Space Sunday: helicopters, craters and a sunny ISS

A perspective view of Korolev Crater, Mars. Measuring 82 kilometres across and located in the northern lowlands, this image of the crater was digitally created from pictures taken by the European Space Agency’s Mars Express orbiter. Story below. Credit: ESA / DLR / FU Berlin

Later this month an Atlas V launch vehicle should depart Canaveral Air Force Station at the start of what will be a 6+ month cruise to Mars for its payload, the Mars 2020 rover Perseverance. A twin to the Mars Science Laboratory (MSL) rover Curiosity that has been operating on the red planet since 2012, the Mars 2020 vehicle carries a range of updated systems and a science package designed, among other things, to investigate the possibility of past life on Mars, and the potential for preservation of biosignatures within accessible geological materials.

I’ll have a lot more to say about the rover – already nicknamed “Percy” in some circles – but here I’d like to focus on the rover’s travelling companion, Ingenuity, the perfectly named Mars helicopter.

Weighing just 1.8 kilogrammes, Ingenuity will make the trip to Mars mounted on the underside of Perseverance, where it will sit until such time in the rover’s surface mission – probably around the 60-day mark – will hopefully be in a position to deploy the helicopter ready to undertake up to five flights under its own power.

Mars Helicopter Ingenuity. Credit: NASA/JPL

The helicopter is very much a proof-of-concept vehicle, but if it proves successful, it will pave the way for future helicopter drones to assist in Mars surface missions. Such drones could, for example, be used to provide better terrain images and mapping when planning routes for future rovers to take, scout locations that may be suitable for more detailed study by rovers, and even undertake the recovery of samples obtained by other missions and left for collection, and return them to the craft that will carry them back to Earth for analysis.

Such future helicopter systems would likely be larger and heavier than Ingenuity, and capable of carrying their own science packages for use for studying things like the atmosphere around them. Further, their use is neither restricted to automated missions or to Mars. There is no reason why, if successful, Ingenuity shouldn’t pave the way for helicopter drones that could be used in conjunction with human missions on Mars, or in automated missions to Titan.

First, however, Ingenuity has to safely get to the surface of Mars – and that means experiencing the same “seven minutes of terror” of the entry, decent and landing (EDL) phase of the rover’s. mission. After that, it has to survive 60 days slung under the rover’s belly, with just 13 centimetres clearance between its protective shield and whatever is under the rover before it is liable to be a a location where it can be deployed. And then the fun begins.

Ingenuity stowed under Perseverance. The blue arrow shows the rotor mechanism, the red the helicopter’s body, as it sits on its side under the rover. Credit: NASA/JPL

Ingenuity has to be placed on ground that is relatively flat and free from significant obstacles – an area roughly 10 metres on a side. The shield protecting the helicopter will then be dropped by the rover at the edge of the location, and checks will be made to confirm the shield has fallen clear of both helicopter and rover and that the helicopter’s systems are in working order, a process that will take several days. After this, the rover will be commanded to roll forward several metres in readiness for actual helicopter deployment.

After this, the actual deployment process can commence. Due to its shape, the helicopter is stowed on its side under the rover, relative to the ground. This means the locking system that holds it in place must be released to allow the helicopter to drop through 90º, bringing two of its landing legs parallel to the ground. The remaining two legs will then be released to drop and lock into position, a the helicopter itself released from its restraining clips and literally drops down to the ground, and the rover drives clear, leaving Ingenuity to go through final checks head of its first flight.

The reason the helicopter is carried horizontally under the rover is because its rotor system makes it taller than it is wide, and the engineering team didn’t want to complicate the design by making it such that rotors would have to be unpacked / unfolded / deployed; they are instead ready for use once the helicopter is upright.

Ingenuity has two contra-rotating main rotors, one above the other. These not only provide lift and motion; the fact that they are contra-rotating means they each cancel the torque they would each induce in the helicopter’s body, something that would otherwise require a tail rotor to prevent it from also spinning when flying.

Once ready to go, Ingenuity is expected to fly up to five times, as noted, reaching heights of between 3 and 10 metres and potentially covering 300 metres per flight. Data from each flight will be shared from the helicopter and the rover using the Zigbee wi-fi low-power communications protocol, with Perseverance acting as the helicopter’s communications relay with Earth. Cameras on the helicopter should also provide the first ever bird’s eye view of low-level flying above Mars.

