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Questions tagged [measurement]

Questions about the methodology and results of collecting data.

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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 ...
5
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1answer
143 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, ...
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1answer
93 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 (...
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2answers
466 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 (...
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3answers
350 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
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0answers
247 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) ...
6
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1answer
114 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 ...
5
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2answers
254 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
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1answer
180 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 ...
2
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0answers
128 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 ...
5
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1answer
71 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 ...
9
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1answer
916 views

What are these structures on the Lunar Ranging Retro Reflector (LRRR) arrays for?

In this question I used images of the retro-reflector arrays that were left on the moon by Apollo 11, 14, and 15. The Lunar Ranging Retro Reflectors (LRRRs) are there for Lunar Laser Ranging. The ...
5
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1answer
369 views

How are precision trajectory measurements made of trans-Neptunian spacecraft?

This question asks if Voyager suddenly encountered unexpected gravity from an unseen object, how would it be detected, and there are several answers. For the farthest probes - those now farther from ...
27
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2answers
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How can a sounding rocket accurately take the temperature of the atmosphere while flying through it at high speed?

A sounding rocket is a rocket that ascends into the high atmosphere in order to take all sorts of measurements so we can learn more about the upper atmosphere. They don't go into orbit, so they can be ...
7
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2answers
191 views

How can an orbiting spacecraft's motions yield the orbitee's deep structure?

I've always been a fan of satellites like GRACE and GRAIL, where two satellites orbit a body, precisely measuring the changing distance between them in order to sense gravitational anomalies caused by ...
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0answers
71 views

What instruments are necessary to measure/determine the process that generates Saturn's internal heat?

I am writing a paper about a possible mission to Saturn but I am a business and Spanish student and am quite ignorant when it comes to the engineering and science behind probes and their instruments; ...
5
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3answers
923 views

How are IMU positions decided for rockets and spacecraft?

I imagine that engineers have to decide where an inertial measurement unit (or just an accelerometer, gyro, etc.) is placed in a rocket or spacecraft. I'd like to know how are these positions decided? ...
9
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1answer
161 views

Measuring the pressure and temperature of Pluto's atmosphere using stellar occultations

Is this primarily done analyzing the Voigt profiles absorption bands on background of stellar spectra or on re-emission bands of atmospheric compounds? Assuming Pluto's atmosphere behaves like an ...
3
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1answer
281 views

How is real position of probes orbiting other planets measured?

I imagine that measuring real positions and orbital elements of satellites orbiting other planets after they perform braking maneuver to get to their final orbit must be rather difficult. Especially ...
6
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3answers
433 views

How does an atmospheric probe measure temperature during descent?

I heard that the Galileo spacecraft sent Galileo Probe into Jupiter, and it reported temperatures reaching 153 degrees Celsius. The question is, when you send a probe crashing into a planet that has ...
11
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4answers
4k views

Accelerometer in space

If my understanding of the General Theory of Relativity is correct, according to the Equivalence Principle, forces due to gravity and acceleration are indistinguishable. If that's the case, then an ...
7
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2answers
1k views

Rocket Propulsion Elements: Total Impulse Problem

I figured this is probably an okay place to post this question. I managed to get (a), (c) and (d) (quite simply), but I have absolutely no idea why I can't work out (b). I used $$ I_{sp}=\frac{I_t}{...
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4answers
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Has an interplanetary date/time system been established yet?

Obviously, with no humans living permanently off-planet yet, Earth-style dates and times are the most common system is use, and reasonably so. And it helps that Mars's day is almost the same length ...
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1answer
130 views

Sensitivity of Space Telescopes and Instruments

I have been doing a bit of light reading on space telescopes and have been amazed by the reported sensitivity of some of the instruments. In particular, the Laser Interferometer Space Antenna (LISA) ...
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1answer
159 views

Could we send lots of cheap measurement devices in random directions into the space?

As a layman, I like to read about space exploration and come up with ideas. One of them that I couldn't refute was a sort of firework that would scatter thousands or even millions of self-locating ...
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1answer
238 views

How are base temperature units found on other planets?

On Earth, our temperature scales are calibrated based on some universal (on Earth) values. For example, 212°F and 100°C are defined as the temperature water boils at sea level. How are these ...
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3answers
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How do we measure height on celestial bodies with no significant atmospheric pressure, no seas, or no surface to speak of?

On the Earth, measuring elevation above sea level is relatively easy. Throughout the years of evolving these measurements to not rely on different reference points of the Mean Sea Level (MSL) of ...
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6answers
3k views

How do you weigh things in a micro-gravity environment?

Obviously a balance scale is not going to add value to the task in free-fall. Weight in space is more accurately described as mass, but the need to define it still exists. Regardless of if you're ...