Constant 1G thrust

Space Travel Under Constant 1g Acceleration

The basic principle behind every high-thrust interplanetary space probe is to accelerate briefly, and then coast, following an elliptical, parabolic, or mildly hyperbolic solar trajectory to your destination, using gravity assists whenever possible. But this is very slow. Imagine, for a moment, that we have a spacecraft that is capable of a constant 1g (“one gee” = 9.8 m/s2 ) acceleration: your spacecraft would accelerate for the first half of the journey, and then decelerate for the second half of the journey to allow a visit at your destination. A constant 1g acceleration would allow human occupants the comfort of an Earth like gravitational environment where they would not be weightless except during very brief periods during the mission. Granted such a rocket ship would require a tremendous source of power, far beyond what today’s chemical rockets can provide, but the day will come, perhaps even in our lifetimes, when probes and people will routinely travel the solar system in just a few days.

In space 1g is actually a very high acceleration, just to travel to Saturn (about 9 AU closest point, and then at its most distant point, it’s 10.1 AU) is a serious struggle. It would take 1,000s of GJ of energy just for a Mars trip (albeit in days instead of months)

Mean distance from Earth to the Moon: 384,399 km

Mean distance of the planets from the Sun (in AU)

Mercury 0.39

Venus 0.72

Earth 1.00

Mars 1.52

Jupiter 5.20

Saturn 9.58

Uranus 19.23

Neptune 30.10

Further out

At 1g, you get to relativistic speeds in under a year. Theoretically if you could maintain 1g acceleration it would take 353,7 days of constant 1G (9,81 m/s^2) acceleration to reach the speed of light(if it was possible as the spaceships mass increases close to the speed of light so does the energy required, never getting to the speed of light. As you got very close to light speed you would experience relativistic and accelerating time dilation.

Distance to the nearest star outside our solar system Proxima Centauri 4.243 ly giving a Ship time of 3.6 years and an Earth time: 5.9 years as the peak velocity of 95% c has relativistic effects.

Distance to the exoplanet with the highest Earth Similarity Index (ESI) Gliese 667C c 22 ly

If you could keep accelerating at 1g; inside the spaceship allowing for time dilation you could cross the galaxy in twelve years (and the known universe in twenty).

1 AU = 1.495978707 x 10^11 m

1 ly = 9.4607304725808 x 10^15 m

Great Video on 1g by Fraser Cain and Jason Harmer

A big issue facing ships using constant acceleration is colliding with matter and radiation while en route. In mid-journey any matter the ship strikes will be impacting at high or even relativistic speed, so the impact will be dramatic.