# Tag Info

87

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 ...

58

They designed the morse code holes on purpose, and added holes to the wheels in order to let rocks and regolith out of the wheels. The cause of the tearing in the wheels is not attributed to the holes, but to the angular shape of the grousers, which snagged on deeply embedded rocks and caused punctures. The large, sharp, deeply embedded rocks were not found ...

49

No. Curiosity took 3 years to travel 10 km. There are no plans to visit InSight, Curiosity's mission is to survey Gale Crater and climb Mount Sharp. Curiosity can travel on the order of 100 m/day. At that rate it would take 20 years to get to InSight. The RTG can provide enough power for about 14 years. The wheels are rated for ~40 km depending on the ...

48

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 ...

40

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 ...

40

I am Jose Juan Lopez Moreno, co-I (co-investigator) of TGO-NOMAD and I feel obliged to respond to PearsonArtPhoto's answer. There is something real: TGO carries 2 independent instruments with a sensitivity high enough to detect methane with a low limit of 0.05 ppbv. Those independent instruments are led by different and independent teams. They are far from ...

37

There's a lot to unpack here, so let's look at the various discoveries of methane on Mars. The first discovery came from multiple groups in 2003-2004 using first Mars Express, followed by Earth based instruments. The measured amounts were small, and being from Earth, could be tricky to know for sure. Mars Global Surveyor data was studied, and it seemed to ...

35

Good answers about the deterioration of the wheels, but no explanation on the purpose of the morse code. The three letters of the code, JPL, stand for Jet Propulsion Laboratory (Pasadena, California), which is the lab which manages the rover mission for NASA. Moreover, the morse code track is univocally recognised by the visual-odometry systems of Curiosity. ...

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 ...

33

Curiosity does not have speakers. As the OP's linked article states: This was accomplished using Curiosity's Sample Analysis at Mars (SAM) instrument. It "sang" the song by vibrating at different frequencies. More information on how this was accomplished is available in this LA Times article: The Sample Analysis at Mars instrument, or SAM, isn't ...

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

Why not? Because we can't. We don't have full-time communication with Curiosity: Curiosity sends data to the Mars Reconnaisance Orbiter and Mars Odyssey. These are overhead twice a day at 12-hour intervals. MRO and MO are in sun-synchronous orbits, so the planet rotates underneath the orbiter and they cover the entire planet in 1 day. Both are in orbits ...

30

There is Carnot's theorem for the theoretical maximum efficiency of heat engines. It is valid not only for mechanical engines like steam engines or Stirling engines but also for solid state devices like the thermocouples used in RTGs. The Carnot efficiency depends on the upper and lower working temperature. $$\eta = 1 - \frac {T_c}{T_h}$$ Tc is the cold ...

29

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 ...

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 ...

24

Yes, this is a real Lincoln cent and it makes part of the camera calibration target for the Mars Hand Lens Imager (MAHLI) instrument. A geologist tradition is to place coins (or other object of a known size) besides photographed objects to show the scale of the photograph. This seems to be a homage to this tradition. For details see: Lincoln Cent on Mars ...

24

At first glance, the RTG does not pose a risk. It is powered by Pu-238, which is primarily an alpha emitter throughout its decay chain. Alpha particles can be stopped by a sheet of paper. An astronaut is perfectly safe in his suit, even if the RTG were disassembled and the Pu lying around unprotected. The RTG is built to survive a launch failure, i.e. it ...

24

Most conventional motion detectors wouldn't work well on Mars. PIR: Usually only works well with warm bodies such as humans and animals. Would probably never trigger on Mars Ultrasonic: Due to the extremely low pressure on Mars any acoustic sensing through the atmosphere would be greatly hindered. These sensors usually only pick up on very large, ...

24

It crashed and the aftermath was photographed. https://www.space.com/mars-perseverance-rover-photo-sky-crane-crash A moment of respect for the descent stage. Within two minutes of safely delivering me to the surface of Mars, I caught the smoke plume on one of my Hazcams from its intentional surface impact — an act that protected me and the scientific ...

22

This NASA doc explains fairly clearly why the skycrane system was used: Why not rockets, like the Viking missions? "With a payload this size, the rockets could kick up enough dust to compromise the rover and its instruments," explains Sell. "And the rockets could excavate craters Curiosity would have to avoid as it drives away. Add to that the risk of a ...

22

Almost all in C on the rover computer. On MSL, some of the C was generated automatically using UML state charts. I don't know the exact team sizes. On the order of 20 on MER and 40 on MSL for the flight software on the rover computer. You would also need to consider the software on the instruments. And the radio. And the motor controllers. Here's a ...

22

It is actually too likely to find water there. There are 3 categories of Planetary Protection missions for a mission to Mars, IVa, IVb, and IVc. Curiosity meets the IVa criteria, a mission not intended to seek life on Mars. A IVb mission looks for life, and a IVc enters a special region which is: A special region is a region classified by COSPAR where ...

22

Yes, they could theoretically communicate with each other over the DSN, however in practice this will not happen (as it has no current uses). The amount of functions that Curiosity can perform autonomously is very limited and predetermined. It usually involves some sort of deterministic operation such as moving a rover arm or performing a drill sample (...

21

AutoNav is simply given a set of waypoints, which the software then has to, on its own, plan and execute a route. You can imagine the waypoints as lawn darts on the 3D terrain map built from the previous sol's images. In fact, in the rover planning tool, the waypoints are displayed as actual lawn darts. The plan is executed about a meter at a time, heading ...

21

To add to Jezero's answer, as is covered in the link provided, the other problem is the structure of Curiosity's suspension. This front "rocker" and the middle section of the suspension (the "bogie") is angled downwards. This means that while the wheel can survive resting on a pointed rock, if it drives into an immobile rock (e.g. ...

20

The main reason for the MSL driving slower than physically possible is hazard avoidance (and also navigation/visual odometry): Source: Introduction to mobility for MSL Heverly, Matthew C. 10-Sep-2012 Hazard avoidance and navigation Drive rates (m/hour): Absolute top speed: 151.2 (On rigid terrain with zero slip) Blind drive: 139.5 (top speed for ...

20

When calibrating a camera, there are typically 3 things that are used: Some sort of a color pallet A line chart of some sort to identify the fine resolution A real object, to make sure there isn't something fundamentally wrong. NASA followed this same suit, choosing the penny to be the real object, claiming that it give homage to the practice of using ...

20

Yes and no. The no part first: Mars 2020 had sensors and effectors attached to the non-important parts of your diagram, many of which had various degrees of smarts. Star trackers are very sophisticated cameras. The have their own computers that control mode (e.g., lost in space versus locked) and that perform pattern matching on an self-contained star map. ...

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