H3 rocket, launch plaftorm

ALOS-3 | H3-22

Lift Off Time
(Subject to change)
March 7, 2023 – 01:37:55 UTC | 10:37:55 JST
Mission Name
Launch Provider
(What rocket company is launching it?)
Mitsubishi Heavy Industries
(Who’s paying for this?)
Launch Location
LA-Y2, Tanegashima Space Center, Japan
Payload mass
~3000 kg (~6600 lb)
Where is the satellite going?
Sun-Synchronous Orbit, 669 km altitude
Will they be attempting to recover the first stage?
No, this is not a capability of H3
Where will the first stage land?
It will crash into the Pacific Ocean
Will they be attempting to recover the fairings?
No, this is not a capability of H3
Are these fairings new?
How’s the weather looking?
This will be the:
– 1st H3 flight
– 2nd orbital launch from Japan in 2023
– 10th launch from pad LA-Y2
– 87th launch from Tanegashima Space Center
– 31st orbital launch attempt in 2023
Where to watch
Official livestream

What Does All This Mean?

Mitsubishi Heavy Industries is flying JAXA’s ALOS-3 payload on board the maiden flight of the new H-3 rocket. The H3-22 configuration indicates that there are two solid rocket boosters attached to the first stage.

What Is ALOS-3?

The Advanced Land Observation Satellite (ALOS), known as “Daichi”, is an Earth observation satellite. It features a multi-spectral sensor operating in the visible and near infrared ranges.

ALOS-3 satellite (Credit: JAXA)
Mission instrumentsWide-swath and high-resolution optical imager

Panchromatic (black and white)
Ground resolution: 2.5 m – 0.8 m (at nadir) / Swath width: 70 km at nadir
Wavelength: 0.52 – 0.76 μm

Multispectral (color)
Ground resolution: 3.2 m / Swath width: 70 km at nadir
Band 1 0.40 – 0.45 μm (Coastal)
Band 2 0.45 – 0.50 μm (Blue)
Band 3 0.52 – 0.60 μm (Green)
Band 4 0.61 – 0.69 μm (Red)
Band 5 0.69 – 0.74 μm (Red Edge)
Band 6 0.76 – 0.89 μm (Near-Infrared)
Data transmissionDirect transmission (Ka band : 1.8 Gbps, X band : 0.8 Gbps)
Optical inter-satellite communications: 1.8 Gbps
Size5.0 m × 16.5 m × 3.6 m
Mass~3000 kg (~6600 lb)
Design life7 years
Operational orbitSun-synchronous sub-recurrent* orbit at an altitude of 669 km
Revisit time 35 days (Sub-cycle: about 3 days)
Local solar time at descending node: 10:30 (a.m.) +/- 15 minutes
ALOS-3 specifications (Credit: World Meteorological Organization)

(*) subrecurrent means that the angle of incidence of sunlight on the Earth’s surface is almost constant. This is not the same as standard sun-synchronous orbit, as shown in this illustration from JAXA.

Standard Sun-synchronous orbit vs sub-recurrent orbit. (Credit: JAXA)

What Are Earth Observation Satellites Used For?

Uses for Earth observation satellites (Credit: JAXA)

The information in the list below was provided by JAXA on their website:

  • Marine pollution – we can see distribution condition of marine pollution caused by oil spill etc.
  • Drift ice situation – we can see distribution of drift ice and its movement.
  • Sea surface temperature and phytoplankton density – data is utilized for monitoring ocean environment, clarification of fluctuation process and prediction of fishery.
  • Earthquakes – data is utilized for anomaly detection of crustal variation and ground deformation, clarification of mechanism of earthquake occurrence, assessing damage situation in natural disasters. This is particularly relevant given the recent devastation in parts of Turkey and Syria.
  • Inundation – data is utilized for estimation of inundated area caused by flood and tsunami, assessing flood condition and disaster prevention activity.
  • Volcanic activity – data is utilized for monitoring active volcano and assessing damage situation at the time of eruption.
  • Deforestation – by using syntheic aperture radar (SAR), it is possible to observe penetrating clouds even in the tropics which have many clouds. The data is utilized for detecting deforestation.
  • Land use – We can see how the land is used such as urban area, forest, farmland and so on.
  • Vegetation – we can see distribution and change of forest, grassland etc. and know the information of forest resources.
  • Topography – we can confirm complex landform, characteristic mountain range, ruins etc.
  • Land surface temperature – we can see seasonal and day-and-night variations of land surface temperature. At the same time, the data is utilized as environmental information related to ecosystem.

What Is The H-3 Rocket?

H-3 is Mitsubishi Heavy Industries’ latest medium lift launch vehicle, intended to replace the existing H-II rocket. It is a 2 stage rocket, with options for either 0, 2, or 4 solid rocket boosters. Both stages are fueled with liquid hydrogen.

H3 configurations

This maiden flight of the H3 is flying in the H3-22S configuration, indicating that it has 2 liquid engines on the first stage, 2 solid rocket boosters and the shorter payload fairing.

ConfigurationSolid Rocket BoostersFirst stage enginesFairing size

Solid Rocket Boosters

The solid rocket boosters used on the H3 are known as SRB-3, and the design is derived from an earlier booster SRB-A. The propellant is based on polybutadiene. Each motor has a maximum thrust of 2,158 kN (485,000 lbf). The motor has a specific impulse of 283.6 seconds, and burns for a duration of 105 seconds.

The motor has a length of 14.6 m and a diameter of 2.5 m. It has no thrust vector capability.

First Stage

Depending on the first numeric digit following the hyphen, the first stage has either 2 or 3 LE-9 engines. The LE-9 engine runs on liquid hydrogen and uses the expander bleed cycle. Each engine has a thrust of 1,471 kN (331,000 lbf). The core stage has a 5.2 m diameter.

MHI claims that the LE-9 is the world’s first rocket engine on a first stage that no auxiliary combustion chamber. This is due to its use of the expander bleed cycle.

Appearance and schematic diagram of the LE-9 engine (Credit: MHI)

Second Stage

The second stage is also fueled with liquid hydrogen and uses a single LE-5B-3 engine. This also uses the expander bleed cycle. This stage also has a diameter of 5.2 m.

Upgrades to the LE-5B-3 engine compared to the earlier LE-5B-2 (Credit: MHI)

  1. Why is this a ‘success’? The rocket launch halted several seconds after ignition and then was announced to be postponed.

    1. The first stage engines shut down automatically when the solid rocket boosters failed to ignite.

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