Space Sunday: Perseverance departs, Endeavour returns

The moment of ignition as the Atlas V booster lifts-off from SLC-41 at Canaveral Air Force Station, Florida, Thursday, July 30th, 20020. Credit: NASA TV

At precisely 11:50 UTC (7:50am EDT) an Atlas 5 rocket thundered into near-perfect skies over Cape Canaveral Air Force Station in Florida, carrying aloft NASA’s Mars 2020 on the first stage of its 7-month trip to the red planet.

The launch marked the last of the “big three” missions to launch during the 2020 opportunity, following on the heels of China’s Tianwen-1 orbiter / lander / rover mission and the UAE’s Hope orbiter mission. Carrying the Perseverance rover and Ingenuity helicopter drone, Mars 2020 is the most scientifically complex of the three missions, and potentially set to be the longest running of all three: providing it doesn’t fall foul of any major issues, Perseverance (Or “Percy” as some have dubbed it) could be operational on Mars for 12-14 years, thanks to its nuclear power supply.

A pictorial history of NASA’s successful Mars missions from Mariner to MSL / Curiosity, together with Mars 2020 and the proposed sample return and orbital ice mapper missions. Credit: NASA

In the days leading up to departure, there had been concerns the attempt might have to be postponed thanks to the approaching Tropical Storm Isaias, but on the morning of the launch, conditions couldn’t have been better. There was, however, some pre-launch excitement on the other side of the United States, where the Jet Propulsion Laboratory in (JPL) – mission control for the mission once en route to Mars, was lightly shaken by a local 2.9 magnitude earthquake just 30 minutes prior to lift-off.

Just under 2 minutes after launch, the Atlas V dispatched its four strap-on boosters, allowing the core stage to continue towrds low earth orbit. Less then 2 minutes later, with the vehicle at an altitude of 392 km, the payload fairings were jettisoned, exposing the payload to space. The Centaur upper stage then commenced its “chill down” phase, readying its motor for operation once the Atlas core stage had detached.

BECO and separation: a camera mounted on the Centaur upper stage captures the Atlas V core stage as it falls away following separation and ignition of the EL-10 engine. Credit: NASA TV

BECO – Booster Engine Cut-Off – came 4 minutes and 20 seconds after launch, the core stage separating to allow the Centaur commence its work with and initial engine burn to further raise the vehicle’s orbit around Earth before the RL-10 motor was shut down and the reaction control system (RCS) was fired a number of times to set the stage and the payload rotating along their longitudinal axis, a move designed to ensure the payload would be spin-stabilised during its cruise to Mars.

This part of the journey started some 90 minutes after launch, on the “night” side of Earth relative to JPL. As this point, the RL-10 re-ignited, pushing the Centaur and its payload into a Trans-Mars Injection (TMI) orbit around the Sun before the two separated. As there was no “live” video of the separation, mission managers had to wait for NASA’s Tracking and Data Relay Satellites (TDRS) and Deep Space Network (DSN) on the ground to acquire a direct signal from the payload and its cruise “bus” to confirm they were safely on their way.

The Mars 2020 rover Perseverance. Credit: NASA

This TMI engine burn ensured Mars 2020 would cross the orbit of Mars, but it would do so before the planet reached the same point in space. This was because had both been on a course to intercept Mars, the Centaur booster would crash into the planet, potentially contaminating it. Instead, Mars 2020 will make two mid-course engine burns from the motors on its cruise “bus”, shifting its trajectory onto that will intercept the planet, leaving the Centaur to fly harmless by.

As well as searching for signs of ancient microbial life and advancing NASA’s quest to explore the past habitability, Mars 2020 will also form the first half of a sample return mission – as I’ve previously noted, it is equipped to leave up to 23 sealed sample containers on the surface of the planet, at least one of which may be retrieved by a future NASA/ ESA sample return mission, although such a mission has yet to be formally approved by either agency. In addition, Perseverance carries with it experiments geared towards learning more in preparation for the future human exploration of Mars.

