Throughout the history of America’s human spaceflight program, there’s been an alternating pattern in regards to abort systems. From Alan Shepard’s first flight in 1961 on, every Mercury capsule was equipped with a Launch Escape System (LES) tower that could pull the spacecraft away from a malfunctioning rocket. But by the first operational flight of the Gemini program in 1965, the LES tower had been deleted in favor of ejection seats. Just three years later, the LES tower returned for the first manned flight of the Apollo program.
With the Space Shuttle, things got more complicated. There was no safe way to separate the Orbiter from the rest of the stack, so when Columbia made its first test flight in 1981, NASA returned again to ejection seats, this time pulled from an SR-71 Blackbird. But once flight tests were complete, the ejector seats were removed; leaving Columbia and all subsequent Orbiters without any form of LES. At the time, NASA believed the Space Shuttle was so reliable that there was no need for an emergency escape system.
In the post-Shuttle era, NASA has made it clear that maintaining abort capability from liftoff to orbital insertion is a critical requirement. Their own Orion spacecraft has this ability, and they demand the same from commercial partners such as SpaceX and Boeing. But while all three vehicles are absolutely bristling with high-tech wizardry, their abort systems are not far removed from what we were using in the 1960’s.
Let’s take a look at the Launch Escape Systems for America’s next three capsules, and see where historical experience helped guide the design of these state-of-the-art spacecraft.
Spaceflight is inherently dangerous. It takes a certain type of person to willingly strap into what’s essentially a refined bomb and hope for the best. But what might not be so obvious is that the risks involved aren’t limited to those who are personally making the trip. The construction and testing of space-bound vehicles poses just as much danger to engineers here on the ground as it does to the astronauts in orbit. Arguably, more so. Far more individuals have given their lives developing rocket technology than have ever died in the cockpit of one of them.
Ultimately, this is because of the enormous amount of energy stored in the propellants required to make a rocket fly. Ground support personnel need to exercise great care even when dealing with “safe” propellants, such as the classic combination of kerosene and liquid oxygen. On the other end of the spectrum you have chemicals that are so unstable and toxic that they can’t be handled without special training and equipment.
One of the most dangerous chemicals ever used in rocket propulsion is hydrazine; and yet from the Second World War to the present day, it’s been considered something of an occupational hazard of spaceflight. While American launch vehicles largely moved away from using it as a primary propellant, hydrazine is still commonly used for smaller thrusters on spacecraft.
But soon, that might change. NASA has been working on a project they call the Green Propellant Infusion Mission (GPIM) which is specifically designed to reduce modern spacecraft’s dependency on hydrazine. In collaboration with the Air Force Research Laboratory at California’s Edwards Air Force Base, the space agency has spearheaded the development of a new propellant that promises to not just replace hydrazine, but in some scenarios even outperform it.
So what’s so good about this new wonder fuel, called AF-M315E? To really understand why NASA is so eager to power future craft with something new, we first have to look at the situation we’re in currently.
Have you looked up into the night sky recently and seen a bizarre line of luminous dots? Have you noticed an uptick in the number of UFO reports mentioned in the news and social media? If so, you may have already been touched by what many have come to affectionately call Elon Musk’s “Space Train”: a line of tightly grouped Starlink satellites that are making their way around the globe.
Some have wondered what’s so unique about the Starlink satellites that allows them to be visible from the ground by the naked eye, but that’s actually nothing new. It’s all about being in the right place at the right time, for both the observer and the spacecraft in question. The trick is having the object in space catch the light from the Sun when it has, from the observer’s point of view, already set. It’s essentially the same reason the Moon shines at night, but on a far smaller scale.
What makes the Starlink satellites unique isn’t that we can see them from the ground, but that there’s so many of them flying in a straight line. The initial launch released 60 satellites in a far tighter formation than we’ve ever seen before; Elon even warned that collisions between the individual Starlink satellites wasn’t out of the realm of possibility. The cumulative effect of these close proximity satellite flares is a bit startling, and understandably has people concerned about what the night sky might look like when all 12,000 Starlink satellites are in orbit.
The good news is, the effect is only temporary. As the satellites spread out and begin individual maneuvers, that long line in the sky will fade away. But before Elon’s “Space Train” departs for good, let’s look at how it was created, and how you can still catch a glimpse of this unique phenomena.
It’s true that I’m not known for keeping particularly regular hours, but even I had my doubts about this plan. We’d go to sleep around midnight, wake up at 3 AM, drive up the coast aimlessly, then turn around and attend a full-day event where we’d have to maintain at least some semblance of professionalism. It was a bad idea, terrible even. But there I was at 11:30 PM sitting in a Waffle House with Thomas, the Supplyframe videographer, getting dangerously close to signing off on it.
Officially we were there to cover the Cornell Cup Finals being held at Kennedy Space Center, but as it so happens, our arrival in Florida perfectly coincided with the launch of CRS-17, SpaceX’s latest International Space Station resupply mission. Technically this was not part of our assignment. But really, what choice did we have?
Even if our respective bosses didn’t see it as a wasted opportunity, we had to consider the locals. In the few hours we’d been here, it seemed the launch was all anyone wanted to talk about. Everyone from the airport shuttle driver to the waitress who brought us our hash browns reminded us a rocket would be lifting off soon. If we didn’t go, then come Friday afternoon we’d be the only people in Cape Canaveral who didn’t have a personal account of the event. By all indications, an unforgivable cultural faux pas in central Florida.
