Spacing Out: StarShip Explodes (Again), Passenger Space Flight, Space Bugs, Astronaut Bone, And Martian Water

This time I promise I only have a couple of stories from Elon Musk’s company. SpaceX’s latest Starship test launch ended in another explosion, proving that space hardware remains hard to get right. We’ll keep watching as they keep launching, and it can’t be long until they’ve ironed out all the problems. Meanwhile there’s brighter news from the company’s Crew Dragon, a modified version of the capsule with the forward docking ring replaced by a transparent dome is planned for launch in September with the company’s first flight carrying civilian passengers. It’s doubtless unwelcome news for Virgin Galactic, whose suborbital passenger flights are edging closer to reality with the unveiling of their first SpaceShip III craft. Finally, a Falcon 9 upper stage broke up on re-entry over the northwestern USA, giving observers on the ground a spactacular show.

Spectacular view of the Falcon 9 debris. Via Lu Jerz

Meanwhile up there in orbit there have been found on the ISS some strains of bacteria previously unknown to scientists on Earth, but it’s not yet time to panic about Mutant Bugs From Space. It seems these bacteria are of a type that is essential in the growing of plants, so it’s likely they originally hitched a ride up with one of the several plant-growing experiments that have taken place over the station’s lifetime. Staying on the ISS, astronauts visiting the station have been at the centre of a recently published study looking at loss of bone density over long periods in space. The bone experts found that bone density could still be lost despite the astronauts’ in-flight exercise programs, and concluded that exercise regimes pre-flight should be taken into account for future in-orbit exercise planning.

Further away from Earth, the ESA Mars Express satellite has been used for a multi-year study of water loss to space from the Martian atmosphere. The ESA scientists identified the seasonal mechanism that leads to the planet’s upper atmosphere having an excess of water and in particular the effect of the periodic planet-wide dust storms on accelerating water loss, but failed to account for the water that they estimate Mars must have lost over its history. From a study of water-created surface features they can estimate how much liquid the planet once had, yet the atmospheric losses fail to account for it all. Has it disappeared underground? More studies are required before we’ll have an answer.

The exciting news over the coming days will no doubt be the Ingenuity Martian helicopter, which we have seen slowly unfolding itself prior to unloading from the belly of the Perseverence rover. If all goes according to plan the little craft will be set down before the rover trundles off to a safe distance, and the historic flight will take place on April 8th. We’ll be on the edges of our seats, and no doubt you will be, too.

Putting Perseverance Rover’s View Into Satellite View Context

It’s always fun to look over aerial and satellite maps of places we know, seeing a perspective different from our usual ground level view. We lose that context when it’s a place we don’t know by heart. Such as, say, Mars. So [Matthew Earl] sought to give Perseverance rover’s landing video some context by projecting onto orbital imagery from ESA’s Mars Express. The resulting video (embedded below the break) is a fun watch alongside the technical writeup Reprojecting the Perseverance landing footage onto satellite imagery.

Some telemetry of rover position and orientation were transmitted live during the landing process, with the rest recorded and downloaded later. Surprisingly, none of that information was used for this project, which was based entirely on video pixels. This makes the results even more impressive and the techniques more widely applicable to other projects. The foundational piece is SIFT (Scale Invariant Feature Transform), which is one of many tools in the OpenCV toolbox. SIFT found correlations between Perseverance’s video frames and Mars Express orbital image, feeding into a processing pipeline written in Python for results rendered in Blender.

While many elements of this project sound enticing for applications in robot vision, there are a few challenges touched upon in the “Final Touches” section of the writeup. The falling heatshield interfered with automated tracking, implying this process will need help to properly understand dynamically changing environments. Furthermore, it does not seem to run fast enough for a robot’s real-time needs. But at first glance, these problems are not fundamental. They merely await some motivated people to tackle in the future.

This process bears some superficial similarities to projection mapping, which is a category of projects we’ve featured on these pages. Except everything is reversed (camera instead of video projector, etc.) making the math an entirely different can of worms. But if projection mapping sounds more to your interest, here is a starting point.

[via Dr. Tanya Harrison @TanyaOfMars]

Continue reading “Putting Perseverance Rover’s View Into Satellite View Context”

Hackaday Links: March 21, 2021

If you think you’re having a bad day at work, pity the poor sysadmin at Victoria University of Wellington in Australia New Zealand, who accidentally nuked the desktops of pretty much everyone at the university. This apparently happened last week and impacted everyone connected to the university network with a Windows machine, which had any files stored on their desktops deleted and also appears to have reset user profiles to the default state. This caused no end of consternation, especially among those who use their desktop folder to organize work in progress; we’d imagine more than one student at VUW is hating life right now for not storing work on a backed-up network drive. The problem seems to have started with an attempt to clean up files and profiles left behind by former students; how that escalated to nuking files on the desktop will require some ‘splaining.

