection and defence due to their speed, manoeuvrability and low altitude of flight. 
  2. Ground based radars or terrestrial radars cannot detect hypersonic missiles until late in the flight of the weapon. 
  3. This delayed detection makes it difficult for the responders to the missile attack to assess their options and to attempt to intercept the missiles. 

• Countries possessing it: US, Russia and China are in advanced stages of hypersonic missile programmes, India, France, Germany, Japan and Australia too are developing hypersonic weapons.

What is Mach number?

• Mach number, in fluid mechanics, ratio of the velocity of a fluid to the velocity of sound in that fluid, named after Ernst Mach (1838–1916), an Austrian physicist and philosopher.
• In the case of an object moving through a fluid, such as an aircraft in flight, the Mach number is equal to the velocity of the object relative to the fluid divided by the velocity of sound in that fluid.
• Subsonic conditions occur for Mach numbers less than one, M < 1 .
• Supersonic conditions occur for Mach numbers greater than one.
• For speed greater than five times the speed of sound, M > 5, the flow is said to be hypersonic.

News Source: The Hindu, Indian Express