# Tag Info

74

+1 Good question! It's not actually gold, but I think this is a common misconception, so allow me to elaborate for a bit. The stuff that you see satellites covered in is not normal foil, its just the outer layer of so-called "Multi Layer Insulation" or MLI. That means that there are several layers of foil, each separated by a spacer, so that transfer ...

61

I've done a lot of work on this subject with researchers and engineers at JPL, NASA Langley, and NASA Ames. There are some interesting things that come out of high-fidelity CFM (Computational Fluid Mechanics) modeling of entries or re-entries, and also from flight experience. This FAA tutorial segment is a good general reference for the principles involved. ...

41

To reduce the force of the impact on landing the heat shield was designed to separate and be held on by a skirt that acted as an airbag. From the NASA list of Mercury illustrations: Figure 46: Impact attenuation When the heat shield was released the impact skirt would fill with air, but when the heat shield hit the water the air being forced out the holes ...

30

F9 can enter engine first because it isn't returning from orbital speeds. While fast, it's a fraction of the speeds something returning from orbit (or further) comes in at. So the engines are out as an entry surface, you need more protection. One way to achieve this is Dragon-style: put a heat shield on the bottom, and engines in the sidewalls. Great for ...

23

There's a Spinoffs from the Space Shuttle Program page hosted on the NASA Marshall Space Flight Center portal. According to it: Jewelry Design — Jewelers no longer have to worry about inhaling dangerous asbestos fibers from the blocks they use as soldering bases. Space Shuttle heat shield tiles offer jewelers a safer soldering base with temperature ...

21

The columbium jet nozzles themselves can take the heat, but "penetrations" of the spacecraft heat shield are a definite potential failure point, including penetrations for the Reaction Control System (RCS) jets. The design to preclude hot gas intrusion while preventing damage to the surrounding Thermal Protection System can be quite complex. The forward ...

15

Musk indicated that Dragon 2 could be reused "with minimal rework and fueling" about 10 times between overhauls. This is the target number but these are early days. The previous ablative shield was dumped in favor of a more advanced design. The goal then, for heat shield, engines and other major components would be at Least 10 flights, in theory. Regards ...

14

The dimpled sphere may produce lower drag (though as Uwe points out I’m not sure if that is true in hypersonic flight). However, this does not mean that it will be better at surviving reentry. Higher drag implies a faster reentry and shorter exposure to extreme temperatures. Conducting heat to the core takes time, so even if the outer layer is ablating, the ...

13

If you're only referring to surviving the phase of peak heating, then Mars is easier than Earth. The entry velocity is more like 6 to 7 km/s at Mars vs. 11 to 12 km/s at Earth, due to their respective gravity and typical approach velocities. Everything else about landing on Mars is harder, due to the low density of the atmosphere. The density can be a ...

12

The outside of the Command Module is covered by a heat shield. According to this report (page 5), the forward portion of the heat shield (i.e. the part covering the cone-shaped part of the CM) is a 0.5" thick layer of phenolic resin. It is covered by several outer layers: a pore seal, a moisture barrier (which is white) and the outer layer is a silvered ...

11

Astronaut spacesuits use gold (thin layer) Gold coating protects eyes from harmful sunlight Gold is also used by NASA in the construction of spacesuits. Because of its excellent ability to reflect infrared light while letting in visible light, astronauts’ visors have a thin layer of gold on them to protect their eyes from unfiltered sunlight. Satellites ...

10

It's not the surface area by itself. There are two main factors. The first is the ballistic coefficient, $\beta$, which is the mass divided by the product of the surface area and the coefficient of drag: $\beta={m\over C_D A}$. The second is the lift over drag (L/D) of the vehicle, which for these blunt vehicles is usually obtained with an offset center ...

10

NASA is working on an inflatable heat shield. Not quite a blimp, but a heat shield that's inflatable to a size much larger than the probe it's attached to. The extra area helps decelerate the spacecraft. So inflatable structures can be made to withstand the heat of reentry. Because Mars' atmospheric density is only 0.6% of Earth's, a blimp's lift will ...

10

There is a fixed amount of energy which has to be dissipated. You can, to some extent, choose how fast this is done -- more air resistance (either by getting into thicker air or having a bigger surface) dissipates it faster, with higher g forces. Less air resistance dissipates it slower, but you do have to make sure to get rid of it all before you hit the ...

9

The outside of the Soyuz is covered in multilayer vacuum-screen thermal insulation. Its Russian acronym is ЭВТИ, long for экранно-вакуумная теплоизоляция or Shield Vacuum Thermal Insulation. It apparently is in many layers of metalized film and fiberglass cloth. Its purpose is to protect the modules during ascent and orbit. It doen't seem to be designed to ...

