Crew's preparation for the International Space Station

For the National Aeronautics and Space Administration (NASA), bringing crew-astronauts to the International Space Station (ISS) is critical for the pursuit of the national’s scientific and technological goals.


To proceed successfully with the Crew Transportation System (CTS) to an orbital destination, a guideline has been formulated in the Design Reference Missions (DRMs). 
A guideline for the CTS is more than necessary because, for some years, partnerships with private space companies have enhanced the availability of new launchers for missions to LEO and the ISS. That starting with cargo supplies, and now, commercial providers have the capability to transport astronauts in space.
To attein NASA's requirements, all providers, like SpaceX and Boeing, are responsible for the design, development, production, operation, management, and integration of their end-to-end CTS. 
In the CTS, the flight system must includes the launch vehicle, the crewed spacecraft, the cargo to be transferred to the orbital destination, and the flight crew equipment.
About the Ground System, the provider must have the detail of the equipment, infrastructure, facilities, and personnel necessary for the operations. That must also includes the support to the mission design, production, assembly, integration, test, launch preparation and operations, as well as flight operations and recovery activities.


The atmosphere of another planet may not be compatible with our basic survival requirements of oxygen, carbon dioxide and nitrogen. In all likelihood, any astronauts stepping foot onto this new world need some form of space suit to enable them to function. Many of these risks can be mitigated by understanding in advance the many worlds and moons of our own Solar System. Then there is the journey itself to get to this new world. This will involve traveling across vast distances of space, not depending on any rescue parties and avoiding asteroids or dust particles as they approach with large kinetic energies. Even a single particle can present a significant collision risk if the vehicle is traveling at high speed. This is due to the fact that kinetic energy is proportional to the velocity squared, so the faster the ship or particle is going, the higher the collision energy involved. There is also the risk from bombardment of cosmic rays en route, which may cause cancer. If an artificial gravity field is not created then astronauts should expect significant calcium loss and bone decay.


For the Crew Transportation System, to provide successful services to the ISS, two major objectives must be met. The first one is to insure a crew rotation capability for four NASA or NASA-sponsored crew-members.
The second objective is to transport a limited amount of ISS Program-specified pressurized cargo to the Station, to return that cargo and provide a safe haven when the spacecraft is docked.
Before the launch, NASA astronauts proceed to a pre-launch Health Stabilization Program. Non-NASA crews also use a similar program. A few hours before the launch, NASA completes its crew's medical assessments and transports them to the launch site. The NASA flight surgeons will serve as physicians for the crew during all the phases of the flight.
We have to remember that, because the spacecraft have limited size and power available on-board, it can provide only basic first aid and life support to respond to immediate medical conditions in the free-flight mode.


When everything is ready, all wait for a lift-off that will occur when the launch site passes through the ISS’ orbital plane. Launch and ascent into the 51.6-degree inclination must meet range safety constraints associated with the launch site.

View of Soyuz TMA-20M rocket launch in Kazakhstan. Credit: NASA 
Following ascent, an orbital insertion maneuver is executed and becomes the first of several orbital rendezvous maneuvers to be performed. These maneuvers bring the spacecraft closer towards the Station and when it reaches about tens of kilometers, ship-to-ship voice communications are established.

From aboard the ISS, NASA-Crew Scott Kelly took this Image of a spacecraft approach
During some navigation performed with available cooperative and non-cooperative assets on the ISS, communication and telemetry monitoring are shared between the Commercial Vehicle Control Center (CVCC) and the ISS mission control facilities - Houston (MCC-H). The MCC-H Mission Authority ensures the safety of the ISS, the spacecraft, and the crew.
When the spacecraft is close to the Station, it receives authorization from the MCC-H to begin its final approach to a specific docking port. Once done, the vestibule between the ISS and the vehicle is pressurized and checked for leaks. Then, the crew opens the spacecraft's hatch and goes inside the Station. At this moment, the spacecraft is placed in a semi-quiescent state.

