Frequently Asked Questions
The most-asked questions about suborbital human spaceflights.
What exactly is a suborbital human spaceflight?
It is a crewed flight that crosses the boundary of space (generally 100 km or 80 km above sea level, depending on the authority) but follows a ballistic arc back to Earth rather than reaching the sideways velocity needed to stay in orbit. Passengers get a few minutes of weightlessness before re-entry and landing, with the whole trip lasting minutes to about an hour.
How is suborbital flight different from an orbital flight?
An orbital vehicle must accelerate to roughly 28,000 km/h to keep missing the planet, while a suborbital vehicle simply climbs on a steep arc and falls back down at a fraction of that speed. The practical result is that suborbital missions last 10 minutes to 90 minutes, whereas orbital missions take days or weeks.
Who are the main companies and figures in suborbital human spaceflight?
The two active commercial operators are Blue Origin, founded by Jeff Bezos and flying the New Shepard rocket, and Virgin Galactic, backed by Richard Branson and launching the SpaceShipTwo air-launched vehicle. The historical foundation was laid by NASA's X-15 rocket-plane program in the late 1950s and 1960s, piloted by test aviators such as Scott Crossfield and Michael Adams.
What is the Kármán line and why does it matter?
It is the internationally accepted boundary of space at 100 km (62 miles) above mean sea level, named after the Hungarian-American aerodynamicist Theodore von Kármán. Crossing it is what qualifies a vehicle's crew as astronauts under most national and international definitions, though the U.S. FAA grants its astronaut wings at the lower 80-km (50-mile) mark.
Who were the first humans to fly above the Kármán line on a suborbital trajectory?
Pilots in NASA's X-15 program achieved the first crewed suborbital flights past 100 km in the late 1950s, with Scott Crossfield reaching 128.8 km on 24 August 1957. No earlier crewed vehicle had crossed that altitude, making the X-15 the true pioneer of human suborbital spaceflight.
How long does a typical suborbital spaceflight last?
A Blue Origin New Shepard mission runs roughly 10 to 11 minutes from tower liftoff to touchdown, while a Virgin Galactic SpaceShipTwo flight takes about 90 minutes including the carrier-airplane climb and the air-launch segment. The actual time spent in microgravity is only a few minutes in either case.
What does the ride feel like for a passenger?
After a few minutes of powered ascent that pushes passengers to roughly 3–6 G, the engine or airframe releases and the vehicle coasts on a ballistic arc, giving the crew three to five minutes of free-fall weightlessness. Re-entry then brings another 3–4 G of deceleration before the vehicle lands by parachute (New Shepard) or on a runway (SpaceShipTwo).
How many G-forces do suborbital passengers typically endure?
Most current suborbital vehicles subject the crew to a peak of around 3 to 6 G during the boost phase and another 3 to 4 G during atmospheric re-entry. These loads are brief and comparable to a high roller-coaster, well below the sustained 4+ G loads of a conventional orbital launch.
Where should a newcomer start to learn about suborbital spaceflight?
Watching full unedited mission footage from Blue Origin or Virgin Galactic gives the fastest feel for the flight profile, from pad to landing. Pairing that with a short history of the X-15 program and a basic read on ballistic-trajectory physics provides the context for why suborbital trips are shorter, cheaper, and mechanically simpler than orbital ones.
What are some of the most notable moments in suborbital human spaceflight history?
The 1957 X-15 flight that first carried a human past 100 km, the 2021 New Shepard NS-16 mission that took Jeff Bezos and three companions to space, and the 2021 SpaceShipTwo VSS Unity flight with Richard Branson are widely regarded as watershed events. The 2022 return of both companies to regular crewed flights after pandemic pauses marked the start of a more routine commercial suborbital era.