October 16

Watching Earth from a Fixed Point in Space

1975 — GOES-1 Begins a New Era of Weather Watching

22:40 UTC

On October 16, 1975, a Delta rocket lifted from Cape Canaveral carrying a satellite that would help change the way people watched weather develop across Earth. At launch it was known as GOES-A. Once operational, it became GOES-1—the first Geostationary Operational Environmental Satellite. Its destination was one of the most useful locations in space. A satellite placed in the correct orbit approximately 35,800 kilometers—22,240 miles—above Earth's equator can circle the planet at the same angular rate that Earth rotates. Viewed from the ground, the satellite appears to remain almost stationary above the same longitude. This is a geostationary orbit. For meteorology, the advantage is enormous. A satellite in a low polar orbit repeatedly circles Earth, observing different regions as the planet rotates beneath it. Such spacecraft provide valuable global coverage. A geostationary weather satellite does something different. It watches the same broad portion of Earth continuously. Storm systems can be followed as they develop. Clouds can be tracked. Weather patterns can be compared from one image to the next. Instead of receiving occasional snapshots, meteorologists gain something closer to a moving picture of the atmosphere. GOES-1 was not the first weather satellite. That history stretched back considerably farther. In 1960, TIROS-1 had demonstrated how useful satellite pictures of clouds could be. Other experimental and operational meteorological spacecraft followed. NASA's Synchronous Meteorological Satellites SMS-1 and SMS-2, launched in 1974 and 1975, demonstrated weather observations from geostationary orbit. GOES transformed that experimental capability into an operational system for the National Oceanic and Atmospheric Administration. The distinction matters. An experimental spacecraft asks: Can this be done? An operational system asks: Can we depend upon it? GOES-1 carried a Visible/Infrared Spin Scan Radiometer, or VISSR. The instrument observed Earth in visible and infrared wavelengths. Visible imagery showed clouds during daylight. Infrared observations allowed meteorologists to study cloud and surface temperatures and continue monitoring weather at night. From repeated images, forecasters could follow cloud motion and derive information about winds. GOES-1 was spin-stabilized. Because the entire spacecraft rotated, its instrument viewed Earth only during part of each rotation—roughly 10 percent of the time. Later generations would become far more capable. But GOES-1 gave forecasters something revolutionary: a near-real-time view of changing atmospheric conditions from a fixed location above Earth. The satellite returned its first image on October 25, 1975. Its data quickly became useful to the National Weather Service. GOES spacecraft became especially important for monitoring severe weather. A hurricane evolves over hours and days. Thunderstorm complexes can develop rapidly. Cloud patterns reveal fronts, moisture, atmospheric circulation, and the organization of storms. A satellite that remains above the same hemisphere can watch those processes unfold. The GOES program continued through successive generations of increasingly sophisticated spacecraft. Later satellites no longer had to spin. They could stare continuously at Earth. Their imagers became dramatically more sensitive and faster. Additional instruments monitored the Sun and the space environment. Lightning detection became possible from geostationary orbit. Modern GOES spacecraft can observe hurricanes, wildfires, volcanic ash, fog, severe thunderstorms, atmospheric moisture, and many other phenomena with a speed and detail unimaginable in 1975. Their images have also changed public experience. Satellite views of hurricanes swirling across oceans are now familiar. Weather broadcasts routinely show animated cloud patterns covering entire continents. People can watch storms developing from space on computers and phones. That familiarity can make the achievement seem ordinary. It is not. A machine tens of thousands of kilometers above Earth continuously watches a hemisphere and sends observations back quickly enough to help people make decisions about weather occurring below. The ability to observe Earth from space is one of the most practical consequences of the Space Age. GOES-1 helped make that ability operational.

Why It Matters: GOES-1 inaugurated the operational geostationary weather-satellite system that gave meteorologists near-real-time views of atmospheric conditions from a fixed position above Earth. Its successors became indispensable tools for forecasting hurricanes, severe storms, fires, fog, and other hazards. GOES demonstrates that some of the most consequential uses of space exploration involve turning our instruments back toward our own planet.

