Scan can't be done right now

[sanoj688]

Hey guys,

Loving the update so far, only thing that I find odd is that whenever I use a thermometer or barometer (haven't unlocked the other ones yet) it says 'Temperate/Barometer scan can't be done right now' 9 out of 10 times.

Seems to me that I should be able to do a scan and log the data at any point in time but apparently this is not the case.

Is this a bug or a feature?

[sievers808]

I don't know why the thermometer wouldn't work, but I know the barometer doesn't do anything if you're in space. Barometers measure atmospheric pressure, so when you're in space or on the Mun or something similar with no atmosphere there's nothing to measure, it's a near-vacuum. Try using the barometer at different stages during your launch or re-entry, I haven't tested it myself yet but I'm sure that will yield some results.

[kerm]

Feature. You can't scan for barometric pressure or temperature in deep space. Temperature only works while close to a planet, and barometer only works in atmosphere.

[OrtwinS]

I could only do temperature measurements when landed on some celestial body, or while flying in an atmosphere.

Every time I tried in space it told me it couldn't.

[Catullus]

You can do temperature scans in low orbit around bodies.

[sanoj688]

Okay thanks guys. Call me a perfectionist, but in my opinion it should give the normal window but say something like 'Well there's no pressure here, what did you expect?' With 0 scientific value of course

[Kruleworld]

This is annoying. i'm sure NASA did temperature scans at varying distances from the sun to track it's fall off and so forth. also it'd be interesting to see a difference in temperature from direct sunlight and in shadow of planet/body.

[Yasmy]

I don't know why the thermometer wouldn't work, but I know the barometer doesn't do anything if you're in space. Barometers measure atmospheric pressure, so when you're in space or on the Mun or something similar with no atmosphere there's nothing to measure, it's a near-vacuum.

Thermometers don't work in space for similar reasons that barometers don't: there is (almost) nothing there to measure.

Thermometers work by exchanging heat with their environment, both through collision and through radiation. In an atmosphere, air molecules hit the thermometer and exchange heat with it.

There are particles in interplanetary space. Almost entirely the solar wind. The solar wind is predominately protons and electrons ejected from the Sun. At Earth-like distances from the Sun, the solar wind density is tiny: often in the range of a few to tens of particles per cubic centimeter. At that density, they can not come into thermal equilibrium with a thermometer. If you slapped a thermometer on a spacecraft, all you could measure is the temperature of the spacecraft due to solar radiation. That is valuable info, but not a measurement of the environment.

This is annoying. i'm sure NASA did temperature scans at varying distances from the sun to track it's fall off and so forth. also it'd be interesting to see a difference in temperature from direct sunlight and in shadow of planet/body.

Yes they have, but not with thermometers. Here's some data going out to about 70 AU for the solar wind proton temperature: ftp://space.mit.edu/pub/plasma/publications/jdr_radial_temp2/jdr_radial_temp2.withthumbs.pdf

TL:DR: until about 30 AU, the proton temperature falls off at about 1/T^0.5 to 1/T^0.7. After that, it starts to heat up again.

So this brings up the question of what temperature means. One thermodynamic definition of temperature is the average kinetic energy in a system. A glass of water at room temperature is surrounded by air molecules with the same average kinetic energy as the molecules in the glass and the molecules of water. Thermal radiation and particle collisions even out the average kinetic energy until all parts have the same temperature.

In space things work a bit differently. Solar wind particles don't interact the way gases interact for multiple reasons: they are low density charged particles in a magnetic field. In fact, the solar wind electrons and protons typically have different temperatures! The electron distribution and the proton distribution don't interact so much on a particle by particle basis, but instead as a group. As a result they don't readily come into thermal equilibrium with each other.

One way you measure plasma temperatures is by measuring the velocities of a large sample of solar wind particles and fitting the distribution of velocities to a Gaussian distribution to determine the bulk properties: density, average velocity, temperature, pressure. This is one of the ways Voyager and many other spacecraft measure temperature. You can also measure temperature by looking at plasma waves.

You can associate a temperature with the solar radiation spectrum, but really it's the intensity or energy flux that matters. That temperature won't change as you get farther from the sun. You can sample the relative flux vs distance from Kerbol with a solar panel though. I haven't checked, but I hope they follow a 1/r^2 relation. That is just measuring the fact that the solar panel is catching a smaller patch of sunlight farther it is from the sun.

The temperature difference between sunlight and planetary shadow isn't really a sensible question. The temperature of what? Solar radiation just passes through space more or less unimpeded. It doesn't have a big effect on the plasma temperatures. Space isn't so much hot or cold as it is empty. The temperature of a spacecraft or a Kerbal on EVA on the other hand is a sensible question.

So I think it's good that thermometers only function near bodies. Though I do agree that they could give a zero science value report, rather than an error message.

Edited March 8, 2014 by Yasmy

[Streetwind]

All four science instruments have areas where they don't work.

The thermometer doesn't work while "high in space above <celestial>". The barometer doesn't work outside of an atmosphere. The gravioli detector doesn't work inside of an atmosphere (except when landed). The seismic accelerometer doesn't work anywhere except when landed.

[celem]

Its also worth noting that the oft-forgotten 5th instrument, the atmospheric analysis nosecone (which like the barometer needs atmopshere) and the barometer itself dont actually work until you are properly sub-orbital. Just skimming through doesnt seem to count. These readings are easy to get when landing or taking off, hard to gather in a manner beginning and ending in stable orbit