• Question: Why can rockets break through the surface of the earth but they can only land on other planets?

    Asked by aileenjcat to Shikha on 19 Nov 2014.
    • Photo: Shikha Sharma

      Shikha Sharma answered on 19 Nov 2014:

      Hi aileenjcat,

      Any space craft trying to reach to any planet including earth, it is pulled by planet’s gravitational force. Naturally it accelerates the speed of the rocket and the rocket tends to crash down to the surface. This is “The fact” for any rocket landing on any planet as well as earth. Hence landing on earth is very similar to landing on any other planet. However, scientist developed many techniques so that the rocket can nullify a part of gravitation pull and survive the impact of landing.
      Usually there are 2 types of landing. In hard landing, rocket creates significant impact on the surface of the earth but still survive. In soft landing, rocket lands on the surface at with almost safe speed and then impact is significantly low. There are no of techniques through which these types of landing can be done by reducing the speed of rocket by artificially created force acting just opposite to the direction of gravity. Some these are (a) parachute landing, (b) air bag landing, (c) full throttle landing etc.
      You can check out the history of landing space crafts in the link below,
      http://en.wikipedia.org/wiki/List_of_landings_on_extraterrestrial_bodies

Comments

  • Photo: Kevin

    Kevin commented on :

    Aileen, All space rockets started out as weapons of war. The R7 rockets developed by the Russians was the worlds first intercontinental ballistic missile (ICBM). It was designed to go up and come crashing back down a again delivering a nuclear weapon to the USA! But this R7 rocket was what launched Yuri Gagarin into orbit and the Rocket used to launch the Soyuz craft to the ISS to this day is essentially the same rocket. So the technology for an ICBM can be used to deliver a weapon over great distance or launch people into space. It’s the same technology and you can choose how to use it. For example although the Apollo Lunar Modules all had gentle landings on the moon the upper stage of the Apollos was deliberately crashed into the surface of the moon to act as a mini earthquake to make the moon “ring” to get data for the seismometers that the Apollo 11 astronauts left on the surface. There are plenty other man made object we’ve deliberately crashed into things on purpose so it’s not always gentle landings!