Recently, headlines were made when a ship by Virgin Galactic, known as the VSS Unity, embarked on a trip to the “edge of space”. Suborbital flight, as it is commonly termed, was experienced by a six-person crew. Among the crew members was Sirisha Bandla, an astronaut with Indian roots. She became the third woman of Indian origin to visit space after Kalpana Chawla and Sunita Williams. Virgin Galactic, a British-American company, carries out its spaceflight operations in the United States.
Understanding Suborbital Flight
The term suborbital flight refers to the trajectory an object takes when it travels at a horizontal speed of roughly 28,000 km/hr or more, entering orbit once it ascends above the earth’s atmosphere. For satellites to orbit the Earth, they must meet this threshold speed, also termed as orbital velocity. Despite the gravitational pull towards the Earth, this high-speed horizontal movement counteracts the downward motion, causing the satellite to navigate along a circular path.
However, objects traveling slower than 28,000 km/hr will eventually return to Earth. In case of any object that is launched into space but fails to maintain sufficient horizontal velocity, it falls back to Earth, flying in a suborbital trajectory. This suggests that while these objects may cross the vague boundary of space, they won’t have enough speed to remain in space.
Why are Suborbital Flights Important?
Suborbital flights have certain advantages that make them significant. Firstly, they provide increased access for design innovation and experimental manipulation due to the possibility of high projected flight rates. Secondly, they can be immensely useful for microgravity research. Microgravity is a condition where people or objects seem to be weightless. Such flights can offer an alternative to the zero-gravity simulations currently performed by space agencies in parabolic airplane flights.
Thirdly, they offer a more cost-effective solution compared to transporting experiments and personnel to the International Space Station.
The Concept of “Edge of Space” or The Karman Line
The “edge of space” is a term often associated with the Karman Line. This line, defined by the Fédération Aéronautique Internationale (FAI) as an altitude of 100 kilometers above Earth’s mean sea level, is recognized as the most universally accepted boundary of space. FAI, as the governing body for air sports worldwide, also manages definitions pertaining to human spaceflight.
Named after Theodore von Karman, a Hungarian American engineer, and physicist, the Karman Line represents the altitude where the atmosphere becomes too thin to support aeronautical flight. Interestingly, different organizations do not universally accept this definition. There exists no international law that unmistakably defines the edge of space or the limit of national airspace.
Last Modified: February 15, 2024