 

Also on This Day

2003 — Shenzhou 5 Returns China's First Astronaut Safely to Earth

Landing: 22:23 UTC on October 15 by UTC date; 06:23 Beijing time on October 16

On October 16 according to China's civil calendar, Yang Liwei returned from the historic Shenzhou 5 mission. There is, however, an important date distinction for our chronology. The spacecraft landed at 06:23 Beijing time on October 16. Beijing is eight hours ahead of UTC. The landing therefore occurred at 22:23 UTC on October 15. Under the UTC convention we have established for precise spacecraft events, the physical landing technically belongs to October 15. But October 16 remains historically significant in Chinese accounts because it was the civil date on which the country celebrated the successful completion of its first human spaceflight. The return sequence began during Shenzhou 5's fourteenth orbit. At 05:35 Beijing time, controllers sent the command to begin the return. The orbital module separated. The retrorocket fired. The reentry capsule separated from the propulsion section and descended toward China. At 06:04 Beijing time, the capsule entered Earth's atmosphere. Radio communications were temporarily interrupted during the expected plasma blackout of reentry. Three minutes later, search crews received the spacecraft's radio signal and visually located the descending capsule. Parachutes slowed it. Just before touchdown, small rockets beneath the capsule reduced the final impact speed. At 06:23 Beijing time, Shenzhou 5 landed in the designated recovery area in Inner Mongolia. The actual landing point was reported to be only about 4.8 kilometers from the predicted location. The capsule was intact. Yang Liwei was in good condition. Search personnel reached the spacecraft, and Yang eventually emerged under his own power. China's first human spaceflight was complete. The mission had lasted approximately 21 hours and completed 14 Earth orbits. Its significance depended on both halves of the journey. Launching a person into orbit demonstrates one set of capabilities. Returning that person safely demonstrates another. Reentry requires a spacecraft to surrender orbital velocity while surviving extreme heating, maintain the proper attitude, deploy its parachutes correctly, locate an appropriate landing region, and allow recovery forces to find the crew quickly. Human spaceflight is not successful merely when the rocket goes up. The crew must come home. Shenzhou 5 proved that China possessed that complete capability.

Why It Matters: The safe return of Shenzhou 5 completed China's first human spaceflight and demonstrated an independent end-to-end crewed-spaceflight system—from launch and orbital operations through reentry, landing, and recovery. Because the landing occurred at 06:23 on October 16 in China but 22:23 UTC on October 15, it also provides a useful example of why this chronology distinguishes local civil dates from UTC event dates.

