All Questions

9
votes
2answers
604 views

Is it possible to perform the Galileo's Leaning Tower of Pisa experiment on the Moon?

Since the Moon has no atmosphere, is it possible to perform the Galileo's Leaning Tower of Pisa experiment on its surface? Has any astronaut performed anything similar?
178
votes
6answers
15k views

Can I borrow a lunar rover?

According to Wikipedia there are 3 LRVs sitting on the moon, in very well defined locations. Would China, or whomever gets to the moon with a person next, be able to get in and drive around in an LRV ...
7
votes
1answer
356 views

What caused Cydonia mesas, such as “The Face on Mars”, to be created?

The Cydonia region of Mars is littered with mesas, which are an unusual geographic feature on Mars. A sample of a few of these, including the commonly known as "The Face on Mars", is shown below. How ...
8
votes
1answer
241 views

Has any spacecraft to date suffered catastrophic gasket degeneration in space?

A gasket is a precisely formed body of some (yielding) material placed at a mating surface usually to prevent leakage. It may also be constructed of an alloy as was done in early IC engines. ...
23
votes
4answers
11k views

Why is it so hard to walk on the Moon?

In videos of astronauts walking on the Moon, it seems very hard to move around with any efficiency, and it seems impossible to run. Why is this? What could be done to mitigate these effects?
15
votes
5answers
1k views

How are multiple launches handled?

A spacecraft may launch with multiple payload, as is evidenced by How does a single rocket place multiple satellites into orbit? This question however is not about multiple payload carried in a ...
17
votes
4answers
63k views

How far do you have to be from Earth to be “in space”?

According to a recent news article a group of USC students are attempting to launch a rocket "in to space" with a planned height of 62 miles. Making them "the first group of students to successfully ...
7
votes
2answers
2k views

What kind of engine uses water as a propellant?

I often read about future spacecraft gathering water ice to use as a propellant, yet this doesn't line up with any of the propulsion methods I know to exist today. What type of engine could use water ...
10
votes
1answer
1k views

Would a human colony on Venus be possible?

According to Wikipedia Venus has a gravity of 9/10 Earth which would be very nice for a human to live on, but the temperature seems a bit high. Without terrforming and with our current knowledge and ...
14
votes
3answers
425 views

How would time measurement be done over great distances?

Already on earth the time is a bit of a problem with the time-zones. It is not that big a problem though, since we all "travel" at (nearly) the same speed. Not so in space. With the time dilatation (...
8
votes
1answer
103 views

To what celestial bodies are GRAIL-like missions planned?

GRAIL recently constructed a complete gravity map of Luna's irregular gravity field. Are similar GRAIL missions on the anvil to any other Celestial bodies as yet? As a corollary (probably opinion-...
8
votes
3answers
2k views

How would we communicate over light years?

Anyone who has been in an email conversation where the chain split into different threads, or has been in chat where they receive two diverging comments requiring a response before a reply to the ...
19
votes
2answers
4k views

How was magnetic tape decay prevented in Voyager 1?

I had recently learned that Voyager 1 uses magnetic tape to record data. Voyager 1 has been going on more or less strongly since 1977 (before I was even born!), and the wikipedia article states that ...
7
votes
1answer
333 views

Are custom semiconductors used on board spacecraft/robots?

Spacecraft/robot are usually chock-a-block with instruments. These are usually devices with some electronics to them. These are probably semiconductor, or vacuum-tube devices - I may be wrong! ...
9
votes
1answer
241 views

Would gold in space tend to collect in pockets like it does on Earth?

I was reading Does gold come from outer space?(BBC News). If the majority of gold on Earths surface does come from space would it tend to be equally distributed on comets and asteroids, or would tend ...
22
votes
3answers
16k views

Delta-V chart mathematics

Could someone explain me the mathematics behind the Delta-V charts one can find on internet such as:                 &...
7
votes
1answer
638 views

Smallest launch vehicle by dry mass

What is the smallest launch vehicle, by dry mass, to have delivered a payload to orbit? I am guessing that this might be either a re-purposed sounding rocket or something from the high-end of the ...
8
votes
2answers
143 views

Theories of what asteroid macroporosity actually means

Pretty good science has nailed down the fact that a significant fraction of asteroids have macro-porosity of 10% or more. It seems this was more or less established as of a 2003 paper, and here are ...
7
votes
1answer
180 views

Have Magnetorquers been used anywhere outside of the Earth?

