# Questions tagged [altitude]

Questions regarding the distance of an object above a surface.

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### How does Ingenuity measure its altitude when flying?

The Ingenuity folks at NASA and lots of viewers on the internet I'm sure were pleased to see the first data from "the first flight of powered aircraft on another planet" (by humans at least);...
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### Spacecraft altitude measurement

While in atmosphere, altitude is measured by using pressure gauges - higher the altitude, lower the pressure. How is the altitude measured once we cross the atmosphere?
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### CesiumJS: how to convert Alt/Az as seen from Earth surface in (x,y,z) position w.r.t Earth center?

I know how an antenna located on Earth surface is poiting to an object in space, by means of Altitude and Azimuth. I would like to show the pointed object in the 3d view, so, as far as I can ...
126 views

### Are satellites whose orbits go below 100 km perigee considered having multiple spaceflights?

The International Aviation Federation (FAI) considers the space border at 100 km (330,000 ft) above sea level. So if an orbiting body goes below that altitude and continues its orbit without ...
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### Why does a satellite with a higher mass fall slower?

I was doing simulations in GMAT and I could observe that if I increase the mass of the satellite, the satellite falls slower ... and if I reduce the mass of the satellite, then it falls faster (I only ...
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### Why isn't the Kármán line itself considered to be in outer space?

The Kármán line is the altitude at which the atmospheric pressure is so thin a craft would need to achieve orbital velocity in order to maintain enough aerodynamic lift and control. Therefore, ...
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### Did/does the US use statute or nautical miles to decide who gets astronaut wings?

As mentioned in a few questions and answers (1,2,3,4), US astronauts receive their astronaut wings upon crossing the 50 mile altitude mark. Are these statute miles (1609.344 m, 5280 ft) or nautical ...
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### At what minimum distance does the Earth appear star-like to the naked eye?

At what distance does the Earth become indistinguishable from stars and other planets to the naked eye, like the Pale Blue Dot or like Venus or Mars visible from Earth? Dot-like rather than spherical. ...
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### When did the FAI adopt the 100km line as border to space (for their purposes)?

Let me preface this with a disclaimer: This is not a discussion about which height makes sense. This is purely about international recognition by the FAI. Wikipedia says "An international committee ...
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### Do astronauts set a pressure on the space craft altimeter before launch or zero it?

I was watching First Man (2018) and noticed that just before the launch of Armstrong's Gemini mission the capsule's altimeter read zero. My understanding of the Titan II GLV is that it's 109ft tall ...
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### Differences between Semi Major Axes and ECF Magnitudes for Circular Orbits with J2 Perturbation

I have simulated (in STK) a satellite at near circular orbit, near-equator, with Brouwer Lyddane Mean Long SMA of 6935.31km, inclination 10 degrees, and eccentricity of 0.0001875 (these are solved-for ...
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### How to determine altitude when altimeters fail?

Specifically for high altitude amateur rocketry, how is altitude determined when you get too high(too low pressure) for barometric altimeters to work? I heard about GPS, however, COCOM limitations ...
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### What is the Cheapest way to track my balloon (only altitude or gps coordinates)? [closed]

I want to build extreme cheap high altitude stuff - balloon, paper plane :) anything. Its cold outside now, and i dont want to track, and collect the my landed "spacecraft". So, i need a very cheap ...
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### How would propagation differ between a GEO and a Retrograde GEO?

A Binary Equatorial Synchronous Retrograde Orbit is an orbit that would travel in the opposite direction of GEO and would pass over the same point on Earth twice per day at the same altitude of GEO. ...
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### What are the causes of these episodes of faster than average altitude loss by the ISS?

@Cristiano's question No reboosts for the ISS shows the plot below. I don't have the original source. I've added some annotations including four arrows to indicate what looks like short periods (a day ...
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### How are Hayabusa2's target markers deployed?

This presentation talks about 'target markers' which are five soft, reflective balls that are released onto the asteroid's surface prior to landing. They allow the probe to more precisely locate the ...
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### Is it possible to calculate Max-Q without having to input an altitude

Is it possible to calculate max-q based on just upwards velocity instead of specially inputting a given altitude/air density? Based on this graph of Falcon 9 launches till MECO below "Air Pressure vs. ...
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### What is the deepest place on Mars? Do humans need pressurized suits there?

Is there any particular deep area, trench, fissure, lava tube or otherwise on of Mars in which a person could survive with only an oxygen supply? How deep would plants or animals have to be in Mars ...
547 views

### different ways to calculate satellite height

I found 2 formulas for calculating height. First is: height = magnitude(satillate_position_vector) - Earth_radius Second is: ...
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### Why are orbital periods different for different GNSS positioning system constellations?

My question is restricted to global positioning systems (Regional ones have geosynchronous constraints, which limits drastically the orbit choice) The diagram in this question highlights different ...
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### How is stability of Geosynchronous Orbits (GSO) affected by Earth’s mass?

I'm researching stable orbits slightly beyond GSO and I need to find out how close to GSO I could place an object without risking collision. If the Earth was homogeneous the altitude should be the ...
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### Is it possible for an asteroid to be captured by earth in such a way that it has minimal relative velocity?

