# Tag Info

116

Deimos: Radius 6.2 km, Mass 1.47e15kg. Let's pick an initial circular orbit radius at a safe 8km. Orbital velocity calculator gives 3.502m/s orbital velocity. To deorbit, we'd need to drop periapsis to ~6km so the same calculator gives us 3.242m/s for apoapsis of 8km and periapsis of 6. (lithobraking by digging boots into the surface at 3m/s should be enough ...

77

Yes, here is a picture of the Curiosity lander spacecraft taken by the Mars Reconnaissance Orbiter. The picture was taken about one minute prior to the landing of Curiosity. Image from https://www.space.com/16946-mars-rover-landing-seen-from-space.html If landed craft are allowed, there are also pictures of Mars rovers from Mars orbiters, asteroid ...

59

The Arecibo raqdio telescope has a $300\ \mathrm m$ diameter mirror. Let's consider a radio wavelength of $3\ \mathrm{cm}$ ($10\ \mathrm{GHz}$) for convenience of arithmetic. That gives a diffraction limited beam width of $100\ \mathrm{µrad}$, so at 100 light years, the signal would be spread over an area $10^{14}\ \mathrm m$ across. The Arecibo signal was ...

57

Tardigrades can survive vacuum, low temperatures, and moderate radiation for quite a while. They're multicelled organisms. How tough is the toughest hypothetically viable single-celled extremophile? How sure are you that we've found all of them on Earth already? It's a matter of caution. Contamination of another planet (or moon) is likely to be irreversible,...

54

The Mars Odyssey orbiter was photographed by Mars Global Surveyor in 2005. https://commons.wikimedia.org/wiki/File:Mgs_odyssey.gif https://photojournal.jpl.nasa.gov/catalog/PIA07941 Figure 1: Why There are Two Images of Odyssey NASA's Mars Odyssey spacecraft appears twice in the same frame in this image from the Mars Orbiter Camera aboard NASA's Mars ...

50

I wrote the article you are referencing. @Hobbes has it exactly correct. It is a lightweight vehicle that can launch on even a small rocket, and takes advantage of gravity assists and favorable celestial mechanics to catch Triton at just the right time for encounter with the plumes illuminated. It will image the entirety of Triton in sunlight on approach, ...

43

ERT is Earth Received Time. I.e., when we find out about the event. source

34

@SteveLinton's answer is excellent and I'll just confirm below that its logic and numbers are correct. Then I'll show that you can do it optically as well, but with 10 meter telescopes instead of Arecibos you run into a challenge because each individual light photon carries most of the total received power per second. Radio From this answer: One standard ...

30

some examples: LRO images of the Apollo landing sites. This is Apollo 11: Cassini and Huygens: this is Huygens as seen by Cassini, 12 hours after Huygens was released. Rosetta and Philae. During descent: Philae's final landing location: Hayabusa 2 and its many landers. This is a photo of Minerva-II-2 taken by Hayabusa 2:

27

So back in the summer of 1935, some folks down in Australia were having problems with a beetle's larvae that were nomming on the sugar cane roots and harming crops. Since traditional methods of getting rid of the pest failed, they decided a good approach would be to introduce a few cane toads to go eat the beetles... a hundred or so of them in a couple of ...

26

First order analysis Given that we have practical ion thrusters, it's time to look at them. Deep Space 1 The DS1 probe massed 387kg, had 83kg of fuel, operated for 162 days, and generated 92mN. So, it generated about 0.2mm/s^2. The craft is not tanks-dry, either. It has approximately 6 months (180 days) of fuel per design. That's a roughly 20% fuel ...

25

The journey to the destination is about always completely pre-planned. All the gravity assists, close fly-bys, and so on, are planned before launch - and often long before the probe design is completed, as often the requirements of the trajectory influence design considerations: ability to hibernate, delta-V of the engines, tolerance to heat if the probe is ...

23

Sometimes you don't want to hibernate the craft, because it has scientific operations to perform during the interplanetary transfer phases. But even when you don't: Deep space hibernation is risky. There is always the risk that the wake-up procedure - whether triggered by the vessel or by the ground station - won't work and the vessel will not recover. It ...

22

The Voyagers have been so reliable due to careful design, plus lots of redundancy. Voyager employs three dual-redundant computer systems per spacecraft. The first, the CCS, is nearly identical to that flown on Viking, performing sequencing and spacecraft health functions along with new ones necessitated by the addition of the other computers. Telemetry ...

21

If you only count planets, then I believe it's MESSENGER at six. Though your question was explicitly: "Which probe that we have launched has received the most gravitational assists?" The winner there is Cassini, hands down. It is on Titan flyby number 93 125, so far. And it's flown by other moons of Saturn. Plus the four planetary flybys on the way to ...

