Hot answers tagged

54 votes

Why are the recent flights of two billionaires discussed in terms of space travel?

Did they reach space? Branson: yes The Virgin Galactic SpaceShipTwo class craft "VS Unity" flew Branson up to 53.5 miles (86 kilometres). This altitude is considered "space" by the ...
CuteKItty_pleaseStopBArking's user avatar
37 votes

Is a midspace space station between Earth and Mars practical?

You're right: this has issues. You can insert a station into a circular orbit halfway between Earth and Mars, but because this has an orbital period also in between those of Earth and Mars, your ...
Hobbes's user avatar
  • 125k
25 votes

Elon Musk's ITS Travel Time to Mars Estimate

What is unique about the ITS that would make the travel time so much shorter? Is the propulsion method described in existence today? The current manifestation of the ITS is Starship, and the ...
BrendanLuke15's user avatar
22 votes

Can a launch of a rocket or ship from Earth go so badly that it damages the Solar System?

No. Look at the numbers: ...
Antzi's user avatar
  • 12.6k
19 votes

Space craft and interstellar objects

They don't. The Voyagers have no way to detect objects in the vicinity. We aren't using telescopes to look for objects in their paths either. We can get away with this because space is empty. Even in ...
Hobbes's user avatar
  • 125k
18 votes

What is the fastest rover that has ever traveled on the surface of an extra-terrestrial body?

The manned Apollo Lunar Roving Vehicle from Apollo 17 holds the record of 17km/h achieved by Eugene Cernan. Apollo Lunar Roving Vehicle was also present on Apollo 15 and 16. For traditionally ...
SF.'s user avatar
  • 54.9k
16 votes
Accepted

Can a launch of a rocket or ship from Earth go so badly that it damages the Solar System?

First, some perspective. The impact of a single fragment of the Shoemaker-Levy comet on Jupiter released an estimated energy equivalent of six million megatons of TNT (approximately 600 times the ...
John Bode's user avatar
  • 2,300
16 votes
Accepted

How can we avoid collisions when moving from one orbit to another?

Exactly the same way you avoid collisions when not altering orbit. Altering your orbit does not significantly alter your risk of collisions, other than possibly moving you to a higher or lesser ...
CuteKItty_pleaseStopBArking's user avatar
15 votes

Elon Musk's ITS Travel Time to Mars Estimate

Probably the key term here is pork chop plot. The linked page includes one from 2005 for Mars where the lowest C3 departure was 15.5 and 400 or so days, but doubling that to 30 got a transfer in 125 ...
GremlinWranger's user avatar
14 votes
Accepted

Is it possible for an Orion drive-based spaceship to experience smooth artificial gravity?

You need to realize that the ship is not accelerated by the atomic blast, it is accelerated by the springs(*) that exist between the push plate and the ship. I.e. while the push plate experiences ...
cmaster - reinstate monica's user avatar
13 votes
Accepted

How might Earth's location be referenced in stellar terms?

Like the lower left part of the image below. Define a set of pulsars through describing proportions between their frequencies. Define distances from each of them. This uniquely identifies a point in ...
SF.'s user avatar
  • 54.9k
12 votes

Mechanically propelled spaceship?

It would stand still, because of the equal and opposite force rule (aka conservation of momentum). On earth's surface it's possible to have a self-propelled butt-kicking machine by having a slow "...
Russell Borogove's user avatar
12 votes

If the Alcubierre Warp Drive was used to travel to Alpha Centauri, how much time would pass on Earth?

The Alcubierre bubble could get to Alpha Centauri in less than 4 years according to outside observers, not just observers riding inside the bubble--the exact time depends on the exact 'shape' of the ...
Hypnosifl's user avatar
  • 221
10 votes

Can a launch of a rocket or ship from Earth go so badly that it damages the Solar System?

Not in terms of physical damage, no. Rockets and spaceships and all the energy they contain is just so very, very, very, very small compared to everything. There is one possibility for large scale ...
Innovine's user avatar
  • 4,585
10 votes

Is it possible for an Orion drive-based spaceship to experience smooth artificial gravity?

