45 votes
Accepted

Why does Artemis I need a launch window?

There is an alarmingly thorough article about this on NASASpaceflights’s website (not affiliated to NASA itself). Lunar illumination at arrival plays a part; so does the maximum length of time for ...
Martin Kochanski's user avatar
27 votes

What is the rarest launch window?

Comet West with its unpredictable but estimated at 558 000 years period is a good contender. Since launch windows can aim for the alignment of N objects, the answer obviously tend to infinity. You ...
Antzi's user avatar
  • 12.7k
22 votes

Why does Artemis I need a launch window?

From an orbital mechanics standpoint, remember that: The Artemis launchpad is not located on the equator and does not launch into perfect 0-inclination equatorial orbits The planet Earth is inclined ...
Dragongeek's user avatar
  • 18.6k
21 votes

What is the rarest launch window?

Hohmann launch windows occur each synodic period. Or a more general version of a Hohmann transfer would be a transfer orbit tangent to both departure and destination orbits. This also occurs each ...
HopDavid's user avatar
  • 15.7k
19 votes
Accepted

What's the reasonable "window" in days for a Mars-Earth Hohmann transfer?

Techically a Hohmann transfer is a single instant, but as you mentioned, there is a window about the Hohmann that is nearly optimal. Just to give you an idea, here is the launch window sizes for some ...
PearsonArtPhoto's user avatar
  • 121k
16 votes
Accepted

What is the rarest launch window?

The launch of New Horizons was very critical. The NASA scientists had 5 years to develop a space probe to Pluto and make sure it got a gravity assist through Jupiter, which is only possible if ...
Bharath Simha Reddy's user avatar
11 votes

What factors determine how long a window of opportunity opens for an interplanetary hohmann transfer?

The factor which determines the duration of a transfer window is the performance margin of the launcher or spacecraft. The Hohmann transfer is the minimum delta-v for transfer between two circular ...
Russell Borogove's user avatar
10 votes

How does the Parker Solar Probe have such a wide launch window?

There is some information in this paper although it does not directly address your question. It does mention that the first Venus flyby is at a relatively high altitude (about 2500 km) which may make ...
Steve Linton's user avatar
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9 votes
Accepted

Why was TESS' launch window open for only 40 seconds per day?

The short launch window appears to be due to a combination of the very precise orbit requirements of TESS and SpaceX's tendency to bravado. Other Sources: Information on the exact reasons is thin on ...
Jack's user avatar
  • 9,976
8 votes

Why does Artemis I need a launch window?

If you look at the flight path animation (too large for SE), you'll see it makes two gravity assists from the Moon. So the moon needs to be in a specific point in its orbit so that they line up. ...
Greg Miller's user avatar
8 votes
Accepted

Do geosynchronous satellite launches require a tight launch window?

The maximum eclipse any GSO satellite will be in is 72 minutes, per Intelsat. Thus, a launch can't happen that puts the satellite in an orbit with an eclipse period of longer than 72 minutes, or else ...
PearsonArtPhoto's user avatar
  • 121k
7 votes
Accepted

When are there launch windows to Neptune via Jupiter?

Using the Trajectory Browser, I was able to figure out the following trajectories that are available. The dates are Jan-18-2018, Feb-22-2019, Feb-23-2031, and Mar-29-2032. So basically there are ...
PearsonArtPhoto's user avatar
  • 121k
7 votes
Accepted

How could the landing date of Perseverance Rover be fixed irrespective of 26 days launch window?

It is deliberate choice. See this tweet from Tory Bruno, CEO of ULA who is launching the mission. This of course doesn't tell us the exact reasoning behind the date, however. Why this is is actually ...
PearsonArtPhoto's user avatar
  • 121k
6 votes

Why does Artemis I need a launch window?

The current version of the vehicle does not have enough performance to initiate TLI from a low-earth, circular orbit. Instead the the launch has to be done into an elliptical parking orbit to give ...
BowlOfRed's user avatar
  • 6,852
6 votes

How does the Parker Solar Probe have such a wide launch window?

New launch schedule: Rescheduled to lift off at 3:31 a.m. EDT on Aug. 12, 2018. Scrub Announcement Video: "Parker Solar Probe Launch Postponed". There will be live coverage on the NASA ...
Rob's user avatar
  • 3,266
6 votes

What is the rarest launch window?

Near-optimal (or at least reasonably cheap) encounter between bodies in strongly eccentric, similar orbits (similar argument of periapsis, inclination, period). For optimal transfer, one part of the ...
SF.'s user avatar
  • 55k
5 votes

How does the Parker Solar Probe have such a wide launch window?

You are correct in your assumption that larger launch windows require higher fuel margins on the rocket. Therefore, the main reason for such a large launch window is not because they just want to, but ...
DaGroove's user avatar
  • 1,334
5 votes

Why did GRACE mission have launch window?

There is an extremely detailed paper on this, where a specifically designed tool, the GRACE Orbital Analysis Tool (GOAT) was developed to look at the 5 year orbital stability of a number of potential ...
PearsonArtPhoto's user avatar
  • 121k
4 votes
Accepted

What is the reason for the short-duration cutouts in the Artemis I launch window?

These are COLA (Collision On Launch Assessment / Avoidance) cutouts. In other words: they are to avoid hitting stuff. Since LEO debris and/or satellites are extremely fast compared to the ground, ...
Jörg W Mittag's user avatar
4 votes
Accepted

When the lunar module ascent stage launched to take astronauts back to the command module, how long was the launch window?

There is an answer about launch windows on Space Exploration Stack Exchange here. Basically, there was a launch window of a few minutes every two hours for optimum rendezvous with the Command Module, ...
gandalf61's user avatar
  • 1,421
4 votes
Accepted

Impact of Constellations on Space Debris and Launch Windows

I was an orbit analyst, in the LEO regime for 11 years. My co-worker had been in GEO for nearly 30. Here is a summary of what I have learned on the subject. Note: Keep in mind the 3 basic sizes of ...
Scottie H's user avatar
  • 194
3 votes

What is the rarest launch window?

This question has six answers already, but I would like to include a more general answer: In solar system spaceflight there is a trade-off between fuel (delta-V) and mission duration. You can go ...
Ingolifs's user avatar
  • 6,428
3 votes

What's the reasonable "window" in days for a Mars-Earth Hohmann transfer?

To complement @PearsonArtPhoto's information on upcoming missions, you can also look at the historical launch dates of Mars missions to get a sense of the launch windows actually used. While the ...
Russell Borogove's user avatar
3 votes

Can Falcon 9 be fueled slowed to delay the instantaneous launch window?

For a flight to the ISS, the Falcon 9 should launch into the orbital plane of the ISS. To change the plane later requires extra fuel. There are some reserves for safety but not for launch delays. The ...
Uwe's user avatar
  • 48.9k
2 votes

Can Falcon 9 be fueled slowed to delay the instantaneous launch window?

SpaceX uses a different methodology for fueling, colloquially called "load and go". The idea is you load supercooled fuel (for maximum density) onto the rocket 35 minutes before launch. It's ...
Machavity's user avatar
  • 7,840
1 vote

Why would there be a launch window for a Geosynchronous orbit?

Without knowing the specifics for this launch considerations for airline trafic and shipping could play a part. There might be reasons not to close the range to everyone else indefinetly.
lijat's user avatar
  • 1,798

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