67

I believe the mechanism is this pyro-cutter, photographed by Emily Lakdawalla here. Specifically, I think they were manufactured by PacSci EMC, since they brag about it in this Facebook post. If you'd like to buy one, they sell them here. There's a description of the cutters used by MSL (Curiosity) here with some nice pictures of it in action on page 12.


59

If you watch the coverage on YouTube, they explain hydrazine rockets burn clear. This is supported by the dust flying everywhere when it gets closer to the ground.​


59

RTG technology has been applied on Earth, many times, although not for transportation - they don't produce much power for their weight so any RTG powered vehicle would be very slow. Some pacemakers used to have plutonium batteries, and RTGs were used in remote sites to power sensors, lighthouses and the like in remote areas. It isn't used much anymore on ...


41

I think you may be confused about the nature of the problem the skycrane is trying to solve (however I also may be confused!). The rover, being a rover, does not need to stay at the landing site. If the landing site has a lot of dust blown off it, well, they can go somewhere else where the dust has not been blown off the surface. As the other answer says ...


37

It would be rather surprising if the exhaust from these engines was visible. The engines use hydrazine ($\mathrm{N_2 H_4}$) monopropellant, and the reactions involved (catalysed by iridium) are $$ \begin{aligned} \mathrm{N_2 H_4} &\rightarrow \mathrm{N_2 + 2H_2} &&\text{exothermic}\\ \mathrm{3N_2 H_4} &\rightarrow \mathrm{4NH_3 + N_2} &...


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 ...


32

According to the official NASA press release, pyrotechnic guillotines were used: The footage ends with Perseverance’s aluminum wheels making contact with the surface at 1.61 mph (2.6 kilometers per hour), and then pyrotechnically fired blades sever the cables connecting it to the still-hovering descent stage. The descent stage then climbs and accelerates ...


27

RTGs are expensive to produce, can be politically inconvenient to use, and in the form of a plutonium-bearing device, represent a potential nuclear proliferation hazard (though all RTGs might be used to construct a "dirty bomb"). To compound the issue, their power output simply isn't very big... Perseverance's generator cost about 75 million USD ...


27

I'm quite sure it can move. The first roughly 9 days after landing it needs to get its bearings, look around, plan out a path, and most importantly, be reconfigured to operate on the ground. For comparison, Curiosity landed on August 6th, and didn't start moving until August 15. Perseverance landed on Feb 18, it has only been 11 days, I wouldn't worry too ...


25

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

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

Hobbes' answer explains why live broadcast is currently not feasible from the Mars side. I'd like to complement it with why this is currently not feasible from the Earth side. Mars power budgets are not generous, so by the time spacecraft transmissions get back to Earth they are incredibly faint. The only equipment used to reliably receive these signals is ...


20

I asked one of the copter's engineers, Matt Keennon, what the hole in that one leg's foot was for. He replied that it's only for stowage. ... because of the odd way the copter is held in place under the rover, with all sorts of mechanical constraints from the rover, that one leg could not be held down by a simple lever pressing on the leg strut, so instead ...


20

I think it's important to understand the timeline here. The footage we've all been amazed by was acquired by a collection of slightly-hardened small, light, high-quality commercial off-the-shelf (COTS) cameras, helped by a fast, very-low-power processor (I think a Qualcomm SnapDragon: this processor is much faster than Perseverance's main processors!) and ...


19

No. Perseverance will not enter Martian orbit before descent. It would be a direct descent. For reference, here's a picture of Perseverance's landing procedure. A spacecraft entering into orbit before descent requires a fair bit of fuel. The thrusters on the Backshell are only there for mid-course corrections and for stability during descent. It does not ...


19

A color image would need three times the data and transmission time. The time needed for two black and white images is too short for a single color image. When everything works well after landing and when all status checks are done there is plenty of time for some color images. Persevance was traveling from Earth to Mars for about six months, a delay of six ...


