What to expect when launching Crew Dragon on the International Space Station

Jason Davis • February 27, 2019

It's finally happening. Nearly eight years after the Space Shuttle's last flight, a capable spacecraft is ready to launch again from the Kennedy Space Center in Florida. The SpaceX Crew Dragon is scheduled to take off for a 6-day unmanned test flight on March 2 at 2:49 am EST (07:49 UTC). If all goes well, the spacecraft will be moored at the International Space Station (ISS) on March 3 around 6:00 am EST (11:00 UTC) and will stay there until March 8, when it will return to Earth and will disperse in the Atlantic Ocean. off the coast of Florida.

A big freaking affair

The inaugural launch of Crew Dragon, formerly DM-1 (Demonstration Mission 1) or Demo-1 in NASA jargon, is part of a flight test mission and part of ISS operational mission, all designed to show that the vehicle can safely transport astronauts to ISS without posing any risk to the station. If successful, it will be a milestone for NASA's commercial crew program, which has been waiting for private companies to fly NASA astronauts since the George W. Bush administration first chose SpaceX and Orbital Sciences Corporation (now Northrop Grumman) for Freight Replenishment Missions to December 2008.

At that time, the rocket Ares I and Orion were about to take over the space shuttle intended for the transport of the ISS crew, but the Obama administration was merged with commercial companies by canceling the NASA Constellation program in February 2010. Space shuttles ended in 2011, leaving NASA in the precarious situation of having to pay Russia for taxi rides on Soyuz vehicles.

In 2012, NASA selected SpaceX, Boeing and Sierra Nevada Corporation as crew transportation partners, enabling companies to benefit from paid flights from the ISS. SpaceX predicted that it would launch its first crewed Dragon flight by 2015, but two launching disasters, technical problems, and insufficient budgets for NASA's commercial crews continued to push that commitment into action. l & # 39; future. The future is finally here: NASA claims that the first crewed SpaceX flight, with astronauts Robert Behnken and Doug Hurley on board, could take action in July, provided the test flight this weekend Completes all NASA test objectives without major incident.

Overview of the mission

The crew Dragon that will be launched Saturday morning is designed to work as close to a crewed spaceship as possible, without being human living and breathing on board. There is at least one seat in the capsule, carrying an anthropomorphic test device (ATD) in a SpaceX space suit, equipped with sensors to measure the forces that astronauts will experience when they actually ride Crew Dragon. The vehicle will also have onboard dosimeters to measure radiation levels.

Since Crew Dragon is heading to the ISS, NASA has decided to pack it with about 181 kilograms of cargo. This is much less than a typical cargo flight, but the shipment will include additional equipment and supplies, and the station's astronauts will return samples of cold storage to Earth upon departure. of Dragon.

Here are the official objectives of the test flight. NASA has published them informally on the blog of its sales team. So I asked them for an official list and I received this:

• Demonstration of the operation in orbit of the avionics system, the home system, communication / telemetry systems, environmental control systems (pressure, thermal, humidity, etc.), solar panels and solar panels. power supply systems as well as propulsion systems.
• Demonstrate the performance of the Falcon 9 and Crew Dragon guidance, navigation and control systems during ascent, entry into orbit and entry
• Determine the acoustic and vibration levels, as well as the loads on the outside and inside the Crew Dragon.
• Demonstration of Launch Shutter Trigger Monitoring
• Demonstrate the performance of end-to-end operations

launching

The launch procedure is almost identical to that of a Falcon 9 standard countdown, using SpaceX's accelerated fill-and-go procedure. There is barely 35 minutes between the start of fuel loading (RP-1 propellant and liquid oxygen) and the moment of ignition. The climb path will be sufficiently aggressive and the fuel load large enough so that the first floor of Falcon 9 can not return to the Space Coast. he will land on the drone Of course I still love you.

