Three years after the retirement of the space shuttle, there are measurable signs of progress on its successor at National Aeronautics and Space Administration centres across the United States.
Engineers at George C. Marshall Space Flight Center in Huntsville are testing the avionics of the Space Launch System.
Here a scale model of the Space Launch System, or SLS, is being prepared for a test of the launch pad's sound suppression water system, which will protect the orbiter and its payloads from being damaged by acoustic energy reflected from the platform during lift-off.
Douglas Counter, a Space Launch System engineer explains the importance of rigorous testing.
"Past experience has shown that without this scale model testing, there could be not only problems with the design loads, with the environment, components could fail. So, this is very critical in proving out what the design loads, qualifications, the environment that the vehicle will actually see, the effectiveness of the water and whether your water suppression system -- as designed -- actually did what it was supposed to accomplish."
Another Space Launch System Engineer Curt Jackson describes the flight computers being assembled in the system integration laboratory in Huntsville as the rocket's brain and nervous system.
"This is essentially the brain and nervous system of your rocket. The flight computers are your brain. The various data systems, the various sensors, data from the different boxes -- kind of like your nervous system flow -- to the brian. Your brain is giving, sending out signals through your nervous system to the different parts of your body for, to tell it what to do. And, to tell how things are going."
Jackson agrees that early testing is essential for a smooth test launch.
"And, the whole goal of being able to do this testing as early as possible is, when we get down to the Cape, when we push that button and see the rockets fire, we want to assure that everything is going to work correctly and that the crew is as safe as possible. So, we try to do this testing as early and often as we can and all, so."
Engineers at John C. Stennis Space Center in Bay St. Louis, Miss. are assembling 200-foot-tall engines.
Recently, the United States of House of Representatives Appropriations Committee recommended $17.9 billion USD in funding for NASA in 2015 -- $435 million USD more than requested by the White House. The proposal includes additional funding for SLS and Orion.
But all the same NASA is being thrifty in its reuse of materials as Gary Benton RS-25 Engine Test Project Manager explains.
"Well, what we have here in the building is RS-25 engines that are getting ready to be tested and eventually fly. We've got 16 RS-25 engines left over from the shuttle program. And, since the engine was highly reliable and reusable, we're able to take these engines and use them for the first four flights of SLS."
There is recycling going at the John C. Stennis Space Center in Bay St. Louis, Miss. as well, where an Apollo-era test stand is being renovated ahead of a test of the rocket's core stage.
Richard Rauch is the B-2 Test Stand Project Manager.
"Well, the stand was originally designed in the Apollo era to be very flexible and you could see there's a lot of old equipment up there from the previous testing of the Saturn S-IC and the shuttle main propulsion test article. And, what we're doing is repurposing some of that old hardware -- some of that structural hardware -- a lot of the propellant and cryopiping, to make it adaptable to what's required for the SLS core stage."
Ahead of the first test flight of the SLS, in 2017, engineers at the Michoud Assembly Facility in New Orleans have started to weld sections of the massive heavy-lift rocket.
Jackie Nesselroad, a Boeing Company production operations director at the Michoud facility says "The United States is the leader in the industry. We're the leader for the world. We're providing that next level, that next generation exploration to space, not only for the United States, but, for the world."
According to NASA, the Space Launch System will provide an entirely new capability for science and human space exploration beyond Earth's orbit.
"The Space Launch System will give the nation a safe, affordable and sustainable means of reaching beyond our current limits and open new doors of discovery from the unique vantage point of space," NASA said. "The Space Launch System, or SLS, will carry the Orion Multi-Purpose Crew Vehicle, as well as important cargo, equipment and science experiments, to deep space. The Orion spacecraft will carry up to four astronauts beyond low Earth orbit on long-duration, deep space missions and include both crew and service modules and a launch abort system to significantly increase crew safety."
Earlier this month, a congressionally mandated report from the National Research Council recommended that the United States pursue a disciplined "pathway" approach that encompassed executing a specific sequence of intermediate accomplishments and destinations leading to the "horizon goal" of putting humans on Mars.
The success of this approach would require a steadfast commitment to a consensus goal, international collaboration and a budget that increases by more than the rate of inflation, the National Research Council said.