Last February, NASA began to study about the feasible modification for putting the crew aboard on the Space Launch System. In this regard, they choose Space Launch System's (SLS) first integrated flight mission with Orion-Spacecraft, called Exploration Mission-1.

NASA resolute that SLS is practically capable of human exploration though, it has some negative points like expensive technical factors and risk. That's why NASA feels difficulty to accommodate such modification. However, NASA gets some crucial info during data analyzation which will lead them to resume their original plan for EM1.

Although, NASA is mostly preferred to initialize their SLS's EM1 mission without crewed flight and they already confirmed it. In fact, they considered this approach is the best to enable humans to move sustainably beyond low Earth orbit.

Exploration Mission-1 is the broad series of deep-space exploration missions for humans, and which eventually includes Mars. Actually, this SLS for EM1 is designed for flight test to our entire system. Practically, it isn't only challenging task but also offer the opportunity to better understand our capabilities.

William Gerstenmaier, administrator for NASA's Human Exploration told that they are considering an additional ground test for SLS's heat-shield for EM1. Besides this, they also studying the possibility of advancing the ascent abort test for the Orion launch abort system.

Apart from study, NASA also reviewed the schedule for EM-1, including production schedules across the enterprise, as a part of assessment. They also try to monitor the projected delivery time of the European Service Module, first-time production issues related delays. From these factors, NASA will try to adjust the target launch date of SLS for EM-1 mission to 2019, Geekwire reported.

Now, Flight hardware for SLS and Orion is currently in production for both the first and second missions. The structural test hardware test for SLS engine section is currently ongoing in Marshall Space Flight Center. According to NASA, Engine testing and the Orion abort attitude control system was tested in Mississippi, Maryland respectively.

Moreover, an abort motor for the Orion crew module's launch abort system will be tested in Utah very soon. Avionics of Orion have been integrated into Orion test facility near Denver and heat-shield is being installed in Kennedy Space center. In addition, all the ground system and related software, life-support system, propulsion system for SLS are in development phase.