Space Sunday: Mars, starships, rockets and spaceplanes

A panorama of Jezero crater captured by the Mastcam-Z system on Perseverance showing the stern deck of the rover with the crater rim on the far horizon. It comprises 142 individual images taken on Sol 3, the third Martian day of the mission (Feb. 21st, 2021). Credit: NASA/JPL / ASU / MSSS

NASA’s latest rover arrived on Mars on February 18th, 2021 as the core part of the agency’s Mars 2020 mission, the rover Perseverance, arrived on the red planet (see:  Space Sunday: ‘Perseverance will get you anywhere’ and  Space update: 2020 landing video and audio of the Martian wind).  Since then, work has been continuing in commissioning the rover ready to start its science operations, and it has continued to return images of its new home in Jezero Crater. And as has now been widely reported, it gave Internet sleuths a coded message to decode.

This came in the form of the red and white markings on the mission’s supersonic parachute. Intended to provide data on how the parachute unfurled and performed, it also contained a message in binary code – something hinted at by Allen Chen, the Entry, Descent and Landing lead for the mission whist referencing the parachute’s performance during the February 22nd press briefing I reported on in the second of the two articles noted above.

In addition to enabling incredible science, we hope our efforts in our engineering can inspire others.  Sometimes we leave messages in our work for others to find for that purpose, so we invite you all to give it a shot and show your work.

– Allen Chen, the Mars 2020 EDL lead, February 22nd

With the parachute lines edited out, a graphic overlaid onto the Mars 2020 parachute reveals the hidden message (read counter-clockwise from the centre outwards). Credit: NASA

The message, in binary code, was cracked in six hours, proving to the saying Dare Mighty Things, a phrase attributed to Theodore Roosevelt, the 26th President of the United States and the adopted motto of the Jet Propulsion Laboratory, responsible for the mission, together with the latitude and longitude of JPL’s offices in Pasadena, California.

Nor is the only coded message the rover carries. While its wheels are of  an improved design over those used on the Curiosity rover – which celebrated 3,000 days of continuous operations on Mars on January 12th, 2021 – the wheels on Perseverance also carry the letters “JPL” cut into their treads in Morse code.

Other curios carried by the rover include a “family portrait” of NASA rover types that run from tiny Sojourner, which arrived on Mars in 1998 as a part of the Mars Pathfinder mission, through the twins of Spirit and Opportunity Mars Exploration Rover mission, to Curiosity and Perseverance. Like a plaque to healthcare workers around the globe, this is something of a decorative / commemorative piece.

Captured by the NavCam system, the “family portrait”. of NASA rovers from Sojourner to Perseverance. Credit: NASA/JPL / MSSS

Another of the commemorative piece son the rover is a panel on which are mounted the three microchips that contain the names of the 10,932,295 people who applied to have their name included in the mission (you can also apply to have your name included in future missions), which located on the rover’s aft cross-beam, above its nuclear power supply.

Some of the curios also fulfil a practical use. For example, the SHERLOC ultraviolet Raman spectrometer mounted on the rover’s robot arm includes five samples of materials that may be used in future spacesuits that may be used on Mars.

A cropped view of the panorama seen at the top of this article showing the location of the name-carrying microchips on Perseverance (l). On the right, the microchips shortly after being maounted on the rover’s aft cross-beam. Credit: NASA/JPL

The intent of these samples is to test how the materials in them react to the Martian environment; however one of them – made of the materials used in helmet visors contains behind it a geocache inscribed with the address of the instrument’s fictional name-sake (221B Baker Street).

Mounted on the deck of the rover is a camera calibration target. Located between the colour and reflective marks on the outer ring of the calibration target are a series of symbols representing life on Earth which is intended to reflect the mission’s primary goal of looking for evidence of past life on Mars, whilst the Mastcam-Z system on the rover includes the massage:

Are we alone? We came here to look for signs of life, and to collect samples of Mars for study on Earth. To those who follow, we wish a safe journey and the joy of discovery.

– from the Perseverance rover

The sample panel on the SHERLOC instrument includes 5 samples of spacesuit materials including, left, visor material with a geocache behind it bearing the legendary address of Sherlock Holmes. Credit: NASA/JPL

Since its arrival at Jezero Crater, Perseverance has returned thousands of images of its surroundings,   commissioning and testing continues. It’ll still be another couple of weeks or so before the surface mission properly commences. These have revealed that in coming down roughly 2km from the mid-point of its landing area – a remarkable achievement in itself -the rover has found itself in a rich geological playground, including features formed by both the passage of water and wind.

