User HopDavid

50 votes

Accepted

How fast will 1g get you there?

propulsion

answered Jul 21, 2014 at 4:27

41 votes

Accepted

Why don't we launch spacecraft from the Moon?

answered Aug 4, 2015 at 18:46

25 votes

What's the path of something dropped from a space elevator

space-elevator

answered Sep 1, 2014 at 7:28

23 votes

Accepted

Gravity Assist braking

interstellar-travel gravity-assist

answered Dec 4, 2014 at 18:17

23 votes

Why did SpaceX attempt to land the booster on a barge instead of somewhere on land?

spacex landing falcon-9 reuse

answered Jan 12, 2015 at 19:35

22 votes

Accepted

What's after Pluto for New Horizons?

future-missions new-horizons pluto

answered May 22, 2014 at 4:14

21 votes

Accepted

How long will a 500 km altitude satellite spend in Earth - shade per orbit

orbital-mechanics artificial-satellite low-earth-orbit sunlight

answered Aug 31, 2015 at 23:11

21 votes

What is the rarest launch window?

spacecraft probe interplanetary future-missions launch-window

answered Jul 12, 2018 at 22:01

18 votes

Accepted

Reverse Lunar Space Elevator

the-moon lagrangian-points space-elevator

answered Dec 10, 2014 at 19:24

16 votes

Is a Moon-base inherently more dangerous than a Space Station?

iss the-moon radiation meteorites lunar-base

answered May 30, 2014 at 14:59

16 votes

Could the sun be used as a gravity assist outside the solar system (with current tech)?

orbital-mechanics interstellar-travel gravity-assist xkcd

answered Apr 8, 2014 at 5:29

15 votes

Oberth effect for Earth vehicles

orbital-maneuver physics rockets oberth-maneuver

answered Apr 9, 2014 at 21:01

14 votes

Accepted

Where could we build a space elevator today (2014)?

technology materials solar-system space-elevator

answered May 28, 2014 at 20:09

14 votes

Is a railgun up Olympus Mons possible?

mars mass-driver olympus-mons

answered Feb 3, 2015 at 6:21

13 votes

Accepted

What are speed limits for free fall, orbital trajectory, and unbound trajectory?

orbital-mechanics

answered Dec 21, 2014 at 19:51

13 votes

Space Elevator Between Doubly-Tidally Locked Bodies

space-elevator tidal-locking

answered Aug 18, 2014 at 5:54

13 votes

How feasible would it be to move a Kuiper Belt object (a good sized one) into an orbit around Mars?

terraforming

answered Mar 23, 2015 at 15:12

13 votes

Did the space shuttle fly straight "up" when leaving Earth?

launch space-shuttle

answered Mar 31, 2015 at 23:24

13 votes

Why is L2 Langrangian point stable?

orbital-mechanics orbit

answered May 3, 2020 at 3:50

12 votes

Accepted

Are there any active or recent projects investigating skyhooks for orbital lift?

nasa boeing skyhook

answered Nov 23, 2019 at 15:03

12 votes

If we build a space elevator from Earth surface to GEO, could I step off it at GEO and remain in GEO?

geostationary space-elevator

answered Aug 15, 2014 at 18:26

12 votes

Accepted

Why have no reusable launch technologies been developed?

spacecraft spacecraft-development reuse space-industry ssto

answered Jan 18, 2015 at 15:33

11 votes

Accepted

How far away will I get if I'm --just under-- escape velocity?

launch orbital-mechanics escape-velocity

answered Feb 13, 2015 at 21:18

11 votes

Would it be more viable to process moon rocks into Helium-3 on the Moon than doing so on Earth?

the-moon mining chemistry helium-3

answered Feb 2, 2016 at 18:51

11 votes

Is the ideal transfer between two arbitrary planar orbits always a bi-tangential ellipse?

orbital-mechanics orbital-maneuver delta-v bi-tangential-transfer

answered Jul 1, 2016 at 17:00

11 votes

Why there is no orbiter for Uranus or Neptune?

neptune uranus titania triton

answered Apr 5, 2017 at 16:34

11 votes

How unreachable are Jupiter's moons from Mars with the technology developed for going to Mars?

mars jupiter europa ceres spaceport

answered Feb 23, 2019 at 20:04

10 votes

Accepted

Are there any major flaws with the Mars Architecture used in the Martian?

mars crewed-spaceflight

answered Aug 9, 2017 at 17:17

10 votes

How can delta-v and aerobraking as shown in this chart be explained?

delta-v aerobraking

answered Apr 4, 2016 at 23:11

10 votes

Does a satellite naturally turn in phase with its orbit, always facing Earth?

orbital-mechanics artificial-satellite attitude rotation

answered Jul 25, 2015 at 18:28

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178 Answers

How fast will 1g get you there?

Why don't we launch spacecraft from the Moon?

What's the path of something dropped from a space elevator

Gravity Assist braking

Why did SpaceX attempt to land the booster on a barge instead of somewhere on land?

What's after Pluto for New Horizons?

How long will a 500 km altitude satellite spend in Earth - shade per orbit

What is the rarest launch window?

Reverse Lunar Space Elevator

Is a Moon-base inherently more dangerous than a Space Station?

Could the sun be used as a gravity assist outside the solar system (with current tech)?

Oberth effect for Earth vehicles

Where could we build a space elevator today (2014)?

Is a railgun up Olympus Mons possible?

What are speed limits for free fall, orbital trajectory, and unbound trajectory?

Space Elevator Between Doubly-Tidally Locked Bodies

How feasible would it be to move a Kuiper Belt object (a good sized one) into an orbit around Mars?

Did the space shuttle fly straight "up" when leaving Earth?

Why is L2 Langrangian point stable?

Are there any active or recent projects investigating skyhooks for orbital lift?

If we build a space elevator from Earth surface to GEO, could I step off it at GEO and remain in GEO?

Why have no reusable launch technologies been developed?

How far away will I get if I'm --just under-- escape velocity?

Would it be more viable to process moon rocks into Helium-3 on the Moon than doing so on Earth?

Is the ideal transfer between two arbitrary planar orbits always a bi-tangential ellipse?

Why there is no orbiter for Uranus or Neptune?

How unreachable are Jupiter's moons from Mars with the technology developed for going to Mars?

Are there any major flaws with the Mars Architecture used in the Martian?

How can delta-v and aerobraking as shown in this chart be explained?

Does a satellite naturally turn in phase with its orbit, always facing Earth?