Orbital vs. Suborbital Human Space Flight

Instructor: David Wood

David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.

Discover the difference between orbital and suborbital space flights. Learn about some examples of each. See if your knowledge has reached a high enough orbit by taking a quiz.

Orbital vs Suborbital Space Flight

Have you ever wanted to blast off into space? It might not be as far off as you think. There are several companies who are trying hard to make space tourism a reality. No doubt it will start off astronomically expensive (so to speak), but before long, the moderately wealthy will be able to go on an adventure. Part of the reason this is even possible is the difference between orbital and suborbital spaceflight.

When you hear the words suborbital, what do you think it means? It sounds like suborbital flight is just lower down than orbital, not as deep into space. But that isn't true at all. It's about your trajectory. A trajectory is a path that your rocket or spaceship takes. For you to be in orbit, you have to be going around the planet continually, moving fast enough that you will keep circling it forever. On the other hand, if you blast off and make a huge arc, eventually falling back to hit the earth, you never made it into orbit. Your flight was suborbital. No matter how far off into space you go, if your path causes you to fall back down to earth, then it is a suborbital flight.

How does this relate to space tourism? Well, let's say that your spaceflight takes you to an altitude of 100 km above the earth. If you wanted to make it into orbit, you would have to reach a speed of almost 8000 m/s. But if you just want to reach 100 km and fall back down to Earth, you would only need to go at a speed of about 1000 m/s. That takes far less energy, and therefore is much less expensive. This is how space tourism could become a reality.

Examples of Human Suborbital Space Flight

There have been surprisingly few examples of human suborbital spaceflights and it wasn't even before an orbital flight. The very first person in space was Russian Yuri Gagarin in an orbital flight in April 1961. The first person on a suborbital flight - and second person to travel to space - was American Alan Shepard in the first of the Project Mercury rockets, launched less than a month later.

Flight path of Freedom 7, the Mercury rocket piloted by Alan Shepard
flight path of freedom 7

But after Alan Shepard, all future missions were planned to be orbital. The next intentional suborbital human spaceflight didn't happen until June 21st, 2004. On that date, SpaceShipOne was launched by a private company, making it the first private spaceflight.

Mercury Rocket
Mercury Rocket

However, suborbital spaceflight as a tourist attraction is a goal of many companies. The most vocal of these is probably Virgin, who call their space program Virgin Galactic. They've sold nearly 700 tickets at a price around $200,000 each. Unfortunately a test flight ended in disaster, and a new spaceplane is being built.

Virgin Galactic Space Ship (Center) Carried By Specially Designed Plane
Virgin Galactic Space Ship (Center) Carried By Specially Designed Plane

Examples of Human Orbital Space Flight

International Space Station
International Space Station

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