Questions tagged [measurement]

Questions about the methodology and results of collecting data.

Filter by
Sorted by
Tagged with
4
votes
0answers
30 views

How many solar system bodies have had their magnetic fields directly measured?

Discussion below this post lead me to wonder: Question: How many solar system bodies have had their magnetic fields directly measured? Inferences from radio or spectroscopic observations don't count ...
2
votes
1answer
137 views

How are astronauts aboard the Tiangong space station keeping busy?

Per Wikipedia's Tiangong space station viewed today: Days in orbit: 3 months, 15 days (13 August 2021) Days occupied: 1 month, 27 days (13 August 2021) Currently it is just the single core ...
2
votes
0answers
32 views

Has opalescence ever been observed on any solar system body besides Earth? Or at least from a sample from one?

New method for exoplanet detection based on iridescence? in Astronomy SE asks about observations of exoplanets, but here I'm asking about our own solar system bodies. Question: Has opalescence ever ...
1
vote
1answer
53 views

Has iridescence ever been observed on any solar system body besides Earth? Or at least from a sample from one?

New method for exoplanet detection based on iridescence? in Astronomy SE asks about observations of exoplanets, but here I'm asking about our own solar system bodies. Question: Has iridescence ever ...
4
votes
0answers
41 views

To what precision were the amounts of the Shuttle propellants known? [duplicate]

A previous question reveals that the Shuttle orbiter was weighed before it was moved to the Vehicle Assembly Building. Presumably, the other dry components of the launch stack (the solid rocket ...
3
votes
0answers
104 views

How does Curiosity's X-ray diffractometer work? Does it measure only one angle at a time or does it have an area detector?

Per this answer to Are quasicrystals common on the Moon and Mars?, Curiosity has an X-ray diffractometer. X-ray diffraction from 3D crystals can (begin to) be understood by embracing Bragg's law. A 3D ...
6
votes
0answers
177 views

What are the various ways that rockets measure the instantaneous thrust of each engine?

@DavidHammen's answer to Engine failure: how to detect? mentions thruster sensors. This intrigued me and so I thought I'd ask about how this is done. Thrust is a critical parameter to know in real ...
7
votes
0answers
162 views

How is the Max-Q of a spacecraft determined?

Maximum aerodynamic pressure of a spacecraft is the maximum force it's hull can withstand during flight. How is the Max-Q of a spacecraft determined? Other related ( optional) queries are: If Max-Q ...
3
votes
1answer
97 views

Local atmospheric pressure and local surface gravity in Jezero crater?

Did Perseverance and/or Ingenuity measure the local atmospheric pressure and local gravity where they are? Ingenuity had been tested in a 0.006 atm chamber on Earth, therefore I guess the local ...
1
vote
0answers
51 views

Is it possible to determine whether a spacecraft is in the thermosphere or in the exosphere?

The Earth's thermopause is varying greatly between 500 km (310 mi) and 1000 km (620 mi) altitude. If a craft orbits inbetween these altitudes, or reaches them at some point of their orbit, is there ...
2
votes
0answers
19 views

What instruments and techniques measured Mars' atmospheric D/H ratio which suggests (all of) it's water didn't evaporate after all?

The Time article Mars Has Much More Water Than Previously Known—But There's a Catch says: The greater weight of deuterium causes it to behave differently in the Martian atmosphere. While free ...
1
vote
0answers
44 views

Did Chang'e-3 and/or Yutu report getting hit by the Earth's magnetotail?

@DavidHammen's answer to If a solar flare happened during a total lunar eclipse, would the Earth block the flare from hitting the moon? And for how long? describes the regular lashing of the Moon by ...
4
votes
1answer
208 views

How do they measure the voltage of the Moon?

@DavidHammen's answer to If a solar flare happened during a total lunar eclipse, would the Earth block the flare from hitting the moon? And for how long? describes the regular lashing of the Moon by ...
2
votes
0answers
103 views

Did the Mars 2020 Mission do any science that wasn't done by Perseverance proper?

Per answers to What is the equivalent of Curiosity's "MSL" in the context of Perseverance? What's the official name of the mission? Are the distinctions similar? Where does MSL end ...
1
vote
1answer
144 views

When they shoot lasers at the Moon for ranging, what is the shape of the beam?

Laser ranging of the Moon is usually done with a Q-switched pulsed laser fed into a big (1 or 2 meter diameter) telescope as a collimator in order to get a tight beam all the way to the Moon in hopes ...
3
votes
1answer
156 views

How can rockets measure their own speed relative to the ground?

