| Ryusei | |
| Mission Type: | Technology |
| Operator: | NASDA |
| Cospar Id: | 1994-007A |
| Satcat: | 22978 |
| Mission Duration: | 2 hours |
| Manufacturer: | NASDA |
| Launch Date: | UTC[1] |
| Launch Rocket: | H-II |
| Launch Site: | Tanegashima Yoshinobu 1 |
| Landing Date: | UTC[2] |
| Landing Site: | Pacific Ocean |
| Orbit Epoch: | 3 February 1994[3] |
| Orbit Reference: | Geocentric |
| Orbit Regime: | Low Earth |
| Orbit Periapsis: | 448km (278miles) |
| Orbit Apoapsis: | 458km (285miles) |
| Orbit Inclination: | 30.5 degrees |
| Orbit Period: | 93.64 minutes |
| Apsis: | gee |
OREX (Orbital Re-entry Experiment) was a NASDA re-entry demonstrator prototype which was launched in 1994 on the H-II launcher; the satellite was renamed . It was a precursor for the Japanese space shuttle HOPE.
OREX tested various communications systems, heating profiles and heat shielding components for HOPE.