question: Why are there always metal foils wrapped around a satellite? What's the difference between the gold and silver colored foils? And why are they always so wrinkly?
comment: It's called "MLI" - multi-layer-insulation. This exist on the satellite to protect electronics from the crazy temperature fluctuations in space. This serves to regulate heat transfer, more than it really does "insulate". It also serves as a bit of protection from dust particles and things that would build up on the surface of internal componentry if allowed to run wild. The different colors are just different materials on the outer layer. Different materials in different combinations have different heat transfer properties so you can assume there was a different desired behavior in the silver location than the gold one.
passages: Different materials resist corrosion in space differently. For example, aluminium is slowly eroded by atomic oxygen, while gold and platinum are highly corrosion-resistant. Gold-coated foils and thin layers of gold on exposed surfaces are therefore used to protect the spacecraft from the harsh environment. Thin layers of silicon dioxide deposited on the surfaces can also protect metals from the effects of atomic oxygen; e.g., the Starshine 3 satellite aluminium front mirrors were protected that way. However, the protective layers are subject to erosion by micrometeorites.
   Section::::Materials.
  
  Corrosion in space has the highest impact on spacecraft with moving parts. Early satellites tended to develop problems with seizing bearings. Now the bearings are coated with a thin layer of gold.
   Section::::Manufacturing.
  
  First developed by NASAs Marshall Space Flight Center in 1964 for the US space program,
  
  the material consists of a thin sheet of plastic (often PET film) that is coated with a metallic reflecting agent, making it metallized polyethylene terephthalate (MPET), usually gold or silver in colour, which reflects up to 97% of radiated heat.
   The ANDE MAA sphere is made from a proprietary alloy of AL 6061 that is castable, while the FCAL sphere is made from brass. The ANDE FCAL sphere has the distinction of being the only micro satellite to have its structure composed primarily of brass. The differences in materials and hence density and mass of the spheres will cause them to separate from each other along track over time. This separation will be measured and compared to predicted models of where the satellite should be based on computed models of the space environment.
  
  Section::::Uses.
   BULLET::::- LAGEOS 1
  
  BULLET::::- LAGEOS 2, see STS-52
  
  BULLET::::- LARES
  
  BULLET::::- Larets
  
  BULLET::::- LCS-1
  
  BULLET::::- PAGEOS
  
  BULLET::::- PAMS-STU, see STS-77
  
  BULLET::::- Reflector
  
  BULLET::::- PasComSat
  
  BULLET::::- Rigid Sphere 1 (AVL-802H)
  
  BULLET::::- Rigid Sphere 2
  
  BULLET::::- Sfera
  
  BULLET::::- Starshine
  
  BULLET::::- Starshine 1, see STS-96
  
  BULLET::::- Starshine 2, see STS-108
  
  BULLET::::- Starlette
  
  BULLET::::- Stella
  
  BULLET::::- WESTPAC 1
  
  Section::::Mostly passive satellites.
  
  BULLET::::- Starshine 3, see Athena I
  
  BULLET::::- Echo project
  
  BULLET::::- Echo 1 (Echo 1A)
  
  BULLET::::- Echo 2
  
  BULLET::::- Elon Musk's Tesla Roadster
  
  Section::::See also.
  
  BULLET::::- List of laser ranging satellites
  
  BULLET::::- Lunar Laser Ranging experiment
  
  BULLET::::- Balloon satellites
  
  BULLET::::- Satellite geodesy
   LCS-1 is a hollow sphere in diameter with a wall thickness of . The sphere was constructed from two hemispheres, made by spinning sheet metal over a mold. These hemispheres were fastened to an internal, circumferential hoop by 440 countersunk screws, then milled and polished. The initial finish had a surface roughness less than 10 micrometres and was expected to last for five years. Since its launch, I-band measurements have shown periodic deviations that likely correspond to one or more new surface irregularities.
   Section::::Satellites.:Type II.
  
  These later satellites were made in the shape of a rectangular prism, measuring 25.3 x 29.8 x 34.9 cm (9.95 x 11.75 x 13.75 in). They were almost fully covered in solar cells, and the antennas were made of flexible steel tape. They were much more compact, and thus worked better as secondary payloads. They were designed to avoid removing covers and panels during satellite pre-launch checks. Their antennas were perforated, to diminish antenna shadow over the solar panels.
  
  Section::::Satellites.:Non-dedicated.
   So-called space blankets, developed in 1964 for the space program, are lightweight and reflect infrared radiation. These items are often included in first aid kits.
  