When we are getting the measurements of speeds of rockets. Is this calculation done through external systems watching the rocket or can the rocket measure its own speed relative to the ground?
2
votes
0answers
91 views

Spacecraft altitude measurement

While in atmosphere, altitude is measured by using pressure gauges - higher the altitude, lower the pressure. How is the altitude measured once we cross the atmosphere?
2
votes
1answer
132 views

Knowing when to stop burning

Navigating in orbit usually relies on firing engines for some amount of time to achieve a specific velocity. This answer, for example, mentions "closed-loop guidance" for the ISS boosting. ...
3
votes
0answers
48 views

How is fuel measured in spacecraft? [duplicate]

On something like a gravity-bound automobile, fuel is measured with a float that moves a variable resistor but I would think this would not be possible on a rocket, one because of extreme G-forces ...
23
votes
1answer
2k views

Why did NASA collect so much data about electrical phenomena at the Apollo 13 launch site?

Apollo 13 was launched at Kennedy Space Center on April 11, 1970. The mission report devotes a considerable amount -- over 7 pages -- to a set of electrical measurements at the launch site: The ...
1
vote
1answer
126 views

What counts as "0 mGal" in these gravity maps?

In the following gravity map of Mars the changes in gravity are shown according to mass distribution: Map removed However, since no moon or planet other than the Earth with 9.80665 m/s² has a ...
27
votes
1answer
3k views

How do we know what percentage of NEOs we've discovered?

I stumbled upon this answer: https://space.stackexchange.com/a/41535/10334 It states the percentage of NEOs we have already discovered. Seeing this I've asked myself: How do we know what percentage ...
25
votes
2answers
2k views

If I wanted to reconstruct an entire Apollo mission's crewed spacecraft trajectories, what are the key sources of historical data I'd look for?

The last few images in Robert A. Braeunig's Apollo 11's Translunar Trajectory; and how they avoided the heart of the radiation belts are fascinating and a bit perplexing as discussed in this answer ...
5
votes
2answers
295 views

Can a spacecraft use an accelerometer to determine its orientation?

I know that almost every spacecraft uses a gyroscope to determine its orientation, but I don't know if an accelerometer could also be used in addition to a magnetometer to calculate it. I have been ...
6
votes
3answers
3k views

How is foot-pounds of energy defined?

Tom Lodgson's classic textbook Orbital Mechanics: Theory and Applications frequently measures energy in foot-pounds, which I'd always thought to measure torque. The book doesn't define it. Is it the ...
1
vote
1answer
254 views

How were Venera's variometers able to measure extremely weak, nano-Tesla magnetic fields?

The image below is from the really interesting page Inventing The Interplanetary Probe (linked by @A.Rumlin here). Above the fluxgate magnetometer there is a pair of short tubes labeled "...
7
votes
1answer
540 views

How soon was the Garn scale of nausea established after the senator's spaceflight?

Then-Senator Jake Garn flew on Shuttle mission STS-51-D in April 1985. He developed the worst documented case of space adaptation syndrome, for which an informal unit of space sickness was named ...
3
votes
1answer
137 views

How would 2 spacecraft be launched to be in sync in opposite directions?

How would 1 spacecraft be launched to have a prograde orbit and the another be launched retrograde to have a mirrored orbital path around the sun or otherwise? Would the 2 spacecraft launch together ...
2
votes
2answers
247 views

Could an Igloo work on Mars?

Could ice make a good habitat like an igloo for colonists or as cold storage for fuel? Could the cavern be sealed and then carbon dioxide melted to create pressure inside the cavern to grow plants or ...
4
votes
1answer
311 views

How many people could the ISS support?

How many people can fit on the ISS? At what person would life support be overwhelmed?
1
vote
1answer
157 views

Fuel vs food on the trip to Mars?

How much food for each person is need and fuel per various engine to go to Mars on the current 9-month trip there then 3 months on Mars and the 9 months back? Can time be saved on the trip to and from ...
1
vote
1answer
112 views

Maximum size for a Ion thruster solar array

In other questions I have asked about using a solar sail to double as a reflective mirror to provide light to an ion engine. What would be the maximum size or surface area of a parabolic sail where ...
5
votes
2answers
303 views

How is atmospheric temperature measured from a satellite?

How does an Earth observing satellite measure the temperature of the atmosphere? Can they measure temperature at multiple altitudes, or measure the temperature of clouds?
3
votes
1answer
198 views

What is the order of magnitude forces due to Earth's magnetic field, sunlight, drag, oblateness and tidal forces compare?

