30

There are limits. For one, there's atmospheric effects that scatter light in visible wavelength spectrum. You might be able to penetrate clouds and haze easier in the lower end of the spectrum and towards the infrared wavelengths, and those might still be usable for facial recognition though. Another limit is aperture of optical equipment used to take ...


27

would the photography be good enough for facial recognition? Not yet. It's not even close. Facial recognition requires 50 to 100 pixels between the eyes, or on the order of 1 millimeter resolution. To see that kind of detail from a distance of 250 kilometers using blue-green light (500 nm) would require a lens or mirror that is 125 meters in diameter. Note: ...


15

Yes, there are methods to track and estimate what a payload is up to. Most methods rely on visual or radar to identify the orbit and its parameters. There are many amateurs that do this. Once an object has been located and its orbit calculated, you can then monitor changes in the orbit. Generally these things are public. Imaging the object is generally the ...


14

What is an atomic force microscope (AFM) in the first place? An AFM uses a very sharp tip to "probe" around the surface of an object. As it gets closer to or further away from the surface, tiny changes in force are observed from van der Waals or similar "atomic" forces. A computer can stitch together a grid of individual passes over the ...


11

Mars Reconnaissance Orbiter has a camera called HiRISE (High Resolution Imaging Science Experiment), launched in 2005-08-12, which is the highest resolution camera in orbit of Mars at an altitude that varies from 200 to 400 kilometers (about 125 to 250 miles) above the martian surface by Carrier rocket Atlas V-401. The High Resolution Imaging Science ...


9

Spacecraft thermal control analysis employs modelling programs that can analyze combinations of conduction, convection, and radiation heat transfer in complex structures. An example is Sinda by MCS Software. I have no association with MSC Software but I did work on thermal analysis problems for the Apollo Service Model in the early 1960s using primitive ...


7

Below is pair of a high resolution images from the OSIRIS camera of where Philae's first touched down, overlaid upon one another. One was pre-touchdown and the other very shortly after touchdown (and bounce): Image source: http://www.esa.int/spaceinimages/Images/2014/11/Philae_spotted_by_Rosetta_after_first_landing The Rosetta operators knew to look at ...


7

If you're not asking specifically about the near IR range photogrammetry but more in a general sense, then one obvious method of detection of covert drug plantations is simply human activity around them and lack of any public records about activities in the area. So even satellite imagery in the visible spectrum could reveal access roads, air strips, piers ...


7

A lot of information could be gleaned simply from determining the orbit and characterizing the type of electromagnetic radiation it emits. Getting a decent picture of the satellite would also help considerably. For example, a GEO satellite is almost assuredly going to be used for communication or very wide field-of-view remote sensing (e.g. weather, missile ...


7

I suggest that the Valles Marineris–Chryse Planitia complex is the largest former Martian river system. Valles Marineris has many features that appear to have been created by water flow and the outflow channels leading from it to the former oceana,b,c,d,e,f in Chryse Planitia are clearly visible and bear many features in common with river systems on Earth. ...


7

A strong candidate for largest river on Mars that I have found is the Kasei Valles region of Mars. According to the Wikipedia entry, this area is home to a geological feature similar to our famous Grand Canyon. . . except for one major difference. This guy is 300 miles wide at maximum instead of 18 miles. Source: Areong via Wikipedia, CC BY-SA 4.0 General ...


6

China's Chang'e 1 (CE-1) and Chang'e 2 (CE-2) lunar orbiters were both equipped with multi-channel microwave radiometers, measuring thermal emissions from the lunar surface and near-surface down to 30 meters of depth. Similarly, Chinese Yutu rover from the Chang'e 3 mission is equipped with a GPR that also operates in microwave frequencies. NASA, to my ...


6

The surface features on Mars are still present because of their resistance to erosion, the magnitude of erosive forces and geological inactivity on Mars: no active volcanoes, no plate tectonics and negligible seismic activity to cause land forms to move or to disrupt the surface of Mars. Erosion is, the action of surface processes (such as water flow or ...


5

I agree with @Heopps answer: No. But there are a few more details. We can measure the D/H ratio in the solar system because much of the hydrogen is in molecules that are gases: water, methane, ammonia, H2, etc. Gaseous species have spectra consisting of very narrow emission and absorption lines (also here) at very accurately known frequencies/wavelengths. ...


5

A good sanity check is to compare your results with what the New Horizons team is reporting. It is also useful to consider whether there are any other factors at play that could throw the numbers off. As a point of reference, this undated article on the New Horizons website discusses the Ultima Thule flyby and states: The pixel sizes of the best expected ...


