Cargo spacecraft

Cargo spacecraft are designed to carry supplies into orbit. During much of the history of space travel, manned space missions were expected to carry all the supplies they would require for the duration of their trip. However, with the creation of the International Space Station (ISS), the first space station to utilize a permanent crew, periodic resupply missions became a necessity.

Some cargo spacecraft are unmanned. They are piloted remotely or by computers and dock at the ISS without pilots or a crew. These vessels typically remain at the station after delivering their supplies and are filled with the station’s waste. They are then sent back to Earth, where they combust in the atmosphere. Other vessels are piloted by a crew, sometimes bringing astronauts to and from the ISS.

Background

During the second half of the twentieth century, humankind developed the first rockets powerful enough to orbit Earth. During World War II, these rockets were used as weapons. After the war, both the United States and the Soviet Union developed their own missile programs. In 1957, the Soviet Union launched into orbit the first successful artificial satellite, Sputnik 1. In 1961, Soviet Yuri Gagarin became the first human being to orbit Earth.

On July 20, 1969, astronaut Neil Armstrong became the first human to walk on the moon. Several more missions to the moon were later conducted. Soon, nations began launching commercial satellites into orbit. These satellites helped with communication, navigation, and many other tasks.

In 1981, the United States launched the Columbia space shuttle. This began the era of reusable space shuttle launches, which were used for scientific experiments and military purposes. However, in 1986, the space shuttle Challenger exploded during liftoff, killing the crew. In 2003, the space shuttle Columbia broke apart during re-entry. Despite these tragedies, manned space missions were still conducted.

Overview

Cargo spacecraft were pioneered by scientists working for the Soviet Union in the 1960s. At the time, the Soviet Union was designing a series of military space stations known as the Almaz. The country was aware that any military installation requires periodic resupply missions and resupplying a military installation that remained in orbit presented unique challenges.

To carry supplies from Earth into orbit, the Soviet Union designed the Transportnyi Korabl’ Snabzhelniia (TKS), which means Transport Supply Aircraft. The TKS required a pilot and included space for both a crew and cargo. Early versions of the TKS successfully completed several test flights. However, the Soviet Union discontinued the Almaz program, and the TKS was cancelled. Its design was reused in future projects, including the Functional Cargo Block, which would later become the template for Russian space station modules.

In 1984, President Ronald Reagan directed NASA (the National Aeronautics and Space Administration) to begin construction of an International Space Station (ISS). Many nations collaborated on the plans, working together to create the first research facility to maintain a permanent orbit. The first segment of the ISS launched on November 20, 1998. Two years later, in 2000, the first crew traveled to the station, residing there for several months. Over the lifetime of the ISS, other modules were shipped into space and added to the station.

To maintain a permanent crew, the ISS required a steady stream of new supplies. The station’s initial plans included the use of the US Space Shuttle, as well as the Russian Progress, to provide the crew with food, tools, and research equipment. However, the international community knew that such a difficult endeavor would require additional vehicles.

The European Space Agency developed the Automated Transfer Vehicle (ATV), which could carry more than 7,600 kilograms on each trip. This was the largest resupply vehicle to ever visit the ISS. The Japanese Aerospace Exploration Agency developed the H-II Transport Vehicle (HTV), which was able to carry roughly 6,000 kilograms of material.

The ATV and the HTV were not manned vehicles, and their launch and docking process were remotely controlled or automated. The vehicles were launched from Earth, then docked on the ISS. Once docked, the crew entered the vehicles, removing any expected supplies and storing them on the ISS. They then began filling the ATV or HTV with waste. After several months, the cargo vehicle detached and began a controlled re-entry into Earth’s atmosphere. The vehicle’s trajectory caused it to combust during re-entry over the Pacific Ocean, safely destroying the waste.

After the retirement of the Space Shuttle, America took an eleven-month hiatus from resupply missions to the ISS. During this time, Space Exploration Technologies Corporation (SpaceX) conducted a resupply mission. Its vehicle, the Dragon, became the first private spacecraft to resupply the ISS. Unlike many other vehicles, the Dragon was a crewed, reusable craft. It was also able to carry a substantial amount of supplies back from the ISS. Though the Russian Soyuz craft had returned with cargo space available, it was only able to return safely while carrying extremely limited amounts of material. The Dragon was able to carry large amounts of unpressurized cargo into space. After its initial run proved successful, SpaceX used the Dragon for several more supply trips to the ISS.

New cargo spacecraft are always in development. Scientists and engineers seek to improve on existing designs, making them safer and more efficient. Many of these vehicles are built by world governments. However, the Dragon’s success showed that the private sector was also capable of successfully producing spacecraft. In 2024, the SpaceX freighter Cygnus successfully docked aboard the ISS with roughly 8,200 pounds of cargo. This success further legitimized the use of private spacecraft.

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