Reimei

{{Infobox spaceflight

| name = Reimei

| image =

| operator = JAXA

| major_contractors =

| bus =

| mission_type =

| launch_date = {{start-date|24 August 2005}}

| launch_rocket = Dnepr

|launch_contractor= ISC Kosmotras

| flight_number =

| launch_site = Baikonur Pad 109/95{{cite web |last1=Wade |first1=Mark |title=Reimei |url=http://www.astronautix.com/r/reimei.html |archive-url=https://web.archive.org/web/20161227224627/http://astronautix.com/r/reimei.html |url-status=dead |archive-date=December 27, 2016 |website=www.astronautix.com |access-date=7 June 2020}}

| mission_duration =

| mission_highlight =

| deactivated =

| decay =

| COSPAR_ID = 2005-031B

| nolink =

| SATCAT = 28810

| webpage =

| launch_mass = {{cvt|72|kg}}

| dimensions = 72 cm × 62 cm × 62 cm

| power =

| batteries =

| orbit_reference = Geocentric

| orbit_regime = Low Earth orbit

| orbit_semimajor = {{convert|6975.4|km|mi|abbr=on}}

| orbit_eccentricity = 0.0027340

| orbit_inclination = 98.1777

| orbit_apoapsis = 616.33149

| orbit_periapsis = 578.19003

| orbit_period = 96.63 min

| orbit_mean_motion = 14.9020938 rev/day

| orbit_epoch = May 3, 2018, 22:37:00.128 UTC{{cite web |url=https://www.space-track.org/basicspacedata/query/class/tle_latest/NORAD_CAT_ID/28810/ORDINAL/1--5/orderby/ORDINAL/format/tle/emptyresult/show |title=INDEX - Orbit |date=May 3, 2018 |access-date=May 4, 2018}}

| instruments = 25 μm-thick polyimide mirrors

}}

Reimei ('Dawn') is the in-flight name for a small Japanese satellite known during development as INDEX (INnovative-technology Demonstration Experiment), developed in-house at JAXA both to serve as a demonstration of small-satellite technologies (particularly high-performance and high-accuracy attitude control) and to perform simultaneous optical and charged-particle observation of the aurora. A notable feature is the 25 μm-thick polyimide mirrors used for concentrating sunlight onto the solar arrays.

It is {{nowrap|72 cm × 62 cm × 62 cm}} and weighs 72 kilograms. The construction budget was $4 million. The satellite was launched into a near-Sun-synchronous 630 km orbit on 24 August 2005 as a piggyback on the OICETS launch on the Dnepr launch vehicle.{{citation |url=http://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1552&context=smallsat |title=Overview and initial in-orbit status of "INDEX" satellite |last1=Saito |first1=Hirobumi |work=Proceedings of the 20th Annual AIAA/USU Conference on Small Satellites |year=2006 |id=SSC06-IV-1}}{{cite web | url=http://global.jaxa.jp/activity/pr/brochure/files/sat19.pdf | title=Innovative-technology Demonstration Experiment REIMEI |publisher=JAXA |access-date=2015-12-19}}