Soyuz Capsule Docking
If the nominal docking attempt is not successful, or if an anomaly occurs near docking, the spacecraft backs out to a short safe distance. The staff-crew reconfigures the maneuver and proceeds to a second approach and docking attempt. If that latter is once again unsuccessful, the spacecraft goes away from the ISS vicinity on a collision-free safe trajectory and prepares for a last docking attempt. If this third attempt is unsuccessful, the mission is terminated and the crew returns to Earth.
Generally, a spacecraft is designed (as Dragon of Space X and the CST-100 of Boeing) to be able to stay attached to the station for 210 days, although nominal crew rotations occur in about 180-day intervals. In collaboration with MCC-H, the Commercial Vehicle Control Center provides routine and periodic support for these docked operations. Also, the ISS provides power and environmental resources to the spacecraft to ensure it is ready to return-to-Earth.
The sample DRMs contained in this document are top-level mission scenarios applicable to potential missions to Low-Earth Orbit (LEO) destinations. As described in the parent certification document, CCTSCR-12.10, Commercial Crew Transportation System Certification Requirement for NASA Low-Earth Orbit Missions, “NASA plans to purchase commercial crew space transportation services to LEO and the ISS as part of its exploration plans and policies. 
This document describes the concept DRMs and is not a required document. The ISS DRM works in conjunction with the processes defined in the Crew Transportation Plan (CCT-PLN-1100) and the Crew Transportation Technical Management Processes (CCT-PLN-1120), the requirements defined in the ISS Crew Transportation and Services Requirements Document (CCT-REQ-1130), the additional requirements defined in the ISS to Commercial Orbital Transportation Services Interface Requirements Document (SSP 50808), and the standards found in the Crew Transportation Technical Standards and Design Evaluation Criteria (CCT-STD-1140) and the Crew Transportation Operations Standards (CCT-STD-1150).
Soyuz rendezvous and docking explained
Soyuz undocking, reentry and landing explained
On the ISS, docking ports are limited. So, it is possible that the spacecraft has to be relocated from one port to another one during increment operations in the Station. To do so, the spacecraft’s crew returns inside and closes the hatch. The crew needs to be in the vehicle to protect it from potential failures, to re-mate it with a docking port, and guarantee a safe return to Earth.
Also, if one of the ISS system fails and the environment becomes uninhabitable, or a medical event occurs, the retreat to the spacecraft may be urgent. In worst cases, the crew can return to Earth within 24 hours of a declaration of an intention to come-back early. When the return to Earth is not required, the crew remains in a safe environment for up 24 hours. If necessary, the spacecraft's atmosphere is purged and the Station provides attitude control during that time.
Seven to 10 days before the departure of the crew, NASA will proceed to the launch of the next rotation mission, resulting in a period where two commercial spacecraft are docked to the ISS.

Capsules SOYUZ_TMA-03M and PROGRESS_M13M docked at the ISS
If a Commercial Provider, like SpaceX, has received NASA's approval to fly a non-NASA crew to the ISS, the Dragon's vehicle has to provide food, water, clothing, Environmental Control and Life Support System (ECLSS) consumables, and other logistics for their own astronauts. This is because, generally, NASA only has these supplies on the ISS for its crews.
After handover is completed in the Station, the current increment crew returns in the spacecraft and performs a vehicle health check, closes the hatches, depresses the vestibule and does a hatch leak check to verify seal integrity. When detached and, if available consumables permit, the spacecraft circumnavigates the ISS in proximity and takes pictures of its external configuration for post-flight analysis.

The Return to Earth

Once the spacecraft begins its return to Earth, it has a time-frame of 4 to 8 hours of free-flight for its landing on the continental U.S. land mass or the sea directly extending from the coast. Landing in the U.S. minimizes rescue force assets needed, it increases proximity to U.S. medical facilities, as well as security, and it ensures a prepared landing site free of hazards.
If the nominal de-orbit maneuver is waived-off after separation from the ISS, a subsequent landing at an alternate site, with nearby recovery forces, will be possible. In this latter case, the spacecraft may perform orbital maneuvers in LEO to better accommodate the new landing site.
Once on the ground, crew-members are physically affected by the Earth's climate because of their long exposure to the micro-gravity and the vacuum of the space environment. They have lost performance at the level of their musculo-skeletal, cardiopulmonary, and their neuro-vestibular capabilities. Because of their state, special considerations need to be provided for their recovery.

Upon arrival at the landing location, the NASA crew is met by a recovery crew to assist them in egress operations and removal of time critical cargo. They begin post-flight medical and science evaluations soon after the egress is completed in a temporary facility.
Subsequently, the NASA crew-astronauts, support personnel, and time critical cargo is transported by a CTS element to a staging location. This is where the handover is completed and the NASA crew and cargo are flown back to Houston using NASA assets.

