In lieu of readers’ wildlife today (the tank is quite low), and because we pay attention to space exploration, take note that the rescheduled Artemis-1 mission is scheduled for this afternoon. That doesn’t mean it will take off, but it means they’ll try.
My friend James “Bat” Batterson, a now-retired physicist who worked for NASA, has patiently answered my inquiries about the Artemis mission, the mechanics of rockets, and so on. So I asked him to write a bit about the launch, which is below. You can watch it from the NASA site, though I prefer Space.com, which you can watch right here. Tune in about 2 pm Eastern time.
After reviewing sensor data and a full physical inspection of the Artemis-1 Space Launch System (SLS) rocket and components, NASA has rescheduled this past Monday’s canceled test flight. The new proposed launch of of this un-crewed vehicle occupies a two-hour window that begins at 2:17 EDT this afternoon.
In a nutshell, after looking at redundant data from other sensors and their experience base, the managers believe that a temperature-sensor reading —one that told them that one of the rocket engines had not cooled to a proper temperature of approximately -420F for launch (it was reading -370F)—was wrong. They’ve also fixed a coupling that leaked on Monday and decided that an insulation crack on the main cryogenic fuel tank did not pose a danger.
Followers of the Shuttle program may recall that a piece of foam insulation that tore loose from Shuttle Columbia’s fuel tank on launch and impacted the Shuttle wing causing a large hole that allowed hot gas into the wing during re-entry into the Earth’s atmosphere a week later. That, of course, led to destruction of Columbia and the loss of all astronauts onboard. The SLS is a safer design with the crew module configured above the tank.
While not as tall as the Saturn-5 that powered Apollo astronauts to the Moon, this rocket is more powerful, allowing for a significantly heavier payload to be delivered into lunar orbit. Its main stage propulsion system uses four RS-25 Space Shuttle engines (the shuttle used three), in tandem with two solid rocket booster engines. Together these provide over eight million pounds of thrust. The solid boosters last for two minutes before being jettisoned. As with the shuttles, the boosters then fall into the Atlantic. The four RS-25’s burn for eight minutes, putting the payload into a 17,500mph low-Earth orbit.
Later, a second-stage rocket burn will accelerate the payload to more than 22,000 mph to send it into a lunar trajectory, a trip that takes several days. [The orbiting of the Moon begins September 8, with the module coming back to Earth on October 11.] CBS News has an excellent write-up here. If you want to know more about the mission details and the ultimate goal of getting people to live on the Moon, go to the Astronomy article here.
And an important note:
This is an engineering test flight, not a demonstration flight. They have tested all the parts in isolation and in partial configurations, but this is a test of the whole system designed to carry out a mission to the Moon and back, ending with a safe splashdown. As I emphasized last week, a whole lot of things need to go extraordinarily right, and those that don’t have been designed in what is known as a “fail/operate” mode* so that the entire vehicle and thus the mission does not fail.
Here’s the best place to watch it: the NASA live site at space.com:
* “Fail/safe” refers to the eponymous book and movie on nuclear war. It refers to a design that, if the booster rocket were to fail, the crew would be rocketed away in their own capsule and splash down safely. The space shuttles obviously were not designed that way, but the space launch system is.
Here’s a diagram of the planned itinerary (from the Astronomy article), with the outbound leg in green and the return leg in blue. Click to enlarge:
Thanks Jim – and PCc(E)!
I was curious about the meaning of Artemis. Wikipedia explains: “In ancient Greek mythology and religion, Artemis (/ˈɑːrtɪmɪs/; Greek: Ἄρτεμις) is the goddess of the hunt, the wilderness, wild animals, nature, vegetation, childbirth, care of children, and chastity.[1][2] She was heavily identified with Selene, the Moon, and Hecate, another Moon goddess, and was thus regarded as one of the most prominent lunar deities in mythology, alongside the aforementioned two.[3] She would often roam the forests of Greece, attended by her large entourage, mostly made up by nymphs, some mortals and hunters.”
And she is the twin sister of Apollo, which is why NASA adopted the name for what is effectively Apollo version 2.
NASA has made a strong effort not only to be inclusive but also to publicly demonstrate inclusivity recognizing that its pretty much total white male world of Project Mercury in the 1960’s was more than just a structural situation but also a cultural one. Among the issues was the pipeline that Jerry often points to and NASA has ongoing outreach to K12 to involve more under represented groups in K12 STEM education, particularly the “E” of STEM – Engineering. The agency efforts at changing an almost all male flight culture includes rejecting the expressions “manned” and “unmanned” and replacing them with gender-neutral “crewed” and “uncrewed”. Artemis brings a female name to a major, very visible spaceflight project.
Right now (14:20 UTC, 10:20 in Florida, around 4 hours before the launch window opens), the engineers are trying to fix a leak where the main hydrogen feed pipe connects to the first stage. They shut off the flow of liquid hydrogen half an hour ago to let the connector assembly warm up a little, then they hit it with a hammer to try to re-seat it. Just kidding. No hammers were involved. Loading of liquid hydrogen has resumed, but at a slower rate than before.
Excellent!
As of 15:00 UTC (11:00 EDT, T-2h46m) the hydrogen leak persists, and the engineers have recommended no-go to the Launch Director.
15:19 UTC (11:19 EDT): The Launch Director has called a scrub for today’s launch attempt. Artemis will not launch today.
Thanks David. Your two comments 5 and 6 show how the process is supposed to work: technical analysis and recommendations by engineers and mid-level managers followed by go/no-go decision by launch director
Kind Sir,
During the last week or so the media has been hammering on the cost of the Artemis system as compared to the lesser cost of the reusable SpaceX system. Is the alleged cost savings of the SpaceX system totally and solely attributable to its reusability? Or is there corner-cutting in certain areas, say, safety? I don’t trust the profit- and cost-cutting-oriented private sector to give safety its due. I’d like to think that Challenger and Columbia sufficiently taught the lesson of safety.
Much thanks for your commentary.
Nobody really knows how expensive or how reusable the SpaceX system is partly because it hasn’t been built yet. They have a booster, but it’s never flown and we have never seen their orbital ship. The demonstrators they have flown so far have only gone to 10 kilometres and didn’t have the capability to get to orbit or to re-enter the Earth’s atmosphere. Four out of five of them didn’t survive landing even from 10km. They aren’t even close to having something that can send people to the Moon and bring them safely back.
Good questions and observations Filippo. I do not know the economics and really doubt that they can be calculated with any confidence. Since my retirement from NASA in 2008, I have not followed things extremely close, but I have kept in touch with the various programs. That said, I do not think that SpaceX is even close to having a booster that can take a payload beyond the space station orbit. Earth orbit is a huge step beyond a suborbital flight and lunar orbit is an additional capability beyond earth orbit. The argument about cost of landing humans on the moon has always been a red herring to me because people going there has been more of an international political goal than a scientific one…a demonstration of engineering will and capability….and the will of a nation to invest a certain amount of its treasure in such an accomplishment.
As far as safety, my observation has been that NASA did not learn any safety lesson from Challenger (as attested to by Columbia), nor did the culture really change even after Columbia. The vast majority of the engineers and technicians remained extremely safety conscious and technically honest, but some higher level managers seemed to wear their political hats in decision-making way too often. Jim’s view.