Questions tagged [trajectory]

Questions regarding the path that a spacecraft will take due to forces acting on the spacecraft, such as gravitational or radiation from the sun.

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Radial hyperbolic trajectories

Wikipedia informs me that In astrodynamics and celestial mechanics a radial trajectory is a Kepler orbit with zero angular momentum. Two objects in a radial trajectory move directly towards or away ...
Starfish Prime's user avatar
5 votes
2 answers
163 views

How do modern space capsules ascertain their position during the communication blackout phase of reentry?

In this video recording of Orion's reentry, you can hear and see the RCS thrusters firing during the communication blackout phase. During the communication blackout, I would assume that GPS would not ...
phil1008's user avatar
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Calculating trajectory of Voyager 1 Python

I want to calculate the trajectory of the voyager 1 probe using python and Kepler equation. I know there are already various program to calculate it but I need to do it on my own via these ...
Gabriele's user avatar
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64 views

How well can we predict asteroid impact location?

concern in December 2004 when initial observations indicated a probability up to 2.7% that it would hit Earth on April 13, 2029 - wikipedia on 99942 Apophis So we can predict that something might hit ...
Vorac's user avatar
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I want to write a program to calculate optimal trajectories, where can I find info on the maths

I want to write a program to calculate the optimal way for a spacecraft with a given engine to reach some body astronomical body with the minimum fuel burn (possibly adding in constraints on time, ...
Pioneer_11's user avatar
4 votes
1 answer
1k views

Is this 62 mile interception altitude reasonable for this stated missile trajectory?

If a missile is launched from Yemen, and destined for Israel which is "nearly 1,000" (less than) miles away, is it likely for that missile to be intercepted at 62 miles of altitude? Where on ...
Evan Carroll's user avatar
8 votes
0 answers
147 views

Was there a close call for Voyager 2's extended mission due to lost uplink during the Jupiter encounter?

In Uplink-Downlink (2001), Douglas Mudgway says: "[The Jupiter radiation environment] . . . resulted in loss of the uplink connection with the [Voyager 2] spacecraft on the day after encounter. ...
Larry Gilman's user avatar
2 votes
0 answers
181 views

Escaping Earth - how could one attempt to find the best solution to this trajectory optimization problem in practice?

If there is a satellite in low Earth orbit, with a limited delta-v budget (but high enough to escape Earth) and limited delta-v-rate (thrust), how could one find an acceleration schedule and ...
2080's user avatar
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6 votes
1 answer
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Comparing Japan's SLIM and India's Chandrayaan-3 trajectories

I was reading this SpaceNews article on the launch, which states: SLIM won’t be taking a direct route to the moon. After a lunar transfer orbit burn, it will make a lunar flyby, heading into a wide ...
fyrepenguin's user avatar
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1 vote
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How can I know which direction a launch will be?

I'm in SOUTH FLORIDA and try to watch all the launches from here. Sometimes, the rocket seems to head south and come right overhead. How can I tell what direction a launch will take? Thank you. M
user51798's user avatar
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Why is the chandrayaan 3 mission taking 40 days to land? A [duplicate]

The Apollo missions took only 3 days. And I think Artemis too took some 26 days. Also, what do you guys think about the 53 million dollar budget?
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Hyperbolic manifolds in the spatial circular restricted three body problem and topology definition

I am approaching the study of hyperbolic manifolds originated from Lagrange point periodic orbits in the spatial Circular Restricted Three Body Problem. I can read in many papers that what we obtain ...
Daki's user avatar
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2 votes
2 answers
274 views

Difference in using flat earth or round earth model for equation of motion

according to the book of Mr. Peter H. Zipfel (Modeling and simulation of aerospace vehicles) for high speed or/and long flight applictions kinematic simulations should be done by round rotating earth ...
Lucas's user avatar
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1 answer
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How to model the gravity of Titan in GMAT

I would like to know how to find the gravity file (.cof) for Saturn's moon Titan. Need this to model the gravity field of Titan.
D P's user avatar
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15 votes
2 answers
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How do the interferometers on the drag-free satellite LISA receive power without altering their geodesic trajectory?

LISA is a proposed space probe designed to measure gravitational waves. It aims to measure gravitational waves directly by using laser interferometry. It uses a drag-free satellite design to protect ...
Woody's user avatar
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“Parabolic”, suborbital and ballistic trajectories all follow elliptic paths. Is there a generic term for these trajectories?

There are three types of trajectories which produce microgravity but intersect with the surface of the earth: Reduced Gravity Flights in airplanes. These are sometimes called “parabolic” but are ...
Woody's user avatar
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How do i correctly calculate the ellipse that illustrates the orbit of an object in space based on initial state values (r0, v0, deltat, and mu)

I'm working on a game that has a primary UI showing the solar system in a top-down (earth's north pole being roughly 'up'). And I have a need to show a semi-realistic path of travel for an object ...
Nieminen's user avatar
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What is the Delta V from the Moon to Earth Sun L1?

