The Sea God Surveys: Watch Rocket Lab launch Japanese Earth-observing satellite today

Rocket Lab is preparing an Electron rocket launch from its New Zealand site. Its payload is an Earth-observing radar satellite built for the Japanese company iQPS. The mission is named "The Sea God Surveys." It matters because the satellite will join iQPS's planned network for monitoring Earth.

The satellite uses synthetic aperture radar, or SAR. Unlike an optical spacecraft, it does not depend on ordinary visible-light views. Radar observation can work through cloud cover and during nighttime. That gives iQPS a way to gather useful Earth data in conditions that can limit optical imaging.

This is Rocket Lab's 10th launch for iQPS. The launch is also Rocket Lab's 99th mission overall and its 90th Electron flight. The launch window opens at 11:30 a.m. EST on Nov. 2, and Rocket Lab plans to provide a live broadcast beginning about 30 minutes earlier.

Rocket Lab has completed 98 missions before the launch described here. The scheduled mission will be its 99th overall. Of those missions, 90 will have used Electron, the company's two-stage rocket designed to give small satellites dedicated rides to space. These figures show both the scale of the company's launch program and Electron's central role in it.

Electron is 59 feet, or 18 meters, tall. It has already flown 16 times during the year described in the article. The rocket launches payloads into orbit, including the iQPS Earth-observing radar satellite on "The Sea God Surveys."

The other nine missions used HASTE. HASTE is a suborbital version of Electron, not an orbital satellite launcher. It carries generally classified payloads so customers can test technology in a hypersonic flight environment. HASTE debuted in June 2023, explaining why it accounts for fewer missions than Electron.

A synthetic aperture radar, or SAR, satellite is an Earth-observation spacecraft that uses radar to study the planet. The article contrasts SAR satellites with spacecraft that view Earth in optical wavelengths. SAR matters because observation does not stop when clouds hide the ground or when sunlight disappears.

The satellite sends radar signals toward Earth and measures the returning signals. As it moves along its orbit, it combines measurements collected from different positions to create detailed radar imagery. This synthetic aperture makes the observing system act like a larger antenna than the spacecraft's physical antenna alone.

For iQPS, SAR supports a planned constellation of three dozen satellites in low Earth orbit. Rocket Lab's launch will add another satellite to that effort. The constellation is intended to provide repeated Earth observations, while SAR's all-weather and day-night capability broadens when those observations can be collected.

Clouds can obstruct an optical satellite because optical systems observe visible or nearby light coming from Earth. Night also removes the sunlight that normally illuminates the surface for many optical observations. SAR avoids both limitations by using radar signals instead of relying on reflected sunlight in optical wavelengths.

A SAR satellite transmits radar toward the ground and records the signal that returns. Radar wavelengths can pass through cloud cover more effectively than visible light, allowing the spacecraft to detect and map the surface beneath. Because the satellite supplies its own signal, it can collect observations during darkness as well as daytime.

That capability is a major advantage highlighted in the article. iQPS is assembling three dozen SAR satellites in low Earth orbit, and Rocket Lab's mission is its 10th launch for the company. Together, the satellites could support frequent observations under varied weather and lighting conditions.

iQPS is assembling a constellation of three dozen synthetic aperture radar satellites in low Earth orbit. A constellation is a coordinated group of satellites rather than a single spacecraft. Its purpose is to expand the company's ability to observe Earth and collect radar data repeatedly.

Many satellites can spread observations across more orbital passes and locations. As one spacecraft moves away from an area, another may later pass over it. This can shorten the wait between observations and improve coverage. SAR also works through clouds and at night, so the constellation is not restricted to clear daytime conditions.

The article identifies the launch as Rocket Lab's 10th mission for iQPS. The satellite aboard Electron will therefore contribute to a much larger planned system. If iQPS completes the constellation, its three dozen spacecraft should give the company a broader and more regular Earth-observation capability than one satellite could provide.

Electron and HASTE share a rocket family but serve different purposes. Electron is a two-stage, 59-foot rocket that gives small satellites dedicated rides to space. Its launches place payloads into orbit, such as the iQPS radar satellite on "The Sea God Surveys."

HASTE is short for "Hypersonic Accelerator Suborbital Test Electron." It is a suborbital version of Electron, so it is used for high-speed test flights rather than the orbital deployment described for Electron. Customers use HASTE to test technology in the hypersonic flight environment. Its payloads are generally classified.

Rocket Lab's launch record reflects this difference. The scheduled flight will be the company's 99th overall mission and the 90th Electron launch. The other nine missions used HASTE. HASTE debuted in June 2023, while Electron remains the company's main vehicle for dedicated small-satellite launches.

Low Earth orbit, or LEO, places an observation satellite relatively close to Earth compared with higher orbits. That proximity helps the spacecraft collect useful measurements of the surface. The satellite can travel around the planet while its radar observes areas below, building a changing picture of Earth.

A SAR satellite sends radar signals toward the ground and records their returns. As it moves along its orbit, it gathers observations from different positions, which can be combined into radar imagery. The orbit also carries the spacecraft over different regions, allowing it to observe more than one fixed location.

The article says iQPS is assembling three dozen SAR satellites in LEO. A group of satellites can increase the number of passes over areas of interest and reduce gaps between observations. Rocket Lab's launch will add another spacecraft to that planned constellation, extending iQPS's Earth-observation system.