Surely one of the many questions that many people asked at the launch of the Crew Dragon was: how long will Doug Hurley and Bob Behnken stay in orbit before returning home? Difficult to predict in advance for a number of reasons, so much so that those responsible for NASA and SpaceX have limited themselves to responding with a laconic: “we will only make a decision once the spacecraft is in orbit!”.
In fact, there are many limiting aspects to consider, including the wear of the Crew Dragon photovoltaic panels, the behavior of the spacecraft during orbit operations, maintenance and research activities on the International Space Station, the availability of the Crew Dragon that will fly on the first operational mission and weather conditions at the ditching site. But let’s go in order …
Former astronaut Ken Bowersox, chief executive officer of NASA’s manned mission directorate, replacement ad interim Douglas Loverro after his resignation, reported that the performance and performance of the spacecraft are what was hoped for, and that this makes it possible to extend the mission until the end of July or at the latest in August. However, it is not yet possible to provide a precise date for the return of Behnken and Hurley.
Meanwhile Bob Behnken and Doug Hurley are collaborating side by side with Chris Cassidy, NASA astronaut and commander of the International Space Station, helping him in scientific research, repairs and loading and unloading of supply vehicles. The next 26 June and 1 July Bob Behnken will be the protagonist with Chris Cassidy of two spacewalks, during which the two astronauts will replace the last batch of batteries for the accumulation of electricity produced by photovoltaic panels. We are therefore approaching the completion of the long and complex update work on these components that began in January 2017.
While Behnken and Cassidy will be outside, Doug Hurley will help them from inside the Station by carefully and precisely maneuvering the Canadarm2 robotic arm. At the moment, only two of the four planned extravehicular activities have been confirmed. Perhaps we will know more on the evening of June 24, the day when a press conference by NASA is scheduled at 8:00 pm Italian time.
In addition to providing their valuable contribution to the operations of the Station, Behnken and Hurley are carrying out a series of tests of their Crew Dragon (called “Endeavor”) together with the mission managers. It should not be forgotten that Crew Dragon Demo-2 is always, first of all, a demonstration and testing mission for the SpaceX capsule. These tests are necessary to collect as much data as possible on the spacecraft in anticipation of the first operational flight scheduled for the end of August.
A very important requirement that a crew ship attached to the orbiting laboratory must have is to be able to act as a lifeboat in the event that there is an emergency on board the station which requires its evacuation. With this in mind, SpaceX technicians intend to put the capsule into “hibernation mode”, as would normally happen in a normal 200-day mission, to then reactivate its on-board systems and ensure that it is able to return fully operational on schedule.
Although this Crew Dragon has many affinities with what will be used in the first operational mission, the two spacecraft are different. Bowersox pointed out that Endeavor has the minimum safety requirements for the most stringent return and ditching, and that NASA and SpaceX will take all the time necessary for the best possible weather conditions at the time of the return, being the first time that occurs with astronauts on board .
One of these requirements concerns the wind, which in the ditching area cannot, in certain cases, exceed 9 knots (about 16.6 km / h). Bowersox went on to state that, in August, the wind usually does not give particular concern in the two ditch areas. The main one is located about 45 kilometers from the east coast from Florida, while the reserve one is south of Pensacola, in the Gulf of Mexico.
Finally, it is not excluded that in the presence of favorable conditions the return of the Crew Dragon may be anticipated, however before establishing the exact date we wait for the completion of all the spacewalks scheduled.
Regarding the differences and improvements that SpaceX is making to Crew Dragon for the first operational flight, Steve Stich, deputy director of the Commercial Crew Program NASA released several pieces of information. First of all, the main systems of the spacecraft, such as the life support system, navigation and attitude control, will be almost the same. Among the changes underway, one concerns some external panels in composite material, which have been made more resistant allowing the spacecraft to land in stronger wind conditions. It will also be able to hook into IDA-3 (or International Docking Adapter-3), installed last year by Andrew Morgan and Nick Hague on the zenith hatch (the one facing space) of the Harmony module.
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