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21 votes
3 answers
1k views

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 ...
24 votes
2 answers
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 ...
9 votes
1 answer
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
3 answers
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?
8 votes
4 answers
2k views

What is "aerospace grade"?

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 ...
4 votes
1 answer
182 views

Crew Dragon: Could launch escape thrust determine payload capacity?

The superdracos in Dragon's launch escape system each produce $\color{black}{\texttt{71.2 kN}}$ (16,000 lbf) of thrust. There are eight superdracos, giving a combined thrust of $\color{black}{\texttt{...
5 votes
1 answer
365 views

What was the smallest intentional, acknowledged slingshot maneuver?

I'll keep it short but please read through! Gravitation's $1/r$ potential means everything in the solar system is pulling on everything all the time. Gravitational slingshot maneuvers are normally ...
0 votes
1 answer
128 views

Why aren't clusters of F-15 or SR-71 engines used for a boost stage for rockets? [duplicate]

A cluster of say 8 F-15 or SR-71 engines in my mind could make a viable first stage for a small rocket. Second they can land the stage back to the ground and if my guess is right they could go to up ...
3 votes
0 answers
39 views

How will InSight's hardware be damaged if the heaters fail?

InSight is scheduled to "die" due to the Dust on the solar arrays. From what I understand, once the power goes out, there won't be a way to keep the computers and batteries warm at night, so ...
1 vote
1 answer
111 views

How many times has SpaceX reused Falcon 9 first stage until 20th May 2022? [closed]

How many times has SpaceX reused Falcon 9 first stage until now? Not about the possibility. I want to know the current progress with the Falcon 9 first stage.
7 votes
1 answer
1k views

Could Ingenuity survive if Perseverance failed?

They both landed successfully and Ingenuity was deployed. Perseverance drove away, and then failed. Could Ingenuity survive on its own?
3 votes
1 answer
446 views

Could Perseverance survive if Ingenuity failed?

They both landed successfully and ingenuity was deployed. Perseverance drove away, and then Ingenuity failed. Could Perseverance survive on its own?
0 votes
0 answers
56 views

Can I borrow a Mars rover? [duplicate]

There are many abandoned Mars rovers sitting on Mars, in very well defined locations. Would China, or whomever gets to Mars with a person next, be able to go to it, and do what they want with it? ...
19 votes
4 answers
3k views

What makes aluminum aerospace grade?

So what is aerospace grade aluminum? Aerospace grade and regular aluminum or both aluminum. Do they have a different composition or strength? What makes one aerospace grade?
11 votes
3 answers
430 views

How "locked" are Pluto and Charon? How much does each librate as seen from the other?

Discussion below Are all or some geostationary satellites tidally locked to the Earth? got me thinking about Pluto and Charon. According to Wikipedia: Charon and Pluto orbit each other every 6.387 ...
16 votes
4 answers
27k views

How close can I get to a rocket launch and not get killed?

There was a question regarding the closest distance regular people are allowed to be near a rocket. At that distance (Baikonur I, 1.1 miles), even if a rocket explodes, there is a small chance someone ...
34 votes
4 answers
11k views

Could the Moon keep an atmosphere?

When we think of terraforming a body in our galaxy Mars gets lots of consideration as the closest potential body. But what about the Moon? It is currently beyond our ability to add an atmosphere ...
35 votes
5 answers
7k views

Has any spacecraft ever been flown manually to orbit?

Has anyone ever manually flown a spacecraft to orbit, Kerbal Space Program-style?
4 votes
1 answer
2k views

What are the odds of finding a lifeless planet with breathable air?

As I understand it, our current breathable atmosphere on Earth is the result of early lifeforms transforming huge amounts of CO2 into O2. Before early life, even Earth's atmosphere wasn't livable for ...
13 votes
1 answer
1k views

Does cosmic dust pose a problem for long-term satellites, telescopes and probes?

We have many long-term satellite observatories and probes in outer space way above the Earth's magnetosphere, and some of them progressively cruising out of our Solar system. Off the top of my head, ...
27 votes
5 answers
11k views

Could a helicopter fly on Mars?

Helicopter drones are awesome fun down here on Earth, but what if... we took one to Mars? This sounds like a good question for Randall Munroe. But I read about a proposal to send a helicopter drone (...
35 votes
6 answers
11k views

Why aren't air breathing engines used as small first stages?

I am wondering why we don't use jet engines as first stages. Most small rockets, like the Electron, can lift off with a small thrust. In the Electron's case, 192 kN. Why can't we replace the 9 ...
6 votes
2 answers
282 views

Why did MRO have to "both pitch upward and roll hard to the left" to point exactly at Perseverance during the entry, descent and landing phase?

