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Questions tagged [navigation]

Topics that relate to orbit determination and flight path control. May also be used for navigation on the surface of celestial objects.

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What is the nature of the sextant tests on the ISS for Orion cis-lunar emergency navigation?

According to the NASA Johnson video Space to Ground: A Star to Steer By: 08/10/2018: A tool that once helped sailors cross vast oceans for centuries is now being put to the test in space. The crew ...
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Machine Learning and Classical Navigation, Guidance and Control in Space Exploration

Due to the increasing availability of large quantities of data and computational power, machine learning (ML) is providing increasingly better results in various fields. Much research has been done on ...
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Does the “17” really mean anything with respect to GNSS orbits being rational factions of a sidereal day?

This answer suggests that the orbital periods of the four large GNSSS contstellations are linked to the sidereal rotation period of the earth by rational numbers with 17 or 34 as the denominator in ...
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What is a gyrocompass and how might one be be used by a planetary rover?

In comments and links therein below the question How does Curiosity know how to point and move it's high gain antenna in real time? there is mention of a gyrocompass. I am aware that gyros can be ...
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Was the Apollo sextant used (or tested) to determine position while in Earth orbit?

The video Apollo Program Guidance and Navigation System 79974 explains that the spacecraft's sextant could be used together with the navigation computer to determine a position fix while in Earth ...
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Soyuz has a Space Periscope?

The image Photo ID: ISS049-E-003166 can be found in Flikr and Wikimedia Commons as well as in Spaceflight Now. There is a long (perhaps 1 meter?) green structure that is sticking out from the side of ...
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Is NICER/SEXTANT the first civilian “spacecraft” to determine it's own position in space without GPS or uplinked data?

Computers on board spacecraft can determine their positions using a combination of uplinked data from the ground and for those closer to Earth, GPS/GNSS. (See this answer and this question for ...
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Inexplicable Offset in Satellite Laser Ranging (SLR) observations

I am struggling with the implementation of a Satellite Laser Ranging (SLR) validation tool. The situation is as follows: I am provided with a framework which gives me the position of a SLR ...
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Navigating in space with only cameras

I'd like to figure out how to determine where something is in space (solar system) based only solely on measurements that can be preformed on location visually/with a camera. Let's say I'm floating in ...
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GPS Receiver Autonomous Integrity Monitoring (RAIM) - parity space method

I am trying to understand RAIM. My teacher explained three RAIM methods, I will just quote all of them because I think that the jargon might not be consistent. Maximum separation / Position ...
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1answer
396 views

Does Venus have a north star or south star?

I am trying to figure out how you would navigate on Venus. On Earth you can use Polaris as a North Star to find north. Would there be a star on the Venus sky which could function as either a north ...
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How might Earth's location be referenced in stellar terms?

Apologies if this has been asked before using terminology for somebody more familiar with the subject matter. I've searched but cannot find an answer. Assuming space travel was possible (to other ...
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What's a good source of information on determining spacecraft positions via radio?

I'm willing to spend a decent amount on a textbook, but please tell me about cheap or free sources as well.
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166 views

What determines if a star tracker blends two stars that are close to each other?

If two stars are very close to each other, a star tracker could identify the pair as a single star, with a magnitude and position different from both stars. This obviously impairs the software's ...
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When was stereoscopic photography first used intentionally on solar system body?

I have stumbled across the fascinating page Photogrammetric Analysis Of Apollo 11 Imagery: New camera-station map with improved locations at the following website: https://www.hq.nasa.gov/alsj/a11/...
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Satellite Position

The Voyager 1 took one last photograph in 1990 and after that, the camera equipment was shut off for power saving. However, the estimates of where the photo was taken in space vary by many hundreds of ...
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How do we define geographical coordinates on non-spheroid celestial bodies?

On Earth, we can use latitude and longitude to fairly accurately describe a single point on the surface of the earth. This works because the earth is, for all intents and purposes, a sphere. It got me ...
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166 views

Navigating to Proxima-B

What sorts of unique problems are there with planning a trajectory to Proxima Centauri, besides it being out of the plane of the ecliptic? (I'm guessing if you've got the juice to make it there, ...
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Height of navigation satellites above Earth

What is the distance between the Earth's surface and the motorists' satnav satellites?
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3answers
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How is the trajectory of spacecraft transferring between planets monitored?

The doppler effect can give a pretty measure of radial speed relative to Earth, and radio transmissions can narrow down the radial position, but what about everything else? I can imagine several ways, ...
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1answer
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What naturally occurring navigational information is available for an autonomous return of SLS's EM-1?

This answer details some of the requirements that would need to be met if the Space Launch System's planned Exploration Mission 1 were to be human rated. I've further trimmed that truncated selection ...
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1answer
280 views

Have guidelines for the placement of red/green navigation lights on spacecraft been established?

I am curious if guidelines for the placement of red/green navigation lights on spacecraft been established. In maritime and most aviation situations, right/left have meaning because up/down does. A ...
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How might the Lunar X Prize contestant spacecraft navigate their descent from orbit, to landing?

EDIT: Please note the following items: The Mission Requirements for claiming the Grand or Second Place Prize include the following: Landing – A team must land its craft on the surface of ...
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What was the globe instrument in Vostok 1?

This image was attached to the Wikipedia article on Vostok 1 with a perfunctory caption "Part of the Vostok 1 instrument panel". I'm interested in the globe in the center. What is the name of this ...
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3answers
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How can a deep-space spacecraft determine in real time the direction of delta-v?

My spacecraft knows it wants to add a certain delta-v in a certain direction to its motion, relative to the stars. It will calculate current mass based on propellant usage history, which hasn't been ...
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2answers
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How would you navigate an airship on Venus?