An artist’s impression of Ingenuity flying free of Perseverance, seen in the background. Credit: NASA/JPL

Continue reading “Space Sunday: helicopters, craters and a sunny ISS”

Space Sunday: SpaceX and a rapid round-up

Starship SN7 rises briefly through a cloud of super-cold nitrogen gas after the base of the tank ruptured during a deliberate over-pressurisation teat, June 23rd. Credit: LabPadre

SpaceX has had a busy week. Following the loss of the Starship prototype SN4, the company has been pushing ahead with the construction of prototypes SN5 and SN6 – one of which is likely to complete the first flight tests for the vehicle.

These prototypes look a little odd to some, resembling little more than steel cylinders. This is because SpaceX is currently focused purely on the vertical ascent / decent capabilities of the vehicle, and for this they only need the section of the hull that contains the fuel tanks and the raptor motors. Experience in flying the smaller Starhopper vehicle demonstrated there is no need to include the vehicle’s upper sections or the dynamic flight surfaces – although these will be added as the test flights become more ambitious and broader in scope.

Starships SN5 and SN6 under construction at the SpaceX Boca Chica Midbay building: Credit: SpaceX

Also following the destruction of the SN4 prototype, the company started work on the SN7 vehicle. This caused some speculation as to where it might fit in the test vehicle series. Might it be the start of a prototype that does go on to include the said upper sections and flight surfaces? Was it being built in case SN5 or SN6 went the way of SN4 and SN3?

As it turned out, SN7 was constructed specifically for further tests on tank pressurisation. On June 15th, 2020 the tank, mounted on a test stand was filled with liquid nitrogen (used in testing because it mimics the super-cold temperatures of the propellants the tanks will eventually contain, and so exposes the tank to the same temperature stresses, but if the tank ruptures, it will not explode) to its maximum pressure. It resulted in a slight leak developing, which was repaired. Then, on June 23rd, the tank was once more filled with liquid nitrogen – but this time to a pressure well beyond it would have to face when in use during a launch.

With nitrogen gas still roiling on the ground, Zeus, the robot dog (arrowed) goes in to check the area around the wrecked SN7 tank. Credit: LabPadre

The results were spectacular: an initial rupture occurs in the lower half of the tank, instantly expand into a tear along its base seam that released the liquid nitrogen in such bulk and pressure that it instantly vaporised en masse, venting with a force that lifted tank and test stand sideways off the ground. Immediately after the incident, SpaceX deployed their newest team member, Zeus.

A robot “dog” developed by Boston Dynamics (which they generically call “Spot”), Zeus is being used by SpaceX to assess potentially hazardous situations around the Boca Chica test site – in this case, the ground conditions following exposure to so much liquid nitrogen that took time to completely boil off. In typical SpaceX humour, the company has even erected a large Snoopy-style dog house on the grounds that’s allegedly the robot dog’s home.

And aerial view: the remnants of SN7 can be seen on their side, the test stand attached. The grey area “below” it is the concrete base on which it stood. A second test stand sits “above” the wreck. Credit: RGV Aerial Photography

One of the reasons for taking the test beyond limits was to check the steel used in SN7’s construction. Earlier versions of the Starship prototypes had been built with 301 stainless steel, but the company has opted to switch to the stronger 304L, and the degree to which the tank stood up to the test is being seen as indicative that the 304L is structurally a better choice.

Also during the week, NASA announced that the Crew Dragon currently docked with the International Space Station will likely return to Earth at the start of August 2020, with its crew of Robert Behnken and Douglas Hurley. Its return will pave the way for the first “operational” crew Dragon launch, which will carry astronauts Michael Hopkins, Victor Glover, Shannon Walker (commander) and Soichi Noguchi to the ISS at the end of August or early September.

Starship prototype SN5 being raised on to its test stand. In the foreground is the Spacehopper. Credit: BocaChicaGal

In a separate announcement, the agency further indicated that in a change to their requirements, they will in future allow SpaceX to make use of re-used Falcon 9 first stages in Crew Dragon launches. Previously, the agency had specified that each crewed mission must take place using a new Crew Dragon and new Falcon 9 launcher. The change came after a second Falcon 9 first stage successfully completed its fifth launch and landing.

