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Questions tagged [radar]

Radio detection and ranging devices. Operate by detecting and processing return echoes from objects and surfaces of signals at radio frequencies. Can be used to ascertain spatial coordinates and velocities, surface characteristics, object orientation, aid in object identification. In space applications used for tracking, radar imaging, rendezvous, collision avoidance, and other purposes.

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What are the pros and cons of Doppler radar versus Doppler lidar?

Some spacecraft designed for autonomous landing / hazard avoidance (such as Surveyor) use three-beam Doppler radar for range-rate measurements, and some (such as Morpheus) have utilized a three-beam ...
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What caused so many objects in Earth orbit to “go NEA”? (no elements availabe)

T. S. Kelso tweeted the following, is this a case of lost and found? How can so many substantial objects become lost like this? The list of 23 objects "formerly known as Prince NEA" all seem pretty ...
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What are currently maximum available radar capabilities i.e. performance/distance for Earth surroundings and deep space?

Afaik I know there is a radar for observing space debris in Germany though I don't know whether it can scan the whole Earth surroundings or just a segment. With respect to asteroids, we discover them ...
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Farthest distance to a solar system object that's been determined by spacecraft transponder?

Bouncing radar off of Venus' surface has yielded a rich body of data about the planet. Based on Venus' aphelion and Earth's perihelion, we know then that the answer is at least 38 million kilometers ...
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Farthest distance to a solar system object that's been measured by radar?

Bouncing radar off of Venus' surface has yielded a rich body of data about the planet. Based on Venus' aphelion and Earth's perihelion, we know then that the answer is at least 38 million kilometers ...
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How will the RADARSAT Constellation Mission (RCM) satellites achieve their final orbital spacing?

The informative page shows that the RCM satellites are intended to orbit as follows: Sun-synchronous circular orbit (dawn-dusk mission), nominal altitude = 592.7 km, inclination = 97.74º, period ...
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How does Deep Space Network's DSS-14 transmit radar and receive it at (almost) the same time? (monostatic radar)

@Hobbes' concise yet thorough answer to the question What are monostatic radar observations, and how will Deep Space Network's DSS-13 be used to observe asteroid 1999 WK4's flyby of Earth? tells us ...
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What are monostatic radar observations, and how will Deep Space Network's DSS-13 be used to observe asteroid 1999 WK4's flyby of Earth?

NASA JPL page https://echo.jpl.nasa.gov/asteroids/1999KW4/1999KW4_planning.2019.html says of the radar observations during the close approach of asteroid 1994 KW4 (in part): Update on 2019 May 22: ...
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Separating fact from fiction, how to get from this radar image to this GIF?

The NBC News article Mile-wide asteroid and its tiny moon to zoom past Earth this weekend; Dubbed 1999 KW4, the "binary" space rock will skim past our planet harmlessly at a distance of 3 million ...
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Why does 2018-099 (SpaceX, December 2018) still have a dozen unidentified payloads?

According to today's Raw SATCAT Data from Celestrak, the launch designated 2018-099 (SpaceX, December 2018) still has twelve unidentified payload objects! ...
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How could a hydrazine and N2O4 cloud (or it's reactants) show up in weather radar?

Question: How could a hydrazine and N2O4 cloud (or it's reactants) show up in weather radar? Tweet: This is what an ‘anomaly’ looks like on weather radar. Tweet (with GIF): Dragon's static ...
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How (the heck) do they know some lakes on Titan are 100 meters deep?

JPL News item NASA's Cassini Reveals Surprises with Titan's Lakes NASA's Solar System Dynamics New item Cassini Reveals Surprises with Titan's Lakes point out that some lakes on Titan have been ...
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What is Space Policy Directive 3 and how does it relate to the Space Fence?

In response to a question about the recent ASAT test by India producing a new debris field in LEO, Patrick Murphy, Director of Strategy, Planning, & Integration for NASA Space Technology Mission ...
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What steel ball was thrown out of the ISS to help test how well ground stations can track orbital debris?

The question What kinds of things have been tossed out of the ISS? has a broken YouTube link. This is why it's good to include at least the name of the video in your post (which I didn't back in 2016)....
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Why can Cryosat's dual antenna “better discern steep slopes” of Antarctic ice than Sentinel-3?

The BBC's Climate change: Satellite fix safeguards Antarctic data explains that earlier problems of missing data near the coasts have been addressed, and though scientists are hopeful, there is ...
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What are the trade-offs to use a radio relay orbiter also as a radar science instrument?

Any landed mission could benefit from having an orbiting radio relay satellite to help enhance its data rate to Earth. For polar landers on for example the Moon or Mercury it would be a necessity. For ...
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Space Travel Advanced Recon [closed]

Could a network of probes be sent ahead of a mother ship to form a grid to lay a path for travel inside the solar system? After what certain speed anything larger then a stationary pebble could be ...
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How did NORAD notice Kosmos 954 was making erratic manoeuvres?

In Wiki for Kosmos 954 there is: In mid-December North American Aerospace Defense Command, which had assigned the satellite the Satellite Catalog Number 10361, noticed Kosmos 954 making erratic ...
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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 ...
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Detailed radar imaging of Tiangong-1; how do they do that?

@JamesPoulose's answer shows an advanced radar image of Tiangong-1, 270 km from the Earth's surface. The images was sourced from Space.com's How Was China's Tiangong-1 Space Station Crash Tracked So ...
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How many solar system bodies have had coherent radio transponders?