Mars 2020 is heading for the 49km diameter Jezero Crater on the edge of Isidis Basin in the Martian Hemisphere. The crater has evidence for it once being a wet environment, including a broad inflow delta where water once flowed into the crater from the Syrtis Major uplands that is the landing site for Mars 2020. Credit: NASA

The first of these forms a part of the SHERLOC (Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals) instrumentation. Primarily designed to seek organic compounds on Mars, SHERLOC also contains five small pieces of material that might be potentially used in the outer layers of a future Marts spacesuit. These will be monitored to see how well they deal with possible corrosion by Martian dust and atmosphere under the effects of solar radiation. As a part of its duties, the Mars Environmental Dynamics Analyser (MEDA) will also study the nature of Martian dust so engineers can make better decisions about materials to be used in spacesuits and surface equipment.

Then there is MOXIE – the Mars Oxygen ISRU Experiment – designed to produce oxygen out of the carbon dioxide that makes up 96% of the Martian atmosphere.

Mars Direct (1996): proposed using 6 tonnes of hydrogen carried to Mars by an uncrewed Earth Return Vehicle (ERV) to generate 112 tonnes of oxygen and methane using the 19th century Sabatier reaction. These could then be used propel the ERV (and crew) back to Earth at the end of a mission, while the generate could continue to produce oxygen and methane during the crew’s 700-day stay on Mars after they have arrived 2 years after the ERV. Credit: Orange Dot Productions / Mars Society UK

The idea has its roots in the 1996 Mars Direct mission profile developed by Robert Zubrin and David Baker. They recognised that the biggest encumbrance to a mission to Mars was the amount of fuel required to both get a crew to Mars and then bring them back to Earth. To reduce this, they proposed using the Martian atmosphere to produce both oxygen and methane that could be used to fuel the vehicle a crew would use to return to Earth – massively reducing the mass of a mission. The same technique could also be used to provide a human crew with additional oxygen supplies and fuel for surface vehicles once they get to Mars.

MOXIE is a more modest idea, designed to produce just oxygen from the Martian atmosphere. It’s a proof-of-concept designed to produce 22g of oxygen (O2) per hour with >99.6% purity continuously for around 1230 hours. If successful, it could pave the way for a much large nuclear-powered unit to be delivered to Mars that could be used to produce a large volume of stored oxygen that could be used to produce the atmosphere for a human outpost on Mars and as the oxidiser for powering Earth return vehicles. As with the Mars Direct proposal, the system could be extended to also produce Methane fuel.

The MOXIE experiment aboard Perseverance aims to produce oxygen from the Martian atmosphere. Credit: NASA

Mars 2020 is now en route to Mars in the “cruise” phase of the mission, during which it will study interplanetary space. The next tense moment for the mission comes on February 18th, 2021, when the craft arrive at Mars, and Perseverance and Ingenuity enter the “seven minutes of terror” of the Entry, Descent and Landing (EDL) phase, which should culminate in both being safely delivered to Jezero Crater on the surface of Mars.

A Dragon Comes Home

Sunday, August 2nd, 2020 saw the Crew Dragon Demo-2 mission make its return to Earth. Launched to the International Space Station (ISS) on May 30th, 2020 (see: Space Sunday: how to fly your Dragon) carrying NASA astronauts Bob Behnken and Doug Hurley, the mission was intended to confirm the SpaceX crew dragon vehicle is ready to commence regular crew-carrying flights too and from the space station.

Since then, the vehicle has been docked at the ISS, allowing Hurley and Behnken work as a part of the Expedition 63 crew rotation. In particular, Behnken carried out four EVA space walks alongside of Expedition 63 commander Chris Cassidy, marking them as the third and forth US astronauts after Michael Lopez-Alegria and Peggy Whitson to have completed 10 EVAs during their careers.