18

14 years is the design lifetime for the MMRTGs. The thermocouples do degrade over time while exposed to the high temperatures of the hot side and the temperature changes of the cold side. The output power of the RTGs drops over time by degradation, design lifetime ends when there is too few power left. But many RTGs did work better than conservative lifetime ...


17

2kW is not that much on Earth You've mentioned radiation and convection in your answer (you forgot conduction). Turns out the properties of Earth's atmosphere make conduction and convection way better than radiation for moving heat around. For an illustration, consider the size of a portable, 2kW, oil-filled radiator: this one lists the size as ...


17

Perseverance's umbilical data cable and bridles were cut by exploding bolts. This is the same method that Curiosity used. Exploding bolts are very commonly used in space missions. This is for several reasons. First, the fasteners must be strong enough to hold the pieces together throughout all of the vibrations and motion a spacecraft must endure as it ...


17

All four cables should be parallel to each other no matter where the skycrane camera is located. – azot Maybe we can recreate this. Let's do some arts and crafts! The support cables appear to radiate from the center of the crane, while the data cable is offset. The data cable and one support cable are attached to the rover at the same point. If the camera ...


16

I really hope it won't be able to detect Hope, that's orbiting Mars, not landing on it. InSight was actually made to detect these impacts, as it can help one to understand more about Mars. Fundamentally a heat shield impacting is just a particularly dense meteor. I think it is likely it will detect Perseverance. The two are fairly close. Specifically it ...


15

Faster? No. The speeds of all Mars rovers so far have been limited by the navigation software or the available electrical power, not by physical capability. Spirit and Opportunity were both physically capable of driving more than 2000 meters per day, but rarely actually traveled more than 60. Curiosity is capable of moving 2200 meters per day, but can ...


15

NASA plans multiple translational correction maneuvers for their spacecraft headed toward another planet. The intent of these correction maneuvers is to bring the spacecraft back on track so as to reach the intended target. NASA has become very proud of the fact that the last few correction maneuvers have been waived off; the corrections in the early ...


15

If you look very closely at the video you'll find that the top-right engine is glowing red inside because, while hydrazine burns clear, the engine chamber is still 1000 °C hot. This has been explained also by Scott Manley on Youtube where you can see the footage:


14

This is an addendum to @Uwe's answer. RTG lifetime is a topic of much discussion in the planetary science community, and in particular the MMRTG being currently the only available RTG. MMRTGs decay much faster than GPHS-RTGs (see my comment to Uwe's answer), with an output power half-life of a bit over 16 years, the result of both Pu decay and unicouple ...


14

because it would prevent the rockets from contaminating the landing site. No they weren't There was some possible advantage from that, to be sure. But missions to Mars undergo serious levels of decontamination to ensure contamination from Earth doesn't happen, so the risk was marginal at best. If you meant contamination from hydrazine, that's not a ...


13

The answers claiming danger/toxicity are chasing something that's irrelevant. The real issue is that they don't produce all that much power*. If you want a car that can only drive a few hundred meters a day, an RTG will work just fine. Solar panels aren't all that good on Mars. Not only is the sunlight weaker, and reduced even further by sun angle** and ...


12

The JPL Mars Helicopter Scout transmitter can send data at up to 250 kb/s, an order of magnitude short for HD video. Communications with the rover are through a radio link called Zig-Bee, a standard 900 MHz chipset that will be mounted in both the rover and helicopter.[10] The communication system is designed to relay data at 250 kb/s over distances of ...


12

Here's a brief answer since some people are trying to close the question and prevent answers: As @ikrase points out answers to the Physics SE question Why is the Peltier / Seebeck Effect's efficiency so low in practical devices? are helpful here. Briefly, there are two main parts to an RTG's conversion efficiency Thermodynamics limit The fraction of the ...


12

Lens covers and attachment/deployment infrastructure for the camera mast. The mast hosts 2 round Navcams on the sides, two rectangular Mastcam-Z cameras, and one large Supercam with half-circle top "archway-like" border. Compare: The image taken using the 3D model from NASA site, mirrored by me so that the correspondence is obvious. During ...


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