Is it possible for a metal (or dirt/ice) asteroid of 1km average diameter to enter the Earth-Moon system in such a way that the asteroid behaves as if it were dropped from a height instead of as a ...
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### Satellite altitude as a function of time?

In order to obtain a more accurate radiation estimate in this question, I am trying to approximate and/or determine the altitude of a satellite as a function of time. The satellite has an apogee of ...
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### Why is the LEO/MEO boundary at 2,000 km?

Differentiating Medium Earth Orbits from High Earth Orbits at the geosynchronous altitude makes intuitive sense. Is there some meaningful difference between orbits above vs. below 2,000 km, or is the ...
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### What is the Fischer 1960 Mercury Ellipsoid, and why is it called that?

Don't be distracted by the 1960 Mercury shown below. Reading about Irene Fischer (also here, and mentioned in this answer) and seeing the Fischer 1960 Mercury Ellipsoid turn up in tables of ellipsoid ...
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### How is the altitude of a satellite defined, given that the Earth is not spherical?

The altitude of a satellite is the distance between the Earth's surface and the satellite, but the Earth itself is not spherical. At the equator the Earth's radius is 21 km more than at the poles, and ...
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### Satellite altitude variances in orbit

I understand that all satellites must have burn corrections to keep their orbits where they are needed. However my question is specifically about what those changes are in magnitude from the desired ...
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### Determining altitude of a cubesat/nanosat

I've seen cubesat projects talk about the altitude of their satellite. Starting orbit is, presumably, known based on deployment conditions. But how does one track the altitude once it's been in ...
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### Have there ever been significant changes in the altitude of the ISS?

Have there ever been significant changes in the altitude of the ISS? By significant, I mean changes greater than about 40 km, thus by far exceeding the periodic reboosts. If there haven't been, then ...
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### Altitude control of ISS via Progress-MS

What is the highest altitude the ISS can raise itself to? What about with help from Progress-MS? How much would it cost to raise the ISS by 1km with or without progress?
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### What is the reason for the Ariane 5 launcher with Intelsat 29e losing altitude?

After reaching a peak altitude of 222 km the Ariane 5 launcher with Intelsat 29e starts to lose altitude. What is the reason for this trajectory? Youtube video Paper on Ariane 5
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### What is the ISS maximum altitude?

I see two threats to the ISS as its altitude goes up: Cosmic/solar radiation, which would endanger the crew and the electronics aboard. Orbital debris, which would have higher relative speed and ...
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### Is there an equivalent term for average altitude like semi-major axis?

So if we have a satellite in a non circular orbit, can't state a time independent altitude (we can only state the altitude at a given time). We can however state a constant value for the semi-major ...
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### Relationship between satellite's mass and orbital altitude

Is there a relation between the mass of a satellite and its orbital altitude? I mean, will a heavy satellite orbit at a higher or lower altitude than a lighter one, considering everything else being ...
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### Why is Dawn in a much higher observation orbit than Rosetta?

Dawn orbits Ceres at thousands of kilometers periapsis altitude, and doesn't seem to plan to go lower than 375 km. In contrast, Rosetta has been down to about 30 km altitude, and will finally even try ...
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### Has the U.S. looked at the option of having a space station outside of LEO? If so, why or why not?

I am just curious, in theory about what the potential impacts would be to science if we were to have a space station that was outside of Low Earth Orbit. Of course, it would take longer to get to and ...
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### What altitude would an ocean crossing sub-orbital flight need to reach?

So, let's save some travel time and throw a spaceship, rather than an airplane, across the Atlantic or Pacific ocean on a ballistic trajectory. How high would it have to go? How high do the doomsday ...
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### AOCS for very small satellites (micro, nano, pico, femto)

What does a typical Attitude and Orbit Control System (AOCS) look like for a very small satellite? How does such a satellite control its attitude and orbit? Are there any means of propulsion at this ...
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### LEO insertion altitude

Does anyone know what would be the exact or approximate altitude for the stage separation and spacecraft separation of LEO insertion? Moreover, does anyone has a picture including all step of LEO ...
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### Is an orbital launch more like a vertical climb or a Hohmann Transfer?

It is said that a launch to orbit requires a Delta V of 9.3–10 km/s, and this encompasses orbital speed, air drag, gravity drag, and the energy to raise altitude to low Earth orbit. But I'm troubled ...
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### What altitudes did the first astronauts reach?

Including the suborbital flight of Alan Shepard, what altitudes did the first men in space reach? I am looking for a list of maybe the first 5-10 people who reached orbit, but also the first ...
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### Why did the LLTV have a service ceiling of 6,000 ft?

According to Wikipedia, the Lunar Landing Training Vehicle had a "service ceiling" of 6,000 ft (1,800 m). I assume this is the maximum altitude that it can perform at. What was the limiting factor?
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### Where does a planet end and space begin? [duplicate]

Where does space start? If space starts right beyond the solid part of a planet, then wouldn't Jupiter not be a planet? And if it starts at the end of the atmosphere, at what point does one escape the ...
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### 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 ...
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### How far up have satellites used a GNSS for positioning, and how does the precision degrade with altitude?

GNSS satellites (at least GPS ones) are in Medium Earth Orbit (MEO). LEO satellites can use GNSS for positioning. Is this still possible for satellites in elliptical, such as Molniya, orbits? For ...