Saturday, august 1st, 2020: Crew Dragon Demo-2 backs away from the ISS at the start of a 19-hour journey home. With the nose cap open, the forward docking hatch is visible, with the four black dots of the Draco motors that would later perform the critical de-orbit burn visible around it. Credit: NASA TV

Undocking came at 23:35 UTC (19:35 EDT) on  August 1st, 2020, 19 hours ahead of the planned splashdown, although concerns about Tropical Storm Isaias initially meant that the undocking might have been delayed to avoid rough weather and seas in the Gulf of Mexico south of Pensacola, Florida.

Following departure from the ISS the Dragon vehicle, comprising the capsule Endeavour and its service module (called the “trunk” by SpaceX) that provides long-duration power, life support and primary propulsion, raised itself up and over the ISS to allow it to “drop behind” the space station in their relative orbits prior to dropping down into a lower orbit. This formed the first of several flight manoeuvres that placed the vehicle in the correct orbit before the crew took a meal and had a sleep period.

Endeavour’s main parachutes open as it makes its return to Earth on August, 2nd, 2020. Credit: SpaceX

Final preparations for the re-entry and splashdown commenced just shy of an hour before the vehicle started its descent into Earth’s atmosphere on August 2nd, with the unclamping of the “claw” mating capsule to trunk and relaying power, fluids and atmosphere from one to the other, allowing the capsule to separate from the trunk, which was left to burn-up in the upper atmosphere. Flying free, the capsule then flipped itself over to point its nose in the direction of flight once more. This facilitated the opening of the nose cap to expose the four forward-facing Draco engines.

The latter were then used in a 11-minute de-orbit burn that placed the vehicle on a path of descent into the denser layers of the Earth’s atmosphere. Immediately following this, and still under automated control, Endeavour re-oriented itself to put its heat shield pointing into the direction of travel as the nose cone cover closed and latched. This started a 20-minute descent phase through the upper atmosphere unless Endeavour reached a point where plasma generated by the increasing friction against the atmosphere reached a maximum, blacking out all communications for a 6-minute period.

The moment of Splashdown. “Thank you for flying SpaceX!”. Credit: SpaceX

By the time the blackout ended, Endeavour had reduced its velocity from some 28,000 km/h to just 640 km/h, slowing the capsule to a point where its two drogue chutes could be deployed, stabilising the vehicle in its descent and allowing the four main ‘chutes to be deployed. These slowed the capsule during its final couple of kilometres of descent to just 25.6 km/h, allowing it to splash down precisely on target off the coast of Pensacola.

SpaceX recovery teams using fast motor boats were quickly on the scene and proceeded to carry out checks on the vehicle and the air around it to ensure it was not venting toxic gases while others chased down a recovered the main and drogue parachutes. Check-out operations on the capsule, which is designed to float upright on the water, was somewhat impeded by idiots trying to get close to it in their own power boats, but the support crew were able to rig Endeavour with a recovery harness as the main recovery ship, the Go Navigator, approached in readiness to lift the capsule aboard.

Hoisting the Endeavour aboard Go Navigator as the fast support boats keep onlookers in their own boats at bay. Credit: SpaceX

This was achieved using the a-frame hoist at the stern of the ship, which lifted Endeavour out of the water and onto a special “nest”, a platform that could move the capsule to the crew egress area, an operation completed less than 30 minutes after splashdown.  – in less than 30 minutes after splashdown. Opening the vehicle’s hatch, however was delayed as a result of small traces of potentially toxic Nitrogen Tetroxide fuel vapours from the engine burns remaining in the service space of the capsule where things like the propellant tanks, etc., reside. To avoid risk, this area needed to be purged before the astronauts could exit the vehicle.

This meant it was a further 30 minutes after splashdown that Bob Behnken, the mission pilot,  and mission commander Doug Hurley could be lifted from the the capsule and transferred to the ship’s medical area, where NASA flight surgeons carried out a post-flight medical. After this, both men were given time to adjust back to Earth’s gravity, take a show, get into more relaxed clothing than their pressure suits. They then transferred to a helicopter that rendezvoused with Go Navigator to fly them to Pensacola Naval Air Station and onward transfer to Ellington Field Joint Reserve base and the Johnson Space Flight Centre to be reunited with their families.

