Cosmos-1 Spacecraft Design

The first solar-sail spacecraft, called Cosmos-1, has been developed, built and tested by The Planetary Society, a private, non-profit organization whose goal is to encourage the exploration of our solar system. The Planetary Society contracted a Russian space organization, the Babakin Space Center, to build, launch and operate the spacecraft. The cost of the project is about $4-million and is funded by Cosmos Studios, a new science-based media company.

Cosmos-1 spacecraft

The spacecraft itself weighs 88 lb (40 kg) and can sit on a tabletop. After a first-phase test launch, the spacecraft will be launched into Earth orbit -- 522 mi (840 km) perigee and 528 mi (850 km) apogee. The spacecraft systems include:

Photo courtesy The Planetary Society One solar-sail blade

• Solar sail
  • made of aluminized Mylar
  • thickness of 0.0002 inches (5 microns)
  • area of 6,415 square feet (600 square meters)
  • arranged in eight triangular blades:
    • each about 49 ft (15 m) long
    • consist of inflatable plastic tubes that support the sail (a foam may be used inside the tubes to hold them rigid once inflated)
    • can be pivoted (like a helicopter blade) by electric motors to change its angle relative to the sun
• Solar-sail deployment - A pressurized gas-filling system inflates the plastic tubes.

Solar-sail deployment

Folding Solar Sails The original design of the sail blade had it folded into rolls. However, some tests indicated that folding the sail blades into accordion-like structures might be more reliable, which would still be deployed by inflating the tubes.

• Power - A small array of solar cells supplies all of the electrical power.
• Navigation - It is essential for the spacecraft to know where it is and where the sun is at all times.
  1. A sensor detects the position of the sun.
  2. A global positioning system (GPS) receiver detects the spacecraft's position. (From the ground, the spacecraft orbit will be determined from Doppler tracking data with the aid of on-board accelerometers, which we'll discuss later.)
  3. The information from the sun sensor and the GPS receiver are continuously relayed to the spacecraft's on-board computer.
  4. The on-board computer operate the motors that turn the sail blades to maintain the proper orientation of the sail blades with respect to the sun.
  5. The on-board computer can accept corrections or override commands from the ground.
• Communications - Redundant radio systems are used to communicate with flight controllers on the ground.
  • one UHF band, 400 megahertz
  • one S-band, 2210 MHz
• On-board computer
  • Two 386EX series microprocessors
    • old, but reliable in the harsh environment of outer space
    • can be run in low-power modes, similar to laptop computers
    • programmed to operate the on-board systems, relay information to the ground and receive commands from the ground
  • A software program assigns tasks to each microprocessor based on workload and performance (speed, delay).
  • Each processor has its own small amount of read-only memory (ROM) -- enough to boot the computer and load the operating system into random-access memory (RAM).
  • Three re-writable ROMs contain the operating systems and programs. The copies of ROM are checked before use for errors caused by radiation in outer space.
  • Three RAMs are present to receive the operating system. Again, the integrity of each RAM is checked for errors before loading.
  • The ROM architecture allows programmers on the ground to update and re-boot the spacecraft's software at any time. It also allows the spacecraft to function in the case of severe radiation damage.
  • Data are stored in two separate databases connected by serial and parallel systems.
• Instruments
  • Two on-board imaging cameras (Russian and American) to document the mission
  • On-board accelerometers to measure the acceleration of the spacecraft due to sunlight pressure (non-gravitational acceleration)

In the next section, we'll discuss the details of the Cosmos-1 mission.