A Russian Soyuz capsule departs the International Space Station. (NASA, Public Domain)

After 30 years and 135 flights the United States' world-renowned spaceflight program officially came to an end as the space shuttle Atlantis achieved full “wheels-stop” condition on the tarmac of the Kennedy Space Center early Thursday morning. 

The task of ferrying equipment into space will be carried out by several private companies while NASA focuses on developing a system to send astronauts back to the Moon and beyond.

There are currently five designs of possible Space Shuttle replacements, and the Obama administration has outlined plans to land an astronaut on an asteroid by 2025 and on Mars by the mid-2030s.

In the meantime, there remains a simple question: What about routine transportation to the International Space Station of supplies, scientific experiments, modules, equipment, and personnel? That responsibility, at least for the foreseeable future, has fallen solely to the Russian Soyuz program.

Originally developed as a component of the Soviet Union's moon landing initiative, known as “Moonshot,” in 1967, the Soyuz has long been a staple of manned spaceflight, with 110 completed missions to its name. Its curriculum vitae includes: sending the first cosmonauts to occupy the space station Mir; completing the first joint U.S.-Soviet space flight as part of the Apollo-Soyuz Test Project in 1975; and carrying dozens of astronauts from several different countries to and from the International Space Station. It has been used for the purpose of human spaceflight longer than any other vehicle.

Additionally, there is always a Soyuz spacecraft docked at the ISS as an escape vehicle in the event of a Station-wide emergency necessitating evacuation.

Although developed during a tense period of the Cold War and designed to facilitate the establishment of a Soviet lunar base, Soyuz has also seen the significant expansion of international cooperation in space. The 1975 Apollo-Soyuz Test Project was a resounding success for both nations--technologically and politically. In the fall of 2011, Russia plans to launch a Soyuz mission from a base in French Guinana, which will mark the craft's first launch outside a former Soviet nation. With the retirement of the U.S. Space Shuttle program, Soyuz will gain the additional honor of being the only vehicle in the world capable of carrying astronauts to the International Space Station for at least the next several years.

While the retirement of the Space Shuttle allows NASA to shift its focus to bigger and more complex programs, the decision to leave the United States devoid of any means of sending people into space has some worried. Among the critics are Neil Armstrong, who gained international fame in 1969 for being the first human to walk on the moon; senior NASA managers; and several astronauts of the Apollo era.

In an email to The Associated Press as cited by The Huffington Post, Armstrong said he had “substantial reservations” about the Obama administration's plan, which, in his view, jeopardizes American leadership in space.

However, Buzz Aldrin, the second man on the moon and Armstrong's partner in the famous 1969 landing, in February expressed his complete support for the plan and the international cooperation it requires.

“[The Obama administration's plan is] just what our Nation needs to maintain its position as the leader in space exploration for the rest of this century … Mars is the next frontier for humankind, and NASA will be leading the way there.”

You can reach staff writer Sean McGuire by clicking here.