Some, such as “Seal Harbour Rock” – most likely formed by the passage of wind – already has geologist excited.

Are these volcanic rocks? Are these carbonate rocks? Are these something else? Do they have coatings on them? We don’t know  – yet. We don’t have any chemical data or mineral data on them; but, boy, they’re certainly interesting, and part of the story about what’s going on here is going to be told when we get more detailed information on these rocks and some of the other materials in this area.

– Jim Bell, School of Earth and Space Exploration, Arizona State University

A broader version of the panorama over the back of the perseverance rover, with the position of “Seal Harbour Rock”, likely the result of wind erosion, marked and the rock itself highlighted in the inset image. Credit: NASA/JPL

China Starts Preparations for Rover Landing

Having arrived in Mars orbit the week before Mars 2020 made its Martian debut, China’s Tianwen-1 mission as entered a temporary parking orbit around Mars in anticipation of landing a rover on the planet’s surface in the coming months.

Comprising an orbiter vehicle, a lander and the rover, Tianwen-1 is China’s first interplanetary mission, Tianwen-1 will remain in its new circular orbit for around 3 months. During this time the orbiter, alongside of its main science programme, will collect high-resolution images of the surface of Mars, notably of the proposed landing site for the lander/rover combination.

Released in October 2020, this image captured from a camera mounted off the end of the orbiter’s solar panels shows the gold-colour orbiter an the land / rover contained within their protective aeroshell. Credit: China National Space Administration

The landing itself will follow a similar profile to those of NASA’s Pathfinder and MER missions: after entry into the atmosphere, the lander/rover will be slowed by parachute, with the final part of the decent using rocket motors to reduce speed before airbags are inflated to protect the vehicles through landing.

If successful, the lander will deploy the solar-powered rover, which will collect data on underground water and look for evidence that the planet may have once harboured microscopic life.

Continue reading “Space Sunday: Mars, starships, rockets and spaceplanes”

Space update: 2020 landing video and audio of the Martian wind

A CGI model of the Mars 2020 rover Perseverance on the surface of Mars. Credit; NASA/JPL

On Thursday, February 18th, NASA’s Mars 2020 mission delivered the rover Perseverance, carrying the helicopter drone Ingenuity, safely to the surface of Jezero Crater, Mars (see: Space Sunday: ‘Perseverance will get you anywhere’). Sine then, the rover has been going through its initial checks, and on Monday, February 22nd, members of the mission team gave the latest update on the rover’s status, which included a unique video and an audio recording.

The video was made up of images recorded by a suite of cameras specifically mounted on the rover and its landing systems specifically with the aim of recording the landing event in as much detail as possible. These cameras comprised:

  • A pair of camera on the top of the aeroshell that protected the rover and its “skycrane” descent stage through entry into, and initially deceleration and flight through, the upper atmosphere of Mars. These were intended to capture video of the supersonic parachute deployment.
  • A single camera attached to the skycrane that looked down on to the stowed rover, designed to record the process of winching it down in its harness and then delivering it to the ground.
  • A camera up the upper deck of the rover looking up at the skycrane to record the same, and the skycrane’s departure from the landing site.
  • A camera on the side of the rover and looking down, intended to record the vehicle’s descent via parachute and its approach for landing.
The Mars 2020 EDL cameras. Credit: NASA/JPL

With the exception of one of the aeroshell cameras, which appears to have failed when the explosive “mortar” fired the parachute package clear of the aeroshell, all of these camera captured some incredible footage of the landing sequence.

Once retuned to Earth, the footage was poured over by the mission’s imaging team at the Jet Propulsion Laboratory (JPL), with elements combined with audio recorded at JPL’s mission control during the landing, to produce an incredible short film, that puts the audience right there with the rover as it landed on Mars, as you can see below.

The first part of the film showed the deployment of the parachute system. This comprised firing the 67 Kg parachute pack out of the top of the aeroshell at 150 km/h, detaching a protective cover from the aeroshell (parts of which broke off) in the process.

The aeroshell cameras capture the deployment and unfurling of Mar 2020’s supersonic parachute. Credit; NASA/JPL

The package pulled the parachute harness out behind it until it reached its full extent (about 46 metres), which caused the 21.5m diameter parachute to deploy at a time when the vehicle was still travelling at around Mach 1.75. In all, this process took around 1.5 seconds to complete.

At this point the the rover down-look camera started recording, capturing the jettisoning of the heat shield that formed the lower part of the aeroshell. This demonstrated its aerodynamic nature by falling away without tumbling, leaving the rover’s look-down camera to film the inflow delta to one side of the crater  – and the intended landing point –  as the rover and aeroshell swayed under the parachute.