9

There are several misconceptions in your question/proposal: The Orion and the Dragon as well as other reentry capsules do not fly with the cone tip forward. They fly with the blunt "bottom" side forward. (fixed in the revised question) Plasma is created by the very passage of the vehicle through the air at high hypersonic velocities. At lower velocities, ...

9

Surprisingly the answer is yes there was studies done on that subject. A simple google search could yield this result: BUOYANT PLANETARY ENTRY https://apps.dtic.mil/dtic/tr/fulltext/u2/642361.pdf In this study, it was assured that the large buoyant volune is deployed prior to atmospheric entry. The effect of buoyancy on the entry dynamics was ...

8

The CST-100 heat shield is replaced each flight because it is discarded as part of the landing process. The capsule has airbags, between the heat shield and bottom of the capsule. As the parachutes slow it down for landing, it discards the heat shield, inflates the airbags, and lands on the ground. Thus they can never reuse a heat shield, they throw it ...

8

Take the super-optimistic 500 kJ/kg energy density of flywheel energy storage. In reality 10% of that would be a great result. $E_k = {1 \over 2} mv^2$ so 0.5*1kg*(8km/s)^2 = 32MJ per kilogram of orbital mass. If the craft was nothing but the flywheel, you'd still receive 64 times more energy than you can most optimistically contain. Your flywheel would ...

7

The heat shield (TPS) is not meant to protect the spacecraft from dust impacts. The statement is not quite accurate and (from a recent search) seems to have been removed from site. As an engineer on the Parker Solar Probe team, I have been involved in the Preliminary and Critical Design Reviews for the mission which include presentations on Dust Protection ...

7

The main problem is thermal control: you need a heatshield on your spacecraft to survive through the close pass. It is a solved problem though, meaning that NASA is planning to send a mission in 2018 to explore the close environment of the sun as low as 8 solar radii: http://solarprobe.jhuapl.edu/mission/index.php https://en.wikipedia.org/wiki/...

7

Apparently the technology wasn't even patented. "Lockheed refused to file a patent, saying there was no market for it," Forsberg said. "It was put on the shelf and his research stopped for two years. Then interest from the shuttle program revived it." As described in Heppenheimer's Development of the Space Shuttle, 1972-1981 Chapter 6, Thermal ...

7

Saiboogu's answer about protecting the engines is great. Just want to add that Falcon 9's supersonic reentry burn is a delicate issue already (*). Starting the engines and keep them burning would become even more an issue if reentry speed was orbital. Another downside for engines first reentry from orbit is efficiency: aerodynamic drag would be lower, i.e. ...

7

The heat protection material on the Vostok spacecraft is a resin-drenched asbestos fabric. https://habr.com/ru/post/230445/ Heat protection was mainly asbestos fabric, impregnated with bakelite resin. The maximum thickness of thermal protection in the frontal part was 110 mm, and the minimum - 40 mm in the rear. http://epizodsspace.airbase.ru/...

6

The book "Soyuz: A Universal Spacecraft" by Rex Hall, David Shayler (2003) has the text on page 41: Propulsion Module, ... Descent module, ... Orbital Module... materials used in the fabrication of these modules .... an aluminium alloy was finally chosen. The thermal insulation covering the modules consists of two layers - the upper layer consisting of an ...

6

SpaceX made improvements in several areas: Production cost. PICA-X is 10 times less expensive than the original. Resilience. As you noted, PICA is structurally weak. Reportedly, PICA-X is better in this regard: it's more resisant to cracking, so it can be manufactured in large tiles (notice the tile size in this image): Heat resistance. SpaceX also ...

6

It certainly is possible to have enough of the spacecraft shielded to have it all land; that's what the Space Shuttle was designed for. However, if you want to be able to land with a heat shield, you must first get it into space to begin with. The heat shielding for the Apollo Command Module has a density of 32 pounds per cubic foot. In total, the heat ...

6

Special high-altitude balloons are used to do research or other measurements (weather balloons) in the higher atmosphere, by carrying sensors. Those are especially made to expand much more that your usual party balloon. They usually burst between 30 and 50 km in altitude. At the ground there appears to be almost no gas inside them, because it expands and ...

6

Apparently, black was chosen despite its thermal properties. This 2005 paper was written at the end of the assessment phase where technical feasibility of the mission has been demonstrated. It shows several options were studied, including a white shield. Materials with a/e (absorption/emission constant, ed.) close to 1 could also be used. Typically ...

5

Making it cost effective One how the large expenses in the shuttle program was to inspect and overhaul the heat shield after each flight. A major condition for re-use to be feasible is that the equipment is expensive, and still useful after flight. Even if they are specialized and single-purpose, thermal tiles are not exactly expensive to manufacture, and ...

Only top voted, non community-wiki answers of a minimum length are eligible