The short answer is to use a lot of pulses/second. They'll more or less average out into a steady(ish) push. That's why a 12 cylinder engine vibrates far less than a 1 cylinder engine.
Dan Pichelman's user avatar
9 votes
Accepted

Do we travel horizontally in same plane or vertically while exploring space?

This is the result of two physical facts: that gravity, pointing toward the center of the Earth, is the only way to define "down", and that most of the Solar System is quite close to a single ...
Nathan Tuggy's user avatar
  • 4,548
9 votes

What is the amount of force needed to move an object in space?

That depends on how much time you want to spend. Space is frictionless, you could move a planet by applying a force of 1 N. It would just take a very long time for the planet to move 1 m in response ...
Hobbes's user avatar
  • 125k
9 votes

How much gravity is actually needed to avoid serious health consequences?

We do not know yet. The main issue is a lack of empirical data. There are only four specially trained volunteers with more than one year exposure to microgravity. We'd need hundreds of volunteers ...
choeger's user avatar
  • 2,443
9 votes

What is the fastest rover that has ever traveled on the surface of an extra-terrestrial body?

The highest speed was recorded by an Apollo Lunar Roving Vehicle: The rovers were designed with a top speed of about 8 mph (13 km/h), although Eugene Cernan recorded a maximum speed of 11.2 mph (...
Hobbes's user avatar
  • 125k
8 votes
Accepted

What is the fastest we could travel in space, or have ever traveled in space?

If you want speed, look for mass. Things closest to the Sun will tend to be moving the fastest. For example the Messenger spacecraft reached almost 63 km/s when in an elliptical orbit who's ...
uhoh's user avatar
  • 149k
8 votes

Would it be possible to reach Mars using the same fuel-saving method SpaceIL's Beresheet is using?

The advantage of progressive orbit-raising is that it can be done with very short burns near perigee, maximizing the Oberth effect. You can look at it as either the Oberth effect saving fuel relative ...
Russell Borogove's user avatar
8 votes

What are/were the Customs requirements for astronauts?

Before launch, NASA (or whatever space agency a particular astronaut is affiliated with) keep their passports and visa, and bring it back to them when they land. Since the astronauts land in ...
Star Man's user avatar
  • 5,908
7 votes

Is it theoretically possible to create absolute velocity?

Which is the reference point? is not answerable because we are free to choose any point and velocity as a reference to calculate the position and velocity of an object. There isn't any universal ...
uhoh's user avatar
  • 149k
7 votes

How do we get to Mars in a week (7 days)?

You are travelling in days a distance that planets travel in months. From a trajectory perspective, that means that neither the velocities of Earth and Mars, nor the gravity of the Sun are ...
SE - stop firing the good guys's user avatar
7 votes

Is it possible for an Orion drive-based spaceship to experience smooth artificial gravity?

Wikipedia's long article says: The pusher plate would be mounted on large two-stage shock absorbers that would smoothly transmit acceleration to the rest of the spacecraft. A diagram there confirms ...
Camille Goudeseune's user avatar
6 votes

What is the fastest we could travel in space, or have ever traveled in space?

The only absolute limit imposed by physics is the speed of light, but with our current technology -- reaction engines based on Newton's laws of motion -- we're limited by practical engineering issues ...
Russell Borogove's user avatar
6 votes

How much gravity is actually needed to avoid serious health consequences?

We don't know. We currently only have good data for how humans are doing in 9.81 m/s² or in 0 m/s² acceleration. The only case where humans were ever exposed to anything between 1g and 0g for longer ...
Philipp's user avatar
  • 9,336
6 votes
Accepted

Which is the longest distance traveled by a space craft?

The spacecraft farthest away from Earth is Voyager 1. But that's not necessarily the longest distance traveled. If you accept the distance traveled while in orbit, a spacecraft can rack up a lot of ...
Hobbes's user avatar
  • 125k
6 votes

Why are the recent flights of two billionaires discussed in terms of space travel?

Is this all just advertising, or do these events carry serious implications for astronautics? Am I simply mistaken (very likely - I'm a complete layman) or have large parts of the media fallen for (or ...
Machavity's user avatar
  • 7,780

Only top scored, non community-wiki answers of a minimum length are eligible