There are various proposals to build infrastructure at Earth/Sun L1 point, such as discussed in this question. From LEO the Delta V cost to L1 is about 3.5 kms or about kg of propellant in LEO for ...
GremlinWranger's user avatar
-4 votes
1 answer
155 views

Why "The Gateway" could not use Circumlunar trajectory? [duplicate]

My question should have being: "Is it possible to have a stable (minimal Delta-V) Circumlunar trajectory that goes around Earth and the Moon? " Circumlunar free return trajectory Lunar ...
TheMatrix Equation-balance's user avatar
1 vote
1 answer
222 views

Distance between a satellite and an orbit

I would like to compute the distance between a satellite and a specified orbit. For instance, for an orbit at 897 km altitude, 0 degree eccentricity, 99 degree inclination, and RAAN of 0 degrees on ...
Troy Rockwood's user avatar
4 votes
1 answer
399 views

Is there an accepted method to compare orbits?

I'm wondering if there is a universal or accepted way to compare orbits. For example, I have a spacecraft orbiting Earth and it is slowly increasing its altitude every time it passes a local midnight ...
Scotch Jones's user avatar
17 votes
1 answer
3k views

Why is Artemis 1 swinging well out of the plane of the moon's orbit on its return to Earth?

According to the 3-D model of the Artemis 1 mission (click on the "Mission View" button and use the slider to zoom out a bit), the outbound trip was close to the plane of the moon's orbit, ...
Dave Tweed's user avatar
2 votes
2 answers
982 views

Powered Explicit Guidance - Why wouldn't it be used?

I keep reading that the Powered Explicit Guidance equations (PEG) (detailed in the Technical note linked below) is (an approximation of) the most efficient way to get to space. That being said, I know ...
user49768's user avatar
1 vote
1 answer
185 views

What makes a spacecraft maintain its trajectory?

I have searched a lot about this topic and also got similar questions but not the answers that I wanted. All answers talk about the engines that the spacecraft uses but how is that done? I came to ...
Ayush's user avatar
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1 answer
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Falcon Heavy will launch Europa Clipper - are details available for public?

NASA Europa Clipper spacecraft will be launched by Falcon Heavy launcher. But very small amount of details can be found, to my surprise. For example, I've been guessing will additional solid-fuel kick ...
Heopps's user avatar
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1 answer
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How do I make a attitude trajectory of a satellite so the attitude always points towards a point on earth given its current orbital position?

Let us say there is an antenna on earth and I have a satellite in an orbit how do I make the trajectory (not control, so body velocities of the satellite) to make it point toward the earth when it is ...
Hamzalihi's user avatar
0 votes
0 answers
198 views

Can we have launch trajectories in GMAT?

Is it possible to model launch trajectories from ground to a certain earth orbit in GMAT?
Taha Merchant's user avatar
25 votes
2 answers
5k views

Why don't we know exactly where the Chinese rocket will fall?

China has launched another Long March 5B rocket that seems liable to fall anywhere Although the overall risk of harm to people is low—there is only a 0.5 percent chance of injury or death to a human, ...
Machavity's user avatar
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4 votes
3 answers
626 views

Is a low-energy cruise an option for manned lunar flights?

Some lunar probes such as GRAIL travelled on a different trajectory to the Moon that went even much farther than the Moon itself is from Earth, to a Langrangian point, so why isn't this option ever ...
Nullnummer's user avatar
2 votes
0 answers
115 views

What is the optimal acceleration for a direct ascent to the moon? [duplicate]

If a rocket flies to any object using a direct ascent it is best for it to reach the needed speed as soon as possible because of the Hohmann effect. When it launches from the ground there is air ...
The Rocket fan's user avatar
5 votes
0 answers
89 views

Interstellar travel by lightsail – what are the main factors of the trajectory uncertainties?

Lightsail (solar sail or sail accelerated by lasers) is a theorized as realistic way for interstellar travel. Breakthrough Starshot is the most prominent example. Let’s assume we have a thin enough ...
Heopps's user avatar
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2 votes
2 answers
244 views

How does one design a trajectory involving a lunar and Earth flyby and Lagrange points? What tools are used to calculate the initial guesses?

I'm trying to design a trajectory that takes a spacecraft from Sun-Earth L2 to a lunar flyby, to an Earth flyby and then to Mars (two flybys might be too complex, I might just do one). I've optimized ...
kardalos's user avatar
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0 answers
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Is it possible to estimate the angle of attack or flight path angle of a launch vehicle from mission web casts?

The altitude and speed is shown in the web casts of Falcon 9 missions. Is it possible to estimate the angle of attack or flight path angle?
جامکلو حسن's user avatar
1 vote
1 answer
517 views

Why does the Falcon 9 come back to the launch pad despite having considerable speed after boost back burn after separation?

After separation, the first stage of a Falcon 9 makes a boost back burn. When watching the webcast of the NROL 108 mission, after boost back it has a speed of 830 km/h at an altitutde of 148 km, then ...
جامکلو حسن's user avatar
5 votes
0 answers
129 views

How large is the AoA during the ascent and descent of a Falcon 9?