Continue reading “Space Sunday: SpaceX and a rapid round-up”

Space Sunday: a ring of fire, 6 billion Earths and an FRB

The “ring of fire” of the June 21st annular eclipse as seen from Taiwan. Credit: unknown, distributed via Twitter.

For parts of East Africa, the Middle East and Asia, the 2020 summer solstice of June 21st was marked by an annular eclipse of the Sun.

Solar eclipses – when the Moon passes between the Earth and the Sun – take a number of forms, of which the most spectacular is, of course, a total eclipse. These occur when the distance between the Earth and the Moon is such that entire disk of the Sun is covered by the Moon, and the Moon’s shadow – called the umbra – falls directly onto the Earth’s surface, reducing the landscape directly below it to a state of dusk-like darkness called Totality. And just before that period of Totality, that can last several minutes, the solar corona is displayed as a beautiful halo of pearly white light.

A combination of pictures showing the June 21st eclipse as seen from (top l to r) Kurukshetra, Allahabad, Bangalore; (bottom l to r) Kolkata, New Delhi, Bangalore. Credits: Jewel Samad, Manjunath Kiran, Sanjay Kanojia, Dibyangshu Sarkar, Sajjad Hussain/AFP via Getty Images

However, as the Moon’s orbit around the Earth is elliptical rather than circular, for a total eclipse to occur, the Moon needs to be around 379,100 km from Earth. At this distance, the conical shadow of the Moon (the umbra) is sufficient for us to witness Totality. When the Moon is further away from Earth – say at the 381,500 km of the June 21st, 2020 event – , we have an annular eclipse, in which the Moon’s umbra “falls short” of reaching the Earth’s surface. This means that only around 99-99.5% of the Sun’s disk is covered by the Moon when observed along the path of the umbra, leaving the Sun and Moon appearing as a “ring of fire” hanging in the sky. It is this “ring of fire” that makes an annular eclipse the second most spectacular type of solar eclipse.

The needle of the Burj Khalifa, Dubai, magnificently set against the backdrop of the June 21st 2020 eclipse. Credit: unknown, distributed via Twitter

This particular event began at 03:45 UTC on June 21st, 2020, with the Moon “cutting in” to the disk of the Sun, and ended at 10:34 UTC as the Moon moved clear of the Sun. However, the period of maximum eclipse – the time at which the “ring of fire” might be seen – occurred at 06:54 UTC and was visible along a narrow track of the eclipse path just 21 km wide for around 35-60 seconds. Even so, it was still spectacular for those who witnessed it.

For people north and south of this narrow band of passage, the eclipse varied in nature from a partial ring of fire (where the disk of the Moon is jut off-centre enough relative to the Sun for the ring not to be completed) to a partial eclipse (where the disk of the Moon partially sits between the Earth and the Sun, but leaves a fair amount of the latter visible.

As direct viewing of the Sun is dangerous, ahead of the event, Astronomers Without Borders – a global group based out of the United States – worked with regional governments and astronomical groups and societies in Africa to get 16,000 pairs of solar glasses distributed to help people view the eclipse safely. For those well outside the path of the event who wished to witness it, the eclipse was streamed through You Tube and other platforms by a number of organisations such as SLOOH.

The track of the June 21st 2020 eclipse. The central orange band marks the track  along with the “ring of fire” could be seen. Credit: timeanddate.com

Eclipses are seasonal in nature, and generally occur in pairs: one lunar – when the Earth is between the Sun and the Moon, so that the later moves within the Earth’s shadow. This annular solar eclipse was preceded by a penumbral lunar eclipse on June 5th. However, and somewhat unusually, it will be followed by a further penumbral lunar eclipse on July 4th / 5th. A penumbral eclipse is one where the Moon is only within the outermost extent of the cone of Earth’s shadow, dimming it as it reflects the Sun’s light, rather than blocking sunlight falling on it entirely.

The next pair of eclipses will take place in November / December 2020, with a penumbral lunar eclipse on November 30th and a total solar eclipse visible from Chile and Argentina occurring on December 14th. For now, here’s a video of the June 21st event.

Six Billion Earths?

