HackingTheUniverse

In what may be the most serious test of solar sail technology to date, Japan’s Aerospace Exploration Agency (JAXA) will launch IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) on May 18, 2010. IKAROS will use a rotational maneuver to unfurl and deploy the sail, which is 20 meters across, 0.0075 mm thick and coated with thin film solar cells to collect energy from the sun to power an ion propulsion drive. The sail is also expected to produce acceleration from the push of solar radiation.

Maiden voyage for first true space sail – [newscientist.com]

Made of polyimide resin, IKAROS’s sail measures 20 metres from corner to corner, but is just 0.0075 millimetres thick. To survive the launch and the trip into space, the gossamer sail will be folded accordion-style, then wrapped around the centre of the spacecraft.

To unfurl its sail, IKAROS will spin some 25 times per minute. The spacecraft’s rotation will be used to extend four “arms” of folded material, and the rest of the sail will follow (see diagram). On 18 May, an H-IIA rocket will carry IKAROS into space along with its main payload, Japan’s new Venus orbiter.

IKAROS Project – [jaxa.jp]

A Solar Sail gathers sunlight as propulsion by means of a large membrane while a Solar “Power” Sail gets electricity from thin film solar cells on the membrane in addition to acceleration by solar radiation. What’s more, if the ion-propulsion engines with high specific impulse are driven by such solar cells, it can become a “hybrid” engine that is combined with photon acceleration to realize fuel-effective and flexible missions.

JAXA is studying two missions to evaluate the performance of the solar power sails. The project name for the first mission is IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun). This craft will be launched in 2010 together with the Venus Climate Orbiter, “AKATSUKI”(PLANET-C), using an H-IIA launch vehicle. This will be the world’s first solar powered sail craft employing both photon propulsion and thin film solar power generation during its interplanetary cruise.

IKAROS Mission Overview – [jaxa.jp]

Vast, thin, and strong solar sail
A solar sail can move forward without consuming propellant as long as it can generate enough energy from sunlight. This idea was born some 100 years ago, but it had lots of technical hurdles such as the appropriate material and deployment method for the sail. Recently, we have finally seen some prospect of using this technology practically. The sail of the IKAROS is a huge square some 20 meters in a diagonal line, as thin as 0.0075 mm, and made of polyimide resin. On the membrane of the sail, thin film solar cells are attached as well as an attitude control device and scientific observation sensors.

This thin and light solar sail membrane will be deployed using the centrifugal force of spinning the main body of the IKAROS before its tension is set. The deployment is in two stages. The first stage is carried out quasi-statically by the onboard deployment mechanism on the side of the main body. The second stage is the dynamic deployment. As this deployment method does not require a strut such as a boom, it can contribute to making it lighter and thus can be applied for a larger membrane.

SEE ALSO:
Solar Sails