NASA astronaut Bob Behnken gives a thumbs-up to the video camera after being helped out of Endeavour. Credit: SpaceX

Endeavour, meanwhile, will be taken back to SpaceX facilities where it will be refurbished and  prepared for the second operational Crew Dragon flight, following NASA’s change of mind and allow SpaceX to re-use their capsules for multiple crewed flights to the ISS. In the meantime, the first operational flight of Crew Dragon is set to fly NASA astronauts Shannon Walker, Michael Hopkins and Victor Glover, together with Japanese astronaut Soichi Noguchi to the ISS in September 2020.

Space Sunday: supergiants on camera and more to Mars

Are they stars? No, they’re a pair of exoplanets 310 light years away. Credit: ESO/Bohn et al, 2020

The above picture may not look that spectacular, just a couple of stars against the backdrop of space – exception the two disks it shows are not stars, they are planets – exoplanets, in fact, orbiting a star 310 light years away. As such, it is the first visible light photograph of multiple planets orbiting a Sun-like star taken from Earth.

Called TYC 8998-760-1, the star in question is of the G2V spectral class, and the closest Sun-like star to the solar system. However, whereas the Sun is some 4.6 billion years old, TYC 8998-760-1 is a mere stripling – just 17 million years old. It lies within the southern hemisphere constellation of Musca – a constellation which though small, contains a number of notable stars including Alpha, Beta, Gamma and Zeta Muscae, part of a group of hot blue-white stars that seem to share a common point of origin and motion within the galaxy, HD 100546, a blue-white Herbig Ae/Be star that is surrounded by a complex debris disk containing a large planet or brown dwarf and possible protoplanet, and  Theta Muscae, a triple star system, the brightest member of which is a Wolf–Rayet star.

The image was taken by the European Southern Observatory’s (ESO) Very Large Telescope (VLT) using the Spectro-Polarimetric High-contrast Exoplanet REsearch instrument (SPHERE). This instrument utilises a coronagraph to block out much of the light from a star, allowing the light reflected by any planetary bodies to be visible.

TYC 8998-760-1 is an interesting planetary system for a number of reasons. Given the relative youth of the parent star, it might be said that the system represents a glimpse of the early formation of the solar system. However, it is on a scale far vaster than our own. Both of the planets are gas supergiants, the innermost, called TYC 8998-760-1 b, being some 14 times the mass of Jupiter, whilst the outermost, TYC 8998-760-1 c, is around 6 times Jupiter’s mass. Both also orbit their parent at incredible distances in comparison to the planets of our own system:  TYC 8998-760-1 b averages 162 AU (1 AU being the average distance the Earth is from the Sun), and TYC 8998-760-1 c averages some 320 AU. By comparison, Neptune, the most distant of our major planets, averages a “mere” 30 AU from the Sun.

The complete image captured by the SPHERE instrument on ESO’s Very Large Telescope, showing the star TYC 8998-760-1 above centre, left, with three additional stars above it and its two supergiant planets below (arrowed). This image marks the first time astronomers have directly observed more than one planet orbiting a star similar to the Sun. Image Credit: ESO/Bohn et al, 2020.

These vast distances make both planets curiosities: exoplanets that are large and orbiting far from their host stars are very difficult to fit into the protoplanetary and accretion disk model(s ) that are generally used to explain planetary formation. Further, both planets appear to occupy relatively stable, circular orbits. Astronomers believe this could indicate that the two planets formed more-or-less where they are now and their near-circular orbits may indicate the presence of a still-to-be discovered third large body orbiting even further from the star (and TYC 8998-760-1 c was unknown prior to SPHERE capturing it) – or that their orbits might indicate their are the result of very specific ejections from an unseen stellar companion to  TYC 8998-760-1.

