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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General guidelines for modeling a low thrust ion spiral?

I've been told that for low thrust ion spirals, delta V would be the difference between speeds of departure and destination orbits. For example the delta V between a 7.7 km/s LEO and a 3.1 km/s GEO ...
HopDavid's user avatar
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If I wanted to reconstruct an entire Apollo mission's crewed spacecraft trajectories, what are the key sources of historical data I'd look for?

The last few images in Robert A. Braeunig's Apollo 11's Translunar Trajectory; and how they avoided the heart of the radiation belts are fascinating and a bit perplexing as discussed in this answer ...
uhoh's user avatar
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What is the analytical closed-form solution of the two-body problem to verify its numerical integration results?

The purpose is to study the motion of two celestial bodies analytically. What is the closed-form of the two-body problem if I was to solve it analytically without using a numerical approximation ...
John's user avatar
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Is 678 km the new altitude record for a rocket shot "straight up" (vertical launch)?

The Space Daily April 10th Rocket Science item Europe's largest sounding rocket launched from Esrange says: MAXUS 9, Europe's largest sounding rocket for experiments in microgravity, successfully ...
uhoh's user avatar
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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
SE - stop firing the good guys's user avatar
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Do any launches bypass LEO?

If sending a payload to GEO (geosynchronous orbit) or any other high orbit, you could start off launching to LEO (low Earth orbit), and then use a Hohmann transfer to raise the height of the orbit. I ...
AlanSE's user avatar
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Puzzler: Precisely what maximum distance from the Earth did the Apollo 13 astronauts achieve?

tl;dr: Both this answer to Which astronaut travelled farthest from Earth? this answer to How far have astronauts been in space? quote Wikipedia to state that the Apollo 13 astronauts reached 400,171 ...
uhoh's user avatar
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Dragon re-entry flight profile?

I was looking online for a profile depicting the Dragon re-entry similar to those showing the launch and first stage re-entry (e.g. https://www.elonx.net/wp-content/uploads/...
Peter - Reinstate Monica's user avatar
21 votes
4 answers
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Has Luna been used for gravity assist for interplanetary probes?

The Earth's natural satellite has a great deal of angular momentum that seems to me could be used to derive a considerable boost for leaving the local SOI. Has any probe used a Lunar flyby as part of ...
Jerard Puckett's user avatar
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Did Apollo's velocity slow down after TLI due to Earth's gravity?

I assume Apollo's velocity slowed down after it left Earth orbit, for how long was it decelerating. Did it start accelerating as it approached the Moon. What was the rate of deceleration due to ...
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How can I find sources for Launch Trajectories?

The trajectories of space launches and the deployment of their payload (both scientific and commercial) are certainly carefully monitored by the space agency or company providing the launch capability,...
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Is it possible to "map" the Interplanetary Transport Network?

Cartographers have always been valued members of any exploration team. Even the teenage George Washington had experience with the "compass and chain." Every Terra Incognito is in need of a good map. ...
Jerard Puckett's user avatar
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What does the BackFlip lunar cycler do in its pass by Earth?

This paper describes an Earth-moon cycler orbit. In this concept, a 180 degree "BackFlip" is used to modify a more simple cycler orbit. However, I can't figure out what cycler orbit it modifies, and ...
AlanSE's user avatar
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How precise are spacecraft trajectory measurements?

Interplanetary mission trajectories are frequently likened in popular media to hitting a small target with a dart from vast distances, but in reality, spacecraft don't need absurdly high precision, ...
Russell Borogove's user avatar
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Understanding gravitational keyhole analysis for Near-Earth Objects

I've been studying the resonant return and gravitational keyhole analysis for NEOs and using the extension of Öpik's theory of close encounters (aka Öpik-Valsecchi theory, Valsecchi et al., Astron ...
Astroynamicist's user avatar
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How to get true anomaly from time?

An exercise that was left unsolved from last year's class gives me this equation : $$ t-t_{p} = \sqrt{\frac{a^3}{\mu}}*(\arcsin(X) - e*X) $$ where : $$ X = \frac{\sqrt{1-e^2}*\sin(v)}{1+e*\cos(v)}. $$...
Magix's user avatar
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Will the Emirate Mars Mission, Tianwen-1 and Mars 2020 Mission get closer to each other or spread out on their way to Mars?