Speaking of mea culpas, there was quite a dustup this week in the Cricut community. It started when the maker of CNC cutting machines announced its intention to limit uploads to their online design software unless the user signs up for a $10 a month account. After getting an earful from the users, the CEO of the company announced that these changes would be delayed until the end of 2021. That decision still didn’t sit well with the community, which includes a fair number of users designing PCBs, and two days later, the CEO announced that they were throwing in the towel on the whole plan, and that everything was going back to status quo ante. Story over? We’ll see — it seems like Cricut has tipped its hand here that they’re looking to extract more money from the users, and the need for that likely hasn’t gone away just because they relented. As Elliot Williams pointed out when we discussed the whole debacle, it’s easy to see how Cricut could start adding new features to the paid version of their software, basically abandoning the free user base. We’ll have to see how the obviously vociferous community responds to something like that.

Much interesting news from Mars this week, where the Perseverance rover is getting used to its new home and getting itself ready to roll. Late last week, Perseverance successfully dropped the “belly pan” that was covering the sensitive instruments under the rover, including the Adaptive Sample Caching system that will seal up Martian core samples and drop them out onto the surface for later pickup. This seemingly simple task was a critical one; had the pan not cleanly separated, the mission could have been severely impacted. Perseverance also did a little test drive this week, and recorded what it sounds like to drive on Mars. The audio clip is 16 minutes long, and the noises coming from the billion-dollar rover are just awful at times. We hear clunks and clanks and squeals galore, and while we’re sure they all have a good explanation and will provide valuable engineering data, they sound somewhat alarming to us.

But not so alarming as the sounds that must have come from a Jeep that suffered a bad tow job recently. The cringe-making story starts with a brand-new Jeep being towed on its wheels behind a motorhome, which allows the RV owners to park their rig and still have something to drive around in while they camp. The towed vehicle, or “pusher”, is normally equipped with a manual transmission, as towing with the wheels on the ground for extended distances is easier with them. Unfortunately, the Jeep’s owner set up the shift levers wrong and left the transmission in first gear, with the transfer case in low range. The linked article estimates the gearing ratios meant that the poor Jeep’s engine was being spun at something like 54,000 RPM; chances are good the engine exploded long before that point. The damage shown in the video accompanying the article is just brutal — the oil pan and bell housing are gone, the bottom of the crankcase is blown out, and at least two pistons and their share of the crankshaft are missing in action. We feel sorry for the owner, but really wish the Jeep had had a belly cam like the one on Perseverance.

A Technical (But Not Too Technical) Explanation Of Landing Perseverance Rover On Mars

There was a lot of enthusiasm surrounding Mars arrival of Perseverance rover, our latest robotic interplanetary explorer. Eager to capitalize on this excitement, NASA JPL released a lot of information to satisfy curiosity of the general public. But making that material widely accessible also meant leaving out many technical details. People who crave just a little more can head over to How NASA’s Perseverance Landed On Mars: An Aerospace Engineer Breaks It Down In Fascinating Detail published by Jalopnik.

NASA JPL’s public materials mostly explained the mission in general terms. Even parts with scientific detail were largely constrained for a target audience of students K-12. Anyone craving more details can certainly find them online, but they would quickly find themselves mired in highly technical papers written by aerospace engineers and planetary geologists for their peers. There is a gap in between those extremes, and this write-up slots neatly in that gap. Author [Brian Kirby] is our helpful aerospace engineer who compiled many technical references into a single narrative of the landing, explained at a level roughly equivalent to undergraduate level math and science courses.

We get more details on why the target landing site is both geologically interesting and technically treacherous, requiring development of new landing smarts that will undoubtedly help future explorers both robotic and human. The complex multi-step transition from orbit to surface is explained in terms of managing kinetic energy. Condensing a wide range of problems to a list of numbers that helps us understand why, for example, a parachute was necessary yet not enough to take a rover all the way to the surface.

Much of this information is known to longtime enthusiasts, but we all had to get our start somewhere. This is a good on-ramp for a new generation of space fans, and together we look forward to Perseverance running down its long and exciting to-do list. Including flying a helicopter, packing up surface samples of Mars, and seeing if we can extract usable oxygen from Martian atmosphere.