A new study from the University of British Columbia estimates that there could be as many as six billion Earth-type planets in the Milky Way galaxy orbiting within the habitable zone of stars with the same G_Type spectral class as our own Sun.

This may seem a surprisingly high number, but it requires context. In this case, it is estimated our galaxy has 400 billion stars of which some seven percent are G-Type. This means that if the study’s findings are correct, Earth-type planets orbiting in the habitable zone of G-Type stars averages out as just 0.18 per star.

Could Earth have as many as 6 billion “cousins” orbiting G-Type stars? Credit: NASA

The study findings are based on extrapolations from the data on 200,000 stars in the Kepler Space Telescope catalogue, with some adjustments to calculations.

The adjustments were required because Kepler used the transit method of exoplanet detection: watching for regular dips in a star’s brightness. However, given that a large planet will cause a correspondingly greater dip in a star’s brightness than one the size of Earth, the Kepler data is naturally biased towards finding larger planets. Further, it is possible that the dips caused by Earth-sized worlds could be mistaken for transient data rather than actual planets. So to handle things, Michelle Kunimoto, one of the researchers in the study used a technique called forward modelling.

I started by simulating the full population of exoplanets around the stars Kepler searched. I marked each planet as ‘detected’ or ‘missed’ depending on how likely it was my planet search algorithm would have found them. Then, I compared the detected planets to my actual catalogue of planets. If the simulation produced a close match, then the initial population was likely a good representation of the actual population of planets orbiting those stars.

– Michelle Kunimoto, University of British Columbia

Continue reading “Space Sunday: a ring of fire, 6 billion Earths and an FRB”

Space Sunday: a touch of astronomy

 

Images of Proxima Centauri (l) and Wolf 359 (r) captured by NASA’s New Horizons spacecraft 7 billion km from Earth, are overlaid against images taken of the two stars from Earth-based telescopes, showing how the stars appear to “move” depending on the viewpoint. Credit: NASA

For the first time in history, a spacecraft has been used to demonstrate parallax as it applies to the stars – and in the process, underlining the fact that the constellations beloved of astrology are little more than a matter of line-of-sight as  seen from Earth.

The spacecraft in question is New Horizons, the mission that performed a fly-by of Pluto in 2016, and which is now some 7 billion kilometres from Earth – far enough to give it a unique view of the heavens around our solar system. On April 2nd/23rd, 2020 the spacecraft was commanded to turn its telescope on two of our nearest stellar neighbours, Proxima Centauri and Wolf 359 (a star doubtless familiar to Star Trek: The Next Generation), some 7.9 light years from Earth, to take pictures of both.

When compared to images of the two stars as seen from Earth, those from New Horizons clearly show how differently the two appear against the background of other stars when seen from different points of observation that are sufficiently far apart.

The New Horizons spacecraft. Credit: NASA

Use of parallax is a common astronomical exercise, used to measure the distance of stars from Earth. However, up until the New Horizons experiment, the average separation between points of observation have been opposite sides in Earth’s orbit around the Sun – or a mere 297,600,000 km apart when averaged out. That’s far enough to allow for an accurate measurements of other stars, but not far enough to show how differently a star might appear from different points in the sky.

It’s fair to say that New Horizons is looking at an alien sky, unlike what we see from Earth.nd that has allowed us to do something that had never been accomplished before—to see the nearest stars visibly displaced on the sky from the positions we see them on Earth.

– Alan Stern, Principal Investigator, New Horizons

For the experiment, the images from New Horizons were compared with images captured by the Las Cumbres Observatory, Panama, operating a remote telescope at Siding Spring Observatory in Australia, and from the Mt. Lemmon Observatory in Arizona, both of which imaged the stars on the same night as New Horizons captured its images, so as to provide a direct comparison.

Witnessing the Birth of Stars

The Rho Ophiuchi cloud complex is a dark nebula of gas and dust that is located 1° south of the star ρ Ophiuchi in the constellation Ophiuchus. Some 460 light-years from Earth, it is one of the closest and active start-forming regions to the Sun.

It’s called a “dark nebula” because the dust cloud is so dense, visible light from stars within it is almost completely obscured. However, astronomers using the Atacama Large Millimetre/submillimetre Array (ALMA) have found something of interest within the cloud.

