Though they’re not as frequent, space launches from Japan are always welcome news. The Epsilon rocket has successfully kept up its pace of continuous improvements at a rate of about one launch per year. Liftoff of the Epsilon 4 mission was at 0050 UT on 18 January from the Uchinoura Space Centre in Kagoshima.
JAXA has so far used the Epsilon rocket mainly for science, research, and development payloads. Epsilon mission 4 was just a little different, with a unique commercial payload added to the mix. The manifest included 7 payloads: 4 microsats and 3 cubesats.
| Payload | Size | kg | Operator | Purpose |
| RAPIS-1 | 108 cm | 200 | Axelspace | Multi-experiment tech demo |
| ALE-1 | 80 cm | 68 | ALE Co.Ltd. | Artificial meteor shower |
| MicroDragon | 50 cm | 50.5 | VNSC, Keidai | Ocean / Air EOS, Materials |
| RISESAT | 50 cm | 39.3 | Tohokudai | Multi EOS, Optics |
| OrigamiSat | 3U | 4.1 | Tokodai | Mechanical deployment |
| Aoba VELOX-IV | 2U | 2.6 | KIT | Pulsed Plasma Thruster |
| NEXUS | 1U | 1.3 | Nichidai | Amateur Radio |
The primary payload, RAPIS-1, was a coordinated effort led by prime contractor Axelspace. The satellite features seven contributed experiments and subsystems from various universities and engineering firms, on an ambitious timeline that began in June 2016. The other large payloads are the MicroDragon, built in cooperation with the Vietnam National Space Council; the ALE-1 satellite from Astro Live Experiences, which will provide an artificial meteor shower, possibly for display during the Tokyo 2020 Olympic Games; and RISESAT, which is an international collaboration with payloads related to optics and multispectral imaging. The manifest is rounded out by three university cubesats.
The propulsion systems aboard the payloads will demonstrate some concepts that are catching on in the space industry. The RAPIS-1 on-orbit thruster will use hydroxylammonium nitrate (HAN) instead of hydrazine. HAN is called a “green propellant” because it replaces hydrazine, which is extremely hazardous. HAN isn’t non-toxic, but it is significantly less harmful, and offers equivalent or better performance as a propellant. The Aoba VELOX-IV cubesat will use a pulsed plasma thruster, which offers a very small but repeatable electronically controllable thrust, which is very useful for kilogram-scale satellites.
Epsilon itself uses three solid rocket stages to reach LEO. An optional fourth stage, added to Epsilon 4, uses liquid monopropellant to boost smaller payloads to higher orbits, in this case, in this case 370 kg to 500 km SSO. Compared with other active launch systems, Epsilon is in the same category as the Arianespace Vega, ROSCOSMOS Rokot, and Northrop Grumman’s Minotaur. ExPace and Firefly are also developing new commercial rockets close to this size.
Further news
Early on the 15th, the Iranian Space Agency launched the 90 kg agricultural earth-observation satellite AUTSAT-1, but due to an unspecified third stage problem, the payload crashed into the Indian Ocean rather than reaching a 500 km orbit. Iranian launches typically spark diplomatic concerns, though at least one independent analyst agrees that the Simorgh orbital rocket is a peaceful design.
On 19 January, there was a successful Delta IV Heavy launch from Vandenberg AFB. That launch, plus the launch of New Shepard on 23 January, completed the missions from the ostensible “day of launch” that was meant to occur 19 December 2018. New Shepard carried 8 NASA payloads on a suborbital trajectory with an apogee just under 107 km. The rocket and capsule were successfully recovered.
Also of note, astronaut Mae Jemison spoke on Dr. Martin Luther King, Jr. Day in St. Paul.