Further study is required to determine exactly how the planets may have formed, but their presence does raise the questions on whether smaller, rocky planets might orbit closer to the star – possibly within its habitable zone. As it is, SPHERE’s ability to gather data on planets has yielded a lot of information on the two gas giants that will keep astronomers busy. And while this is only the third image of exoplanets currently on record, with the upcoming generation of high-powered Earth and space-based telescopes, that number will increase over the coming decades.

Heavenly Questions En-route to Mars

The Long March 5 carrying China’s Tianwen-1 mission to Mars lifts-off on July 23rd. Credit: CCTV / China National Space Agency

In my previous Space Sunday update I covered the launch of the UAE’s Hope mission to Mars, launched as that article was being written, and the (then) forthcoming launch of China’s ambitious Tianwen-1 (“Quest for Heavenly Truth” or “Questions for Heaven”) orbiter / lander / rover mission.

At that time, it wasn’t clear just when China’s mission would lift-off, but going on past launches of the Long March 5 booster that would be hefting the mission away from Earth have generally been within 6 days of the rocket being delivered to the launch pad, speculation was that the Tianwen-1 launch would come in he week of July 20th through 24th, given its launcher arrived on the pad on July 17th.

A view of the Long March 5 booster ascending to orbit, showing the dual exhaust configuration of its first stage boosters. Credit: CCTV / China National Space Agency

Those speculations proved to be correct, because Long March 5 launch Y4 took to the skies from the Wenchang Satellite Launch Centre on Hainan Island in the South China Sea, at 04:41 UTC on the Morning of July 23rd (11:41 local time).

Continue reading “Space Sunday: supergiants on camera and more to Mars”

Space Sunday: a Martian Hope and Heavenly Questions

An artist’s impression of the UAESA Hope satellite in orbit around Mars. Credit: Mohammed bin Rashid Space Centre

late July and early August mark the period of the 2020 Mars opposition launch window, once again offering opportunities to send missions to the Red Planet. This period occurs once every 26 months, when the orbits of Earth and Mars are both on the same side of the Sun (so Mars and the Sun are on “opposite sides” of Earth, hence the name “opposition”) and positioned relative to one another (with Earth “catching up” with Mars as they both move around the Sun) such that the flight time from Earth to Mars is at its shortest – around 6-7 months.

Because of this, these periods tend to be fairly busy, and 2020 is particularly so, with three missions heading for Mars. The most prominent of this missions in terms of publicity is NASA’s Mars 2020 Perseverance rover, scheduled for a July 30th 2020 launch. The second is China’s ground-breaking orbiter / lander / rover mission (of which more below), whilst the third  – and first to launch – is possibly the most overlooked of the three: the Hope, or Al-Amal, orbiter mission developed by the United Arab Emirates.

Hope under assembly at the Mohammed bin Rashid Space Centre (MBRSC). Credit: MBRSC

Hope is a remarkable mission for the UAE; the mission was announced in 2014, literally as the country formed its fledgling space agency, employing just 75 people – a number that has since grown to 150. At that time the UAE had developed and flown – in partnership with other nations – a total of 5 communications satellites and two Earth observation platforms, so the idea for the country’s new space agency setting its sights on Mars was seen as incredibly ambitious.

However, over the course of the last six years the United Arab Emirates Space Agency (UAESA) has worked steadily on the the project, and has drawn on space development expertise in France, Japan, the UK and USA both for its own development and for the Hope spacecraft, moving the project forward and at minimum cost – just US $200 million.

The Mohammed bin Rashid Space Centre, Dubai, UAE, headquaters for the Hope mission and the UAE’s space efforts, on the night of the Hope mission launch. Credit: UAE television

Roughly cubic in shape, Hope measures 2.37m wide and 2.90m in length and has a mass of just under 1.4 tonnes (including its propellant fuel load). Solar-powered, it is billed as the “first true weather satellite for Mars” and is intended to develop a complete picture of the Martian atmosphere.

