Questions tagged [moons]

Questions about celestial bodies that orbit another celestial body.

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1 vote
6 answers
3k views

Why is there never enough room on satellites to hold all the equipment needed?

Why can a satellite run infrared and other forms of data collecting equipment and stream live results back for the public, but not take photos or video? I am guessing there is never enough room to ...
1 vote
0 answers
60 views

Diameters of moons in solar system

I would like to programmatically find all moons in our solar system above a certain diameter. I would like to use the api to jpl horizons if possible. (For context I am then going on to find ...
3 votes
1 answer
2k views

Delta V required to land and then ascend from the surface of every celestial body

I've been doing some research to figure out how feasible grand tour manned missions to the surface of the moons of each outer planet. This is related: Where can I find a delta v map of landing ...
6 votes
2 answers
359 views

Is it possible to create an analytical ephemeris from raw position and velocity of a Body?

I would like to have an analytical ephemeris for various bodies of the solar system (planets, natural satellites and asteroid). I have at my disposition spice kernels from which i can extract position ...
6 votes
1 answer
722 views

How close do gravitational 2-body hierarchy levels get?

Due to very few 3-body arrangements being stable (this question thus excluding co-orbital objects like trojans), objects in space usually arrange themselves in a hierarchy of 2-body systems. When the ...
1 vote
0 answers
57 views

Arctic underwater analogue?

Just want to know if the underneath of the arctic ice sheet is a viable analogue for underwater habitation on the larger moons of the gas giants? (Galilean, large Saturnian) I feel like it would be a ...
5 votes
1 answer
347 views

Tallest mountains on the Galilean satellites?

Suppose I want to climb the tallest mountain on each of the four Galilean satellites. Is it known what they are? Io has one of the most spectacularly tall mountains in the solar system, Boösaule ...
9 votes
1 answer
265 views

Which moon is best? (for gravity assists)

Inspired by my answer to Is a ballistic Jovian capture using the Galilean moons possible from interplanetary entry? in which I discovered that Callisto offers a stronger gravity assist than Ganymede ...
3 votes
1 answer
296 views

Can we land on either of Mars' moons?

Is it possible for anything to land safely of Deimos or Phobos? If so, are there any current or past proposals? If not, why? The only missions to Mars' moons I know of are Phobos 1 and Phobos 2 (both ...
-2 votes
1 answer
165 views

Which of Jupiter’s Galilean moons would be easiest to establish a permanent presence on? [closed]

The moons of Jupiter are numerous and varied. Which of them would be easiest to colonise in terms of technological complexity?
12 votes
2 answers
13k views

Would it be possible to "fall off" Phobos? [closed]

Phobos (one of Mars' moons) has the following dimensions: 27 × 22 × 18 km. It has low mass, and little or no gravity/atmosphere. Let's just assume that it's possible to walk around on Phobos without ...
3 votes
0 answers
75 views

Melting probes in low pressure environment

The icy moons in our solar system Enceladus und Europa are very interesting targets for research because they sport deep oceans of liquid water under their thick shells of ice. But above that icy ...
4 votes
0 answers
119 views

Efficiency of "liquid cooled" RTG

One of the big problems in the vacuum of space is getting heat away. RTG that rely on a temperature differential from the hot to the "cold" side to produce electricity will probably suffer a ...
4 votes
0 answers
120 views

Just how locked is Titan? Does it exhibit libration due to eccentricity? Have residual oscillations not yet damped out been detected or ruled out?

Under Where is the Selk crater on Titan with respect to Saturn? there is @BrendanLuke15's comment which provides a helpful hint: Tidally locked moons have their 0° longitude defined as the 'sub-...
7 votes
1 answer
768 views

Smallest known asteroid with moon

The asteroid Didymos is only 780m in "diameter" with a moon, Dimorphos only 170m across. Is Didymos the smallest object known to have a natural satellite? Also, contact binaries where the ...
9 votes
3 answers
779 views

Did the spacecrafts Galileo or Juno use the Galilean moons for a gravity assist before entering Jovian orbit?

Galileo and Juno are the only two spacecraft to have entered orbit around Jupiter. Did either of them use one of the Galilean moons for a gravity brake before in order to enter a stable orbit around ...
6 votes
2 answers
696 views

Where does Io's sulfur come from?

This answer on Movies.SE collects some fascinating facts about the sulfur-dominated surface and atmosphere of Jupiter's moon Io. But it made me wonder where all the sulfur comes from in the first ...
30 votes
3 answers
5k views

Are all satellites of all planets in the same plane?