On Earth, small satellites often include Magnetorquers. A magnetorquer allows the satellite to re-orient itself without using fuel in a way more permanent than magnets. While not every planet has a ...
7
votes
1answer
238 views

Could a magnetorquer be used in orbit around Mars?

One way to align a spacecraft into a certain manner while in orbit around a body is the use a Magnetorquer. Does Mars have enough of a magnetic field to allow such a device to operate?
5
votes
1answer
258 views

Any other advantages to passive atmospheric reentry besides reaction mass economy?

From Vostok 1 to date, atmospheric reentry has been essentially passive. Passive here means that retrorockets are used to de-orbit, and then aerobraking is provided by the atmosphere. In contrast, ...
8
votes
2answers
594 views

Could Magnetorquers be used on the ISS?

The way that the ISS manages it's attitude now is to use a set of reaction wheels for primary control, and occasionally firing small thrusters to allow the wheels to despin themselves. This isn't ...
17
votes
3answers
3k views

How long did it take, at a minimum, to prep a shuttle for launch after it landed?

The Space Shuttle relied on a pair of SRBs, and fuel supplement in the External Tank for it's launch. Assuming Payload, Service parts/consumables, Crews, SRBs, and ET were ready - How long did it ...
11
votes
2answers
1k views

Nuclear thermal rocket specific impulse calculation uses 1 amu, is that wrong?

Following the parameters in the Wikipedia nuclear thermal rocket article, it seems to paint somewhat of a shaky world view. Consider these quotes: Current (2010) 25,000 pound-thrust reference ...
30
votes
3answers
4k views

Why do the exhaust flames from cryogenic stage engines appear to be separated from the nozzle?

Why do the exhaust flames from cryogenic stage engines appear to be separated from the nozzle?
15
votes
1answer
34k views

What is the current cost per kg to send something into GSO/GEO?

I was reading this article and thought it was reasonably cheap, probably because I mistook LEO for GEO. What is the going rate to get something into GeoStationary Orbit and Geosynchronous Equatorial ...
8
votes
2answers
7k views

What's the maximum amount of time the ISS can go between resupply runs?

Typically a cadence of one resupply mission every couple months is maintained. If this cadence were to be interrupted for whatever reason, how long could, say, the current crew size of three members ...
5
votes
1answer
179 views

What were Prince Sultan's duties in STS-51-G?

Prince Sultan bin Salman Al Saud was the first (and so far only) Saudi astronaut, and was included in the crew of STS-51-G as a payload specialist representing Arabsat. Does that mean his role was ...
7
votes
1answer
385 views

How much power loss does the LLCD suffer in transit?

Space.com writes to say (freeform improved quote): The LLCD (Lunar Laser Communication Demonstration) space terminal is designed to beam data from the moon at a rate six times faster than the best ...
5
votes
0answers
397 views

What can an astronaut do better than the Curiosity rover? [closed]

Firstly, I want to say that I'd be the first person with their hand up when asked, "So who wants to go to space?". There's nothing I'd love more than to go. But from looking at the amount of ...
15
votes
2answers
712 views

How would a probe land on Europa?

Say we send a craft to Europa which would then launch a probe to land on the surface of Europa. Let's say for the sake of this question that the probe weighs more or less like the Opportunity rover. ...
9
votes
1answer
420 views

Has a non-space treaty citizen ever been in orbit?

The Outer Space Treaty of 1967, according to Wikipedia is ratified by any country with a chance of getting there - Article VI Makes each member country responsible for it's citizens actions. ...
8
votes
1answer
397 views

Cargo delivery from the ISS to Tiangong

Consider I have a 10 kg object I want to deliver from the ISS to Tiangong-1 station. The object can not go through the land and launch again cycle. Can any of the present day spacecrafts do the ...
21
votes
4answers
2k views

Can you buy land on the moon?