Background & Introduction: On August 2, 2020 the brand new Where Is Roadster page Spacecraft launched to Mars in 2020 (announced here) said that it had been: 13 days, 3 hours, 47 minutes and 13 ...
uhoh's user avatar
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Did SpaceX intend to overshoot Mars?

There seems to be a lot of buzz around the Internet that the now famous Roadster is going to overshoot mars. Was this intentional, just to show the kind of capacity it is capable of? Or was there some ...
corsiKa's user avatar
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What is the feasibility of launching a probe to Sedna?

This dwarf planet reaches perihelion in the summer of 2076. At a distance of 76 au, is it feasible to launch a probe that would reach Sedna in time? With an orbital period of over 11,000 years, this ...
Jerard Puckett's user avatar
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5 answers
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Would leaving the ecliptic plane offer any benefit to interstellar travel?

Aside from the obvious answer of being able to easily avoid the larger bodies in the Solar System. I'm primarily curious as to the mechanics of this endeavor -- would there be any benefit to ...
Anthony Neace's user avatar
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Space travel using constant acceleration drive: Earth to Europa

Long story short: I'm writing sci-fi and taking my protagonist to Europa. He's got 2 weeks to one month to get there from Earth, give or take a few days. That sounds, of course, preposterous in this ...
adamholtwrites's user avatar
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2 answers
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If something "falls off" the L2 or L1 point, where will it go?

The L1 and L2 points are thought to be unstable "saddle" points, meaning that there is stability in two directions of movement, but not in the other. That raises an obvious question - when a ...
AlanSE's user avatar
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Explanation of single-burn trajectories from Lunar surface to Earth surface

I learned of the fine book Soviet Robots in the Solar System from this excellent answer. One chapter in it describes how the Soviets had extreme mass limitations on their lunar sample return vehicle ...
Organic Marble's user avatar
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Is a lunar Sun-synchronous orbit possible at the "frozen" inclination of 86°?

I have been considering if it would be possible to place a satellite in a Sun-synchronous orbit in one of the lunar frozen orbits at 86°. According to NASA scientists there are four inclinations for ...
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Are ion thruster trajectories classified as brachistochrones?

Usually, when performing trajectory optimizations for chemical rockets, the limiting factor is the $\Delta v$ budget. That means velocity change is the optimization factor, with things like transfer ...
SE - stop firing the good guys's user avatar
10 votes
6 answers
719 views

How was Juno's arrival set up to be on the evening of July 4th?

Presumable it is largely a coincidence that Juno arrives at the perfect moment for American pride in NASA's achievements, but not entirely. The video below of the trajectory, released in July 2011 ...
kim holder's user avatar
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Does trajectory of an object orbiting a planet depend on the object's mass? (With hypothetical Apollo example)

For example (hypothetically), if an Apollo crew of one of the lunar missions went on EVA just after Trans Earth Injection burn and carefully released a small bolt, or a plastic package from their food,...
Sergiy Lenzion's user avatar
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876 views

What is the numerical procedure to find the next closest approach between two bodies on keplerian orbits?

Given two bodies on Keplerian orbits, what is the procedure to find the next closest approach of the two bodies? The bodies would be effectively massless objects like two spaceships orbiting around a ...
lamont's user avatar
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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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Why is NASA proposing an EMEJ (MEGA) trajectory for Europa Clipper instead of EEJ?

A launch service request was recently put out for Europa Clipper to do a flyby of Mars on its way to Jupiter. How is that a better trajectory than an EEJ, similar to Juno? Launch Vehicle Performance: ...
PearsonArtPhoto's user avatar
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4 votes
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What exactly is rhumb-line control in the context of a launch trajectory?

The conference paper SS-520 Nano satellite launcher and its flight result SSC18-IX-03 from the 32nd Annual AIAA/USU Conference on Small Satellites linked in this answer describes the use of rhumb-line ...
uhoh's user avatar
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Relationship of 'C3' to Delta-V for interplanetary missions

In what way does the concept of 'C3' relate to 'Delta-V' in interplanetary missions?
MercuryPlus's user avatar
1 vote
2 answers
465 views

How to understand this NASA animation of Juno's passes near Jupiter?

I don't understand! Rotating frame? I see Orion pass by around 00:30 to 00:36, that's a clue. Why the first two passes are on the same side (in this view) but the rest alternate? edit: This is ...
uhoh's user avatar
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18 votes
4 answers
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Can we set up an orbiting transporter between Earth and the Moon?

