# Tag Info

153

Fun question! Provided the three Lunar Roving Vehicles (LRV) left on the surface of the Moon by the last three Apollo program missions were not, tongue-in-cheek, towed away for unpaid parking, reckless driving and littering fines, or clamped by the Lunar people (not to be confused with Lunatics), I don't see why not, provided you have brought along all the ...

102

Very good question! The answer boils down to statistics of failure. Some aspects involve the statistics of "random" failures—for some reason some critical component just bites the dust—and some involve event-driven failures, such as failures induced by landing shocks, long engine burns, atmospheric entry stresses, etc. When someone (a government, usually) ...

97

Probably, but you likely wouldn't drive it away. Not only will the batteries be completely discharged, but the rovers have gone through a large number of lunar days since then, creating a large thermal cycle. The number of thermal cycles is on the order of 500 for each one, and the cycles are brutal, going from -150C to as high as 120C each time. Even ...

82

Mars' temperature range is rather large, with temperatures down to -107 °C measured by the Viking landers. This is below rubber's glass transition temperature of -70 °C, below which rubber becomes brittle. So you can't use rubber. A rubber tire is heavy. The tread of a normal road tire is more than 1 cm thick, off-road tires are thicker and heavier. It also ...

67

Mars has two disadvantages compared to Earth: it's farther form the Sun, so you get less sunlight. Atmospheric density on Mars is 0.011 kg/m3 (at the surface, at a temperature of 0 °C). On Earth: 1.2 kg/m3, so Mars' atmosphere has 1% of the density of Earth's. Lift is proportional to air density, so a wing will have 1% of the lift on Mars. Gravity is 38%...

54

No, because Mars can't have eclipses. Strictly speaking, Mars has only transits. The difference is that Mars's moons are smaller than the Sun as viewed from Mars, thus they don't block out the entire sun. Eclipses are defined as only occurring if the entire sun is blocked, or at least the vast majority. Phobos blocks out only about 60% of the sun at most. ...

54

They reformatted the flash memory area and, after finding the defective memory bank, modified the software in the rover to avoid using that area. The hack in itself reduces the amount of available memory (you lose one bank), but as the rover was avoiding flash memory entirely, you have a net gain by being able to reenable it. https://www.jpl.nasa.gov/news/...

48

To first answer the question ad litteram, NASA has so far successfully landed four stationary labs on Mars (Mars landing dates in parentheses): Viking Lander 1 (July 20, 1976), Viking Lander 2 (September 3, 1976), Mars Pathfinder (July 4, 1997) and Phoenix Mars Lander (May 25, 2008). Here are their landing sites on a map of Mars generated with Mars ...

48

There are a lot of generic answers here about spacecraft. I will try to answer the question specifically for Spirit and Opportunity. 90 sols was deemed sufficient to conduct the primary mission of the rovers, so the systems were designed and tested to assure full capability through the entire 90 sols. The first thing expected to take a rover below full ...

47

Short answer: More wheels results in greater stability, allowing the rover to traverse more varied types of terrain. It also provides redundancy, in case one of the wheels breaks, the rover is not completely crippled. Long answer: The Mars rovers all use the same design, called the Rocker-Bogie. This is a special design which allows the rover to ...

45

It is not practical to use this approach from orbital (1.6km/s) or escape velocity (2.4km/s), for two major reasons. The first is the acceleration reason. The kinematic for bringing objects to a stop under constant acceleration is $$d = \frac{v^2}{2a}$$ from which we can quickly solve for the acceleration to be $$a = \frac{v^2}{2d}$$ Even with 10 meters of ...

43

NASA have deployed 4 rovers to Mars, and are working on the fifth. ESA is working on nr. 6. Sojourner: tiny, limited. Spirit and Opportunity (MER): much larger than Sojourner. No reuse possible. Spirit and Opportunity were identical. Curiosity: much larger than MER. No reuse possible - but it does use technologies proven on MER, like the suspension design. ...

39

Yes, it is a mosaic made of 55 images from the MAHLI camera on the arm. The arm was deliberately removed from the images where bits of it showed up. See this description, including a video of how it was done. The arm motions were very carefully planned to cover the rover and surface around it by changing the angle of the camera, but not the absolute ...

37

Probably no. First there are the technical issues that have already been nicely covered. There are also political issues, which are more driving than the technical ones. There are treaties, space law, and maritime law to serve as a precedence where space law doesn't exist. NASA's stance As far as NASA is concerned, those lunar rovers are not abandoned ...

34

Not a chance. From NASA, here's the locations of everything that's landed on Mars (Well, NASA missions) Curiosity is kind of close to Spirit, but keep this in mind. The equatorial circumference is about 13,000 miles. I'd guess the distance is over 1000 miles, far further than any rover has gone before, or is likely to ever go. There's just much more ...