I'm aware of the fact that all planets are almost in the same plane as the Sun and the Earth(ecliptic) plane except Mercury and Pluto(which are more tilted). Are all satellites of all the planets also ...
1 vote
1 answer
2k views

Are there photos taken by rovers, with both moons visible in the martian night sky?

Are there night photos from curiosity or early of Mars's skies? Two moon on the sky. Photos from ground. From rovers. Perhaps not exactly like this: but more like this: but at night and two moons.
23 votes
5 answers
6k views

Can a moon orbit its planet faster than its planet rotates?

Can a moon orbit its planet faster than its planet rotates? Can a moon orbit its planet more than once per the planet's day? It seems possible but I'm not sure. Are there any known examples of this ...
1 vote
1 answer
852 views

The Earth's Moon versus Phobos and gravity

Our Moon weighs 7.35 x 1022 kg and Mars' moon Phobos, weighs 10.6 × 1015 kg. How much would need to be added to Phobos to give it the same gravitational "impact" on Mars, as the Moon ...
5 votes
1 answer
172 views

How were scientists able to experimentally confirm that Saturn's ravioli-shaped moons had highly porous surfaces?

The NASA News article NASA's Cassini Finds Saturn's Rings Coat Tiny Moons says: The new research, from data gathered by six of Cassini's instruments before its mission ended in 2017, is a clear ...
7 votes
2 answers
1k views

Would a Foucault pendulum work on the Moon and on the Galilean moons?

I wonder whether the Moon and the Jovian moons spin fast enough for a Foucault pendulum to swing on their poles. For instance, I think that it wouldn't swing on Mercury and Venus because these planets ...
6 votes
3 answers
8k views

Which planets and moons can you walk on?

Which planets and moons have a surface where you could survive with a conventional or near-future spacesuit? Assume oxygen, water, and food supplies are accounted for, but roughly current limitations ...
20 votes
2 answers
3k views

Escaping moons conflict with what I understand of gravity

I have known that the Earth's Moon, let's call it Luna (tip of the hat to The Expanse), has been slowly but surely increasing it's distance from the Earth by a small measure each year. This week I ...
7 votes
0 answers
142 views

Why couldn't New Horizons try again to search for small moons of Pluto?

I was reading Alan Stern and David Grinspoon's Chasing New Horizons, the story of the quarter-century effort to prepare, enable, and run New Horizons' mission to Pluto. As many readers know, it ...
7 votes
3 answers
362 views

Why is Enceladus the "most interesting place for astrobiology" in the Solar System other than Earth?

In season 1 episode 1 of Space's Deepest Secrets (IMDB), Dr. Chris McKay, a planetary scientist for NASA, says around 1h:40m into the show, "This is the single most important and interesting place for ...
51 votes
6 answers
16k views

Is it possible for a moon to have a higher surface gravity than the planet it is attached to?

Is it possible that a moon has a higher surface gravity than its planet? I guess it would mean that the moon has a higher mass, but then it would be the planet gravitating around the moon and the ...
0 votes
2 answers
327 views

How big a nuke would be needed to break Phobos out of orbit?

Phobos Radius: 11.267 km Orbital period: 8 hours Equatorial rotation velocity: 11.0 km/h (6.8 mph) (at longest axis) With an 8 hour orbit around Mars it must be going at a fair clip already which ...
11 votes
2 answers
4k views

Is there a term to refer to a planet and its accompanying moons as a whole collection?

I am trying to find out of there is a term that can be used when referring to both a planet and any accompanying moons (if present) as a whole collection. For example if you were to refer to Mars and ...
4 votes
0 answers
99 views

Iapetus - Destabilized rings to mountains?

I was reading an article about a ring that was destabilized out of orbit on one of Saturns moons. I got there by looking for mountains because of this question (unrelated mostly). Here's a picture of ...
8 votes
1 answer
384 views

Many moons in same orbit

Is it possible to have a stable orbit comprised of many moons(>2) that keep themselves roughly equal distance apart? Sort of like Epimetheus and Janus around Saturn but comprised of many moons. The ...
9 votes
1 answer
483 views

Why were Nix, Cerberos and Styx discovered later than Charon?

