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The square sail, deployed via a spinning motion using tip masses (key item 1 in figure at right), is on the diagonal and is made of a thick sheet of
File:IKAROS solar sail.jpg, IKAROS spaceprobe in flight (artist's depiction)
File:IKAROS-SAIL.jpg, IKAROS model
Successful Image Shooting by the Second Separation Camera
– 28 June 2010 JAXA press release
Solar Sail Navigation Technology of IKAROS
* {{DEFAULTSORT:Ikaros 2010 in Japan Japanese space probes JAXA Solar sail spacecraft Space probes launched in 2010 Spacecraft launched by H-II rockets
IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) is a Japan Aerospace Exploration Agency (
(ISAS)' 2nd Large Mission Class. The winning mission was LiteBIRD.
JAXA
The is the Japanese national air and space agency. Through the merger of three previously independent organizations, JAXA was formed on 1 October 2003. JAXA is responsible for research, technology development and launch of satellites into o ...
) experimental spacecraft. The spacecraft was launched on 20 May 2010, aboard an H-IIA
H-IIA (H-2A) is an active expendable launch system operated by Mitsubishi Heavy Industries (MHI) for the Japan Aerospace Exploration Agency. These liquid fuel rockets have been used to launch satellites into geostationary orbit; lunar orbi ...
rocket, together with the ''Akatsuki'' (Venus Climate Orbiter) probe and four other small spacecraft. IKAROS is the first spacecraft to successfully demonstrate solar sail
Solar sails (also known as lightsails, light sails, and photon sails) are a method of spacecraft propulsion using radiation pressure exerted by sunlight on large surfaces. A number of spaceflight missions to test solar propulsion and navigati ...
technology in interplanetary space. The craft's name is an allusion to the legendary Icarus
In Greek mythology, Icarus (; , ) was the son of the master craftsman Daedalus, the architect of the labyrinth of Crete. After Theseus, king of Athens and enemy of King Minos, escaped from the labyrinth, Minos suspected that Icarus and Daedalu ...
(, ''Ikaros''), who flew close to the Sun on wings made of bird-feathers and wax.
On 8 December 2010, IKAROS flew by Venus
Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker ...
at a distance of , successfully completing its planned mission, and entered its extended operation phase. Its last transmission was received in 2015. The operation was terminated officially on 15 May 2025.
Purpose
The IKAROS probe is the world's first spacecraft to usesolar sail
Solar sails (also known as lightsails, light sails, and photon sails) are a method of spacecraft propulsion using radiation pressure exerted by sunlight on large surfaces. A number of spaceflight missions to test solar propulsion and navigati ...
ing as the main propulsion. It was designed to demonstrate four key technologies (comments in parentheses refer to figure):
# Deployment and control of a large, thin solar sail membrane (grey-blue areas numbered 3)
# Thin-film solar cells integrated into the sail to power the payload (black rectangles numbered 4)
# Measurement of acceleration due to radiation pressure
Radiation pressure (also known as light pressure) is mechanical pressure exerted upon a surface due to the exchange of momentum between the object and the electromagnetic field. This includes the momentum of light or electromagnetic radiation of ...
on the solar sail
# Attitude control
Spacecraft attitude control is the process of controlling the orientation of a spacecraft (vehicle or satellite) with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, ...
by varying the reflectance
The reflectance of the surface of a material is its effectiveness in reflecting radiant energy. It is the fraction of incident electromagnetic power that is reflected at the boundary. Reflectance is a component of the response of the electronic ...
of 80 liquid crystal panels embedded in the sail (orange rectangles numbered 2)
The mission also includes investigations of aspects of interplanetary space, such as gamma-ray burst
In gamma-ray astronomy, gamma-ray bursts (GRBs) are extremely energetic events occurring in distant Galaxy, galaxies which represent the brightest and most powerful class of explosion in the universe. These extreme Electromagnetic radiation, ele ...
s, solar wind
The solar wind is a stream of charged particles released from the Sun's outermost atmospheric layer, the Stellar corona, corona. This Plasma (physics), plasma mostly consists of electrons, protons and alpha particles with kinetic energy betwee ...
and cosmic dust
Cosmic dustalso called extraterrestrial dust, space dust, or star dustis dust that occurs in outer space or has fallen onto Earth. Most cosmic dust particles measure between a few molecules and , such as micrometeoroids (30 μm). Cosmic dust can ...
.
The probe's ALADDIN instrument (ALDN-S and ALDN-E) measured the variation in dust density while its Gamma-Ray Burst Polarimeter (GAP) measured the polarization of gamma-ray bursts during its six-month cruise.
IKAROS was to be followed by a sail, the Jupiter Trojan Asteroid Explorer, which was intended to journey to Jupiter
Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...
and the Trojan asteroids, with a proposed goal of returning an asteroid sample to Earth in the 2050s.Institute of Space and Astronautical Science
, or ISAS, is a Japanese national research organization of astrophysics using rockets, astronomical satellites and interplanetary probes which played a major role in Japan's space development. Established as part of the University of Tokyo ...Design
The square sail, deployed via a spinning motion using tip masses (key item 1 in figure at right), is on the diagonal and is made of a thick sheet of polyimide
Polyimide (sometimes abbreviated PI) is a monomer containing imide groups belonging to the class of high-performance plastics. With their high heat-resistance, polyimides enjoy diverse applications in roles demanding rugged organic materials, suc ...
