4
$\begingroup$

Is there a limitation of speed of a spacecraft in space because of suns gravity? Is the speed purely dependent on the engineering? Or other factors comes into play?

$\endgroup$
2
$\begingroup$

Propellant: This is the main practical limitation on Δv, of the rocket's ability to change speed (go "faster" or "slower"). Assuming conventional-matter engines, no exterior propulsion, and that you want to slow down again at a destination, the maximum speed you can approach is half the speed of light.

In-practice, spaceships tend to be unable to accelerate by more than a few tens of kilometers per second. Although we do have the technology to get up to a few percent of the speed of light fairly easily, these are mostly nuclear technologies which the main spacefaring nations are too timid to ever dare launching.

Relativity: You cannot approach or depart a destination at a relative speed of more than the speed of light.

Interplanetary/Interstellar Medium: If you move relative to the tenuous gas/plasma in space at a high speed, it can damage your spacecraft. Things like "hydrogen atoms" start looking more like "proton and electron radiation".

$\endgroup$
  • 3
    $\begingroup$ "Half the speed of light" sounds like a nice round number. Do you have any references to support your assertions? $\endgroup$ – Organic Marble Jun 9 '18 at 0:41
  • $\begingroup$ gravity slingshot can also be tried i guess $\endgroup$ – Paran Bharali Jun 9 '18 at 3:24
  • $\begingroup$ "...by more than a few tens of kilometers per second..." I estimate here the top speed of the Parker Solar Probe to be 190 km/s. Of course it is a bit of a special case, and uses orbital mechanics rather than propellant to do that. $\endgroup$ – uhoh Jun 9 '18 at 3:38
  • 1
    $\begingroup$ @OrganicMarble This comes from substituting best-case ISP ($30570000$) into the relativistic generalization of the classic Tsiolkovsky rocket equation to get a (rest-frame-relative) Δv of $c$. You then divide this by two to get the Δv you can use to speed up. You can read more about relativistic rockets here. $\endgroup$ – imallett Jun 9 '18 at 5:43
  • 1
    $\begingroup$ @uhoh Yes. An additional example would be ion engines which, due to their significantly higher ISP than chemical thrusters, can have higher Δv. The Dawn spacecraft, for example, had 11km/s Δv from its ion thrusters, yet carries significant payload. A chemical rocket with this kind of Δv in a single stage would have a mass ratio of ≈19.7. $\endgroup$ – imallett Jun 9 '18 at 5:48

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.