The heat shield is jettisoned and falls away with great stability. Credit: NASA/JPL
Not long after this, the rover and its skycrane descent stage dropped clear of the aeroshell, the view of the ground shifting dramatically as the descent stage used its motors to  propel itself away from the areoshell to avoid any risk of collision before gently veering back to centre itself over the landing zone.

This footage – still via the rover’s down-look camera – then captures the thrust from the rocket motors as the skycrane comes to a hover some 20 metres above the ground, then there is a sharp jerk as the rover is released to be lowered to the ground by the skycrane and its harness.

As the rover is released by the descent stage, so the remaining camera systems come into play, one looking down from the skycrane as the rovers is lowered, and the other on the rover looking up as it leaves the skycrane as it hovers steadily over the landing zone.

The skycrane and the rover capture the latter’s deployment just before touch-down from opposite ends of the harness. Credit: NASA/JPL

It was also this up-look camera that caught the last images of the skycrane as, with the rover on the ground, the harness cables and data umbilical detached, it re-oriented itself to fly away to crash some 700m from the rover.

As well as cameras to record the images of the landing, it had been hoped that one of the rover’s two microphones would record the sounds of the descent and landing. Unfortunately, it failed to do so, but over the weekend, it did capture the sigh of a gust of wind passing over the rover at about 5 metres/second, giving us our first direct recording of the Martian wind.

Since landing, various checks have been performed on the vehicle, and instrument packs deployed. The most important of these has been the RSM – the Remote Sensing Mast. This houses a range of instruments, including the SuperCam, the Mastcam-Z high-resolution camera and the rover’s main navigation cameras (NavCams). The latter are, like their cousins on Curiosity’s RSM, designed to assist with rover driving and navigation. However, they are far more capable and much higher resolution, each one capable of take up to a 20 megapixel image.

For their initial testing, there were operated at one-quarter of this capacity, taking a series of images around the rover, which were shown at the February 22nd press conference without any colour processing or white-balancing, so they showed Mars exactly as it were appear to a human standing there.

Two relatively low resolution images taken by the NavCams on Perseverance during initial check out. They show the rover and its surroundings in natural colour and lighting. Credit: NASA/JPL

Over the next few days, the remaining systems on the RSM will be tested, and the rover will also go into a data download mode.

Since launch, the on-board computers have been configured with software required to keep the rover safe during Mars transit and to allow it to play its part in the EDL phase of the mission.  As this programming is no longer required, mission control will transmit the initial data sets required for the rover and its systems to go through their commissioning procedures – which are liable to take a few weeks – and prepared it for its initial science mission software. During this week, further tests will also be carried out, including allowing the rover to complete a short drive.

I’ll have more on all of these actives in future Space Sunday updates, but for now, why not scroll back up and what that video again?

Space Sunday: ‘Perseverance will get you anywhere’

A CGI model of the Mars 2020 rover Perseverance on the surface of Mars.  Credit; NASA

NASA once again has more than one rover operating on the surface of Mars. On Thursday, February 18th, the Mars 2020 mission, comprising the rover Perseverance and the aerial technology demonstrator Ingenuity, arrived in Jezero Crater in the northern hemisphere of the red planet.

The landing followed the same profile as that of NASA’s other operational rover, Curiosity, which arrived on Mars as the physical element of the Mars Science Laboratory (MSL) mission in August 2012, and which is still exploring Aoelis Mons, the huge mound at the centre of Gale Crater, although there were some notable differences.

Referred to as “the seven minutes of terror”, the landing involved the rover and its helicopter payload and landing system packed within an aerodynamic aeroshell, slamming into the upper reaches of the tenuous Martian atmosphere at 20,000 km/h, then the rover and payload touching gently down on Mars on the end of a winch just seven minutes later.

Some ten minutes prior to atmospheric entry, the mission had separated from its supporting cruise stage – the component that that provided it with power, heat and communications with Earth. Small reaction control thrusters on the aeroshell fired shortly after, slowing the spin induced to assist with stability during the 3.4 million km cruise out from Earth so that it would interfere with the vehicle’s passage through the atmosphere.

Mars 2020 Entry, Decent and Landing (EDL).  Credit; NASA

Protected by the heat shield that formed the lower part of its aeroshell, Mars 2020 passed through the searing heat of atmospheric entry, the friction of its passage helping to decelerate it. From here on in, things happened fairly rapidly.

