Suborbital Flight | 14 Jul 2021

Why in News

Recently, a six person crew on Virgin Galactic’s VSS Unity spaceship undertook a brief trip to the “edge of space” which is known as Suborbital Flight.

• Sirisha Bandla, an astronaut born in India, was a part of the crew. She was the third woman of Indian origin to go to space after Kalpana Chawla and Sunita Williams.
• Virgin Galactic is a British-American spaceflight company, operating in the United States.

Key Points

• Suborbital Flight/Trajectory:
  
  • When an object travels at a horizontal speed of about 28,000 km/hr or more, it goes into orbit once it is above the atmosphere.
    
    • The satellites need to reach that threshold speed (orbital velocity) in order to orbit Earth.
  • Such a satellite would be accelerating towards the Earth due to gravity, but its horizontal movement is fast enough to offset the downward motion so that it moves along a circular path.
  • Any object travelling slower than 28,000 km/hr must eventually return to Earth.
  • Any object that launches to space but does reach sufficient horizontal velocity to stay in space falls back to Earth. Hence they fly in a suborbital trajectory.
    
    • It means that while these vehicles will cross the ill-defined boundary of space, they will not be going fast enough to stay in space once they get there.
• Significance of Suborbital Flights:
  
  • Increased Access:
    
    • It would provide increased flight access for design innovation and experimental manipulation due to high projected flight rates.
  • Research:
    
    • Suborbital flights will be helpful for microgravity research. Microgravity is the condition in which people or objects appear to be weightless.
    • Suborbital flights could also be an alternative to parabolic flights in aeroplanes that space agencies currently use to simulate zero gravity.
      
      • Zero Gravity or Zero-G can simply be defined as the state or condition of weightlessness.
  • Cost Effective:
    
    • They would be far less expensive than carrying experiments and people to the International Space Station.
• Edge of Space/Karman Line:
  
  • The most widely accepted boundary of space is known as the Karman line. The Fédération Aéronautique Internationale (FAI) defines Karman Line as the altitude of 100 kilometres above Earth’s mean sea level.
    
    • FAI is the world governing body for air sports, and also stewards definitions regarding human spaceflight.
  • The Kármán line has been compared to international waters, as there are no national boundaries and human laws in force beyond the line.
  • It is named after Theodore von Karman (1881–1963), a Hungarian American engineer and physicist, who was active primarily in aeronautics and astronautics.
    
    • He was the first person to calculate the altitude at which the atmosphere becomes too thin to support aeronautical flight and arrived at 83.6 km himself.
  • However, other organizations do not use this definition. There is no international law defining the edge of space, and therefore the limit of national airspace.

Source: IE