A transponder amplifies, (often) frequency-shifts, and rebroadcasts a received signal. Old-style telephone and TV distribution satellites in GEO used simple transponders to rebroadcast the uplinked ...
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Why are Titan's lakes “black” in radar images rather than transparent?

Searching after reading Titan rover questions (1, 2, 3) lead me to Space.com's Titan Has More Oil Than Earth which says in part: "Titan is just covered in carbon-bearing material — it's a giant ...
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Number of spectral bands on radar satellites

I have learned that optical earth observing satellites have spectral bands often in groups (e.g. panchromatic, multi-spectral, SWIR, etc.). What about radar satellites such as RADARSAT-1? It seems it ...
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Is there really a frozen lake near the equator on Mars?

Figure 1. Views of plate-like terrain on Mars, and pack-ice on Earth. From the paper linked below. a, Part of an HRSC image of Mars from orbit 32, with a resolution of 13.7 m per pixel, centred at ...
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How does the SpaceBEEs' experimental passive radar reflector work?

My Question: What is the nature of the "experimental passive radar reflector developed by the U.S. Navy’s Space and Naval Warfare Systems Command"? How does it work, and why does it work for only a ...
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How can ICEYE-X1 capture 2D high resolution SAR images in “tens of seconds”?

The PRNewsWire release First ICEYE-X1 Radar Image from Space Published says: The full image transmitted to the ground from ICEYE-X1 exceeded 1.2GB of raw data and spans an area of roughly 80 x 40 ...
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How does a three-way doppler shift measurement work?

I was looking at this document who's name I can only speculate. Its title and designation includes: 810-005, Rev. E, 201, Rev. B, DSN Telecommunications Link, Design Handbook, 201, Rev. B, ...
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Why are there so many waveguide feeds (?) near the focus of Cassini's dish antenna?

Cassini has quite a complex Radio Science Subsystem. Accorting to that article (and confirmed in Wikipedia): Cassini is the only deep space mission to transmit to Earth at three radio wavelengths (...
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Is 2012 TC4 part of the Near-Earth Object Human Space Flight Accessible Targets Study?

This nifty answer describes and provides links to the data of the recovery of near earth object 2012 TC4, and the answer also shows the first actual image of the body for this pass. At apparent ...
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Why do radar maps of the surface of Venus have missing slices?

The visually opaque clouds of Venus still pass radio and some microwaves, and so powerful radar signals can be used to map the surface. This is probably done using some kind of delay-Doppler technique,...
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How many antennas does Kurz use in toto, and what are each of their functions?

I learned about the Kurz docking system in this answer, then found out what they looked like in this and in this answer. Those images show several tiny dish antenna structures sticking out from ...
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Parallel orbits around the Earth - effectively?

edit: For the purposes of this exercise, one could consider using three or four identical spacecraft, and using the "best two out of three (or four)" for interferometry at any given moment. In 1994, ...
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Is delay-doppler radar imaging of NEO asteroids possible only if it spins fast enough?

Emily Lakdawalla's blog on the Planetary Society's page explains some of the basic principles in the delay-doppler radar imaging of asteroids, and other astronomical bodies by extension. Radar from a ...
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Why was the 100m Green Bank dish needed together with DSN's 70m Goldstone dish to detect Chandrayaan-1 in lunar orbit?

The Phys.org article New NASA radar technique finds lost lunar spacecraft describes the use of radar to relocate two spacecraft that were in orbit around the moon but who's orbit had not been actively ...
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How can ISRO's RISAT satellites search for the lost IAF AN-32?

The Indian Air Force has lost contact with AN-32 (transport aircraft) on a mission. ISRO is going to deploy RISAT to search for the missing plane as the search area has widened. How will such ...
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Fielding Photonic radar in outer space

A new type of radar. How will photonic radar behave in outer space? What will be challenges faced by such radar ? How will it differ from pesa on Soyuz-MS ? Will such radar be termed as space weapon ...
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What is the current record for the farthest detection of a “dead” spacecraft?

In order to better defend my position that trying to track Juno from Earth once it can no longer transmit would be Quixotic, I'd like to ask what the current record is for the farthest detection from ...
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Is this the longest that a spacecraft “went to sleep” and then woke up on schedule?

For various reasons, spacecraft are sometimes "put to sleep" for periods of time on long voyages. Many systems are shut down, and radio communications suspended. Tracking of spacecraft at very large ...
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Is radar & passive radar significantly different in space?

How effective are different types of radar in space over large distances? Is radar significantly different outside of the atmosphere of Earth? Would you need to generate a more powerful signal to ...
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Interplanetary ranging accuracy?

What are the two or three most accurate technologies used to determine interplanetary spacecraft distance (e.g. Doppler / radiometric tracking...), and what accuracy is currently obtained from such ...
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How does radar calibration using LEO orbited calibration spheres work?

On December 28, 2013 two Russian SKRL-756 calibration sphere satellites will be launched during the maiden flight of the Soyuz-2.1v, a brand new lightweight derivative of the Soyuz launch vehicle, ...
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What type of onboard radar did the Surveyor landers use?

The Surveyor landers are the second generation of US lunar spacecraft following the Ranger series. They paved the way for the later soft landings of Apollo. What type of onboard radars were used in ...