2021 — Lucy Begins Its Journey to the Trojan Asteroids

09:34 UTC

On October 16, 2021, an Atlas V rocket lifted from Cape Canaveral carrying a spacecraft toward a population of objects no mission had ever visited. The spacecraft was Lucy. Its targets were the Jupiter Trojan asteroids. At 09:34 UTC, Lucy began a journey designed to investigate remnants from the earliest history of the solar system. The Trojan asteroids occupy an unusual relationship with Jupiter. They do not orbit Jupiter like moons. Instead, they orbit the Sun, sharing approximately the same orbital distance as the giant planet. They congregate around gravitationally stable regions associated with the L4 and L5 Lagrange points, roughly 60 degrees ahead of and behind Jupiter in its orbit. Thousands are known. They may preserve clues to a chaotic period when the giant planets were forming and migrating through the young solar system. Modern models suggest that many small bodies may have been scattered enormous distances before some became trapped in their present orbits. If so, the Trojans may not all have formed in the same region. Their diversity could preserve evidence about conditions across widely separated parts of the early solar system. That makes them something like astronomical fossils. The mission's name reflects that idea. Lucy was named after the famous fossil skeleton of an early human ancestor discovered in Ethiopia in 1974. That fossil helped scientists investigate human origins. NASA's Lucy spacecraft was designed to investigate planetary origins. Reaching the Trojans requires an extraordinary trajectory. Lucy does not simply fly straight from Earth to Jupiter's orbit. Instead, it repeatedly uses Earth gravity assists to reshape its orbit around the Sun. The mission was designed to visit multiple asteroids with different characteristics and histories. Before reaching the Trojans, Lucy would encounter objects in the main asteroid belt. Then it would travel outward to the Trojan swarms. Its path was designed to carry it past more independently orbiting asteroids than any previous spacecraft mission. The mission also demonstrates how much planetary exploration depends upon celestial mechanics. Lucy carries no propulsion system capable of simply powering it from target to target across billions of kilometers. Instead, engineers use carefully timed encounters with Earth and the geometry of the spacecraft's solar orbit to redirect it. Gravity becomes part of the propulsion system. The mission's targets are small. But the question Lucy seeks to answer is enormous: How did the solar system become the system we see today? The planets did not necessarily form exactly where they now orbit. The young solar system was dynamic. Worlds interacted gravitationally. Small bodies were scattered. Some were ejected completely. Others were captured into new orbital populations. The Trojan asteroids may preserve evidence from that upheaval. Lucy therefore travels toward small objects in order to investigate one of the largest stories astronomy can tell—the formation of an entire planetary system.

Why It Matters: Lucy is the first spacecraft mission designed to explore Jupiter's Trojan asteroids, a diverse population of small bodies that may preserve evidence from the formation and early rearrangement of the solar system. By comparing multiple Trojans, Lucy seeks to reconstruct processes that occurred more than four billion years ago.

 

The Bigger Picture

October 16 asks a deceptively simple question: Where should we look? GOES-1 looked back at Earth. Shenzhou 5 carried a human being around Earth and safely home again. Lucy looked outward toward ancient remnants of planetary formation. All three directions matter. Space exploration is sometimes imagined principally as a movement away from Earth. Farther seems automatically more adventurous. The Moon. Mars. Jupiter. Saturn. The outer solar system. Eventually, perhaps, the stars. But distance alone does not determine scientific or human value. GOES-1 traveled only as far as geostationary orbit. Yet the system it helped establish affects everyday life. Satellite observations help forecasters warn communities about hurricanes and severe storms. They help track fires and volcanic eruptions. They allow scientists to watch Earth's atmosphere operate as a global system. Sometimes the most important reason to go into space is to gain a better view of home. Shenzhou 5 represents another relationship with Earth. Yang Liwei traveled into orbit, but the mission could not be called successful until he returned. Human spaceflight always carries this duality. Exploration pushes outward. Survival demands a pathway back. Lucy represents the opposite extreme. Its purpose is not immediate practical benefit on Earth. It is historical investigation on a planetary scale. The Trojan asteroids may contain information preserved from the solar system's infancy. By traveling billions of kilometers to study small worlds, Lucy may help explain why Earth, Jupiter, and the other planets occupy the orbits they do today. These missions therefore demonstrate three reasons humanity goes into space. To understand Earth. To learn how humans can live and travel beyond it. To understand where our planetary system came from. Those goals are not separate stories. They are different parts of the same effort to understand our place in the universe.

At a Glance

1975 — 22:40 UTC — GOES-A launches from Cape Canaveral; after reaching operational orbit it becomes GOES-1, inaugurating NOAA's operational geostationary environmental satellite series.

2003 — 06:23 Beijing time October 16 / 22:23 UTC October 15 — Shenzhou 5 lands safely in Inner Mongolia, completing China's first human spaceflight. Under this chronology's UTC convention, the physical landing belongs to October 15.

2021 — 09:34 UTC — NASA's Lucy spacecraft launches from Cape Canaveral on the first mission dedicated to exploring Jupiter's Trojan asteroids.