Progress - The Swiss Army Knife of Spacecraft

Shortly after noon today, a Soyuz rocket blasted away from the Baikonur Cosmodrome in Kazakhstan, carrying a cargo vehicle known as "Progress" to the International Space Station. There are a number of spacecraft resupplying the ISS these days* but Progress is (arguably) the most versatile.

In order to operate a space station you need a number of recurring services:

• Delivery and return of crew members
• Delivery of consumables (food, water, oxygen, fuel)
• Delivery of hardware (station parts, spacesuit parts, science experiments)
• Removal of waste (food packaging, broken hardware, completed experiment hardware)
• Orbit and/or attitude adjustments (rotate orientation, increase or decrease altitude to avoid orbital debris or to compensate for atmospheric drag--yep, at 250 miles there's still enough air to slow it down!)

Progress can handle all of those tasks but one; carrying crew to and from orbit. The reason for this lack of capability is that Progress is a direct descendant of the crewed Soyuz spacecraft, which has been the workhorse of Russian spaceflight in constant operation (and upgrade) since 1967, with great successes**. Rather than develop a completely new vehicle, the Russian space program chose to adapt their proven design into a cargo-only vehicle.

The Progress is composed of three segments: a pressurized cargo module, a refueling module, and an instrumentation/propulsion module.

The forward, somewhat spherical segment is the pressurized cargo area that will contain nearly 4,000 lb. of hardware, food, and some water that the cosmonauts and astronauts will manually remove once this portion of the vehicle docks with the ISS. In the months after this cargo is unloaded, that same area will be filled with the multiple forms of waste that life inevitably generates.

At the center of the spacecraft is the refueling module. As you can see in the diagram, this segment is filled with a number of tanks that contain fuel, oxidizer, and sometimes water. Not all missions require more water to be transported so there is some variation in this segment. Again, this segment could hold nearly 4,000 lb. The fuel can be transferred from Progress to ISS by connections in the docking ring, where the two spacecraft meet, eliminating the need for crew to be exposed to hazardous materials. As far as I know, Progress is currently the only spacecraft capable of this function, making it that much more important to station operations.

In the crewed Soyuz this space is the descent module where the crew's seats and instruments are located. To return to Earth, the forward segment and propulsion segment behind it would detach and a heat shield between descent and propulsion modules would protect the crew during atmospheric reentry. No such shielding is needed for Progress. Remember all that trash to be loaded in the cargo area? It's meant to be burned during atmospheric reentry.

The final segment at the rear of the vehicle not only does the work of navigating Progress to the ISS, it also serves as an instrument of orbital adjustment. While the ISS has it's own on-board engines for attitude and orbit adjustment, it is wiser to use those of the visiting spacecraft because the hardware on the ISS must remain on orbit for years (in the end it will be multiple decades) while the visiting spacecraft is newer and more recently inspected to assure safe and effective operations. This also reduces the need to transfer fuel between vehicles. The Space Shuttle was able to facilitate these orbital adjustments but that system was retired in 2011. The Japanese HTV can also provide reboosts but is an infrequent visitor to ISS, leaving the Russian Soyuz and Progress to do much of the work.

So as you can see, Progress really serves as many vehicles. It is the delivery truck, it is the fuel tanker, it is the tow truck, and it is the garbage truck for the International Space Station. It's not glamorous work but it all has to be handled. With all of these support tasks taken care of, the crew can get down to their true purpose on orbit: scientific experiments that, in one way or another, will advance the knowledge and abilities of humanity as a whole. So I suppose you could say that ISS needs Progress to enable progress.

Has there ever been a more appropriately named vehicle?

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*Current: Progress (Russia), Dragon (USA), Cygnus (USA), H-II Transfer Vehicle (Japan)
  Retired: Space Shuttle (USA), Automated Transfer Vehicle (Europe)
  Future:  Dream Chaser (USA)

**Of course, Soyuz has also had its set of failures. But that's a matter for another time.

The Second Space Age: An Overview

Whether the general public knows it or not, we're in the middle of something amazing. We're living through a "Second Space Age." These past couple years, new rockets and new spacecraft have been coming online and entering service as spaceflight in the United States shifts from government-based to commercially-operated. During the Space Shuttle era, NASA owned and operated their fleet of vehicles and over the shuttle's 30-year history that ownership and operation proved to be more costly than anticipated. While it allowed us to build the International Space Station, the next necessary step to permanent human habitation off this planet, the complex and maintenance-heavy shuttle fleet also drained funding away from new vehicle development. So many people were screaming out to the whole of the internet when the shuttle fleet was retired, fearing that NASA was closing up shop, giving up on sending people into space...but the reality is the exact opposite. NASA had cleared up an immense portion of their ever-declining budget to move on to the next target: exploration beyond Earth orbit.

NASA's new capsule, the Orion, has been making steady progress towards providing us with a vehicle that can take us to asteroids, the moon, and beyond. Most people seem to think it's still just an idea, a concept on a drawing board, but in September of this year the Orion is scheduled to make its first unmanned trip into space. Several years from now it will ride skyward with a crew atop one of the newest and largest rockets in the world: the Space Launch System (SLS).

This rocket makes use of flight-proven hardware such as solid rocket boosters and Space Shuttle main engines (which were so reliable that they were reusable) while also adding in 21st century technology such as composite structure fuel tanks that will be lighter and stronger than the old aluminum alloy tanks. Less weight there means more weight that can go into space. More bang for the buck, figuratively and literally.

But what about the Station? It's still there and still needs to be resupplied and crews exchanged every few months, right? Of course, and this is where the Second Space Age really comes into being. In the short term we've been able to ride with our partners from Russia, who took up the task of manned flight with their Soyuz spacecraft, a vehicle with an impressive safety record over its nearly 50 years of operation. (Don't worry, it's had many upgrades and modifications since the old days!) That's the beauty of an International Space Station, you can work with others to assure continued service.

A lot of people in this country, however, disapprove of sending astronauts (and dollars) to another country to get to space. The long-term side of the plan has been for NASA to work with private corporations to develop several different spacecraft and rockets that will be able to deliver crew and cargo to the ISS, in a way handing over the "routine" aspect of space to private companies that can compete to do it efficiently and at competitive costs. NASA has shared its vast technical knowledge with US-based aerospace corporations and some of those companies are already providing results. 

SpaceX's Dragon and Orbital Sciences' Cygnus have already made trips to the ISS under cargo resupply contracts and may just be a few years until we see private companies operating crewed spacecraft. And the day that a commercially operated, manned vehicle makes it to space will be a VERY big day.

So to summarize the future: private companies operate the rockets that put people into earth orbit and send cargo to the ISS, leaving NASA a bigger chunk of budget to do the bolder, more ambitious projects that take us away from Earth.


There's an impressive collection of companies and individual that are doing amazing things now and in the near-future. Through this "Second Space Age" series you'll be introduced to the new rockets, the new spacecraft, the companies that are building/operating them, and the amazing way it all fits together to expand humanity's ability to understand and navigate through our universe.

Any questions or feedback will be much appreciated. I want to write what you want to read about so let your opinions be known!