Got Oxygen? Future Mars Missions Are Relying On The MOXIE Of Perseverance

The rule of thumb with planetary exploration so far has been, “What goes up, stays up.” With the exception of the Moon and a precious few sample return missions to asteroids and comets, once a spacecraft heads out, it’s never seen again, either permanently plying the void of interplanetary or interstellar space, or living out eternity on the surface of some planet, whether as a monument to the successful mission that got it there or the twisted wreckage of a good attempt.

At the risk of jinxing things, all signs point to us getting the trip to Mars reduced to practice, which makes a crewed mission to Mars something that can start turning from a dream to a plan. But despite what some hardcore Martian-wannabees say, pretty much everyone who goes to Mars is going to want to at least have the option of returning, and the logistical problems with that are legion. Chief among them will be the need for propellants to make the return trip. Lugging them from Earth would be difficult, to say the least, but if an instrument the size of a car battery that hitched a ride to Mars on Perseverance has anything to say about it, future astronauts might just be making their own propellants, literally pulling them out of thin air.

Continue reading “Got Oxygen? Future Mars Missions Are Relying On The MOXIE Of Perseverance”

NASA’s Perseverance Rover Makes Its First Martian Tracks

There’s a special kind of anxiety that comes from trying out a robotic project for the first time. No matter the size, complexity, or how much design and planning has gone into it, the first time a creation moves under its own power can put butterflies in anyone’s stomach. So we can imagine that many people at NASA are breathing a sigh of relief now that the Perseverance rover has completed its first successful test drive on Mars.

To be fair, Perseverance was tested here on Earth before launch. However, this is the first drive since the roving scientific platform was packed into a capsule, set on top of a rocket, and flung hundreds of millions of miles (or kilometers, take your pick) to the surface of another planet. As such, and true to NASA form, the operators are taking things slow.

This joyride certainly won’t be setting speed records. The atomic-powered vehicle traveled a total of just 21.3 feet (6.5 meters) in 33 minutes, including forward, reverse, and a 150 degree turn in-between. That’s enough for the mobility team to check out the drive systems and deem the vehicle worthy of excursions that could range 656 feet (200 meters) or more. Perseverance is packed with new technology, including an autonomous navigation system for avoiding hazards without waiting for round-trip communication with Earth, and everything must be tested before being put into full use.

A couple weeks have passed since the world was captivated by actual video of the rover’s entry, descent, and landing, and milestones like this mark the end of that flashy, rocket-powered skycrane period and the beginning of a more settled-in period, where the team works day-to-day in pursuit of the mission’s science goals. The robotic arm and several on-board sensors and experiments have already completed their initial checks. In the coming months, we can look forward to tons of data coming back from the red planet, along with breathtaking pictures of its alien surface and what will hopefully be the first aircraft flown on another world.

Demonstrating The Mars Rover Pendulum Problem With A Drone On Earth

The sky crane system used on the Perseverance and Curiosity Mars rovers is a challenging control system problem that piqued [Nicholas Rehm]’s curiosity. Constrained to Earth, he decided to investigate the problem using a drone and a rock.

The setup and the tests are simple, but clearly illustrate the problem faced by NASA engineers. [Nicholas] attached a winch mechanism to the bottom of a racing-type quadcopter, and tied a mass to the end of the winch line. At first, he built a foam model of the rover, but it proved to be unstable in the wake of the quadcopter’s propellers, so he used a rock instead. The tests start with the quadcopter taking off with the rock completely retracted, which is then slowly lowered in flight until it reaches the end of the line and drops free. As soon as the rock was lowered, it started swinging like a pendulum, which only got worse as the line got longer. [Nicholas] attempted to reduce the oscillations with manual control inputs, but this only made it worse. The quadcopter is also running [Nicholas]’s own dRehmFlight flight controller that handles stabilization, but it does not account for the swinging mass.

[Nicholas] goes into detail on the dynamics of this system, which is basically a two-body pendulum. The challenges of accurately controlling a two-body pendulum are one of the main reasons the sky crane concept was shelved when first proposed in 1999. Any horizontal movement of either the drone or the rock exerts a force on the other body and will cause a pendulum motion to start, which the control system will not be able to recover from if it does not account for it. The real sky crane probably has some sort of angle sensing on the tether which can be used to compensate for any motion of the suspended rover. Continue reading “Demonstrating The Mars Rover Pendulum Problem With A Drone On Earth”