Just under five minutes from touchdown, the vehicle used programmed control checks to align itself onto a course towards its intended landing site and entered what NASA call the “straighten up and fly right” manoeuvre – jettisoning a final group of balance masses whilst using its aerodynamic shape to steady itself on course ready for parachute deployment. This occurred with the craft just 20.8 km up-range of its landing site and still travelling at more than 2,000 km/h – or supersonic speed.

With the parachute deployed, the heat shield could be jettisoned, exposing the rover vehicle and its instruments to Mars for the first time. This meant camera and radar systems could start operating (as could the on-board microphones), and the craft could enter an entirely new mode of robotic landing.

Given the distance between Earth and Mars, two-way communications are impossible, so Martian landing have to be programmed in advance and triggered triggered by events such as velocity, atmospheric pressure, elapsed time, etc., but without any means to deviate from programming in any way. However, Mars 2020 was equipped with Terrain Relative Navigation (TRN).

What TRN means for landing accuracy: superimposed over Jezero Crater, the white ellipses representing the potential landing sites for various missions. The outermost is that of Mars Pathfinder (1998) and reflects the lack of detailed data available on the proposed landing site for that mission. By 2012, and the MSL rover Curiosity, engineers had more then enough data to target a substantially smaller area for landing. Thanks to TRN, this could be reduced still further for Mars 2020 (note the InSight lander (2018) has a large landing ellipse because the amount of data available on the regions around the north and south poles of Mars is not as extensive as is the case with latitudes moving towards the planet’s equator. Credit: NASA

This essentially took readings of the ground below and ahead of the craft as it descended under its parachute,  comparing the findings with high-resolution terrain maps of the landing site and surroundings. If it noted any potential hazard, it would cause the vehicle to use its thrusters to steer itself away from the hazard whilst maintaining its overall heading towards the landing site. TRN also allowed the vehicle to identity any obstructions within its target landing area and feed the data necessary to avoid them to the rover’s skycrane system that would handle the final part of the landing.

Weighing around a tonne, Perseverance, like Curiosity before it, is too heavy to rely solely on parachutes to make a landing. Instead, both rovers relied upon a jet-powered “backpack” – the skycrane. This, with the rover strapped underneath it, fell clear of the backshell and parachute just 1.6 km above the surface of Mars. Once safely clear of the backshell, rock motors on the skycrane fired, reducing the rate of descent from around 360 km/h to just 3 km/h whilst also flying the rover directly over the ideal landing point.

Seconds from touchdown: this remarkable image was captured by a camera mounted on the Mars 2020 skycrane. It shows the Perseverance rover with wheels deployed and other systems (Mastcam camera systems, robot arm) still stowed, as the rover is winched away in preparation for delivery onto the surface of Mars on February 18th, 2021. The bin-like section of the rover, top right, is the shielded housing for its plutonium nuclear “battery” power source. Credit: NASA/JPL

Entering a hover some 21.5 metres above the landing site, the skycrane held steady as it released the rover on a winch mechanism and lowered it towards the ground. This triggered the rover’s wheels, which had been folded stowed against its body, to deploy and lock themselves into their operational position. With the rover at the extent of the cables, the skycrane eased it down to deliver it to the surface.

Once the rover was able to confirm it was firmly on Mars – a matter of a second or so using sensors in its wheel mechanisms – it sent a message up the wire to the skycrane telling it to detach. This it did before carefully piloting itself away along a course that prevented the rocket motor exhausts washing over the rover and possibly damaging / contaminating it, before crashing into the surface of Mars.

The entire EDL – Entry, Decent and Landing – phase of the mission had been watched over by three of the craft currently in orbit around Mars. The first of these was the Mars Reconnaissance Orbiter (MRO – now approaching 15 years of continuous operations in Mars orbit) that was specifically tasked to act as both observer and communications relay. Also recording the event was NASA’s MAVEN spacecraft – it would transmit the data it received some time after the landing had been completed, whilst ESA’s Mars Express orbiter (currently the longest-running operational Mars orbital mission, with 17 years under its belt in Mars orbit) acting as a back-up relay.

Not only was NASA’s MRO vehicle performing the role of active communications relay during the Mars 2020 landing, it was actually observing the landing using its phenomenal HiRISE camera system, which actually caught Mars 2020 suspended under its parachute as it drifts towards and inflow delta within Jezero Crater (see on the left side on the main image). Credit NASA/JPL

In addition, it had been hoped that NASA’s InSight Lander, although over 2,000 km from Jezero Crater, might be able to hear the sonic booms of Mars 2020’s passage through the Martian atmosphere. However, at the time of writing, I’m not sure if this was successful.

Continue reading “Space Sunday: ‘Perseverance will get you anywhere’”