I will give an example with the moon. If some spacecraft is put either in orbit around both earth and moon or in highly eccentric orbit that intersects with the moon orbit, some other spacecraft can ...
Nikolai Frolov's user avatar
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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Climbing at terminal velocity minimizes losses? But why? And "of what"?

A lucky discovery of a Kerbal engineer's writing gave this deep insight into the mechanics of climbing to orbit: the best way to minimize d/v losses through the atmosphere is to always go at ...
AlanSE's user avatar
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13 votes
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Why don't we take the shortest route to Mars?

As far as i understand we are going on a route shown in the picture. When we can actually let Mars do the travelling for us and just take the short route and wait for Mars to arrive... Won't that be ...
Steven Lebègue's user avatar
13 votes
4 answers
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What is the least energetic trajectory design to send uncrewed supplies to Mars?

Both Mars One and NASA have suggested sending uncrewed supply ships to Mars as part of a manned mission or colonization. These payloads can take all the time they like, not being constrained by human ...
Jerard Puckett's user avatar
12 votes
2 answers
3k views

Can the Falcon Heavy handle deep space missions?

Can the Falcon Heavy rocket handle sending payloads past Jupiter like the Atlas V?
CBredlow's user avatar
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12 votes
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Mathematics used for SpaceX first stage re-entry burn guidance?

I thought it would be fun to make a basic simulation of a first-stage fly-back of SpaceX's Falcon 9, but was wondering what mathematics is used to perform something like this. Looking at this page: ...
InquisitiveInquirer's user avatar
10 votes
1 answer
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Software to simulate / optimize ascent trajectory

I read the previous question on this site about astrodynamics software and I have tried STK (free version) and GMAT, but I could not find software to simulate and optimize a launch trajectory. Is ...
gosnold's user avatar
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How can I predict what an object's orbital state vectors will be in the future?

I have a position and velocity vector for an orbiting object and can calculate the orbital elements. From a simple two-body situation, how can I predict where in the orbit the object will be at some ...
Stu's user avatar
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9 votes
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Optimal trajectory for solar electric propulsion?

Consider using solar electric propulsion for, e.g. Earth-Mars trip, or for asteroid retrieval mission. Is there a benefit to first entering an eccentric orbit so that part of the time is spent ...
Alex I's user avatar
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How to optimize time of ignition for an on-orbit burn and/or coast phase on ascent?

I've been playing around linear tangent based guidance laws (specifically the old Atlas-Centaur Surveyor guidance, Apollo IGM and Space Shuttle PEG code) and while PEG has an option for a coast phase ...
lamont's user avatar
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8 votes
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How long will it take for Starman to complete one orbit of the sun?

I have seen that the original estimate to pass by Mars was about 6 months, but the current trajectory overshot Mars by quite a bit. How long until Starman and the Roadster return to complete their ...
dansalmo's user avatar
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7 votes
2 answers
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How would a bulk payload like fuel (instead of delicate technology) change boost to LEO optimization?

This answer suggests that if a payload were simply bulk propellant, such as LH2 and LOX, and not delicate technology such as an interplanetary probe or communications satellite, then there may be some ...
uhoh's user avatar
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How useful is the Interplanetary Transport Network?

Wikipedia summarizes the Interplanetary Transport Network/Interplanetary Superhighway fairly succinctly, although it's pretty vague to someone who doesn't know what's going on: The Interplanetary ...
cartographer's user avatar
6 votes
1 answer
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Tutorial for orbits from TLE data

I've been looking for a new hobby, and have been reading some about satellite tracking. I was wondering if there was a good tutorial that walks through how to use TLE data. So far I have found ...
UVphoton's user avatar
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1 answer
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What (the heck) are "space-fixed coordinates" as described in Apollo mission trajectory analyses?

@Ludo's answer to If I wanted to reconstruct an entire Apollo mission's crewed spacecraft trajectories, what are the key sources of historical data I'd look for? shows the table and its source shown ...
uhoh's user avatar
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Where did the Herschel Space Telescope go in 2013?

The Herschel space telescope wins as largest optical telescope mirror in space when "optical" includes far infrared (~55 µm). The Wikipedia article Herschel Space Observatory lists the orbit ...
uhoh's user avatar
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