5

I've looked through your numbers, and they do seem to be correct. The range values included are likely intended to be in km, but seem to be inaccurate. The range values are not official at this point in time, and do not have access to the spacecraft ephemeris data yet. I suspect when that data comes down the range values will be estimated better. Bottom ...


5

There is an effort to map Earth's gravity, GRACE, which has been ongoing since 2002. It's produced this: Neat, right? Several GRAIL-like missions are planned / in progress / completed. Mars Express. LISA, a probe designed to measure gravitational fields in space, with hopes of finding black holes. Magellan mapped Venus' gravitational anomalies. MESSENGER ...


5

Some rarely discussed option also include naturally occuring self-organising and self-replicating helical plasma structures, at least in theory: DOI:10.1088/1367-2630/9/8/263 This article studies the theoretical possibility that some plasma structures with properties usually used to describe living organism. Given the right environment, these structure ...


4

Stellar occultations of distant atmospheres produce light curves that are almost entirely due to refraction, not opacity (absorption), in those atmospheres. Ray paths of light rays encountering the atmosphere bend slightly toward the planet (or moon, in cases like Triton) due to refraction. During immersion (movement of the ray path deeper into the ...


4

Wikipeida has a decent article about hypothetical forms of life. Silicon shares many chemical properties with Carbon, making it a good candidate. However, carbon is much more versatile than other similar elements in terms of what they can bond to. Silicon has limitations and interacts with much fewer elements than Carbon. One characteristic of "life as we ...


4

The DDM term is mostly used in the GNSS Reflectometry (GNSS-R) scope, but is conceptually equivalent to the radar ambiguity function. In fact, a GNSS-R system can be understood as a bistatic radar, that is to say, a configuration in which the transmitter (the GPS/Galileo/GLONASS/Beidou satellite) and the receiver (which receives the reflected signal) are ...


3

Update: As of 2019-01-17, the page has been updated with range figures more in line with what you've calculated. According to the JHUAPL website (click on 'Learn more about these images ', for some reason a direct link didn't work), range should be in km: The following ancillary information is provided for each image posted: the date of the observation ...


3

Talus is also referred to as scree, which is, a collection of broken rock fragments at the base of crags, mountain cliffs, volcanoes or valley shoulders that has accumulated through periodic rockfall from adjacent cliff faces. Landforms associated with these materials are often called talus deposits. Such deposits are formed as a result of, physical and ...


2

Are we searching for life “as we don't know it”? Of course not. How could we? We are (barely) searching for life by looking for electromagnetic signals from some distant civilization, but since we use electromagnetic signals for communication, that is life "as we know it". That parenthetical "barely": The organization that is doing this is SETI. NASA along ...


2

Use radar. (or even just light detection, with a suitable flashbulb) Just use a slightly more energetic pulse generator, allowing a spherical impulse to still be strong enough to get a detectable echo from an AU of distance away. I advise the "Tsar Bomba" brand of pulse generator for this.


2

First, everything in the Oort Cloud is really, really far apart. You could spend years looking and never see anything because of the reasons you gave. As for your ideas… The shadows idea is a great one, and might be your best bet, depending on the size of the objects and the equipment you have with you. You'd probably have to look in a lot of ...


2

Since they managed to acquire some more data points they can now estimate at least the axis towards the second landing spot, and the smart Flight Dynamics team should be able to calculate the landing area. OTOH, ~200m (my calculation; 28cm/px, 730px distance) traveled from the landing site at 15:34 until 15:43 (= 9 minutes) is about 0.37m/s in horizontal ...


2

The DDM measures both the delay that a reflected signal takes to get back to you and the doppler (frequency) shift of that signal. In your left most figure, what you are looking at is a picture of how a GPS signal reflected off of the ocean. The bright red spot is the point of "maximum specular reflection", that is, the point directly underneath the ...


2

I have seen pictures from CubeSats, but you are right they are hard to come by. In addition to the camera failures you allude to, there is the issue that many CubeSats (especially those with cameras) are student projects with poor followup. One other complication is that the failure to take a (nice) picture can often be due to bad attitude control, so it ...


2

The pointing stability requirement of a platform is dictated by the payload that will use the platform. What will the payload do? What pointing accuracy and stability does it require to function well and do what it is supposed to do? Just as one particular example, if it has a camera and will photograph the Earth, then you need to look into the ...


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