You are here:

Space Exploration/space travel time and speed


I figure that man is limited to an acceleration of one G.  Therefore if one could travel at 1-G, to the nearest star what would be their speed at the half way point when they would need to turn around and start slowing down at one G to arrive safely?  A related question is how long would it take to get to the half way point?  My guess is that the speed of light is so fast that even if it was possible to accelerate that long they still would not attain the speed of light, and it would take 70 years to get half way.

Hello Peter,
Sorry, not feasible. Man can travel for very short time for up to 10 G; Saturn V rocket experiences 1.14 G, and the Shuttle 3 G of force. "One G" would be a comfortable acceleration as it is equal to the daily gravitational force we feel. It is not realistically used in space travel because it requires a lots of energy, the same energy needed to keep the spacecraft and its contents above the ground. The Saturn V rocket spent accelerating at 1.14 G  and you would need to accelerate all the fuel you need to fire rockets like that for a few weeks!

Let us calculate.
Acceleration a = 10 m/sē
Half the distance to Alpha Centauri is d = 1/2 x 4,66 LY x 9460730472580800 meters
t = time to get half way

a = d/tē

Therefore t = square root of d/a

t = 148470542 seconds
= 1718 days

Speed half way is v = a X t
= 10 x 1718 x 24 x 3600
= 1484705420 m/s
= 1484705 km/s

The speed of light is 300000 km/s so at 1G to the next star one would reach the speed of light within the first half of the journey. This is impossible too!



Note: I believe that every star has an Oort Cloud and the material in them is shared by the stars. This material ccould be used for interstellar travel a similar way air is used in a ramjet engine.  

Space Exploration

All Answers

Answers by Expert:

Ask Experts




I can answer most questions about the past, present and future space missions. As a hobby since the 1969 Moon Landing, I have been watching and studying space travel and have many resources and theories concerning the future. I have visited NASA many times and have communication with ESA. I have developed a new theory as to what gravity is, mainly that tachyons (bosons) are radiating beyond the speed of light from black-holes and it is those waves when hitting material, causing the material to be heavy or "appear" to attract each other. This is why the universe is expanding.


Hobby but I would give 5 years of my salary to travel in space for just a few days!

Organizations &

BSc (Bachaelor of Science)

Awards and Honors
not yet!

©2017 All rights reserved.

[an error occurred while processing this directive]