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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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Celestrak GLONASS TLE's showing satellite numbers not listed in the GLONASS constellation, others missing

For a project, I'm retrieving TLE information live from http://celestrak.com/ and using them to simulate satellite orbits. The TLE's for the GLONASS constellation (http://celestrak.com/NORAD/elements/...
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When did Houston figure out where the Eagle had landed?

Between starting the descent burn three seconds late, and having to avoid landing in a boulder field, the Apollo 11 descent module almost completely missed the target landing ellipse. During Apollo ...
6
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1answer
158 views

Spacecraft Navigation

Reading fascinating things about New Horizon's journey in the Kuiper Belt, I asked myself the following question: how can one know the spacecraft's position and speed, and with which precision? Of ...
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107 views

A gedanken on being able to navigate back to Earth

Imagine a sphere centered at Earth with a radius of 4 light years. Suppose we pick a random point on the surface of this sphere and drop someone, let us say, "Joe" there. Will Joe be able to come back ...
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How can New Horizons reliably approach Ultima Thule over a huge distance? [duplicate]

How did New Horizons navigate to Ultima Thule over 80 million miles from Pluto given the chaotic effect of gravity (from unpredictable local and distant matter) on New Horizons and the fact that the ...
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Why doesn't New Horizons have a tracking function

Dr. John Spencer mentioned in the live feed for the Ultima Thule flyby they're taking a series of LORRI shots along a precomputed path hoping to capture the KBO. What were the obstacles to equip the ...
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How presise could 2 satellites “thread the needle” in orbit?

I have a question about using a magnetic field to propel 2 satellites off each other while traveling in opposite directions on the same orbital plain to intersect either 2:1 or 1:1 on each orbit ...
6
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1answer
211 views

What coordinate system was used for the Apollo missions?

This is specifically about the Apollo missions, which are not touched in this related question. Did they use one coordinate system throughout the entire mission, or did they switch depending on the ...
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635 views

Is it possible to navigate space travel with no computer?

From launch to land could a person travel in space with only mechanical devices like a sextant? With enough experience what would be the minimum devices needed? Which vehicle currently would be easier ...
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Why would someone use Modified Rodrigues Parameters over Quaternions for spacecraft attitude estimation? And vice versa?

I see quite some papers on spacecraft attitude determination and control, that rely on quaternions. While some others rely on MRPs. The advantage that I see so far is that... for quaternions, the ...
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1answer
118 views

Has a cubesat in LEO determined its orbit and position using only terrestrial cameras plus the Sun? (no GPS, starcam, uplink, magnetic sensors, etc.)

From LEO, a cubesat with several reasonable cell phone-like cameras (or better) can image the Earth and it seems straightforward for some standard pattern recognition algorithms to find the sunlit ...
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Help understanding BepiColombo's weak capture at Mercury's L1 and need for delta-differential one-way range measurements

This four-minute BBC podcast Mission to Mercury: BepiColombo spacecraft ready for launch highlights several challenges of the BepiColombo mission, including its orbital-mechanical aspects and is worth ...
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1answer
133 views

What brand and model is the hand-held sextant tested on the ISS?

Astronaut Alexander Gerst is testing an hand-held sextant on the ISS in the context of the experiment Sextant Navigation for Exploration Missions, see picture below. What is the brand and model of ...
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1answer
171 views

How was the Apollo IMU calibrated?

Both the command and lunar modules of the Apollo spacecraft has navigation systems with inertial management units. IMUs are known to drift over time. How were they recalibrated? My answer below ...
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4answers
315 views

How would blockchain be integrated into spaceflight? Have any methods been proposed yet?

Blockchain offers a way of keeping track of information such that its authenticity can be verified and it can not easily be falsified. In a space environment with an increasing number of both active ...
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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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0answers
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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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1answer
482 views

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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317 views

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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3answers
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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 ...
5
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1answer
832 views

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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3answers
543 views

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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1answer
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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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1answer
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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 ...
6
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1answer
369 views

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
461 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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5answers
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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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2answers
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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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1answer
188 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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3answers
215 views

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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2answers
243 views

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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379 views

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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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
396 views

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, ...
4
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1answer
160 views

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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Have guidelines for red & green navigation light placement on spacecraft been established?

update: Cropped screen capture from SpaceX Demo-1 Crew Dragon Docking to ISS - Part 2 after about 00:25:00 in the video: I am curious if guidelines for the ...
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How might the Lunar X Prize contestant spacecraft have navigated 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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892 views

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
286 views

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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1answer
289 views

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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1answer
266 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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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
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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 ...