27
votes
Optimal depth for underground flyby?
The Optimal Depth is Precisely (Almost) No Depth
I solved this problem using a numerical differential equation solver to investigate a range of flyby approach angles. The results are fascinating!
I ...
- 1,648
20
votes
Can a meteor shower have a interval greater than 1 year?
This is really more of a question for Astronomy.SE, in general this doesn't happen, but circumstances can work out that it does, see the updated last few paragraphs.
Every meteor shower with an ...
- 4,901
18
votes
What caused the jitter in the DART video as it approached Dimorphos?
This is an extended comment to your self-answer, so I'm making it community.
From your answer,
As to why they weren't able to do a single, early course correction and just glide smoothly in for the ...
12
votes
Accepted
Optimal depth for underground flyby?
Assuming a uniform planet with radius $1$ and gravitational parameter $1$, if $V_\infty$ is the speed at infinity and $r$ is the closest approach to the center, then the maximal speed is $V_m = \sqrt{...
- 1,845
10
votes
Would the Dzhanibekov effect be a problem for Von Braun Wheels?
No... a Von Braun wheel would not ever 'flip' from Dzhanibekov effect. The effect comes from spinning something about its intermediate (and inherently unstable) axis. A Von Braun station is spinning ...
- 2,501
9
votes
Optimal depth for underground flyby?
Adding my own numerical time-step simulations here.
The effect seems to be quite subtle, only increasing the deflection angle by a fraction of a degree at shallow depth.
For a unit mass, with unit ...
7
votes
What caused the jitter in the DART video as it approached Dimorphos?
I'm revising my answer based on the comments and on the community answer started by David Herman.
Corrections were not made right up until the end, but stopped with 500 miles to go. This is according ...
- 7,434
7
votes
Accepted
Is this a typo in the Python Skyfield API? "International Coordinate Reference Frame (ICRF)"?
The quotation correctly (though not completely) describes the International Celestial Reference Frame, so I'm comfortable calling "Coordinate" a typo.
- 6,132
6
votes
Accepted
At what point on the Earth's surface does the +X axes of the J2000 coordinate system intersect?
I started this as a comment, but ran out of room. It doesn't actually answer the question, but explains why the question can't be answered in a meaningful way.
I'm sure you're aware that Jan 1 isn't ...
- 549
5
votes
Draper Semianalytical Satellite Theory (DSST) C/C++ version
The way I read the literature, the Java Orekit version is the only publicly accessible version. If I am wrong, someone please tell me!
The C++ conversion was done later (2017-2020 vs. 2012-2015), by ...
- 6,132
4
votes
what is 'f' (true anomaly) for in the orbital inclination change equation
Let's see.
What if we have a circular orbit ($e = 0$) with no argument of periapsis ($\omega = 0$), normalised to a unit mass, unit radius, so $a = 1$ and $n = 1$?
The formula then simplifies to
$$\...
3
votes
Satellite position using 2 station ranging
If the orbit is exactly geostationary, meaning inclination and eccentricity are both zero, then $z$ is zero, so you're done.
Real satellites, on the other hand, are never precisely geostationary. In ...
- 6,132
2
votes
what is 'f' (true anomaly) for in the orbital inclination change equation
This answer addresses the possibilities for altering inclination outside of the context of the particular equation in the OP.
In isolation it is incorrect to say that there are "only two possible ...
- 8,968
2
votes
Mars transfer window frequency
You both are really right. A nominal Hohmann transfer takes 257 days (0.7 years). It is the least possible energy. However, Zubrin in the book cited recommends a 180 day transfer, which uses a little ...
- 21
2
votes
Could we use Mars as as an asteroid mining base?
The main benefit of Mars for asteroid mining would be for accessing asteroids that are further out, not ones that are closer to Earth than Mars itself.
Transporting propellant from anywhere else to an ...
- 8,430
2
votes
Would the Dzhanibekov effect be a problem for Von Braun Wheels?
Starting with a circular wheel spinning on its axis of symmetry (maximum inertia), can one then add masses in such a fashion that the conserved angular momentum ends up on an intermediate axis?
The ...
- 3,674
1
vote
Optimal numerical method to solve BVP for optimal low thrust control
ESA's PyKep will likely work very well. It allows you to solve lots of BVP, model low thrust propulsion, load SPICE files, etc.
- 5,925
1
vote
Could we use Mars as as an asteroid mining base?
If you can build a space elevator then you've just removed any need to use Mars or anywhere else other than Earth as a base for exploration/exploitation. With the massive cost of lifting materials to ...
- 19k
1
vote
NASA GMAT: Any good tutorials or methods to learn how to use patch points and control points to come up with viable and optimal trajectories?
I started using GMAT last week and I am roughly at the same point you were when you posted this message.
I am trying to create a Low Energy transfer to the moon and trying to get the optimum launch ...
- 11
Only top scored, non community-wiki answers of a minimum length are eligible