Of course, the truth of the matter is that we didn’t actually need any convincing to go on this adventure. We had the supreme good fortune of finding ourselves in the vicinity of Kennedy Space Center a few hours before they were going to send a rocket thundering off into the black, and there was no way we could just sleep through it. No, there was never any choice in the matter. We were going.
When it comes to SpaceX, or perhaps more accurately its somewhat eccentric founder and CEO Elon Musk, it can be difficult to separate fact from fiction. For as many incredible successes SpaceX has had, there’s an equal number of projects or ideas which get quietly delayed or shelved entirely once it becomes clear the technical challenges are greater than anticipated. There’s also Elon’s particular brand of humor to contend with; most people assumed his claim that the first Falcon Heavy payload would be his own personal Tesla Roadster was a joke until he Tweeted the first shots of it being installed inside the rocket’s fairing.
So a few years ago when Elon first mentioned Starlink, SpaceX’s plan for providing worldwide high-speed Internet access via a mega-constellation of as many as 12,000 individual satellites, it’s no surprise that many met the claims with a healthy dose of skepticism. The profitability of Starlink was intrinsically linked to SpaceX’s ability to substantially lower the cost of getting to orbit through reusable launch vehicles, a capability the company had yet to successfully demonstrate. It seemed like a classic cart before the horse scenario.
But today, not only has SpaceX begun regularly reusing the latest version of their Falcon 9 rocket, but Starlink satellites will soon be in orbit around the Earth. They’re early prototypes that aren’t as capable as the final production versions, and with only 60 of them on the first launch it’s still a far cry from thousands of satellites which would be required for the system to reach operational status, but there’s no question they’re real.
During a media call on May 15th, Elon Musk let slip more technical information about the Starlink satellites than we’ve ever had before, giving us the first solid details on the satellites themselves, what the company’s goals are, and even a rough idea when the network might become operational.
There’s no shortage of ways a satellite in low Earth orbit can fail during the course of its mission. Even in the best case scenario, the craft needs to survive bombardment by cosmic rays and tremendous temperature variations. To have even a chance of surviving the worst, such as a hardware fault or collision with a rogue piece of space garbage, it needs to be designed with robust redundancies which can keep everything running in the face of systemic damage. Of course, before any of that can even happen it will need to survive the wild ride to space; so add high-G loads and intense vibrations to the list of things which can kill your expensive bird.
After all the meticulous engineering and expense involved in putting a satellite into orbit, you might think it would get a hero’s welcome at the end of its mission. But in fact, it’s quite the opposite. The great irony is that after all the time and effort it takes to develop a spacecraft capable of surviving the rigors of spaceflight, in the end, its operators will more than likely command the craft to destroy itself by dipping its orbit down into the Earth’s atmosphere. The final act of a properly designed satellite will likely be to commit itself to the same fiery fate it had spent years or even decades avoiding.
You might be wondering how engineers design a spacecraft that is simultaneously robust enough to survive years in the space environment while at the same time remaining just fragile enough that it completely burns up during reentry. Up until fairly recently, the simple answer is that it wasn’t really something that was taken into account. But with falling launch prices promising to make space a lot busier in the next few years, the race is on to develop new technologies which will help make sure that a satellite is only intact for as long as it needs to be.
Things aren’t looking good for NASA’s Space Launch System (SLS). Occasionally referred to as the “Senate Launch System”, or even less graciously, the “Rocket to Nowhere”, the super heavy-lift booster has long been a bone of contention for those in the industry. Designed as an evolution of core Space Shuttle technology, the SLS promised to reuse existing infrastructure to deliver higher payload capacities and lower operating costs than its infamous winged predecessor. But in the face of increased competition from commercial launch providers and proposed budget cuts targeting future upgrades and expansions of the core booster, the significantly over budget and behind schedule program is in a very precarious position.
Which is not to say the SLS doesn’t look impressive, at least on paper. In its initial configuration it would easily take the title as the world’s most powerful rocket, capable of lifting nearly 105 tons into low Earth orbit (LEO), compared to 70 tons for SpaceX’s Falcon Heavy. It would still fall short of the mighty Saturn V’s 155 tons to LEO, but the proposed “Block 2” upgrades would increase SLS payload capability to within striking distance of the iconic Apollo-era booster at 145 tons. Since the retirement of the Space Shuttle in 2011, NASA has been adamant that the might of SLS was the only way the agency could accomplish bigger and more ambitious missions to the Moon, Mars, and beyond.
Or at least, they were. On March 13th, NASA Administrator Jim Bridenstine testified to Congress that in an effort to avoid further delays, the agency is exploring the possibility of sending their Orion spacecraft to the Moon with a commercial launcher. The statement came as a shock to many in the aerospace community, as it would seem to call into question the future of the entire SLS program. If commercial rockets can do the job of SLS, at least in some cases, why does the agency need it?
NASA is currently preparing a report which investigates what physical and logistical modifications would need to be made to missions originally slated to fly on SLS; a document which is sure to be scrutinized by SLS supporters and critics alike. Until the report is released, we can speculate about what this hypothetical flight to the Moon might look like.