What in order of magnitude does pressures vary in LEO due to diamagnetic repulsion of Earth's magnetic field, sunlight, drag, oblateness and tidal forces compare on an ideal satellite? Is there any ...
4
votes
0answers
237 views

How to measure the temperature inside a combustion chamber

This question is inspired by How do you determine what the temperature will be in the combustion chamber of a rocket engine? . I wonder how you would mesaure the temperature on the inner surface of ...
1
vote
1answer
60 views

What is VBB recentering (InSight lander's Very Broad Band seismic pendulums)?

From the Planetary Society Blogpost InSight Update, sols 25-42: Seismometer sensors working! Tricky setup and cable management on Mars This is an animated GIF: It's fairly subtle, you may not notice ...
2
votes
0answers
153 views

How much does Six Sigma relate to space exploration?

Six Sigma allows industrial quality control at 99.99966% that is if you have some repeated processes you improve until you have a guarantee that only 0,00034% of all processes fail. A six sigma ...
6
votes
2answers
146 views

When were the presence of specific elements on asteroids first identified?

Is there an approximation on when scientists first found out about certain elements on asteroids? What about gold in particular?
1
vote
2answers
135 views

How could a sextant be used to help in a docking procedure, hypothetically?

If a spacecraft's standard radar and optical metrology were lost, could a sextant be used to determine range and relative position of another spacecraft in order to execute a docking maneuver? Let's ...
7
votes
1answer
460 views

How precise are spacecraft trajectory measurements?

Interplanetary mission trajectories are frequently likened in popular media to hitting a small target with a dart from vast distances, but in reality, spacecraft don't need absurdly high precision, ...
4
votes
1answer
214 views

Why do the LAGEOS' satellites have four germanium corner cube reflectors out of over 400?

When I was writing this answer about the LAGEOS satellites, I noticed that only four of the over four hundred corner reflectors are made of optical germanium rather than fused silica. Fused silica (...
10
votes
2answers
742 views

Why do most Measurements in Space use km?

I understand the use of metric, the real question is: with how vast space truly is, why do we not use other prefixes like we do for computer memory? 1kilometer = 1,000 meters (...
6
votes
3answers
743 views

Could daily variations of weight on Earth really be 0.003%?

I've been reading about accelerometers. On earth, in a lecture demonstration, in a table-top experiment, they will generate a signal equal to the sum of the acceleration you'd like to measure plus the ...
7
votes
0answers
303 views

Have LAGEOS' germanium corner cube reflectors ever been used?

When I was writing this answer about the LAGEOS satellites, I notices that four of the over four hundred corner reflectors are made of optical germanium rather than fused silica. Fused silica (FS) ...
7
votes
0answers
2k views

For the mathematical relationship between J2 (km^5/s^2) and dimensionless J2 - which one is derived from the other?

The term $J_2$ seen in discussions of nodal precession of orbits (e.g. sun-synchronous) appears to come in two flavors. For example, in the Wikipedia article Geopotential model it has a value of $1....
5
votes
1answer
128 views

Could a Kuiper Belt object fly by probe measure star distances by parallax better than Gaia?

Could a New Horizons class probe aimed to fly by a Kuiper Belt object 100 AU from the Sun use its camera, built to image the Kuiper Belt object, to also measure distances to stars (and distant Solar ...
7
votes
2answers
712 views

What forms of water ice have been observed and verified in the solar system?

The cool plot in this answer (from here) got me thinking about the more than sixteen distinct forms of ice, and how many of them have been actually seen to occur naturally in the solar system. There ...
4
votes
2answers
303 views

How will OSIRIS-REx scan and characterise the near-earth asteroid Bennu?

The 34 day launch window for the OSIRIS-REx probe will open in about five weeks (early September 2016), and it's approach to the near earth asteroid 101955 Bennu (provisional designation 1999 RQ36) is ...
3
votes
0answers
204 views

What is the electromagnetic spectrum profile of rocket flame/exhaust?

...from common observation, I can easily conclude there is a lot of infrared (from burning, superheated fuel), ending somewhere near yellow of visible spectrum; there should be next to none of UV and ...
4
votes
1answer
84 views

Earliest gravitational map of a planet/moon?

When was the first gravitational map of a planet or moon made by measurements from space? I'm guessing it was a map of Earth, since that's the closest planet to us,[citation needed] but for all I've ...