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.

Filter by
Sorted by
Tagged with
71
votes
2answers
64k views

When will New Horizons overtake Voyager 1 in distance from the Sun?

Basically, what the title asks. To my understanding, New Horizons is currently the fastest spacecraft that's moving away from the Sun, with arguably only Helios-A and Helios-B possibly faster still, ...
39
votes
6answers
15k views

Given small computational resources, how was navigation implemented? (Not samples of old guidance software)

Update 2 : The youtube vidoe How did NASA Steer the Saturn V answers this question and then some, a must watch. Update: I really wanted to know how spacecraft navigation (not guidance) computers ...
34
votes
1answer
12k views

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 ...
31
votes
8answers
4k views

How could one navigate on Mars?

There are two primary systems of navigation on Earth today, using maps/compass, and using GPS satellites. It seems unlikely there will be a full constellation of GPS satellites prior to the first ...
24
votes
2answers
1k views

Is there a Martian “North Star”, usable as Earth's North Star?

Mars has a different axial tilt than Earth. It stands to reason that the constellations will remain identical from Mars, but their locations will be somewhat different. On Earth, the North Star is ...
23
votes
2answers
7k views

How did astronauts using rovers tell direction without compasses on the Moon? [duplicate]

I read that the astronauts who used Lunar rovers used heading indicators, which typically use compasses, for direction. How, on the Moon, did their equipment tell the direction of travel, presuming a ...
22
votes
2answers
787 views

How can spacecraft navigate without contact from Earth?

My understanding is that probes within the Solar system primarily rely on Earth-based tracking networks and ephemeris data to navigate. Once they get really close to their destinations, they can ...
20
votes
3answers
5k views

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 ...
20
votes
2answers
2k views

How did NASA determine the distance and velocity of voyager 1?

According to Wikipedia At a distance of about 125.97 AU (1.884 × 10$^{10}$ km) from the Sun as of September 9, 2012, it is the farthest manmade object from Earth As of 2013, the probe was moving ...
19
votes
5answers
1k views

What is the deepest position in space we can get a GPS signal?

Can we use GPS in orbit at the moon? What about on Mars?
18
votes
1answer
3k views

How does the star tracker in Voyager 1 lock onto a specific star?

How does the Voyager 1 star tracker lock onto a specific star and how reliable is it? Are there approaches in more modern trackers used such as pattern recognition or other methods which would enable ...
18
votes
1answer
843 views

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 ...
17
votes
1answer
16k views

How do spacecraft navigate through the Asteroid belt to avoid collision?

Have any spacecraft been lost transitioning between Mars and Jupiter? How do spacecraft navigate that field unscathed as well?
17
votes
1answer
8k views

What coordinate system is used in space for navigation?

On Earth is possible to define the position of something using WGS, and the same system is used for navigation. What is used in space instead? Are different systems used for Earth-orbiting objects (...
16
votes
2answers
1k 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 ...
15
votes
2answers
2k views

Can the satellites in Martian orbit be put to use providing a rudimentary GPS system on Mars?

This website conveys the impression a rover on the Martian surface necessarily navigates by dead-reckoning. Stereo images are used to determine how far a rover has travelled; an advancement over older ...
15
votes
2answers
4k views

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 ...
14
votes
1answer
2k views

Radar Altimeter in Space Shuttle

I was going throught the Space Shuttle Handbook, chapter Guidance and Navigation. In one of the Note boxes, it is written Radar altimeter altitude is not used for navigation or guidance. The ...
14
votes
1answer
538 views

How dense are Saturn's rings?

How high is the density of asteroids in the rings of Saturn? Would it be possible for a spacecraft to fly through the thicker rings without colliding with asteroids? Would it be necessary to avoid a ...
13
votes
1answer
664 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 ...
12
votes
3answers
192 views

Would tethering to a large mass be an efficient way to change velocity?

Changing velocity rapidly in space is a bit of a problem requiring either the expense of propellant, or aiming past a planet for a gravitational slingshot. If you could fire out a strong tether and ...
12
votes
1answer
361 views

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 ...
12
votes
2answers
914 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: ...
11
votes
5answers
910 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 ...
11
votes
4answers
5k views

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 ...
11
votes
3answers
447 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, ...
11
votes
2answers
4k views

How does GPS work exactly?

For a GPS receiver to estimate its position, it first receives signals from at least 4 satellites. Does the receiver calculate the distance that separates it from each satellite, or does it just ...
11
votes
2answers
264 views

How much adjustment of position is required when making long flights through the solar system?

It is hard enough to exactly aim a rocket when you know all the forces on it, but on a long journey there must be any number of minor gravitational attractions to rocks and other mass in space, and ...
11
votes
1answer
361 views

In LEO, what is the precision of GNSS-based position compared to traditional methods?

GNSS satellites (at least the GPS ones) are in MEO, so LEO spacecraft can use GNSS for their positioning. I've read that it's quite low-cost compared to the alternatives. How does the precision of ...
10
votes
2answers
7k views

How does a rocket navigate during launch?

From what I understand, a rocket changes its direction during launch by gimbaling its engines (i.e. swiveling the engine nozzles so the thrust of the engine points in the correct direction). But what ...
10
votes
1answer
733 views

How would the state vector be updated in the Apollo Guidance Computer during coasting to/from the moon if communication with Earth was lost entirely?

This source https://www.hq.nasa.gov/alsj/alsj-average_g.html states that: From time to time, Houston could update the onboard SV using tracking and other available date; [sic] but, generally, it ...
10
votes
1answer
448 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 ...
10
votes
1answer
917 views

How do probes locate themselves?

There's no way for any probe that is sent to orbit/land on a distant body to get there only on precalculated flight parameters alone - minuscule errors in the beginning of flight would convert to huge ...
9
votes
2answers
254 views

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 ...
9
votes
2answers
1k views

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 ...
9
votes
1answer
316 views

How did the star tracker on the Corona (Key Hole) satellite work?

The first Corona Photographic Surveillance Satellite was launched in 1959. Starting from the third mission, launched in 1961, the satellites were equipped with a star tracker. From Wikipedia: ...
9
votes
1answer
466 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 ...
9
votes
1answer
447 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 ...
9
votes
1answer
528 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 ...
8
votes
1answer
551 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,...
8
votes
1answer
829 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 ...
8
votes
1answer
958 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)?
8
votes
1answer
1k 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 ...
8
votes
1answer
268 views

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 ...
7
votes
2answers
159 views

Perseverance Rover to drive carefully for months while helicopter hangs from underside?

The image below is cropped from the high resolution version of NASA's Mars Helicopter and Perseverance Rover PIA23824 and shows the helicopter in it's stowed position on the underside of the rover ...
7
votes
3answers
942 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 ...
7
votes
1answer
681 views

What conventional reference frame is used for interplanetary telemetry and navigation?

Specifically a location in the celestial sphere that is fixed, most likely a star, which creates a set of still coordinates with respect to the Sun. There are many ways to do this, but I am interested ...
7
votes
1answer
150 views

How did early inertial navigation systems handle vibration?

In the early ICBM-era rockets, it seems that inertial navigation accuracy was critical. How did these systems filter out the noise in the data due to the vibration of the rocket? If a fairly slow ...
7
votes
1answer
309 views

How quickly could a craft find its location using only pulsars?

I'm only just beginning to scratch the surface of the possibilities in interstellar travel. I know that pulsars can be independently identified by means of measuring their pulses, and that once enough ...
6
votes
2answers
135 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 ...