Two infra-red images of the Rho Ophiuchi nebula showing the IRAS 16293 system within it, as captured by ALMA showing (l) what was thought to be a binary system of stars (A and B), and a closer view of A (r), revealing its own binary nature. The two stars of A re some 54 AU apart. All three stars are surrounded by accretion disks, with the energised dust surrounding the A stars also visible. Credit: Maureira et al

The item in question is IRAS 16293-2422, a system that has a long history of being observed in the infra-red. However, it had been thought the system comprised a binary pairing of protostars, simply referred to as A and B some 700 AU apart. However, the new study has revealed that the star known as A is actually itself a pair of stars, now called A1 and A2. They are both of similar in mass to the Sun – A1 being slightly smaller, and A2 around 1.4 times larger, and each is surrounded by its own accretion disk from which it is drawing material.

These stars and their disks have certain fascinating aspects. The first is that they are only separated by a distance slightly greater to that of Pluto when at aphelion relative to Earth. They also complete an orbit around one another one every 360 terrestrial years. In addition, the accretion disks around A1 and A2 are also unique.

Detailed view of the binary protostar system within IRAS 16293-2422 and with a size comparison to our solar system. The separation between the sources A1 and A2 is roughly the diameter of the Pluto orbit. The size of the disk around A1 (unresolved) is about the diameter of the asteroid belt. The size of the disk around A2 is about the diameter of the Saturn orbit. Image Credit: © MPE

Both disks are extremely active, filaments of matter streaming into the stars at the heart of each, and further filaments of dust flowing into the disks from the nebula. In addition, the disk around A2 disk appears to be oddly inclined compared to the disks around A and the more distant B, suggesting complex interactions may be at play around it. The disk also appears to have parts rotating in opposite directions relative to one another, the first time such a phenomenon has been seen in a protostar accretion disk. It suggests that should planets eventually form around the star, those nearer to it may orbit the opposite direction to those further out.

Organic scans of the disk also detected glycolaldehyde — a simple form of sugar – and Chloromethane, also called methyl chloride, an important biomarker, together with Carbon Sulphide, Isocyanic Acid, Formamide, and Formic Acid. The presence of the organics is important as it shown that the basic building blocks of life can exist within the accretion disks around stars, and so may be available when the remnants of that disk forms planets.

It’s not clear if / when the formation of either star may reach a point of nuclear ignition, or how such an event might affect the other. However, their confirmation provides astronomers with a first-hand opportunity to witness the earliest stage in the process of stellar evolution.

Continue reading “Space Sunday: a touch of astronomy”

Space Sunday: moving a mole and Planet Nine

InSight’s scoop gently presses against the top of the “mole” of the HP³ experiment, ready to gently push it down into the Martian regolith. Image Credit: NASA/JPL

NASA and its partner, the German Aerospace Centre (DLR) finally have some good news about the Heat Flow and Physical Properties Package, or HP³, carried to Mars by the InSight Lander: they’ve made some progress towards perhaps getting moving again.

As I’ve noted in past Space Sunday articles, the experiment has been a source of consternation for scientists and engineers since InSight arrived on Mars in November 2018. Following the landing, HP³ was one of two experiment packages deployed directly onto the surface of Mars by the lander’s robot arm. One of the key elements of the experiment is the “mole”, a self-propelled device designed to drive its way some 5m into the Martian crust, pulling a tether of sensors behind it to measure the heat coming from the interior of Mars.

After a good start, the probe came to a halt with around 50% of its length embedded in the soil. At first it was thought it had hit solid bedrock preventing further motion; then it was thought that the mole was gaining insufficient traction from the hole walls, on account of the fine grain nature of the material it was trying to move through. That was in February 2019.

The InSight lander was commanded to deploy the HP3 drill system on February 12th, 2019. Credit: NASA/JPL

Since then, scientists and engineers have been trying to figure out what happened, and how to get the mole moving again – because of the delicate nature of the sensor tether, the HP³ experiment couldn’t simply be picked up and moved to another location and the process started over. instead, various attempts were made to try to giving the mole material so it might gain traction.

Most of these revolved around using the scoop at the end of the lander’s robot arm to part-fill / part compress the hole created by the mole, the theory being that loose regolith would gather around the head of the mole and help it regain the necessary fiction to drive itself forward once more. Initially, some small success was had – until the mole abruptly “bounced” almost completely back out of the hole.

