All Questions

2
votes
0answers
42 views

Discrepancy between Launch Vehicle Performance website on Atlas V 551 with Juno

I was looking at the Juno space probe which was launched in August 2011 onboard an Atlas V 551. In particular I was looking at https://elvperf.ksc.nasa.gov/Pages/News.aspx and using the performance ...
2
votes
0answers
28 views

What Methods are Used for Satellite to Site Visibility Calculation?

In the paper, Rapid Satellite-to-Site Visibility Determination Based on Self-Adaptive Interpolation Technique it is claimed that "Satellite-to-site visibility periods are typically determined by the ...
2
votes
1answer
108 views

Have astronauts lost fingernails on spacewalks before?

Spacewalks can be notoriously taxing on the body - a multi-hour spacewalk is often compared to a marathon in how much the astronaut must exert to overcome the stiffness of the suit. I remember ...
5
votes
2answers
215 views

What did India's recently tested ASAT vehicle really look like?

Following up to India just shot down a satellite from the ground. At what altitude range is the resulting debris field? which shows the first image below (also seen in video) I also found the second ...
4
votes
2answers
132 views

How much of the exhaust speed is due to combustion and how much is due to the injection?

The thrust $F$ of a rocket engine is given by $$F=\dot{m}v$$ where $\dot{m}$ is the mass flow and $v$ is the exhaust speed. Now the first factor, $\dot{m}$, is almost entirely due to the turbo pumps (...
3
votes
0answers
103 views

What is holding SLS back from launching?

I'm kind of confused on this point SLS has engines, a tank, side rocket boosters, a capsule, and seemingly all of the pieces. What is the major technical issue right now that is keeping SLS from ...
-1
votes
1answer
198 views

99.99% pure iron meteorite [closed]

[![enter image description here][1]][1] I have a 99.99% pure iron meteorite. It is 4,902 grams.
0
votes
1answer
108 views

Could rockets benefit from Reaction Engine's Air-Breathing Rocket Engine in terms of payload?

While I get that one is a vertically launched rocket and the other is a space plane, is it even wildly possible that there could be a vertical intake version of the SABRE engine? Maybe it can be used ...
2
votes
1answer
47 views

Is there mineral nitrogen on Martian surface? [closed]

I am aware of the atmospheric composition and pressure. I am looking for research papers which state the mineral content of Martian soil.
18
votes
2answers
864 views

Who is accountable for damage caused by the debris field of a successful ASAT test

I just saw India just shot down a satellite from the ground. At what altitude range is the resulting debris field? about today's Indian ASAT test... As far as I know an "ASAT Missile" sounds military ...
35
votes
5answers
8k views

India just shot down a satellite from the ground. At what altitude range is the resulting debris field?

This tweet from India's prime minister Narendra Modi says: मेरे प्यारे देशवासियों, आज सवेरे लगभग 11.45 - 12.00 बजे मैं एक महत्वपूर्ण संदेश लेकर आप के बीच आऊँगा। I would be addressing ...
4
votes
1answer
159 views

Do owners of reentering spacecraft notify the countries' whose airspace they are likely to violate and seek permission?

@PearsonArtPhoto's answer contemplates: Any object that is below 100 km now is considered an aircraft, and technically needs the permission of the country over which it is flying to enter that air ...
7
votes
1answer
156 views

Is there a crewed moon lander currently in the works

Recently, the US vice president directed NASA to land astronauts on the moon within the next 5 years [source]. While there are big rockets (SLS, Falcon Heavy, etc.), and crew capsules (Orion, Crew ...
0
votes
0answers
56 views

Which would be more prone to regolith-ice-melting issues, a rover's wheels or an astronaut's boots?

This answer to Has NASA “gone south”? Why are astronauts needed to explore the Moon's south pole? and the question What would happen if an Apollo astronaut landed on Pluto? both touch on issues of ...
6
votes
2answers
204 views

Has NASA “gone south”? Why are astronauts needed to explore the Moon's south pole?

Wired: Why America Wants to Send Astronauts to The Moon's South Pole “Before we put boots on the ground at the poles, we urgently need a robotic water ice prospecting mission to the lunar poles,” ...
0
votes
1answer
30 views

Instantaneous positions of a central body of specified mass that results in an osculating orbit?

