Testing,Testing,A-1 to -3…

Engineers at NASA’s John C. Stennis Space Center are hard at work to prepare the facility for testing the J-2X rocket engines and rocket stages that will help carry humans back to the moon.

Steel work is progressing on the A-3 Test Stand, which will be used to perform high-altitude testing of the J-2X engine, a cornerstone of NASA’s Constellation Program to go back to the moon and beyond. By February, workers were completing the seventh of 16 stages of steel work necessary to erect the tower that is 300 feet tall.

Meanwhile, modification and maintenance work continues on the A-1 Test Stand, which also will test the J-2X engine and its components. It is the most extensive modification effort performed on the stand since the early 1970s, when it was converted for testing space shuttle main engines.

Engineers also continue major modifications on the B Complex Test Facility to prepare for testing stages of the Ares rockets to be used in the Constellation Program. Stennis is responsible for testing the upper stage of the Ares I crew launch vehicle and the first stage of the Ares V cargo launch vehicle. To that end, engineers are creating and installing new control systems and data acquisition and recording systems at the test complex. They also are upgrading fire and gas detection systems on the B Test Stand.

Finally, engineers are installing a new liquid nitrogen pump system at Stennis’ high-pressure gas facility. One of three pumps has been installed and already is matching the output of four older pumps while using less power and experiencing less mechanical strain and much less propellant loss. All three new pumps are scheduled to be in place in time to support the liquid nitrogen needs involved with J-2X and Ares stage testing.

Staging the Ares I

When NASA has built a rocket, it has historically been done in segments, or stages.  For example, the Saturn V used to take astronauts to the moon during the Apollo program had three stages. The Constellation Program’s new Ares I rocket will have two stages – the first and upper stages.


Some have asked, why do you need stages? Why not build one large ship and be done with it? The reasoning for this is simple — most of the structure used in a launch vehicle houses the fuel needed to power the propulsion system. As the vehicle burns fuel, it no longer needs the full-sized structure to reach orbit; therefore, it becomes excess weight. By staging or dropping off these stages, the vehicle becomes lighter and the propulsion system has to push less weight into orbit. 


While staging is a necessary part of the launch process, it does have potential risks and is given additional scrutiny because of the relative complexity. As with all launch events, staging is studied carefully by project engineers to ensure mission success. This is a normal part of the NASA development process.  For Ares, NASA has evaluated the first-stage-to-upper-stage-separation event from the perspective of ensuring the ability to separate, being able to confirm separation has occurred, and having sufficient clearance to not re-contact the J-2X engine nozzle with the interstage as it is pulled away from the Ares I upper stage. 


The separation of the Ares I stages is carefully timed and based upon preset acceleration levels. Separation will occur when those levels are read by on-board accelerometers, which takes place when the first stage runs out of propellant and the internal pressure reduces. A set of linear shaped charges between the upper stage and first stage will fire, separating the metal between the first stage and the interstage. At the same time, ten booster deceleration motors fire to pull the first stage directly backward, while eight ullage settling motors fire to push the upper stage forward. After the segments separate, the first stage tumble motors fire to slow the stage for its return trip to Earth and eventual recovery.


As part of this process, NASA engineers ran thousands of physics-based models (“Monte Carlo” analyses) to evaluate the first stage/upper stage separation. These models are developing and continue to improve. In addition, engineers analyzed and evaluated the system redundancies and potential for re-contact between the J-2X nozzle and the interstage. NASA’s analyses concluded that there will be a good separation, even in a worst case scenario. Because this is a critical event, NASA had the Aerospace Corporation perform an independent analysis and their conclusions supported the NASA analysis.

This along with many other developments is a key “risk” that will continue to be watched closely, and managed and mitigated using proven risk management techniques as we proceed with the final design phase of Ares I.



Sleeping on The Moon

One of the comments we received on the Altair video asked about possible sleeping arrangements for the astronauts. Well, we are exploring various configurations for crew sleeping accommodations. One option is certainly fold-down beds. Currently, we are experimenting with a hammock concept for Altair, in which a fabric hammock is supported by two poles, which attach to the forward walls of the cabin.  In this scenario, we would deploy four such hammocks vertically, similar to how crew sleep stations are arranged on many naval vessels.  When not in use, the poles would be stowed flush with the cabin walls and the hammocks would be folded up and stowed in lockers.  This arrangement worked well in recent evaluations and allowed our test subjects to “sleep” without disturbing each other, and it allowed any crew member to get up in the middle of the night (e.g., to get a snack, complete a task) without causing the others to have to move their sleep stations out of the way.  We will continue to explore additional concepts in the future as we search for the ideal solution to incorporate into the Altair.  It will be interesting to see what kind of sleeping accommodations eventually fly.

Here’s a look at some of the testing being done on the sleep stations inside one of the Altair mock-ups.

The Towers Rise


This is a shot of Pad 39B at the Kennedy Space Center, which is being prepared for the Ares I-X test flight later this year. That particular pad — as well as its twin, pad 39A — was the site of space shuttle launches since the 1980s until 39B was retired in 2006 (pad 39A is now the primary site). In this picture, which was taken at dawn, you can see the towers of the new lightning protection system for the pad. Each of the three new lightning towers will be 500feet tall with an additional 100-foot fiberglass mast on top of them. This work is being done because the Ares and Orion stack will be much taller than the shuttle is, coming in at more than 300-feet tall.

Take a Spin Around The Inside of Altair


One of the things we get a lot of questions about is what the inside of the Altair lunar lander will look like. Well, initial concept work is already underway, and the NASA team is busy exploring Altair’s design. While the details of what the crew cabin will look like are still being figured out, what is known is that Altair will carry four astronauts to the lunar surface and will serve as their home for up to a week.

Altair is big. One current concept is that it will stand more than 30 feet high and will be almost 45 feet wide at the footpads. There are mock-ups already built at the Johnson Space Center in Houston where habitability teams are working inside, trying out different configurations. These teams are taking a look at how astronauts will live and work inside, so that Altair can be built in the best way possible for the mission.

Click on the link below and take a quick spin around the inside of Altair. It’s a conceptand NASA is exploring othersbut as you can see, it will be very different from anything we’ve designed before.

Click here to view the video in Windows Media Player format

Click here to view the video in RealPlayer format


What Does It Mean to 'Human Rate' a Rocket?


A lot of people have asked what it means to “human rate” a rocket — to put people on top of a rocket and send them into space.  How does an agency like NASA take on this challenge?  And what considerations do engineers give human rating as they design Ares to deliver astronauts to the International Space Station by 2015 and for future trips to the moon and beyond?

In a nutshell, human-rating a rocket means that we take our understanding of how the rocket can fail to a higher level of fidelity (than for a non-human rated rocket), and then take steps to prevent failures or have it fail in such a way that the crew can survive the failure (e.g. crew abort).

For NASA, the Ares I rocket is being designed from the outset to fly humans as its primary role vs. modifying an existing system.

To get a little deeper into the subject, I talked with some senior NASA Marshall Space Flight Center engineers, Neil Otte and Gary Langford, who work this challenge for NASA and here’s how they explain it:

Let’s clearly define some of the primary human rated attributes and what they mean. First, human safety is the measure of risk of injury, or loss of life, to any spaceflight personnel. NASA’s policy is to protect the health and safety of humans involved in or exposed to space activities, specifically the public, crew, passengers, and ground personnel. Specifically human rating is involved with the risk to the flight crew. Risks to ground crew and the public are covered under other NASA policy directives and are inherent in all missions regardless of the presence of a flight crew.

A human-rated system accommodates human needs, effectively utilizes human capabilities, controls hazards and manages safety risks associated with human spaceflight, and provides, to the maximum extent practical, the capability to safely recover the crew from hazardous situations. This statement makes up the basic three tenets of human rating:  assuring the total system can safely conduct the mission, incorporate design features that accommodate human interaction with the system, and incorporate design features and capabilities to enable safe recovery of the crew from hazardous situations.

Simply put, human rating is a thorough process that consists of many variables being taken into account to safely design, build and launch a crewed spacecraft and return that spacecraft, and its crew safely to the earth. The process begins at program inception and continues throughout the life cycle of the program and includes: design and development; test and verification; program management and control; flight readiness certification; mission operations; sustaining engineering; maintenance, upgrades, and disposal.

We can now look closer at human rating. The first tenet is to safely conduct the planned mission. To accomplish this requires a very careful design. This design is accomplished by a careful examination of the hazards and design features that prevent the hazard known as hazard controls. In the design, the first step would be to try eliminating the hazard; if that is not possible then hazard controls can be put into place to prevent the occurrence of the hazard. Hazard controls can take many forms such as failure tolerance by incorporating redundant or backup systems and components, application of system margins to assure function of the system even under the most extreme conditions, and quality assurance from early material and component selection through final assembly and checkout operations. If applied to a simple example of say a home heating system, the hazard would be that the house is too cold for the health and safety of the occupants. Moving to a warmer climate, however, could eliminate the hazard, if not possible then hazard controls are put into place. Use of redundant systems or components can be applied.  For example, many heat pump systems have backup electrical or gas systems to provide heat in the event of a compressor failure or the inability of the compressor to meet the needed heat requirements. The system is carefully sized to provide adequate heat under the most extreme expected winter temperatures for the local climate, and the equipment manufacturer and the installation contractor control quality.  

For the Ares I rocket the foundations of the first basic tenet in developing a human rated system have been carefully laid out. Factors such as hazard elimination and hazard controls have been carefully thought out and placed as requirements in the system design. In addition, program management and control places additional requirements on the development to assure adequate system margins, proper test and verification, and safety and mission assurance practices to further minimize the risk to the flight crew.

Even with all the care that goes into the system design and development, the system design must accommodate failure. Sometimes failure is dealt with by simple redundancy that allows mission continuation. In some cases, however, mission continuation is no longer possible and steps must be taken to safely return the crew. For the example of the house, for extreme cold and total system failure, the occupants could choose to leave, go stay with family or friends, or stay in a hotel until repairs are made. In short you remove the humans from the hazard. Ares accomplishes this by incorporation of the launch abort system (LAS). The LAS allows the spacecraft to be lifted away from a failing launch vehicle and allows for spacecraft reentry and rescue of the crew by search and rescue forces.

Launch of a crew to low earth orbit is an energetic process that inherently has significant associated risk. The process of human rating attempts to eliminate hazards, control the hazards that remain, and provide for crew survival even in the presence of failures that expose the crew to the hazards. The Ares Projects team was assigned the task of designing a launch vehicle capable of carrying the Orion crew exploration vehicle, with a crew of four to six astronauts, to the International Space Station AND later support lunar missions.  NASA’s top priority is to design and build a vehicle that supports the crew with the safest design possible given real external constraints. The Ares design is a culmination of years of studying the best attributes for a human rated launch system. Every aspect of human rating has been taken into account in the Ares design, therefore the Ares I rocket will be fully human rated, something only achieved by a small fraction of launch vehicles.

The Ares I rocket is three years into its development process and has successfully passed every major design review. Ares is being designed with human rating in mind as the primary requirement vs. modifying an existing rocket. Human rating has been an integral part of the Ares I development since day one.