Further attempts were made to compress the ground around the hole, but all forward motion remained stalled, leading scientists to believe the mole had struck a layer of “duricrust” – a hard layer formed as a near the surface of soil as result of an accumulation of soluable materials deposited by mineral-bearing waters that later leech / evaporate away. These layers can vary between just a few millimetres to several metres in thickness, and are particularly common to sedimentary rock, which itself has been shown to be common on Mars.

The rub for the InSight mission is that if it is a layer of duricrust beneath the lander, it is impossible to tell just how thick it might be.

This images shows how difficult “pushing” the mole would be. The scoop (upper right) had a very small surface area at the end of the mole with which it could safely make contact, shown circled, without potentially damaging the tether harness. Credit; DLR

Earlier this year it was decided to use the scoop on the robot arm more directly, positioning it over the exposed end of the mole and applying pressure in the hope it could push the mole gently down into the ground in a series of moves that would allow the mole to get to a point were it could resume driving itself into the ground.

However, this approach has not been not without risk. The end of the mole has a “harness” – a connector for the tether, so the scoop has to be precisely positioned and any sort of pressure applied very gently and carefully to avoid any risk of slippage that might result in damage to the tether and / or harness and render its ability to gather data and information from the probe useless.

However, on June 3rd, NASA announced that a series of gentle pushes had resulted in the mole being completely below the surface, and with no apparent damage to the tether or harness. However, whether or not this means the mole is able to proceed under is own self-proplusion is unclear, as NASA noted in their tweet.

In all, the tip of the mole is now some 3m below the Martian surface. That’s deep enough for it to start registering heat flow, but to be effective, the mole still needs to drive itself down the full 5 metres. It is only at this depth that the mole and sensors can correctly start to measure the sub-surface geothermal gradient, and thermal conductivity, the two pieces of information required by scientists to obtain the heat flow from deeper in the planet. By studying the thermal processes in the interior of the planet, scientists can learn a lot about the history of Mars, and how it formed. They may also gain insights into how other rocky bodies formed.

Attempts have yet to be made to see if the mole can move under its own spring-driven propulsion, but for now NASA and DLR are rightly treating the current status of the probe as a victory. The tether harness at the end of the mole is undamaged, so if the mole can resume progress under its own power, there’s not reason why it shouldn’t start recording information.

Continue reading “Space Sunday: moving a mole and Planet Nine”

Space Sunday: how to fly your Dragon

The International Space Station imaged from 200 metres by the docking systems camera looking out of the forward hatch window of SpaceX Crew Dragon Endeavour. Credit: SpaceX / NASA

On Saturday, May 30th, 2020 the United States successfully launched astronauts into orbit from American soil for the first time since July 8th, 2011. It came after an initial attempt on May 27th, 2020 had to be scrubbed (called off) due to adverse weather conditions putting the launch vehicle at risk of a possible electrical strike.

As I noted in my previous Space Sunday piece, the primary goal of the mission is to confirm the SpaceX Crew Dragon vehicle is ready to commence operations ferrying crew to and from the International Space Station. Intended to fly up to four crew at a time on such missions, for this final test flight, Crew Dragon lifted-off with only two crew aboard: NASA veterans Robert L. Behnken (flight pilot) and Douglas G. Hurley (commander).

NASA astronauts Bob Behnken (l) and Doug Hurley, photographed at the top elevator station at Launch Complex 39A, Kennedy Space Centre, at a dress rehearsal for the Crew Dragon Demo-2 flight, May 24th, 2020. Credit: SpaceX

Weather was also a concern in the run-up to the May 30th launch, with NASA putting a chance of lift-off at 50/50 through to less than an hour ahead of the launch time. However, after a burst of rain in the area of Kennedy Space Centre as the Falcon 9 launch vehicle was being prepared for lift-off, the weather situation both around the Florida Cape and downrange of the launch site and along the track of the vehicle’s line of ascent, cleared sufficiently for the launch to go ahead.

