The LightSail is a solar sailing spacecraft that has been launched by the planetary society. It is based on the “solar sail” concept, which uses a large reflective foil to harness the suns energy as a means of propulsion. The planetary society write about solar sails:
Solar sails use the sun’s energy as a method of propulsion—flight by light. Light is made of packets of energy called photons. While photons have no mass, a photon traveling as a packet of light has energy and momentum.
Solar sail spacecraft capture light momentum with large, lightweight mirrored surfaces—sails. As light reflects off a sail, most of its momentum is transferred, pushing on the sail. The resulting acceleration is small, but continuous. Unlike chemical rockets that provide short bursts of thrust, solar sails thrust continuously and can reach higher speeds over time.
Currently a test mission of the LightSail concept is under way. The LightSail is in orbit and expected stay in orbit for about 1-2 months. Initially the mission had trouble with communications, but after an automatic reboot of the on board computers they have now confirmed that the LightSail is transmitting properly.
With an RTL-SDR and appropriate satellite antenna, it should be possible to monitor the LightSail. The LightSail transmits at a frequency of 437.435 MHz with the AX.25 protocol, FSK encoding at 9600bps and with a call sign of KK6HIT. The LightSail can be tracked at http://sail.planetary.org/missioncontrol and the planetary society are also requesting that amateur radio tracking enthusiasts email over any data they capture. Over on twitter some users have confirmed LightSail downlink hits: