# All Questions

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### What is the probability of impact?

Space Track is a website dedicated to passing along information about satellites to consumers, primarily satellite operators. The information comes from the US military. In addition to providing the ...
9k views

### Why did SpaceX choose to use Hydrazine over newer "green" propellants for Dragon 2?

Firstly, I understand the need to use hypergolics over cryogenics as part of Dragon 2's abort and landing sequence - they provide "instant on" thrust and are throttlable with very wide ...
258 views

### Would this Starship design alternative be viable?

Considering Starship's atmospheric entry, belly dive and "bellyflop", latest iteration displays four aerodynamic surfaces, two aft fins and two canard fins. Soon, this configuration will be ...
1 vote
314 views

### What is the maximum orbital speed beyond which the orbit around any large object in the Solar System becomes unstable?

How fast is too fast to stay in orbit around any particular large body in the Solar System?
2k views

I recently asked this question. There, I was also linked to this other question. Both, however, could benefit from the answer to one fundamental point. What is "aerospace grade"? If ...
182 views

55 views

### Repeat ground track with 1 day repetition

I'm struggling with a doubt regarding repeating ground tracks (RGT). I've a satellite in a LEO circular orbit with a predefined non-polar inclination (64°) and I want to determine the needed semi-...
135 views

### What if Perseverance had experienced a fault after dropping Ingenuity?

When Ingenuity was released on the Martian surface in April 2021, Perseverance had to drive away to let the helicopter recharge its batteries with its solar panel. Was there a concern that the rover ...
141 views

### Is there any chance that Opportunity survived, but NASA kept pinging it at the wrong time?

In 2018, NASA's beloved little Opportunity (oppy) was declared dead after a dust storm "killed" it. It may still be OK, but when NASA began recovery effort, they pinged oppy when it was ...
352 views
+100

### What were Hubble's jerk and jounce limits? Did JWST have the same?

From Wikipedia: In physics, jerk is the rate of change of acceleration; that is, the derivative of acceleration with respect to time, and as such the second derivative of velocity, or the third ...
764 views

### How does the launch risk posed by plutonium compare to the launch risk posed by propellants?

For outer solar system exploration, virtually the only feasible power subsystem are Radioisotope thermoelectric generators (RTGs). These include plutonium, which may carry considerable risks (see ...
278 views

### At what point of travelling progressively faster around the Earth you are not going to fall back again?

My dad and I thought about a problem we had when discussing Earth's gravitational field. This wasn't the original question but I still would like to know the answer. So essentially my question is: Is ...
10k views

### How can Mars have dust storms with such a thin atmosphere?

Mars, as I understand, has a very thin atmosphere. However, it still has weather like this: What causes the thin atmosphere to move fast enough to cause such a monster wave of dust?
427 views

### How much land does a colony on Mars need to start off?

Assume that we need just the following Martian resources for our colony: O2 N2 H2O Regolith for radiation shielding Regolith for construction Regolith for printing tools Martian compounds for rocket ...
202 views

### Why does Vandenberg have the most launches?

Why does Vandenberg SFB have the most launches? Is it related to location, when it was founded, something else, etc? It would make more sense for Florida to have more launches. It is illegal for ...
122 views

### Largest single burn spacecraft delta-v in deep space?

This 700 m/s maneuver that was avoided got me thinking and then CNN's NASA mission will zoom by asteroid before returning sample to Earth said: "Leaving Bennu's vicinity in May puts us in the '...
192 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? ...
65 views

### Mars planet exploration [duplicate]

Ultralight Helicopters As part of Mars planet exploration, could there be aviation i.e. airplanes, helicopters flights possible on the planet?
51 views

### Reaction control system testing

How are RCS (reaction control systems) for Launch vehicles usually tested? After going through some literatures, I came across two different testing schemes, Leans more towards testing the Cold gas ...
2k views

### How strong and "hot" is the wind on the payload after the fairing is deployed at ~110km?

In the question What makes 21st century fairings so valuable that they'd potentially be recovered and re-used? I said: 21st century fairings are much more than passive rooftop boxes to "keep the ...