  Section::::Health and medicine.:3D foods printing.
  
  BeeHex developed 3D food printing systems for pizza and later desserts and icings following an SBIR grant that began as a NASA-funded project.
  
  Section::::Transportation.
  
  Section::::Transportation.:Aircraft anti-icing systems.
   BULLET::::- IRS-P4 27 May 1999
  
  BULLET::::- IRS-P3 21 March 1996
  
  BULLET::::- IRS-P2 15 October 1994
  
  BULLET::::- IRS P1 (also IE)("Crashed, due to launch failure of Polar Satellite Launch Vehicle, 20 September 1993)"
  
  BULLET::::- IRS-1D 29 September 1997
  
  BULLET::::- IRS-1C 28 December 1995
  
  BULLET::::- IRS-1B 29 August 1991
  
  BULLET::::- IRS-1A 17 March 1988
  
  Section::::Misc.:JAXA (former NASDA).
  
  BULLET::::- MOS-1 (Momo-1)
  
  BULLET::::- MOS-1b (Momo-1b)
  
  BULLET::::- JERS-1 (Fuyo-1)
  
  BULLET::::- ADEOS (Midori)
  
  BULLET::::- ADEOS II (Midori II)
  
  BULLET::::- GOSAT (Ibuki)
  
  BULLET::::- ALOS (Daichi) PALSAR, AVNIR-2 and PRISM
  
  BULLET::::- ALOS-2 (Daichi-2) PALSAR-2
  
  Section::::Misc.:Lembaga Penerbangan dan Antariksa Nasional (LAPAN INDONESIA).
  
  BULLET::::- Lapan-TUBsat
   For spacecraft that spend the majority of their time in orbit, some variety of the Whipple shield has been almost universal for decades. Later research showed that ceramic fibre woven shields offer better protection to hypervelocity (~7 km/s) particles than aluminium shields of equal weight. Another modern design uses multi-layer flexible fabric, as in NASA's design for its never-flown TransHab expandable space habitation module,
  
  and the Bigelow Expandable Activity Module, which was launched in April 2016 and attached to the ISS for two years of orbital testing.
  
  Section::::History and shielding technologies.:NORAD, Gabbard and Kessler.
   At design level, GPS receivers should be located in a place where satellites vision line is as direct as possible in order not to be out of range with these ones during the flight. In a metallic structure CanSat, the receivers should be always located where the structure does not affect this vision line.
  
  Section::::Operation of the CanSat.:Secondary elements.:Camera.
   BULLET::::- Structures: The structures team was responsible for designing, analyzing, and manufacturing the body of the satellite as well as the logistics of the internal components.
  
  BULLET::::- Survivability: The Survivability team was responsible for analyzing and controlling the satellite's thermal, electrical and vibrational environment on the ground, during launch, and in orbit. Analyzed effects include ESD, atomic oxygen effects, venting and outgassing.
   BULLET::::- Mercury (25 cm in diameter) is placed at Stockholm City Museum, 2,900 m from the Globe. The small metallic sphere was built by the artist Peter Varhelyi.
   BULLET::::- Specifications
  
  The main structure is high, wide and deep. The total mass of the spacecraft is .
  
  Section::::Spacecraft.:Power.
  
  Electrical power was generated by a photovoltaic system composed of 30 panels of silicon solar cells producing 295 W at one AU. The solar panels were mounted on the satellite's exterior surfaces and the electrical power was stored in one lithium-ion battery providing up to 24 amp-hours of 28-volt power.
  
  Section::::Spacecraft.:Propulsion system.
   List of passive satellites
  
  List of passive satellites is a listing of inert or mostly inert satellites, mainly of the Earth. This includes typically various reflector type satellites used for geodesy and atmospheric measurements
  
  Section::::Passive satellites.
  
  BULLET::::- Ajisai, Experimental Geodetic Payload
  
  BULLET::::- Beacon-C, Beacon Explorer C, BE-C, Explorer 27
  
  BULLET::::- BLITS
  
  BULLET::::- Calsphere satellites
  
  BULLET::::- Calsphere
  
  BULLET::::- Calsphere 1A
  
  BULLET::::- Calsphere 2
  
  BULLET::::- Calsphere 3
  
  BULLET::::- Calsphere 4
  
  BULLET::::- Calsphere 4A
  
  BULLET::::- Calsphere 5
  
  BULLET::::- Dragsphere 1
  
  BULLET::::- Dragsphere 2
  
  BULLET::::- Etalon
  
  BULLET::::- Kosmos 1989
  
  BULLET::::- Kosmos 2024
  
  BULLET::::- Explorer 9
  
  BULLET::::- GFZ-1
  
  BULLET::::- Humanity Star
  
  BULLET::::- LAGEOS
   BULLET::::- nose-cone enclosure for protection of payload during launch, provided by Boeing.
   BULLET::::- Strengthened EP (Exposed Pallet) maximum payload to 1.9 t from previous 1.6 t to carry Li-ion batteries.
  