If we divide the mission into ascent, descent before reentry burn, and descent after that, how large is the AoA (Angle of Attack) in each of these three phases? Is there any difference between the ...
جامکلو حسن's user avatar
2 votes
0 answers
68 views

Manual techniques for trajectory design

I am trying to locate methods of trajectory design that can be performed by hand calculations, specifically for low thrust methods of propulsion like ion thrusters. Can anyone recommend me any ...
Gwyn Davies's user avatar
4 votes
2 answers
702 views

Satellite’s Position and Path on 2D Map [duplicate]

When the ISS orbit the Earth, its path traced on a 2D Mercator Earth Map is similar to a sinusoidal wave. I am wondering is there any way to determine the trig function of the wave, knowing the ...
Darmstadtium's user avatar
4 votes
1 answer
531 views

Plot ellipse using elements from TLE

I am trying to draw an ellipse as satellite orbit in three.js, It has an EllipseCurve class which takes these inputs and draws an ellipse around center. EllipseCurve( aX : Float, aY : Float, xRadius : ...
Sourav Anand's user avatar
2 votes
0 answers
183 views

Earth to Mars Transfer using GMAT

I saw a couple of people mention here that in order to change the epoch date from the given Mars transfer example on GMAT I would need to change and re-optimize initial conditions. How would I do that?...
user47478's user avatar
4 votes
0 answers
207 views

I'm trying to create a trajectory to Mars for a low thrust ion thruster engine using astrogator

I'm trying to create an optimize a trajectory to Mars for a number of low thrust high specific impulse engines. I am having trouble with the initial set up. I created a LEO exit spiral using a ...
Gwyn Davies's user avatar
0 votes
1 answer
541 views

Why is my C++ code for an orbit propagator wrong?

I tried making an orbit propagator C++ code. Its values seem to be propagating evenly but still I get a straight line orbit instead of an elliptical one. Why? ...
Sargunjit Bedi's user avatar
3 votes
0 answers
134 views

Porkchop plots/launch windows for Sun-Earth L2 to Mars transfers?

I've been using Earth-Mars launch windows, found with NASA's Trajectory Browser and EasyPorkchop, as launch windows from the Sun-Earth L2 Lagrange point to Mars, with the logic that since the L2 point ...
kardalos's user avatar
  • 339
2 votes
1 answer
215 views

Is there any software or other resources that can find optimal launch windows and gravity assist trajectories involving Lagrange points?

I've been using GMAT to make various trajectories involving the Sun-Earth L2 point. Earth-L2-Mars, Earth-L2-Earth flyby-Mars, etc. However, the main source of optimal launch windows I've been using is ...
kardalos's user avatar
  • 339
2 votes
2 answers
411 views

Is there a parameter that describes the angle between the spacecraft's position and the sun angle or direction of the Earth's motion?

I am trying to design an Earth flyby for gravity assist in GMAT, and I know from theory that the spacecraft should pass in front of a planet with regard to its heliocentric direction of motion in ...
kardalos's user avatar
  • 339
16 votes
3 answers
11k views

How can Artemis 1 take so much longer for Earth-Lunar transit than the Apollo missions did?

The Artemis I mission will take 8-14 days to get from Earth to the Moon. Apollo 11 only took 3 days. Similarly the return will be 9-19 days for Artemis I and just over 2 days for Apollo 11. Why is the ...
Ludo's user avatar
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5 votes
1 answer
356 views

For launch vehicles, during atmospheric stages, are there constraints on the yaw angle?

Most of the literature discusses the pitch angle and constraints on it, namely, trying to keep it zero for load relief. This leads to the gravity turn. I understand that ideal trajectories are within ...
SpacePotato's user avatar
3 votes
1 answer
527 views

Code to generate Sun-Earth L2 halo orbits for given epoch?

I am working on a GMAT script out of personal interest (not part of a job) that involves a spacecraft orbiting the Sun-Earth L2 point. I have found some orbital state vectors for the spacecraft that ...
kardalos's user avatar
  • 339
5 votes
2 answers
186 views

Where is the Wind going? Where has it been? (Global Geospace Science spacecraft 1994-071A)

This excellent answer to Why put DSCOVR in a Lissajous orbit? Wouldn't a halo orbit completely avoid the Sun exclusion zone? explains that the Global Geospace Science or Wind spacecraft ...
uhoh's user avatar
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2 votes
0 answers
37 views

Mission maneuver to Enceladus, I have some results from JPL trajectory browser, what comes next?

I am working on a project titled 'Astrodynamic mission maneuver to Enceladus'. I have found the launch date using NASA trajectory Browser. Can you let me know how to proceed further?
Smily's user avatar
  • 21
-1 votes
4 answers
887 views

How can I find the x, y position of apogee and perigee, if I only have the value of distance vector (position) and velocity vector?

I am currently working on a 2D space simulator where I have two bodies; one is still and other is an orbiting object, which I can also control like a rocket. I'm using the Newton's gravity: $F = \...
user325's user avatar
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