(key item 3 in figure at right). The polyimide sheet had a mass of about , resulting in a total sail mass of , excluding tip masses, attached panels and tethers. A thin-film solar array is embedded in the sail (key item 4 in figure at right). PowerFilm, Inc. provided the thin-film solar array. Eighty blocks of LCD
A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers to display information. Liquid crystals do not em ...
panels are embedded in the sail, whose reflectance can be adjusted for attitude control
Spacecraft attitude control is the process of controlling the orientation of a spacecraft (vehicle or satellite) with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, ...
(key item 2 in figure at right). The sail also contains eight dust counters on the opposite face as part of the science payload.
Mission progress
IKAROS was successfully launched together with ''Akatsuki'' (the Venus Climate Orbiter) aboard an H-IIA rocket from the Tanegashima Space Center on 21 May 2010. IKAROS spun at 20–25 revolutions per minute and finished unfurling its sail on 10 June 2010. The craft contains two tiny ejectable cameras, DCAM1 and DCAM2. DCAM2 was used to photograph the sail after deployment on 14 July 2010. Acceleration andattitude control
Spacecraft attitude control is the process of controlling the orientation of a spacecraft (vehicle or satellite) with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, ...
(orientation) were successfully tested during the remaining six-month voyage to Venus. On 9 July 2010, JAXA confirmed that IKAROS was being accelerated by its solar sail, and on 23 July announced successful attitude control. Over a 23-hour period of time, the solar angle of the sail was changed by a half a degree, not by using thrusters, but by dynamically controlling the reflectivity of the 80 liquid crystal panels at the outer edge of the sail so that the sunlight pressure would produce torque.
IKAROS continues to spin at approximately 2 rpm
Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or r⋅min−1) is a unit of rotational speed (or rotational frequency) for rotating machines.
One revolution per minute is equivalent to hertz.
Standards
ISO 80000-3:2019 def ...
, requiring the LCD panels to be cycled at that rate for attitude control.
According to JAXA, IKAROS finished all planned experiments in Dec 2010, but the mission continued beyond that date "in order to enhance the skill of controlling solar sail". On 30 November 2012, JAXA announced that IKAROS had been recognized by Guinness World Records
''Guinness World Records'', known from its inception in 1955 until 1999 as ''The Guinness Book of Records'' and in previous United States editions as ''The Guinness Book of World Records'', is a British reference book published annually, list ...
as the world's first solar sail spacecraft between planets, and that its two separated cameras, DCAM1 and DCAM2, had been recognized as the smallest size of a spacecraft flying between planets.
As of 2012, the IKAROS continued to spin, but its attitude control had degraded. This resulted in unexpected sail motions and as a result, downlink through the medium-gain antenna was only intermittently available. The project team was dissolved on 28 March 2013, although a trial receipt of data was planned for a later date.
The project was reactivated on 20 June 2013 in the expectation that the satellite would wake up from a hibernation state as more power from the solar panels became available. The team was able to receive telemetry from the IKAROS between 20 June and 12 September 2013, after which contact was again lost. The loss of contact was around the predicted time of the spacecraft again entering a low-power hibernation mode as power from the solar panels decreased. Available communication time through the Usuda Deep Space Center antenna was limited, so data was gathered only intermittently to estimate the speed, trajectory and rotation of the satellite. As of August 2013, acceleration from the IKAROS sail had changed the craft's speed by approximately in total.
Transmissions were again received on 22 May 2014, the spacecraft flying at a distance of about 230 million kilometers from the Earth. By May 2014, IKAROS was on a ten-month orbit around the Sun, spending seven months of each orbit in hibernation mode due to insufficient power. By 23 April 2015, the spacecraft woke up from hibernation mode for the 4th time and was flying at a distance of about 120 million kilometers from the Earth. On 21 May 2015, JAXA could not receive a signal from IKAROS and concluded that the spacecraft had shifted to the hibernation mode for the fifth time, as expected. Based on the last data received during May 2015, the position of IKAROS at the time was about 110 million kilometers away from the Earth, and about 130 million kilometers from the Sun.
The operation was terminated officially on 15 May 2025.
Scientific results
From the gamma-ray polarization data of GAP, Toma et al. put a stricter limit on CPT violation. It is an improvement of eight orders of magnitude over previous limits. JAXA scientists stated on 9 July 2010 that the measured thrust force by the solar radiation pressure on IKAROS' sail is .See also
* * * * * * *Notes
References
* *External links
Successful Image Shooting by the Second Separation Camera
– 28 June 2010 JAXA press release
Solar Sail Navigation Technology of IKAROS
* {{DEFAULTSORT:Ikaros 2010 in Japan Japanese space probes JAXA Solar sail spacecraft Space probes launched in 2010 Spacecraft launched by H-II rockets