ISS Crew after touchdown in Kazakhstan, March 2, 2016.
Once recovery operations are completed, the spacecraft is saved and transported to a location for subsequent post-flight evaluation.
Source: Commercial Crew Program
John F. Kennedy Space Center / Crew Transportation System - Design Reference Missions, CCT-DRM-1110 Revision: Basic-3, December 8, 2011.

Commercial Crew Program - The Essentials

NASA's Commercial Crew Program (CCP) was formed to facilitate the development of a U.S. commercial crew space transportation capability with the goal of achieving safe, reliable and cost-effective access to and from the International Space Station (ISS) and Low-Earth orbit (LEO).  
To support the development of human spaceflight capabilities, NASA's CCP has invested in numerous American companies, such as SpaceX or Boeing. These companies are now able to design and develop space commercial transportation vehicles and systems.
Once a transportation capability is certified to meet NASA requirements, the agency will fly missions to meet its space station crew rotation and emergency return obligations.
Throughout this process, NASA and industry have invested time, money and resources in the development of their systems for the emergence of new space markets.    
To accelerate the program’s efforts and reduce the gap in American human spaceflight capabilities, NASA awarded more than $8.2 billion in Space Act Agreements (SAAs) and contracts. These amounts have been allowed under the two phases of the Commercial Crew Development (CCDev1 & 2), the Commercial Crew Integrated Capability (CCiCap) initiative, the Certification Products Contract (CPC) and the Commercial Crew Transportation Capability (CCtCap).
The CCP is primarily based at NASA’s Kennedy Space Center in Florida, the space agency’s premier launch site. About 200 people work in the Commercial Crew Program for NASA, with almost half working at other NASA centers, including the Johnson Space Center in Houston and the Marshall Space Flight Center in Huntsville.

Previous approach for the Crew Transportation Systems (CTS)

In the beginning, the CTS was built by an aerospace contractor hired by the agency. The CTS was designed according the NASA's standards and its engineers and specialists oversaw every aspect of the spacecraft, its support systems and operations plans necessary to carry astronauts into orbit.
Then, NASA personnel were deeply involved in the processing, testing, launching and operation of the crew transportation system to ensure safety and reliability.
Until the arrival of commercial companies, the development of spacecrafts and missions to orbit such as Mercury, Gemini, Apollo and the Space Shuttle, used this model of CTS.

Commercial Crew's Approach for Obtaining CTS

Today, NASA's engineers and aerospace specialists work closely with commercial companies to develop a CTS that can safely, reliably and cost-effectively carry humans to LEO, or the ISS, and return them safely to Earth.
Private space companies can design transportation systems, but they must meet NASA's requirements through all the development's phases and certification. Then, NASA allows a company, such as SpaceX, to use its most efficient and effective manufacturing and business operating techniques to build it. 
During a contract, a commercial company can use NASA's technical expertise and resources, but it must own its spacecraft and infrastructure. Whether or not a company uses NASA's assets, NASA's engineers will follow the development process.

Complementary Approaches to Complementary Goals      

When NASA supports the development of a new U.S. human spaceflight for LEO, its commercial partners must give a specific plans of the design and its possibilities. Also, they have to determine the private investment ratio, the milestone achievements, the success criteria and the time lines to reach it. Once an agreement is reached, NASA's expert teams for the Commercial Crew Program work closely with these companies to provide technical support and determine when milestones are met.
With the Space Act Agreements, NASA establishes the safety and the requirements for missions to the ISS. During the development phase, companies under a contract can choose to design their systems. To support the certification of these systems, NASA granted Certification Products Contract (CPC) and Commercial Crew Transportation Capability (CCtCap) contracts.

Commercial Development with Space Act Agreements

NASA uses the Space Act Agreements to achieve, reliable and cost-effective access to and from LEO for commercial customers. This program is for domestic companies capable of developing U.S. human spaceflights.