Since there is no magnetic field compass is out. No GPS satellites either. I guess some old school methods could be used but I see some potential problems. Assume we are over the cloud tops, can we ...
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Does NASA use Newtonian model of gravity for plotting the course of Juno or general relativity?

With the huge mass of Jupiter and its fast, approximately 10 hours daily rotation, there may be substantial twisting of space-time around it. A distortion of such magnitude that may call for ...
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227 views

Deep space craft antenna aiming

In order to aim an antenna at Earth, how do unmanned spacecraft find their own orientation (xyz position in space, what direction it is flying and which direction the antenna is pointing)? Are they ...
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391 views

How would an interstellar probe navigate the pull of gravity from stars and other large objects on the way?

Refer to the ambitious probe sent by Yuri Milner, Stephen Hawking and Mark Zuckerberg to Alpha Centauri: Yuri Milner is spending $100 million on a probe that could travel to Alpha Centauri within ...
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1answer
436 views

Will Glonass, Galileo, or BeiDou-2 satellites provide better cis-lunar navigation than GPS?

My question is: Has there been any effort to improve or optimize the radiation patterns on the subsequent satellite navigation constellations (e.g. Glonass, Galileo, BeiDou-2) to facilitate trans-GEO ...
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Has GPS been used beyond GEO? [duplicate]

When researching this question I came upon a presentation entitled Enabling a Fully Interoperable GNSS Space Service Volume; slides 12, 24, 25, 26 are also shown below. The idea is that while GPS ...
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How is space mapped out?

Here on earth, we have four directions(East, West, North, South). We have earth maps which shows our exact location from any other location in 2D plane. But in space, planets and stars are in three ...
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How are GPS satellite clocks synchronized with each other in the earth's frame of reference?

I have been looking at different threads. It seems like the receiver clock on Earth doesn't have to be synchronized with the satellite clocks. But I believe the satellite clocks need to be ...
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How did the Apollo 11's Eagle ascent stage find the CSM after leaving the Moon?

I've always been curious how did the Apollo 11's Eagle ascent stage of the Apollo Lunar Module navigate back to the Apollo Command/Service Module (CSM) that was in lunar orbit? Was it simply a case ...
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State of the art of satellite Attitude Determination and Control Systems

I know I might get an answer like "the sky is not the limit"... But considering the actual state of the art of modern satellites ADC systems. Haven't we reached a "maximum" yet? Or are there still a ...
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Do GPS receivers use trilateration or distances between satellites?

My main question is whether GPS receivers use trilateration or the distances between satellites. On GPS.gov and their videos, it says you receivers use trilateration. But, I have seen people say that ...
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How did astronauts navigate the Lunar Roving Vehicle (LRV) over the surface of the Moon?

The Lunar Roving Vechicle (LRV), also known as Moon Buggy, was used as a form of transportation on the surface of the Moon during the Apollo program. What system did the astronauts use for ...
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575 views

Radiation pattern and signal strength of navigation satellite antennas

Where can I find the actual radiation pattern and signal strength of transmitting antennas used by GNSS navigation satellites/constellations (GPS, GLONASS, IRNSS, etc)?
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708 views

What is the maximum acceptable latency in rocket control computers?

Rockets require real-time computers, in that there are operational deadlines between events and system response. How quickly does the rocket's controller need to respond to sensors and events, without ...
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2answers
375 views

Will New Horizons seek a third target?

New Horizons will fly past the Kuiper Belt object 2014 MU69 in January 2019. This will use 56 m/s of the remaining ∆V budget of 130 m/s (1). The encounter will occur near the inner edge of the belt: ...
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436 views

Autonomous Navigation for deep space missions

Autonomous navigation started in early phases of deep space exploration as a provision to achieve accuracy for planet/natural satellite targeting and approach, where radio tracking accuracies were low,...
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Interplanetary ranging accuracy?

What are the two or three most accurate technologies used to determine interplanetary spacecraft distance (e.g. Doppler / radiometric tracking...), and what accuracy is currently obtained from such ...
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1answer
126 views

Where do the poles of the Solar System point? [closed]

The solar system is like a big rotating disk, so it has an axis. Where do the two ends of the axis point in space? To put it another way, where in the sky are the two furthest points from the ...
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269 views

How is real position of probes orbiting other planets measured?

I imagine that measuring real positions and orbital elements of satellites orbiting other planets after they perform braking maneuver to get to their final orbit must be rather difficult. Especially ...
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Does Philae's waking enable scientists to determine its location?

Now that Philae has woken, is more known about its exact location? In other words: does Philae know where Philae is? Navigation on Churi sounds challenging.
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1answer
372 views

Is this photo of Mars in color?

This recently released terrain of Mars as taken by the Curiosity Rover looks like it was done in black and white. Is this really how it looks like to the naked eye? From here.
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1answer
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How close can Rosetta come to the 67P/Churyumov-Gerasimenko comet?

ESA publishes quite a few images from the 67P comet, sent by Rosetta, from various distances away to collect as much as possible and as varied as possible. As I write, Rosetta is 6 Km away from the ...
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Accelerometer in space

If my understanding of the General Theory of Relativity is correct, according to the Equivalence Principle, forces due to gravity and acceleration are indistinguishable. If that's the case, then an ...
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Navigation within solar system

I know star trackers are used in most cases for attitude determination of space craft traveling within the solar system. But what methods are currently used for coordinate determination, i.e. the ...
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Could a swarm of probes autonomously establish orbit around an asteroid?

To position a spacecraft around an asteroid, one must know the orbital parameters and orientation of the asteroid and the spacecraft. Formation flying will be more complex in terms of positioning ...