If I understand correctly, osculating orbital elements such as those posted in JPL's Horizons represent the mathematical osculating (tangential or "kissing") Keplerian orbit about a specified location ...
1
vote
2answers
52 views

How do scientists determine how big a certain star is? [closed]

I was just wondering, many people say that there are stars that are waay bigger than our sun and in some videos they even try to say the exact diameter of the Sun, but I was wondering: How can ...
2
votes
0answers
31 views

Suggestions required on radiation tolerance solutions

I wanted to know what methods of increasing radiance tolerance for the microcontroller and memory devices for a Cubesat exist. We have read about methods like having dual CPUs but are there any ...
23
votes
2answers
3k views

Why not increase contact surface when reentering the atmosphere?

If a craft were to increase the surface area where contact is made with air during reentry, I imagine the heat quantity per area unit would decrease, making the use of (heavy) heat shields less of a ...
1
vote
0answers
51 views

What is the state of current plans for a permanent moon base?

With all the news regarding SLS/Commercial Crew and the refocus on Moon then Mars, I was curious as to what we will actually be able to do with these upcoming launch capabilities. I'm familiar with ...
1
vote
0answers
40 views

Will a Cygnus and Dragon be on station at the same time in April 2019?

According to the launch schedule at the moment I looked (which is of course only a snapshot in time) there is a Cygnus mission (NG-11) scheduled for Apr 17, 2019. There is a SpaceX Dragon Cargo ...
4
votes
1answer
202 views

Could a “nuclear turbo-jet” be built?

Being familiar with jet engines myself, I wonder whether a similar device could be built to provide high $I_{\text{sp}}$ and high thrust in vacuum and space. Using the tried-and-true turbojet formula ...
-3
votes
3answers
161 views

Which company provided communication equipment for Apollo missions in which Neil Armstrong was a part?

In July 1969, the Apollo mission transmitted Neil Armstrong’s first steps on the moon to millions around the world. Which famous company provided the entire communication equipment for the project?
4
votes
1answer
76 views

How do pressure fed and pump fed systems compare at different scale of rockets

Rocket Design is all about optimising mass, within cost constraints while accepting a certain amount of risk. Both pressure fed and pump fed systems have their pros and cons, but how do they compare ...
2
votes
0answers
42 views

What is the minimal distance of clearance in the direction of flight path for a rocket?

Usually the rocket launch sites are placed on a coast or a place where there's basically no civilian buildings in the direction of flight path. Is there a standard/regulation on the minimal ...
3
votes
0answers
204 views

Could a steam Engine outperform other electric producing devices in space? [closed]

What would be the Specific Impulse of a steam-based propulsion system like this model in space? Are there any types of engine that works this way? Could 2 tanks be designed to rotate slowly in space ...
3
votes
0answers
40 views

Patched conic approximation targeting retrograde LLO yields prograde orbit

I'm playing around with optimization of a patched conic approximation for a transit from earth orbit to LLO, and when I take the resulting retrograde trajectory and plug it into an integrator, I get a ...
3
votes
1answer
82 views

Orion cockpit instrumentation

I'm working on a spaceflight simulator (FSX SpacePort), and currently developing instrumentation for NASA's Orion capsule. I'm using whatever little info is available on line and trying to identify ...
6
votes
1answer
94 views

Calculation of V1 (orbital speed) during ascent

I am studying instrumentation of NASA's Orion spacecraft, and there is a readout for V1 (I am assuming this is the "first orbital velocity", for circular orbit), and it seems to be in small decimals. ...
6
votes
1answer
94 views

How does the sunlight affect the height of the atmosphere?

I was reading this question about how high a Mars balloon could go in the mars atmosphere. How much would the sunlight affect how high the atmosphere reaches? Is the atmosphere on Earth elongated on ...
3
votes
1answer
181 views

For the Starhopper testing, how will SpaceX hold down the vehicle?

SpaceX is testing the Raptor engine on the Starhopper they built in Boca Chica. For static fires of a Falcon 9/Heavy they use the pad itself, the holddowns to the pad, to keep it from taking off. ...
29
votes
3answers
5k views

Why is delta-v the most useful quantity for planning space travel?

Many of the questions and answers on this site make use of the concept of delta-v. Is there an easy to understand the reason why delta-v, the magnitude of the change of the velocity, $|\mathbf{v}|$, ...
5
votes
1answer
73 views

How are gravity coefficients calculated?

I was reading Satellite Orbits - Models, Methods, and Applications by Montenbruck & Gill and was trying to use the equations in it to calculate $J_2$ as used in the GEM and JGM gravity models. ...
1
vote
1answer
49 views

What differences exist between the pressurants and their associated systems between a pressure fed and pump fed liquid rocket engine

There is an apparent need to have pressurants in both pressure fed and pump fed systems. However, since pump fed systems can create the necessary pressure, they can work with less pressurants and ...
21
votes
1answer
6k views

Why is this part of the Space Shuttle launch pad suspended so high off the ground?

http://science.ksc.nasa.gov/shuttle/missions/sts-107/images/high/KSC-02PD-1894.jpg shows a large part of the launch pad suspended off the ground. What is it for and why is there all that empty space ...
8
votes
2answers
2k views

What is the smallest body in which a sling shot maneuver can be performed?

This question asks about the smallest sling shot maneuver performed. What was the smallest intentional, acknowledged slingshot maneuver? I'm asking how small of an object be to perform a sling shot ...
0
votes
1answer
78 views

What types of engines are able to go from Earth orbit to Martian orbit? [closed]

What engine is the most efficient in fuel and/or time to go from Earth orbit to Mars orbit and back again that are not capable of launching from the ground?
2
votes
1answer
116 views

Is post-X-prize Beresheet better than the X-prize candidate?

As mentioned in this question the total budget of the Lunar X-prize was about US \$30 million, and that included some other prizes beside the winner. However the budget of Beresheet post-X-prize ...
8
votes
1answer
120 views

Is there any combustion chamber and nozzle cooled with liquid oxygen instead of fuel?

There are many rocket engines for liquid propellants which use the fuel (rocket petrol or liquid hydrogen for instance) to cool the walls of the combustion chamber and the nozzle. But are there any ...
1
vote
0answers
32 views

Where can I get design details about spacecrafts and space mission? [closed]

I am doing a project on designing a mission to Mars. I am researching similar missions and I want to find information on the mission details like Delta V, trajectories etc. and details of the ...
3
votes
1answer
134 views

Why are JPL using this expression to emulate Schwarzschild orbits?

From the documentation ”Formulation for Observed and Computed Values of Deep Space Network Data Types for Navigation ” expression 4-61 on page 4-42 it can be seen that JPL uses the following ...
8
votes
1answer
801 views

Where did Heinlein say “Once you get to Earth orbit, you're halfway to anywhere in the Solar System”?

I know what it means. I've seen delta-V charts. But I don't know if Robert Heinlein wrote this down, or simply said it off-the-cuff to somebody. Variations include: "Reach low orbit, and your ...
2
votes
0answers
58 views

How is this engine put together? [duplicate]

I'm going through How to DESIGN, BUILD and TEST SMALL LIQUID-FUEL ROCKET ENGINES and am confused how their sample engine is physically built together. This is a picture of their assembly where the ...
21
votes
2answers
3k views

How can Trident be so inexpensive? Will it orbit Triton or just do a (slow) flyby?

The recent NY Times article Neptune’s Moon Triton Is Destination of Proposed NASA Mission says (in part): HOUSTON — Is it time to go back to Neptune? Scientists representing NASA’s Jet ...
2
votes
2answers
155 views

Would a mouse trap snap faster or slower in space than on Earth?

Would a spring loaded mechanism outside a spacecraft activate a lever faster or slower in space with no atmosphere and gravity than on Earth? Basically this is in reference to mechanical instruments ...
0
votes
1answer
60 views

Why would different Shuttle orbits have different mission directors?

The Wikipedia page for NASA Flight director Holly Ridings contains a portrait with two other STS-117 mission flight directors. The caption there says: Flight directors for the STS-117 mission in ...
0
votes
1answer
64 views

How are satellites made “demisable” and what else do recent FAA documents tell us about SpaceX's plans for StarLink satellites?

Comments in chat mention that recent FAA documents show that there have been design changes in the StarLink satellites that make future builds "demisable". This sounds interesting but I don't really ...
0
votes
2answers
132 views

Why would an 8-minute burn result in a 6-month delay?

The Ars Technica article Vice President may tell NASA to accelerate lunar landings ends with: And on Thursday, NASASpaceFlight.com reported that the agency is considering skipping a critical test ...
-2
votes
1answer
114 views

Do all US vice presidents get cool jackets?

The Ars Technica article Vice President may tell NASA to accelerate lunar landings starts with "We're tired of generating PowerPoint journeys that don't go anywhere." and explains that one or ...
5
votes
3answers
167 views

Why do countries or companies still bother sending landers/probes to the moon?

Countries like Israel, South Korea, or China most recently and companies like ispace have plans to send landers to the lunar surface. At least according to this list. Is it because there is little ...

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