Commercial Crew Development Round 1 (CCDev1)

When NASA retired the Space Shuttle, the U.S. lost its capacity to access on a regular basis the ISS and the space. So, the private industry's ability to provide a new access to the ISS was of national interest. In 2010, NASA invested a total of nearly $50 million of the American Recovery and Reinvestment Act (ARRA) funds for CCDev1 program. The goal was to stimulate the private sector's efforts to develop and demonstrate safe, reliable and cost-effective crew transportation capabilities. 
Following the CCDev1, Blue Origin received $3.7 million, Boeing - $18 million, Paragon Space Development Corporation - $1.4 million, Sierra Nevada Corporation - $20 million and, United Launch Alliance - $6.7 million. These amount were to develop and mature systems and subsystems, such as spacecrafts, a launch vehicles, as well as environmental control and life support systems.

Commercial Crew Development Round 2 (CCDev2)

When the CCDev2 program kicked off in April 2011, NASA allocated a total of nearly $270 million to four companies to develop and demonstrate safe, reliable and cost-effective transportation capabilities. In addition to the CCDev2, the agency signed unfunded Space Act Agreements (SAAs) to establish a framework of collaboration with more aerospace companies.
As part of those agreements, NASA reviewed and provided expert feedbacks on overall concepts and designs, systems requirements, launch vehicle compatibility, testing and integration plans, as well as, operational and facilities plans. 
Following this Round 2, Alliant Techsystems Inc. (ATK), Excalibur Almaz Inc. (EAI) and, United Launch Alliance (ULA) received unfunded SAA . For the same CCDev2, Blue Origin received $22 million, Boeing $92.3 million, Sierra Nevada Corporation $80 million and, SpaceX $75 m.
To accelerate development, NASA funded an additional $20.6 million to Boeing and $25.6 million to Sierra Nevada Corporation by exercising optional milestones, which were part of their original Space Act Agreements.
In 2012, the agency extended its CCDev2 agreement with Blue Origin in an unfunded capacity. Through the agreement, the agency continued to support the development of the company's Space Vehicle and related systems.     

Commercial Crew Integrated Capability (CCiCap)

The development of three fully-integrated systems has been supported by the CCiCap. So, through the Space Act Agreements, the industry partners have developed crew transportation capabilities and performed tests to verify, validate and mature integrated designs. For those integrated systems, Boeing received $460 million, Sierra Nevada Corporation, $212.5 million and, SpaceX, $440 million.  
Later, NASA allowed an additional $20 million to Boeing, $20 million to SpaceX and $15 million to Sierra Nevada Corporation.

Supporting NASA’s Mission Needs through Contracts    

To achieve a safe, reliable and cost-effective access to NASA's astronauts to the ISS, NASA awarded contracts for the Certification of the Commercial Crew Transportation systems.
Throughout the first of a two-phase contract for this Certification, companies worked with NASA to discuss and develop data products to implement the agency's flight safety and performance requirements. This included implementation across all aspects of the space system, including the spacecraft, the launch vehicle, and the ground and mission operations. NASA awarded a total of nearly $30 million under the CPC contracts of which, Boeing received $9.993 million, Sierra Nevada Corporation, $10 million and, SpaceX, $9.589 million.      
The Commercial Crew transportation Capability (CCtCap) is the second of the two-phase for the Certification. Following that phase in September 2014, a fixed-price contract for $4.2 billion was awarded to Boeing and one for $2.6 billion to SpaceX.

To conclude

These companies below played roles in the development and certification phases of the Commercial Crew Program. Amounts are totals of all Space Act Agreements and contracts awarded to each company.
Alliant Techsystems - Participated in CCDev2, unfunded partnership.
Blue Origin - Participated in CCDev1 and CCDev2, awarded $25.6 million. Boeing - Participated in CCDev1, CCDev2, CCiCap, CPC and CCtCap, awarded $4.82 billion.
Excalibur Almaz Inc. - Participated in CCDev2, unfunded partnership.
Paragon Space Development Corp. - Participated in CCDev1, awarded $1.4 million.
Sierra Nevada Corporation - Participated in CCDev1, CCDev2, CCiCap and CPC, awarded $363.1 million.
SpaceX - Participated in CCDev2, CCiCap, CPC and CCtCap, awarded $3.144 billion.
United Launch Alliance - Participated in CCDev1 and CCDev2, awarded $6.7 million.

Sources & References

-The Commercial Crew Program:
-Details of CCDev1 partnerships:
-More details about CCDev2 partnerships: Source Selection Statement.
-More details about the Commercial Crew Integrated Capability Agreements: CCiCap Source Selection Statement.
-The Certification Products Contract: