Space Sunday: commercial crew test flights & exoplanets

An artist’s impression of the SpaceX Crew Dragon IFA test as the SuperDraco pushes the Crew Dragon away from a malfunctioning launch vehicle. Crew: NASA / Mack Crawford

Sunday, January 19th, 2020 saw SpaceX complete a major test that should help bring their Crew Dragon vehicle much closer to the point where it can commence carrying crews to / from the the International Space Station (ISS).

The test, referred to as a in-flight abort (IFA) test saw an uncrewed Crew Dragon vehicle launched from Launch Pad 39A at Kennedy Space Centre atop a Falcon 9 rocket in what was primarily a test of the vehicle’s launch abort system, is designed to push the capsule and its crew clear of a malfunctioning launch vehicle. However, the flight also served as an opportunity to test a further update to the vehicle’s descent parachute system (marking the first time this particular type of parachute had been used on a flight) and for SpaceX to further refine its crew recovery procedures for meeting returning Crew Dragon vehicles.

All the early indicators from the test are that everything ran as expected. Following lift-off and ascent, and at 84 seconds into the flight and an altitude of around 19 km, the first stage engine cut-off triggered the simulated malfunction, causing the abort system to release the clamps attaching the Crew Dragon to the dummy upper stage of the Falcon 9, the SuperDraco engines simultaneously firing, each one generating some 16,000 lbs of thrust. These immediately powered the Crew Dragon clear of the booster, travelling at a speed of over Mach 2, just as they would when trying to get a crew away from a malfunctioning rocket during an operational launch.

The moment of lift-off: the thrice-used Falcon 9 booster with a dummy upper stage topped by the Crew Dragon test vehicle, rises from Pad 39A. Credit: NASA

With the capsule detached, the Falcon 9 continued its own ballistic flight upwards, but the open end of dummy upper stage effectively functioned like a large, open-mouthed air brake, putting huge stresses on the vehicle. These caused the booster to break up, the remaining fuel on-board igniting in an explosion the test team had been expecting.

The SuperDraco motors fired for just 10 seconds. However, this was more than enough to put the craft on its own ballistic trajectory, allowing it to reach a peak altitude of around 40 km three minutes into the flight. Shortly ahead of reaching that point, the service module – referred to as the trunk, and designed to provide power and life support to the vehicle –  was jettisoned. Then as the capsule reached the zenith of its flight, the smaller Draco manoeuvring motors fired, stabilising it as it started its descent back towards Earth, enabling the drogue parachutes to deploy.

This pair of small parachutes allowed the vehicle to properly orient itself and act as a trigger for the release of the four main parachutes – as the drogues are jettisoned, they pulled clear a hatch covering the main parachute bay, just below the docking port that forms the nose of the Crew Dragon, allowing them to deploy, slowing the craft and bringing it down to a safe splashdown.

2:24 into the flight and the service module trunk is jettisoned from the Crew Dragon. Credit: SpaceX / NASA

For crew recovery operations, SpaceX make use of two specially-equipped ships, GO Searcher and Go Navigator. Originally leased by the company from Guice Offshore (hence the GO in the name) for use in the recovery of Falcon Payload fairings, Go Searcher was extensively refitted in 2018 to manage recovery operations for Crew Dragon, gaining a new radar system for tracking incoming Crew Dragon vehicles, a new crew recovery area and medical facility for post-flight check-ups of returning crew, and an upper deck helipad for emergency medivac. Go Navigator completed a similar refit in 2019.

Ahead of the test flight, GO Searcher departed SpaceX’s facilities at Port Canaveral, and took up a loitering position on the edge of the expected splashdown zone some 30 km off the coast of Florida. Following splashdown, teams aboard rigid-hulled inflatable boats (RHIBs) raced to the capsule to start the work of safing the craft and securing it ready for recovery. During normal flight recovery work, the recovery vessel and its crew will additionally have the services of Air Force Detachment-3 to call on, an emergency team of divers and personnel trained for astronaut recovery operations. For this flight, once the capsule has been recovered the the GO Searcher’s stern deck, it will be returned to SpaceX’s facilities along with the recovered parachutes for study.

While the initial response ot the flight has been positive, post-flight review is expected to take several weeks, and NASA has pointed out that there are still a number of additional tests that need to be completed ahead of crewed flights.

The GO Searcher, of of the crew recovery ships now operated by SpaceX, undergoing sea trails following her 2018 sea trials. the ship was used to to recover the IFA Crew Dragon capsule. Credit: NASA

There are some additional system-level tests of the spacecraft’s upgraded parachutes still needed to be completed, as well as other reviews of the spacecraft. [But] stepping through that [abort test] together and making sure that we’ve dotted all the i’s and crossed the t’s before our crew demonstration flight is very, very, important We’ve got work to do, but, honestly, getting this test behind us is a huge milestone.

– NASA Commercial Crew Programme manager, Kathy Lueders

As such, no date has been confirmed for the first crewed flight – officially called Demo-2, and which will see a 2-man crew fly a Crew Dragon to the ISS, where it will remains for approximately two weeks before they return to Earth. However, should the post-flight IFA test analysis prove positive, speculation is the Demo-2 flight could be staged as early as March, with “operational” flights starting later in 2020. In the meantime, the test flight can be followed in the video below, which has a start time set to just before the Falcon 9 ignites its main engine.

Proxima Centauri: A Further Planet?

Back in August 2017, I wrote about the discovery of a planet orbiting our nearest stellar neighbour, Proxima Centauri, 4.25 light years away from our own Sun (see: Space Sunday: exoplanets, dark matter, rovers and recoveries). That planet – called Proxima b – lies within the so-called “Goldilocks” habitable zone around its parent star, the orbital range from the parent star in which conditions are “just right” for a planet to harbour an atmosphere and possibly liquid water.

However, subsequent studies suggested that overall, if the planet once had an atmosphere, it likely lost it a long time ago. However, observations have continued in an attempt to learn more about it, and as a result a second planet in the system may have been identified.

Identified in 2017, Proxima b orbits Proxima Centauri within its habitable zone. Now a new planet, Proxima c, is thought to orbit the star, well beyond the habitable zone, and probably beyond the star’s “frost line”. Credit: ESO

Planets are generally discovered using the transit method: variations in a star’s brightness caused by a planet passing between it and our observation point on Earth. However, stars don’t always shine at a constant level; there can be variations in their brightness that result from activity on their surfaces or in their coronas. These variations don’t make them variable, but do need to be understood so they can be differentiated from changes in brightness caused by the passage of any planets.

In observing Proxima Centauri, astronomers noted variations in its brightness that did not coincide with transits of Proxima B and which do not appear to be the result of stellar activity on or around the star itself – although this has not been entirely ruled out. So while it is believed they are most likely generated by a planet orbiting the star, the team responsible for the discovery have requested others check their data and the star to help positively eliminate any misidentification of stellar phenomena that may have been made.

In the meantime, they data that have been able to put together suggests the planet – called Proxima Centauri c – sits well outside the star’s habitable zone, and is likely both solid in nature and about 1.5 times the massive of Earth, likely making it slightly larger than Proxima Centauri b, but smaller than Neptune. What is particularly interesting is that if it turns out to be confirmed and identified as a rocky “super Earth”, it could challenge current models of how such planets evolve, as it exists well outside the so-called “frost line” for the star, and the zone within which solid planets are thought to be able to form.

Boeing Issues Starliner Video

One thing NASA and SpaceX have down to a “T” is video coverage of their flights. As seen with the SpaceX Crew Dragon IFA test, cameras mount on their vehicles capture and live stream launches as a matter of course, showing vehicle exterior shots and – where interesting – internal shots as well.  Boeing, however, isn’t up to the same speed. Take the December 2019 test flight of the CST-100 Starliner. While we could witness the launch and ascent of the booster and capsule, it was disappointing in that there were few shots from cameras mounted on the rocket, and no footage was streamed from inside the capsule.

On January 15th, Boeing sought to correct this by releasing a 3-minutes video of highlights from the flight, recorded by several cameras, one looking outwards through the flight deck window, and two showing interior angles of the crew cabin – one a low angle shot of the seats occupied by “Rosie the rocketeer”, the sensor-laden flight test dummy, and by Snoopy, and other a more general view of the cabin, including the payload packages intended for the ISS crew had the vehicle made a successful ISS rendezvous.

Inside the CST-100 Starliner (now christened Calypso by the first operational crew that will fly it to the ISS in a future mission). On the right is the sensor laden flight test dummy “Rosie the Rocketeer” with Snoopy beside her. Top left is the airlock hatch that connects to the vehicle’s docking adapter. Credit: Boeing

The the view through the window is a little boring until after the ascent cover is jettisoned some 47 seconds into the video, but the low-angle shot from within the cabin does show the airlock hatch for the forward docking port used to move between the Starliner and the space station when the two are docked.

highlights of the video include the ascent cover jettison, orbital views out of the window, Snoopy bouncing around (tethered to his seat) in micro-gravity as the manoeuvring motors misfire as a result of the timing anomaly that prevented the vehicle reaching the ISS (1:10), Earth and Moon rise (1:56), atmospheric re-entry (2:02), and the deployment of the main parachutes, starting with a pyrotechnic flash as the cover for the parachutes is jettisoned (2:30) and the navigation strobes reflecting of the main ‘chutes as the Starliner descends for its touchdown.

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