To do this, the satellite has a primary mission period of a full Martian year (approx. two terrestrial years), with the option for mission extensions through to 2025. During this time, the spacecraft will study the Martian climate and weather on a daily basis from a 55-hour equatorial orbit around the planet that will vary between 20,000 and 43,000 km from the planet’s surface. This high orbit will afford it the best view of weather patterns in both the northern and southern hemispheres, and observe how weather patterns interact along the equatorial regions of the planet. In particular, Hope will be able to study seasonal weather  / climate cycles and record weather events in the lower atmosphere such as dust storms, and the weather at different geographic areas of Mars.

To achieve this, the mission carries a relatively modest number of science packages compared to other missions, comprising:

  • The Emirates eXploration Imager (EXI): developed with assistance from two US research facilities, this is a multi-band camera capable of taking high resolution images with a spatial resolution of better than 8 km. Equipped with a set of 6 filters, it can image in both RGB colour wavelengths and in the ultraviolet bands, and measure properties such as water, ice, dust, aerosols and abundance of ozone in the Martian atmosphere.
  • Emirates Mars Infra-red Spectrometer: developed with the assistance of the Arizona State University, this is an interferometric thermal infra-red spectrometer. It is designed to examine temperature profiles in the Martian atmosphere and record ice, water vapour and dust in the lower to mid-level of the atmosphere.
  • Emirates Mars Ultraviolet Spectrometer (EMUS): is a far-ultraviolet imaging spectrograph for measuring global characteristics and variability of the Martian thermosphere.

As well as carrying out a genuine science mission that will produce data that will be of significant use for future missions up to and including eventually sending human to Mars, Hope is also seen as an inspirational programme intended to “send a message of optimism to millions of young Arabs” and encourage them to consider careers in science, technology, engineering and maths (STEM).

Nor, given the traditional conservative nature of Arab nations, is this inspirational element of the mission directed solely at young men: the deputy project manager and lead science investigator for the mission is Sarah Amiri, who is also is the Chair of the United Arab Emirates Council of Scientists. She has managed the mission’s objectives and overseen the development and integration of the mission’s science packages, and and will continue in that role throughout the mission. Her role is seen as pivotal to encouraging other Arab nations in allowing women greater access to leadership roles and in encouraging young Arab women to consider STEM-based studies and careers.

Left: the H-IIA launch vehicle on the pad at T -25 minutes before launch on Sunday, July 19th. Right Top: Hope mission managers watch the launch preparations from the main control centre at the Mohammed bin Rashid Space Centre while (right lower), engineers monitor data being received from the satellite.

Continue reading “Space Sunday: a Martian Hope and Heavenly Questions”

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: 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: Mars rovers, molecules & 1.8 billion pixels

NASA’s Mars 2020 rover. Credit: NASA/JPL

It might look like the Mars Science Laboratory (MSL) rover Curiosity, but the vehicle seen above (in an artist’s impression) is in fact the Mars 2020 rover that is due to be launched on its way to the red planet in July of this year to arrive in early 2021.

Based on the chassis, body and power plant used by Curiosity, the 2020 rover is a very different vehicle that is tasked with very different roles. And now the 2020 rover has a name as well: Perseverance.

The name was selected following a US national competition in which K-12 students (kindergarten through to 17-19 years of age) were invited to suggest a name for the rover in essay form ( a practice NASA has taken with a number of missions to Mars, including the MER rovers Spirit and Opportunity and with Curiosity). From the initial entries received, NASA narrowed the choice down to nine possible names, with the public asked to cast their vote for their favourite – although the final decision on any name remained with NASA management. Those nine names were: Clarity, Courage, Endurance, Fortitude, Ingenuity, Perseverance, Promise, Tenacity and Vision, with each name identified by a single essay selected by NASA as best representing the goals of the pace agency.