  SFINKS (Solar Cell Film Array Sheet for Next Generation on Kounotori Six) will test thin film solar cells in space.
  
  Section::::Spacecraft.:Kounotori Integrated Tether Experiment.
   There have been hundreds of reconnaissance satellites launched by dozens of nations since the first years of space exploration. Satellites for imaging intelligence were usually placed in high-inclination low Earth orbits, sometimes in Sun-synchronous orbits. Since the film-return missions were usually short, they could indulge in orbits with low perigees, in the range of 100–200 km, but the more recent CCD-based satellites have been launched into higher orbits, 250–300 km perigee, allowing each to remain in orbit for several years. While the exact resolution and other details of modern spy satellites are classified, some idea of the trade-offs available can be made using simple physics. The formula for the highest possible resolution of an optical system with a circular aperture is given by the Rayleigh criterion:
   Electronics need to be rigorously tested and modified to be "space hardened" or resistant to the outer space environment (vacuum, microgravity, thermal extremes, and radiation exposure). Miniaturized satellites allow for the opportunity to test new hardware with reduced expense in testing. Furthermore, since the overall cost risk in the mission is much lower, more up-to-date but less space-proven technology can be incorporated into micro and nanosats than can be used in much larger, more expensive missions with less appetite for risk.
  
  Section::::Collision safety.
   Satellites charge themselves by the bombardment with charged particles of the solar wind. Charging can lead to an arc discharge which can impair the function of the satellite due to magnetic disturbances and material failure. To avoid these impairments, coatings of electrically weak or non-conductive plastic components of thin films of poly(1,1'-ferrocen-silane) were examined. These carry off the charge generated by the irradiation and thus could protect the satellite from overloads.
  
  Section::::Potential applications.:Polymers with high refractive index.
   Picosatellites are emerging as a new alternative for do-it-yourself kitbuilders. Picosatellites are currently commercially available across the full range of . Launch opportunities are now available for $12,000 to $18,000 for sub-1 kg picosat payloads that are approximately the size of a soda can.
  
  Section::::Classification groups.:Femtosatellites.
  
  The term "femtosatellite" or "femtosat" is usually applied to artificial satellites with a wet mass below . Like picosatellites, some designs require a larger "mother" satellite for communication with ground controllers.
   The expected operative life was at least five years, but the mission was interrupted in 2013 after a collision with space debris.
  
  Section::::Structure.
  
  The satellite body consists of two outer hemispheres (radius ) made of a low-refraction-index glass and an inner ball lens (radius ) made of a high-refraction-index glass; the two outer hemispheres and the inner ball are glued together, and one of the outer hemispheres is externally coated with a reflective coating, covered with a protective varnish. The total mass is .
   NEOSSat is a suitcase-sized microsatellite measuring , including telescope baffle, and weighing . It is powered by gallium arsenide (GaAs) solar cells placed on all six sides of its frame; the entire spacecraft uses around 80 watts of power, with the bus core systems consuming an average of 45 watts. The spacecraft uses miniature reaction wheels for stabilization and attitude control, and magnetic torque rods to dump excess momentum by pushing against Earth's magnetic field, so no on-board fuel is required for operation.
   BULLET::::- The CARTOSAT-2B carries a panchromatic (PAN) camera capable of taking black-and-white pictures in the visible region of electromagnetic spectrum which has a resolution of 80 centimetres. The highly agile CARTOSAT-2B can be steered up to 45 deg along as well as across the direction of its movement to facilitate imaging of any area more frequently and offers multiple spot scene imagery.
   Multi-layer insulation used on spacecraft is usually made of polyimide coated with thin layers of aluminum. The gold-like material often seen on the outside of spacecraft is actually single aluminized polyimide, with the single layer of aluminum facing in. The yellowish-brown polyimide gives the surface its gold-like color.
  
  Section::::Applications.:Mechanical parts.
  