34

The video shows only tests within the clean room on smooth clean test floors. The vibration test at first should simulate the conditions during launch. Drive tests on a simulated Martian rough and dirty surface on Earth (see JPL Mars Yard) are not done with the version built for the Mars surface. The flight-ready version is built in a clean room and only ...

33

The Lunar Roving Vehicle did have a (form of) compass. It was gyroscopic rather than magnetic, thus it needed calibration when first powered up using the sun angle as a reference. It's in the upper left of the console here: According to Wikipedia: Navigation was based on continuously recording direction and distance through use of a directional gyro and ...

32

Tracks are heavy, high-friction, and primarily useful in soft/muddy/slippery terrain where the weight distribution is essential to prevent sinking and slipping. They take much more energy to move than wheels, and while on Earth-bound robots that's not so much of a problem, on a lander this is to be or not to be of the mission. They weigh quite a bit. I can'...

32

The mission objectives are: The main scientific objective of CE-4 is to provide scientific data for lunar far side research, including: 1) general spatial environmental study of lunar far side；2) general research on the surface, shallow layer and deep layer of lunar far side；3) detection of low frequency radio on lunar far side using Low Frequency ...

31

That's many questions. Lunokhod 2 lasted for nearly 4 months and held the record for longest distance traversed by an off-Earth robot for over 41 years, until MER-B (Opportunity) beat that in mid 2014, so I wouldn't really say that lunar rovers don't last. It eventually scooped up some regolith dust with its open lid that was also its solar panel, and as it ...

30

Opportunity is roughly 10,000 km away from Spirit in a straight line. At its top speed of 0.05 m/s (0.18 km/h), it would take approximately 2300 days to reach Spirit -- not that Opportunity can maintain that speed. Between limited electrical power, needing to slow down to navigate, and being unable to drive at night, driving is much slower. Based on the ...

30

The navigation system used a combination of magnetic pickups in the wheels (to count how many turns each one has taken) and a directional gyro. This allowed both turn angles and distances travelled to be calculated on board. See this section of the manual, section 1.3.7 "Drive Control Electronics" (page 5 onwards.) Also page 18 of the above link shows the ...

28

Temperature shifts Earth's temperature swings from extreme to extreme is quite moderate. That is, coldest is generally around -40C and warmest is around 40-45C. The Moon has two weeks in blazing hot sunlight, much hotter (depending on your reflectance) but well over 100C, and two weeks of much much colder. Not quite absolute zero (-273C), but pretty cold ...

28

Because of the nature of radioactive decay, Curiosity is going to get a whole lot more than 2 years out of its power source. Curiosity will be getting enough power to keep active for a bare minimum of 14 years (see Specifications> Power Source), though the amount of power it has will steadily decrease over time (from 125 Watts initially to 100 Watts after 14 ...

28

Resilience: There is no way that an inflatable tyre of any kind can be used for remote missions, because they are incredibly unreliable. Think about car or bike tyres here on Earth, where we have a fairly small range of temperatures. They puncture easily, they burst, they lose pressure, the rubber degrades etc. When they have a puncture, fixing them is ...

25

If surviving lunar nights are difficult to ensure the survival of the electronics, say on lunar rovers, in the low temperatures, The temperature itself is not the primary reason. Lunar nights are difficult to survive because you have 14 days of darkness. If you want to design a solar-powered rover that can store enough energy to stay warm for 14 days, ...

24

An additional issue that needs to be addressed: such a drone would need to be completely autonomous, or at least have an autonomous controller (rover?) on the Mars surface. The drone in your example is piloted remotely, but the signal delay between Earth and Mars varies between 4 and 24 minutes (one way), depending on their relative orbital locations. At ...

23

Let's compare with 4G, for which I could find some numbers: Your cell phone is transmitting with speeds of up to 50MBps with a maximum of 1 Watt (can be as low as a few µW!), using a tiny antenna that is often obscured by water bags (human flesh and organs), rocks, buildings, trees, etc. Let's compare this with Mars Express, for example: its maximum ...

22

Mars Pathfinder, Spirit, and Opportunity all could come to rest on any of four sides of the tetrahedral-shaped lander. Just by chance, Mars Pathfinder and Spirit landed with the base petal down. However Opportunity landed on one of the side petals. The system was, of course, designed for that. The three side petals all have motors to drive them open to be ...

22

From Status of the JWST Sunshield and Spacecraft found in @Antzi 's answer: Most of the electronics is on the "hot side" but there needs to be some conventional electronics on the cold side (beside the cooled IR sensor chips). Small thermal environments on the cold side are equipped with heaters to provide mini-environments at normal operating temperature ...

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