The final choice of name, based on a combination of votes for the nine and an internal decision at NASA, was made by the agency’s associate administrator for science missions, Thomas Zurbuchen, who selected the name Perseverance based on an essay by 13-year-old Alexander Mather of Virginia. The formal announcement of the name was made by Zurbuchen at a special event at Alexander’s school on Friday, March 5th.

In making the announcement, Zurbuchen made note of the fact that Curiosity actually started its journey to Mars when Alexander and many of the other competition entrants were babies – or had yet to be born – citing their involvement in the competition as an example of the innate curiosity that draws us to want to explore the planets and stars around us. He also noted why he felt Perseverance was a particularly apt name for the new rover.

Yes, it’s curiosity that pulls us out there, but it’s perseverance that does not let us give up. There’s no exploration without perseverance.

Alex’s entry captured the spirit of exploration. Like every exploration mission before, our rover is going to face challenges, and it’s going to make amazing discoveries. It’s already surmounted many obstacles to get us to the point where we are today – processing for launch. Alex and his classmates are the Artemis generation, and they’re going to be taking the next steps into space that lead to Mars. That inspiring work will always require perseverance. We can’t wait to see that nameplate on Mars.

– Thomas Zurbuchen, NASA’s associate administrator for science missions

As noted above, Perseverance may look like Curiosity, but it is a very different vehicle in terms of mission and capabilities.

An artist’s illustration of the Mars 2020 rover Perseverance, showing the “turret” of science instruments at the end of the rover’s robot arm. Credit: NASA/JPL

In terms of overall science mission, Curiosity was tasked with identifying conditions and finding evidence that show that Mars may have once been capable of supporting life on its surface – a primary mission it actually achieved within three months of arriving on Mars. However, it was not actually capable of identifying whether any of that life – and we’re talking microbial life here – may still be present, or of what it might have been. Perseverance will take the next logical step in the process:  it will look for actual signs of past life, or biosignatures, capturing samples of rocks and soil that could be retrieved by future missions and returned to Earth for in-depth study.

To achieve this, Perseverance will carry a host of new science instruments and more advanced versions of some of the systems found on Curiosity, together with additional enhancements born of lessons learned in operating the MSL rover on Mars for the past 8 years.

This means that the rover is slightly larger than Curiosity somewhat heavier, massing just over a metric tonne compared to Curiosity’s 899 kg. Part of this extra weight is accounted for by the systems that allow it to obtain samples of sub-surface material and seal them in containers for possible later retrieval by sample return missions. These include a larger, more robust drilling system mounted on the “turret” at the end of the rover’s robot arm, which also in part accounts for the increase in weight of that unit from 30 kg to 45 kg.

Perseverance rover: instruments and systems

Also, while Curiosity is equipped with 17 camera systems, with only four of them colour imagers. Perseverance has 23 cameras, the majority of which are colour imaging systems. These include a suite of 7 cameras that will provide unique views of the rover’s descent and landing, including views of the parachute deployment and views of it being winched to the ground by its hovering “skyhook” platform It also has a pair of “ears” – microphones that, if they work (NASA’s past attempts to operate microphones on Mars haven’t been successful), will allow us to hear the Red Planet for the first time.

Two further key differences between the two rovers are that Perseverance has a different set of wheels that are larger and designed to better handle Martian terrain, which has taken its toll on Curiosity’s six wheels. Perseverance’s steering  has been updated to give it better manoeuvring capabilities, while the second major difference is that Perseverance has a massively updated self-driving capability. These updates mean that Perseverance will be able to map its route far better than Curiosity, calculating route options five times faster than the older rover. This will eventually seen the time required to map and plan each stage in the rover’s drive route reduced from around a day to about 5 hours. In turn, this means that while Perseverance will travel at the same speed as Curiosity, it will be able to cover more ground in the same time periods, and gather more samples over the course of its prime mission.

Continue reading “Space Sunday: Mars rovers, molecules & 1.8 billion pixels”