The HiRise camera on the Mars Reconnaissance Orbiter snapped a beautiful photo of Perseverance falling through the Martian atmosphere hanging from its parachute. This photo can be found here on the ...
1 vote
0 answers
95 views

After one year exploring Jezero's crater floor, (why) hasn't there been any investigation into the presence of trace elements with PIXL?

PIXL instrument chart sample Credit:NASA/JPL-CALTECH Of course PIXL has been used already in Jezero crater, but as far as I know only to identify mineral compositions and textures, as described in ...
126 votes
4 answers
33k views

Do the planets really orbit the Sun?

We often say that the planets orbit the Sun, which is usually a reasonable approximation. But in reality both Sun and the planets orbit the center-of-mass/center-of-gravity of the whole solar system, ...
24 votes
1 answer
3k views

What cooling improvements did the Venera missions make?

I've been reading about Russia's (former Soviet Union) Venera missions, and one thing about them that has impressed me is the incremental improvements the landers made in their lifespans before ...
1 vote
1 answer
56 views

Historical Moon’s True Anomaly Numbers

What are moon’s true anomaly angles for new moons in year 1994? Cannot find historical true anomaly numbers on the internet.
7 votes
3 answers
1k views

Who does these mesmerizing simulations of the phases of the Moon? And how?

It's lunar new year here and people will be lighting fire crackers and launching bottle rockets off and on until dawn, so I thought I would read up on it. EarthSky.org's Moon Phases update Your new ...
4 votes
0 answers
140 views

Dinitrogen tetroxide decomposes to nitrogen dioxide at room temperature, but rockets that use it are usually said to use N₂O₄ and not NO₂ - why?

To the best of my understanding, both dinitrogen tetroxide and nitrogen dioxide are usable and perform quite similarly as oxidizers, but rockets that use either are almost always said to use ...
39 votes
5 answers
10k views

What exactly makes a bolt "aerospace grade"?

I'm reading various articles on Tesla S electric car and many of them (one example) say that the car body is very strong because of using aerospace grade bolts. What are those I wonder? I found this ...
2 votes
2 answers
250 views

Won't any space battle fill up the system with supersonic lethal shrapnel, making space very dangerous?

Any explosion in space might produce very fast moving projectiles, that may pick up way more speed after getting slingshot by planets. The same might happen with every bullet that misses. They are ...
10 votes
2 answers
2k views

For how long could the Mars helicopter Ingenuity keep up with the Perseverance rover if it wanted to?

Wikipedia's Mars Helicopter Ingenuity says: It could potentially cover a distance of up to 300 metres (980 ft) per flight. Perseverance is somewhat similar to Curiosity which drove about 22970 ...
9 votes
6 answers
4k views

How could 99942 Apophis, in 2029, be captured and brought into a low Earth orbit?

I'm currently attempting to plan out a mission where, in 2029, during Apophis's close approach to Earth, a rocket is sent up to intercept Apophis and decelerate it, making it orbit the Earth. At it's ...
1 vote
2 answers
1k views

Could there be a phosphorus cycle on Venus?

Most of what I read says there is not any phosphorus on Venus, which I take to mean none in the atmosphere or none detected. I mean, it gets hit by iron-nickel meteorites and probably has some apatite ...
4 votes
2 answers
434 views

Could H₂S₂O₈ (peroxydisulfuric acid), made in the clouds of Venus, be used for making a propellant?

The salts of the peroxydisulfate ion, S$_2$O$_8$$^2$$^-$, are strong oxidants like the perchlorates that are used in propellants for rockets. In this answer on Chemistry stackexchange is a link to a ...
0 votes
0 answers
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-...
3 votes
1 answer
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 ...
5 votes
1 answer
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 ...
3 votes
0 answers
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 ...
17 votes
2 answers
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 ...
4 votes
1 answer
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 ...
22 votes
4 answers
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?
6 votes
1 answer
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 ...
4 votes
1 answer
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 ...
5 votes
1 answer
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 '...
0 votes
1 answer
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? ...
-4 votes
0 answers
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?
2 votes
0 answers
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 ...
16 votes
1 answer
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 ...
14 votes
3 answers
4k views

How does the Curiosity rover survive dust storms on Mars?

According to the answers to this question, a dust storm on Mars can last for many days. Dust is a serious problem for mechanical joints if they use lubrication, because it may stick to the lubricant ...

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