The two primary documents regarding legal niceties on the Moon and often mentioned are: Outer Space Treaty of 1967, which according to Wikipedia is essentially ratified by any country with a chance ...
28
votes
1answer
56k views

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 ...
9
votes
2answers
527 views

Payload mass scale economy

What is the "payload mass" curve in relation to "cost to orbit?" I mean: preparing a whole launch system for delivering a single cubesat to LEO would be an overkill, the cost to bring such a small ...
6
votes
1answer
194 views

What happens to an RTG if the demand exceeds supply?

NASA writes to say As the electrical power becomes less and less, power loads on the spacecraft must be turned off in order to avoid having demand exceed supply. A lead battery would 'die' if ...
5
votes
0answers
1k views

What is the average cost of satellite construction over the last 10 years? [closed]

In the last 10 years what was the Highest and lowest, construction cost of satellites launched? What are the mean and average costs of satellite construction over the same period? Where "a" ...
10
votes
1answer
161 views

Milestones in LEO launch technology

Since the automobile came into existence towards the end of the 19th century AD, motive technology has evolved rapidly Multiple Stroke Engines Rotary engines Square block Vee engines Hybrid engines ...
8
votes
1answer
424 views

Does cost to orbit make the sale for a satellite launch service?

Wikipedia writes to say ...The Space Race sparked unprecedented increases in spending on education and pure research, which accelerated scientific advancements and led to beneficial spin-off ...
7
votes
1answer
813 views

Do rocket exhaust plumes really provide a pathway for lightning?

This Wikipedia article states that Rocket exhaust plumes provided a pathway for lightning when it was witnessed striking the Apollo 12 rocket shortly after takeoff. My question is whether this ...
7
votes
1answer
416 views

Would a frog on the side of a rocket be enough to steer it substantially offcourse?

Recently, someone posted this picture in The Pod Bay, our chatroom: It shows a frog being blown off of the launch of LADEE, a lunar probe. It got me thinking: Would a frog, successfully holding on ...
10
votes
1answer
455 views

What are the chances of getting struck by lightning while in Earth orbit?

Getting struck by lighting in Earths upper atmosphere is a real possibility. It is often found in the 100km range, and can reach 400 km (250 mi) in diameter. The ISS has an orbit of 400km, and as ...
10
votes
1answer
3k views

Did NASA provide the wrong year for Voyager 1's close approach to AC +79 3888?

This article says it will pass by the star in about 40,000 years. However, my quick and dirty calculation shows that Voyager will only be about a few light years away in 40,000 years, still quite a ...
4
votes
1answer
254 views

Can you have a relaxing full body massage in zero G?

This question is a bit more complex then it sounds at first. On Earth when getting a massage you lay on a table and gravity and friction holds you in place while the therapist pushes, pulls and ...
14
votes
1answer
3k views

How does the gravity of a massive non-spherical object act on things around it?

Firstly, not sure if this question ought to be in the physics SE site. Please let me know if it should. Secondly, I don't know a whole lot about physics (I'm just inquisitive). So please try to keep ...
10
votes
3answers
1k views

What's our limit in sending probes to distant bodies?

Currently, we're able to aim probes at various bodies in the solar system pretty well. Do we have the technology to send a probe to Alpha Centauri? If we're aiming at a star, approximately how far ...
10
votes
1answer
583 views

Will Pluto's atmosphere collapse prior to New Horizon's visiting it?

It is thought that Pluto's atmosphere will freeze as it moves further from the Sun. We know that Pluto was it's closest to the Sun in the 1990's. Is it known if the atmosphere will freeze prior to New ...
16
votes
2answers
2k views

Where are the upper stages for the Voyager/Pioneer stages?

I was reading this question, and was trying to remember an article I read many years ago. It seemed the article was indicating that there is a chance that one of the boosters from one of these ...
27
votes
1answer
3k views

How many astronauts have reported an alien encounter of some kind?

This question will be controversial, so I want to start out by saying that I am not advocating any sort of conspiracy. I'm merely acknolwedging the fact that there are numerous claims that some ...

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