Charon, a moon of Pluto, was discovered in 1978. Today we know that Pluto has three additional moons, but they were discovered 3 decades later? Also, Hubble Space Telescope was in operation since 1990 ...
2 votes
1 answer
1k views

Moon Polar Days And Night

Moon's rotation axis from the orbit plane of earth is about 1.54° tilted. Just like earth because of tilt, do polar regions experience 6 months day and 6 months night? If so, aren't these places ...
3 votes
0 answers
55 views

Is there any moon in our solar system which we could terraform relatively fast? [duplicate]

I am just curious as to whether there is any moon in our solar system which could be terraformed or at least made into a livable moon for us. By fast i mean as fast as possible, given our current ...
2 votes
1 answer
162 views

Bombing the Moon: how much debris would there be in stable orbit?

If someone had actually nuked the Moon (e.g. here or Bombing Moon and Mars: What would it look like? ), what's the probability of some debris reaching a stable orbit around the Moon? This would not ...
5 votes
1 answer
184 views

How is salt transported from the subsurface ocean and ejected with the plumes of water from Enceladus?

My limited understanding is that the plumes of water vapor and ice seen rising nearly vertically from the ice surfaces of Enceladus and other ice/water covered moons of Jupiter and Saturn are not ...
16 votes
2 answers
610 views

How large could Hyperion be and stay porous?

Here is a question originating on the Worldbuilding stack. Hyperion is porous, with a density of 0.55 g/cc; a little more than half that of water. from https://www.space.com/20770-hyperion-moon.html ...
3 votes
1 answer
118 views

Would a large impactor on an ice moon cause a thinning of the ice surface?

While it has not been confirmed, Callisto (Jupiter IV) could potentially have a small subsurface ocean below a thick ~100 km ice layer, according to Wikipedia. A mission to explore that ocean might ...
9 votes
1 answer
861 views

Titan - Is the source of so much Methane being overlooked?

Is the source of so much Methane on Titan being overlooked? Tons of very intelligent and knowledgeable people already looked at it, so the answer in undoubtedly "no", so I guess my question is more ...
2 votes
0 answers
223 views

Why haven't Saturn's rings coalesced into moons/satellites? [closed]

The rings of Saturn are made up of tiny particles/rocks/ice that all orbit Saturn. Each individual particle is bound to its orbit because of Saturn's gravity, but each particle also pulls on all of ...
20 votes
1 answer
3k views

If colonists burrowed far enough under the ice on Ganymede or Europa, would the ice provide adequate protection for them from Jupiter's radiation?

This is a hypothetical question I'm asking as a SF writer, and the time setting would be approximately 2,250 AD.
45 votes
7 answers
20k views

Why do artificial satellites need orbit correction, but natural ones don't?

No matter how much you fine-tune a satellite's orbit up front, it needs periodic adjustments. It's usually done through tiny rocket bursts. The system and fuel to do that costs money and weight, and, ...
1 vote
0 answers
134 views

If the moon's orbit decays- how would it effect the moon's phases? [closed]

If a planet passed near the moon and caused its orbit to decay down to earth- how long could it take and how would that effect the visible phases of the moon on earth?
4 votes
1 answer
1k views

Why are most of Jupiter's moons retrograde?

Jupiter's small moons are likely captured objects. I would've expected half of them to be captured in retrograde orbit, between 90 and 180 degrees inclination. But out of 65 lesser satellites, only 11 ...
5 votes
3 answers
1k views

Keplerian approximations for moons as well as planets

I'm writing code to simulate planetary and lunar orbits in a heliocentric reference plane. I'm using E.M. Standish's Keplerian Elements for Approximate Positions of the Major Planets as my reference ...
1 vote
1 answer
170 views

Why is the velocity of a satellite the result of a sum of two velocities? (clarifying img included)

I am a newbie when it comes to orbital mechanics. The velocity of a spacecraft is given by a sum of two types of velocities. But I don't understand the difference between both velocities: $V = V_{кр}...
0 votes
0 answers
91 views

Saturn's Pan and Prometheus orbital resonance

Is it possible for a small object (such as a manned capsule) to realize a maneuver using the orbital resonance influence of Saturn's moons Pan and Prometheus?
4 votes
3 answers
1k views

Data for Moons in the Solar System with Masses

I'm looking for a simple machine-readable table with basic parameters for all the known moons of the planets in the solar system. Stumbling around the internet, I can find plenty of sources like this ...
3 votes
1 answer
108 views

Tides on other bodies

Since the tides on the moon have an antieffect on the other side of earth, (still don't quite understand how that works), shouldn't the gas giants deform when their moons move around in their orbits? ...