21

Power and Mass From this paper (emphasis mine): The specific power of an 241Am-fuelled RTG cannot match that of a 238Pu system (except perhaps at small power output levels); however, the design work undertaken provides confidence in potential capability and performance of 241Am systems for future space missions. Medium-sized RTGs in the 10 W to 50 W range ...

20

The problem with using nuclear fission reactors as means of power to propel spacecraft is twofold: our own aversion to anything nuclear due to environmental hazards and the problem of reaction mass still persisting, regardless of your energy source longevity and power density per its own mass. Let's explain these points a bit more. The reaction mass problem ...

18

Considering that Voyager 1 is already 126 AU from the Sun 36 years since launch, there should be no reason that it would not be possible energetically using a normal launch, small maneuvers, and planetary flybys. Just a Jupiter flyby should be sufficient. Jupiter will also provide the necessary change in inclination. Designing a probe that is assured to ...

18

For a case with more extreme relative motion than most of the other answers, the Lunar Reconnaissance Orbiter (polar orbit) imaged the LADEE orbiter (close to equatorial orbit) in 2014: The LADEE appears rather distorted because the image was taken with a pushbroom camera, not the more familiar framing camera, so LADEE moves between lines relative to the ...

17

Any object in space has several sensor signatures: Reflected optical - light reflected from surfaces. If you illuminate Voyager, its glint will be detectable. Emitted optical - light emitted by bulbs aboard. For energy conservation reasons there are none. If there is an insanely sensitive optical sensor exactly on the line between a star and Voyager, ...

17

OK let's first understand units. The decibel (dB) is a base-10 log scale without units and dBm is a similar decibel scale for power referenced to 1 milliwatt. They also include a factor of 10, so for example 10 dB is a ratio of 10^1, 20 dB is a ratio of 10^2, etc, while 10 and 20 dBm would be 10 mW and 100 mW. But in the block quote, they use dBW instead of ...

16

This is referred to as 'kick stage' motor and is commonly used. One example being Star 37. A larger Star 48 is what sent New Horizons on the way to Pluto

15

DSN time is competitive, and not cheap. So, besides the costs that Tom mentioned in getting the camera there (and an appropriate relay satellite), you have to consider the costs of getting the data back to the earth. For the space station, it's only ~370km (230 miles) up ... relatively close, and they can use much smaller dishes than what's required to get ...

15

The only spacecraft that I'm aware of that were fully sterilized were the Viking 1 and Viking 2 landers. They went through dry heat microbial reduction. That page notes that some parts of the Beagle 2 lander were sterilized. The MSL (Curiosity) drill bits and other components were sterilized, though the drill bits were later exposed to a clean-room ...

15

Currently functional and proven technology is limited to basically no interstellar travel at all. To reach one of our stellar neighbors (like Proxima Centauri), one of the fastest space probes we have now, New Horizons, would take 54000 years. There are multiple proposed methods of sending spacecraft interstellar distances (in shorter time spans) such as: ...

15

It's a fast flyby in the $500M cost class (a Discovery mission). So not really comparable to Beresheet. A rare, low Δv trajectory (Fig. 1) enables an MMRTG-powered spacecraft fitting under the Discovery cost cap. The mission would have to be launched in 2026, for a Neptune encounter in 2038. New Horizons has effectively demonstrated the scientific ... 15 You can also find photos of some Mars rovers from various orbiters/satellites: Opportunity from Mars Reconnaissance Orbiter After a planet-wide dust storm in June 2018 blocked the Opportunity rover's solar panels, NASA scientists waited for images from the planet to clear. This image, captured Sept. 20 by the Mars Reconnaissance Orbiter, was among the ... 15 Very short answer They are different generations of the same family of interplanetary spacecrafts. Short answer Zond 2, as well as Zond 1 and -3; and Venera 2 and -3, were interplanetary spacecrafts (in Soviet/Russian classification this category falls under "automated interplanetary station") of 3MV family 3MV English Wikipedia page (in Russian "3МВ" 3МВ ... 14 You can calculate this using the diffraction limit: $$\sin\theta\approx{\lambda\over D}$$ Where$\lambda$is the wavelength being used for the radio communication,$D$is the diameter of the dish (either on the spacecraft or on the ground), and$\theta\$ is the beam width. You need to point the antenna accurately enough to keep the target in the beam. The ...

14

The closest to this design was the Ulysses probe, which ended up in a heliocentric orbit with a semi-major axis of 3.37 AU and an eccentricity of 0.603, and an orbital period of 6.2 years. (Orbital elements available here.) It was launched in 1990, and operated until about 2008. However, the point of this probe wasn't to take pictures from deep space, but ...

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