The entire launch, from the astronauts suit-up in the crew room at Kennedy Space Centre, through lift-off, ascent to orbit, on-orbit operations and the rendezvous and docking with the International Space Station some 19 hours after launch, was covered entirely live through NASA TV and SpaceX on You Tube and other channels. This coverage made it one of the mos-watched launches of a space vehicle despite the limitations of travel in place due to the SARS-CoV-2 pandemic, with 1.5 million people watching the SpaceX relay of the NASA feed alone.

Thursday, May 21st, 2020: The Falcon 9 / Crew Dragon vehicle bearing the NASA worm and meatball logos, rolls out of the SpaceX vehicle processing building en route to pad 39A

Following their arrival at the launch pad some 2+ hours ahead of the the launch, the astronauts – known as “the Dads” to the SpaceX team – travelled to the top of the launch tower prior to ingressing into the Crew Dragon vehicle and performing a series of pre-flight checks both before and after the crew hatch was closed-out by the fight support crew.

At around an hour prior to launch and with the flight support crew clear of the tower, the access arm was rotated clear and fuelling of the Falcon 9’s first and second stage tanks commenced as the weather clearance was given. Unlike Apollo and the shuttle, the SpaceX vehicles go through fuelling as a last stage of ground operations to minimise the amount of fuel venting / topping-up that is required as the super-cold liquid propellants start to slowly warm despite insulation and cooling.

Ahead of the launch, the ISS passed over Kennedy Space Centre and this photograph was taken. Centre top is the massive Vehicle Assembly Building where the SLS will be assembled for launch and the former Orbiter Processing Buildings, one of which is now used by Boeing for the Starliner crew vehicle and another by the Orion MPCV; The crawler / transporter track runs from the VAB toward the coast, splitting so one leg runs to the right and Pad 39B, which will host the SLS, while the second runs down to Pad 39A where the white SpaceX vehicle assembly building can be seen, with the Falcon 9 on the pad. Credit: NASA

A crucial aspect of the Demo-2 launch was that orbital mechanics demanded the vehicle had to lift-off precisely on time – there could be no “holds” that delayed it beyond the appointed lift-off time. Were launch to be delayed, even by a few minutes, the Crew Dragon would reach orbit at the wrong point related to the ISS, and so and rendezvous would be much harder, if not impossible, given what needed to be achieved in the flight ahead of reaching the space station.

So, at 19:22:45 UTC, precisely on schedule, the nine motors of the Falcon 9’s first stage igniting, lifting the black-and-white rocket and capsule vehicle smoothly off the pad. This marked a further first for the mission: not only was it the first US crewed mission into space undertaken from US soil bult and operated by a private company, the entire launch process was run by SpaceX and not by NASA’s Mission Operations Control Room (MOCR – or “moe-kerr”) at the Johnson Space Centre (JSC), although the latter were obviously looking over SpaceX’s shoulder and monitoring things, with the ISS Fly Operations Centre fully “in the loop”.

A Dragon rises with its riders as the Falcon 9 clears the tower at LC-39A, May 30th, 2020. Credit: NASA live stream

Ascent to orbit lasted some 8 minutes – although to all those watching, it probably seemed a lot quicker. Powering the vehicle through the denser part of the atmosphere, the Falcon’s first stage reached MECO (main engine cut-off) just over 2 minutes after launch. Separating, this continued along a ballistic trajectory, flicking itself around to deploy vanes to help with its descent back though the atmosphere so it might make a landing on the autonomous drone ship Of Course I Still Love You.

Camera footage from the first stage, transmitted as the Falcon’s second stage continued to boost the Crew Dragon vehicle to orbit, showed it orienting itself using its attitude thrusters, prior to three of the Raptor engines firing to slow it down and cushion it as it dropped back into denser atmosphere. From here, it dropped smoothly back towards the drone ship, the deployed vanes holding it upright. Unfortunately, video footage was lost prior to touch-down, but moments later, the feed resumed, showing the stage sitting on the ship’s deck as high above, the Falcon’s second stage reached SECO – Second (Stage) Engine Cut-off, and shortly after, the Dragon separated from it.

Timing in the flight meant that the Falcon 9 first stage successfully landed on the autonomous drone ship Of Course I Still Love You (l) at almost the same time as SECO was reached by the rocket’s upper stage, followed a couple of minutes later by Crew Dragon successfully separating from the second stage (r). Credit: SpaceX

Continue reading “Space Sunday: how to fly your Dragon”