“Uchiage!” NASA and JAXA launch GPM Core Observatory on H-IIA rocket
The island of Tanegashima trembled today, no it wasn’t from a giant radioactive lizard – but rather from the Mitsubishi-built H-IIA launch vehicle which ascended loudly into the sky at 1:37 p.m. EST (1837 GMT). The payload for this flight was a NASA and Japanese Aerospace Exploration Agency led mission which will study the size and frequency of rain and snowfall – the Global Precipitation Measurement Core Observatory or “GPM.”
The launch had been originally slated to occur at 1:07 p.m. EST, but a Launch Readiness Review board opted to push the launch back a half-hour so as to avoid the International Space Station. The flight team, consisting of representatives from JAXA, NASA, and Mitsubishi Heavy Industries, Ltd. reviewed the readiness of the GPM spacecraft and cleared it for launch.
The GPM Core Observatory is an international effort with NASA and JAXA taking the lead, with the French Space Agency (CNES), the U.S. Department of Defense, Defense Meteorological Satellite Program (DMSP); European Organization for the Exploitation of Meteorological Satellites (EUMETSAT); Indian Space Research Organization (ISRO); and the U.S. National Oceanic and Atmospheric Administration (NOAA) also participating.
The GPM Core Observatory will build upon the findings of the Tropical Rainfall Measuring Mission (TRMM), which also is a joint NASA-JAXA spacecraft.
The satellite is planned to work for approximately three years (but will have enough fuel for five) and will orbit at a distance of approximately 253 miles (407 kilometers) at an inclination of 65 degrees. It should complete an orbit of the Earth once every 93 minutes or 16 times per day.
The GPM Core Observatory has two primary scientific instruments which it will use to study precipitation size and rate of fall. The first of these is the GPM Microwave Imager (GMI) which was manufactured by Ball Aerospace & Technology Corp. This instrument will detect the total precipitation amounts within all cloud layers to include light rain as well as snowfall. To accomplish this, it measures the strength of microwave energy emitted from all parts of the Earth system.
GMI utilizes 13 channels to measure the intensity of microwave radiation. The lower channels of the spectrum (10 to 89 gigahertz) are the ones which will be the ones used to detect heavy-to-moderate rainfall.
The other instrument on board the GPM Core Observatory is the Dual-frequency Precipitation Radar or “DPR.” DPR will be used to make 3D measurements of rain and snowfall structures and rates over much of the Earth’s surface. The DPR was designed by JAXA and the National Institute of Information and Communications Technology in Japan and was built by NEC Toshiba Space Systems, Ltd.
The DPR uses a Ku-band radar that will measure moderate-to-heavy rain at 13.6 gigahertz. The instrument also has a Ka-band radar which will measure frozen precipitation (snow) as well as light rain at 35.5 gigahertz. Combined, these two radars could shed new information about the different size of raindrops that are within storm systems and how they are dispersed throughout storm clouds.
“We have spent more than a decade developing DPR using Japanese technology, the first radar of its kind in space,” said Masahiro Kojima, JAXA GPM/DPR project manager. “I expect GPM to produce important new results for our society by improving weather forecasts and prediction of extreme events such as typhoons and flooding.”
These two instruments should provide scientists with a better understanding about the size, shape and distribution of precipitation. This should provide better predictions regarding rain and snowfall estimates across the globe.
“We still have a lot to learn about how rain and snow systems behave in the bigger Earth system,” said GPM Project Scientist Gail Skofronick-Jackson. “With the advanced instruments on the GPM Core Observatory, we will have for the first time frequent unified global observations of all types of precipitation, everything from the rain in your backyard to storms forming over the oceans to the falling snow contributing to water resources.”
Once separated from the H-IIA, the GPM spacecraft will utilize 12 Aerojet Rocketdyne MR-106L 5.0 lbf monopropellant thrusters for attitude control.
“We are proud to be part of a mission that will help advance understanding of Earth’s water and energy cycles, improve the forecasting of extreme events that cause natural disasters, and make use of satellite precipitation information to directly benefit society,” said Warren Yasuhara, vice president of Space Systems at Aerojet Rocketdyne. “Knowing what the weather brings is a key part of being prepared–at work, at home and on the road, and the Aerojet Rocketdyne team is honored to help deliver this capability.”
Mitsubishi’s H-IIA has conducted some 22 missions, 21 of them have been deemed successful. The rocket measures approximately 173 feet (53 meters) tall and some 13 feet (4 meters) in diameter and burns a mix of liquid oxygen and liquid hydrogen as fuel. The H-IIA is Japan’s main launch vehicle and is designed to be capable of handling a wide range of missions including geosynchronous, sun-synchronous, low-Earth-orbit or even planetary missions. Launches are conducted from the Yoshinobu Block House underground control room.
The H-IIA has a success rate of about 95 percent, which puts it on par with United Launch Alliance’s Atlas V and Arianespace’s Ariane 5 boosters. There are two variants of the H-IIA which are currently in service.
The H-IIA follows the proven method of uprating a launch vehicle’s capabilities by adding solid rocket boosters. The first of the H-IIA rockets was launched in August of 2001.
Today’s launch took place at Launch Pad 1 at the Tanegashima Space Center at Tanegashima Island in Japan. Liftoff occurred at the very opening of the amended launch window, with the distinctive whine of the H-IIA as it pushed its charge out of Earth’s gravity well and into the black of space.
Three minutes before the launch, the rocket was switched to internal power. At liftoff the rocket leapt off of the pad, illuminating the early-morning hours with a brilliant light. The first minute of launch went flawlessly but the most dangerous part of ascent was yet to come.
At a minute into the flight, the rocket was beginning to pass the region of maximum dynamic pressure or “max-q.” This is where the rocket’s speed, coupled with the pressure of the atmosphere places the greatest amount of stress on the launch vehicle.
At about a minute and a half into the flight the two solid rocket boosters having completed their task were jettisoned and left to fall back to Earth where they will crash into the Pacific Ocean. The GPM Core Observatory continued to ride the core segment of the H-IIA booster and its LE-7A rocket engine to orbit.
At about four minutes, the stack was some 100 miles down range. Shortly afterward, the payload fairing, which shielded GPM through Earth’s tumultuous atmosphere was jettisoned – revealing the spacecraft. By about five and a half minutes into the flight, the rocket/satellite duo were traveling at some 11,000 miles per hour.
A little more than seven minutes into the flight stage separation took place leaving the second stage to continue sending the GPM Core Observatory the rest of the way. The second stage is powered by a LE-5B engine using the LOX and LH2 cryogenic propellants. The second stage conducted a burn which lasted about eight minutes and placing GPM into orbit.
GPM is the first of five planned Earth observation satellites scheduled to launch this year.
“It is incredibly exciting to see this spacecraft launch,” said GPM’s Project Manager Art Azarbarzin with NASA’s Goddard Space Flight Center. “This is the moment that the GPM Team has been working toward since 2006. The GPM Core Observatory is the product of a dedicated team at Goddard, JAXA and others worldwide. Soon, as GPM begins to collect precipitation observations, we’ll see these instruments at work providing real-time information for the scientists about the intensification of storms, rainfall in remote areas and so much more.”
Video courtesy of JAXA
Jason Rhian spent several years honing his skills with internships at NASA, the National Space Society and other organizations. He has provided content for outlets such as: Aviation Week & Space Technology, Space.com, The Mars Society and Universe Today.