Community Digest

Top new questions this week:

Why doesn’t NASA build its rockets using graphene?

Graphene would be a great material to build a rocket out of. Graphene is extremely thin. One single atom thin layer of graphene can withstand 150 000 000 psi (1034.2136 GPa). A square meter of this ...

rockets nasa design-alternative future-missions research  
asked by The Rocket fan Score of 19
answered by BradV Score of 64

Does the Merlin vacuum engine on SpaceX's Falcon 9 gimbal?

SpaceX uses the Merlin Vacuum engine on the second stage of the Falcon 9 launch vehicle. Does the merlin vacuum engine gimbal or does the second stage uses only nitrogen cold gas thrusters for ...

spacex falcon-9 attitude-determination-and-control vacuum gimbaled-engines  
asked by Ashvin Score of 11
answered by Organic Marble Score of 12

Helium balloon as a rocket

This question is not about rockoons, which are rockets using balloons as launch platforms to start from a greater altitude. This question asks about using the balloon itself as the rocket, like a toy ...

design-alternative balloons monopropellant  
asked by Peter - Reinstate Monica Score of 6
answered by Slarty Score of 5

Can something like SpinLaunch actually work?

Can something like SpinLaunch actually work? It appears that Spinlaunch attempts to accelerate a capsule to very high speeds and then basically throw it into space. A regular rocket is moving slowest ...

launch heat-shield acceleration  
asked by user4574 Score of 5
answered by Slarty Score of 4

Where can I find an up-to-date report on the Hubble Telescope's orbital history and current altitude?

I haven't been able to find a current report on the state of Hubble's orbital decay and I'm hoping someone can direct me to that info. The satellite tracker sites just present an average or estimate ...

asked by numbynumb Score of 5
answered by pathfinder_EOS Score of 4

How could 99942 Apophis, in 2029, be captured and brought into a low Earth orbit?

I'm currently attempting to plan out a mission where, in 2029, during Apophis's close approach to Earth, a rocket is sent up to intercept Apophis and decelerate it, making it orbit the Earth. At it's ...

orbital-mechanics delta-v near-earth-asteroid  
asked by An Axolotl Score of 4
answered by fasterthanlight Score of 13

Is crater counting accurate for relative dating between celestial bodies?

This Planetary Society article explains how crater density per unit area on the lunar surface helps identify what regions are older/younger than others. It also mentions that this chronology can be ...

mars the-moon planetary-science crater  
asked by olamarre Score of 4
answered by Fredrick Germann Score of 3

Greatest hits from previous weeks:

Efficient types of nozzles used in rockets

Is there any other type of nozzle other than common convergent-divergent nozzle (see picture below) which is used in many rockets?             ...

propulsion rockets engine-design  
asked by Hash Score of 14
answered by TildalWave Score of 17

When will New Horizons overtake Voyager 1 in distance from the Sun?

Basically, what the title asks. To my understanding, New Horizons is currently the fastest spacecraft that's moving away from the Sun, with arguably only Helios-A and Helios-B possibly faster still, ...

probe voyager navigation new-horizons  
asked by TildalWave Score of 72
answered by gerrit Score of 85

If we can get people to the moon and back, why are we so adamant that it's impossible to service James Webb at 4x that with a one way robotic vehicle?

Sources, including NASA and media, all emphasise that JWST at L2, is a million miles away, and therefore "if anything goes wrong, nothing can be done, it can't be serviced". But over 50 ...

james-webb-telescope service-utilities  
asked by Stilez Score of 41
answered by GremlinWranger Score of 45

Who was the first human to sleep - perchance to dream - on the Moon?

Incidentally I don't mean "on the lunar surface, asleep laying on the surface of the moon" :) So (A) who (if anyone) was the first human to actually be asleep (that is to say, presumably inside the ...

the-moon astronauts spaceflight-firsts sleep  
asked by Fattie Score of 96
answered by Russell Borogove Score of 175

What is the current cost-per-pound to send something into LEO?

As a student of economics and finance I would love to learn more about the cost structures of sending a payload into orbit. More specifically - What is the cost-per-pound to send something into LEO ...

launch commercial cost  
asked by Stu Score of 30
answered by PearsonArtPhoto Score of 21

Why is the breathing atmosphere of the ISS a standard atmosphere (at 1 atm containing nitrogen)?

The Wikipedia page for the International Space Station says that it has a fairly Earth-like, sea-level atmosphere: 21% oxygen, balance nitrogen at 101.3 kPa. Supposedly it's because a pure-oxygen ...

iss atmosphere life-support  
asked by Nick T Score of 62
answered by David Hammen Score of 77

How realistic is Kerbal Space Program?

Kerbal Space Program is an independent spaceflight simulation game, which has become quickly popular due to being (kind of) precise at simulating actual spaceflights. But how precisely? How close is ...

orbital-mechanics rockets kerbal-space-program  
asked by Zoltán Schmidt Score of 45
answered by PearsonArtPhoto Score of 48

Can you answer these questions?

Low-thrust maneuver validation in GMAT

I'm working on a LEO-to-LEO transfer with low-thrust propulsion. I've generated a control sequence with a direct optimization implemented by me and I would like to use GMAT to validate the maneuver. I ...

gmat low-thrust  
asked by Fede Score of 3

Why "quiet cruise" of a spacecraft would cost NASA 30 mln $ a year?

The 2022 Planetary Decadal Survey (Chapter 22) states that "quiet cruise" phase of an interplanetary spacecraft will cost about 30 million dollars a year for NASA. "Quiet cruise" ...

nasa interplanetary cost  
asked by Heopps Score of 3

Which is the primary spacecraft in a conjunction?

I ask the question in the title because I cannot find a clear answer. It seems that in collision avoidance, the primary spacecraft is always more accurately known then the secondary. But I think this ...

starlink collision-avoidance space-track  
asked by Giacomo Curzi Score of 2
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