Crew Dragon departs from the second leg about 11 minutes after takeoff. Barely a minute later, he opens his articulated nose cone, which protects the vehicle's mounting hardware during launch and re-entry. There are no deployable solar panels to deploy; The Crew Dragon solar cells are integrated into the trunk of the vehicle without pressure. It does not need these larger solar panels, because Crew Dragon's power budget is lower than that of Cargo Dragon, said Hans Koenigsmann of SpaceX last week.

If the launch is cleaned up or delayed, there are 2 backup windows at 3-day intervals; after that, NASA and SpaceX may have to withdraw from the launch of Expedition 59 Soyuz on 14 March.

The reason for these 3-day intervals is due to additional launch window constraints. First, NASA and SpaceX wish Crew Dragon to reach the station in about 24 hours, due to a known problem related to the vehicle's Draco thrusters, where a portion of a thruster can – deflate – come off. The temporary solution is to keep the propeller warm in the sun with fanciful flights. (A permanent fix will be added before the crewed mission, announced last week Bill Gerstenmaier of NASA.)

Another constraint is that Crew Dragon must splash during the day so that the ground cameras can evaluate the performance of the parachutes of the vehicle. Here is the full schedule of launches, compiled from NASA press releases and email exchanges:

In orbit

Once in orbit, Crew Dragon will overtake the ISS through a series of phasing maneuvers, and will arrive at the station approximately 24 hours after launch.

There is one major difference in the way Crew Dragon and Cargo Dragon approach and connect to the ISS. Cargo Dragon approaches the station only from below, on the RBAR (radius), until it is close enough to be entered by Canadarm2, which moves it to an open port for docking.

Crew Dragon, meanwhile, does not stop, it connects directly to the international connection adapter located at the front of the station (IDA connects to pressurized coupling adapter 2, which connects to the node 2 of Harmony). Here is a rendition of Crew Dragon approaching; IDA is the white cap and PMA-2 is the sloped black tunnel connected to node 2.

According to last week's press briefing, it seems that Crew Dragon is approaching the RBAR before switching to VBAR (velocity vector), just like the shuttle. Unfortunately, from Wednesday morning, no press kit from SpaceX or NASA is available for this mission! Here is a reminder of how the shuttle method works. Note step 6, where the shuttle stopped at the translation point to perform a belly roll so that the astronauts of the dome could photograph its heat shield:

Approaching the Dragon crew, NASA astronaut Anne McClain and Canadian Space Agency astronaut David Saint-Jacques will conduct surveillance from the dome and will perform vehicle tests. Once Dragon is docked, NASA TV will cover the opening of the hatch and a welcome ceremony scheduled for Sunday.

Here is the full schedule in orbit:

Departure

After disarming on March 8, Crew Dragon will visually inspect the IDA to which he has just been connected, before leaving the vicinity of the ISS and carrying out a disoriented burn 5 hours later. Unlike Cargo Dragon, which lands in the Pacific Ocean, Crew Dragon will land a few hundred miles off the coast of Florida, where NASA will be able to recover the crew and vital cargo and bring them back ashore. less than 2 hours. For this test flight, the point of departure will be a little further away than for any crewed flights.

Both NASA and SpaceX expect problems during the test flight, but even if all goes well, Crew Dragon still has to overcome some obstacles before transporting astronauts in July. A climb-off test is scheduled for June, during which Crew Dragon will depart Falcon 9 mid-climb. SpaceX must also complete its parachute qualification tests. No less than 17 have been executed so far, but much remains to be done before NASA certifies that the vehicle is safe for the crew. Finally, NASA is still working with SpaceX to ensure that the agency is fully comfortable with SpaceX's resized Composite SVV vessels. A COPV in a second-floor Falcon 9 liquid oxygen tank was at the origin of the 2016 Amos-6 plaque accident.

As mentioned earlier, the next launch of Soyuz's crew will take place on March 14, when Nick Hague, Christina Koch and Alexey Ovchinin will join the Expedition 59 crew. Space is scheduled for late March and early April, followed by a Cygnus supply flight on April 17 and the CRS-17 Cargo Dragon mission later in the month. The Boeing Starliner test flight would likely take place later, followed by a buffer abort test in May.