If all continues on track, Monday, August 29th, 2022 will mark the start of America’s return to the Moon with crewed missions, just a few months shy of the 50th anniversary of the last crewed mission, Apollo 17 (December 7th-19th, 1972). It will come with the lift-off of the Artemis 1 mission, and the maiden flight of NASA’s new heavy lift launcher, the Space Launch System.
The mission will be – as most no doubtless know only too well – uncrewed, and the destination not the lunar surface, but cislunar space in what will be the most comprehensive test of the SLS rocket and the Orion Multi-Purpose Crew Vehicle (MPCV) ahead of crewed flights, which are due to commence with Artemis 2.
The final countdown for the launch commenced on Saturday, August 27th at launch pad 39B within the Kennedy Space Centre, Florida, and providing no significant hitches occur, it is due to terminate at 12:33 UTC on August 29th with the ignition of the booster’s four RS-25 shuttle-derived motors and two massive solid rocket boosters (also derived from those used in the space shuttle programme). At the time of writing this piece, and despite a thunderstorm leading to a lighting strike at the launch facility on the evening of August 27th, everything was on course for the launch, and the forecast indicated a 70% likelihood that the weather at Cape Canaveral and downrange from the launch pad would be good for the launch.
However, all things are not guaranteed, and the mission has a slim 2-hour launch window in which to get off the pad. Should the launch have to be scrubbed for any reason, further launch windows will be available on September 2nd (2 hours), and September 5th (90 minutes).
There is a lot riding on this mission; while Orion has already flown once in space – eight years ago in the uncrewed Exploration Flight Test-1, launched atop a Delta IV Heavy rocket – this will be the first flight of the vehicle outside of directly orbiting the Earth; however, for SLS, the mission could very much be make-or-break. The vehicle has been beset by issues throughout its development programme (many of which amounted to either unforced errors or came as a result of the entire Artemis programme being unduly accelerated by the Trump Administration to achieve a crewed landing by 2024 rather than 2028, as originally planned. As such any major or catastrophic failure could have major repercussions for NASA and the US government space programme.
SLS has been more than two decades in development. It started life in the early 2000s as the Ares V under NASA’s Constellation programme. Instigated by the then NASA administrator Michael Griffin, Ares 5 was to be the heavy-lift launch vehicle intended to help return humans to the Moon and (eventually / primarily) help pave the way to Mars, working alongside the smaller Ares 1 crew launch vehicle and what was then called the Orion Crew Exploration Vehicle (CEV). I say “primarily”, because Griffin was a strong advocate of human missions to Mars and the Ares programme was actually named for (and pretty much lifted from) the Mars Direct humans-to-Mars concept first proposed by Robert Zubrin and David Baker in 1990.
Despite enormous strides made in the development of Ares 1 (the first of which actually few in 2009) and the Orion CEV, the Obama administration opted to scrap the constellation programme on the grounds of cost. While Ares 1 went away in its entirety, Orion and Ares V underwent a redesign process, the former having its capabilities increased, whist Ares V went back to the drawing board to later emerge as the SLS.
The key differences between Ares V and SLS is the former was intended to be a heavy-lift cargo launcher, capable of delivering up to 168 tonnes to low-Earth orbit (LEO), up to 71 tonnes to lunar orbit and around 60 tonnes to Mars, with Ares 1 left to carry crews up to orbit. SLS, on the other hand is intended to be both a crewed and cargo launch vehicle, capable of delivering between 95 and 130 tonnes to LEO depending on the vehicle type, or some 46 tonnes to lunar orbit (Block 2 cargo) and 30-40 tonnes to Mars (Block 2 cargo).
The primary objectives for Artemis 1 are to prove the SLS launch system’s Block 1 launch capabilities; achieve a distant retrograde orbit (DRO) around the Moon, and make a safe return to Earth with a successful atmospheric re-entry and splashdown by the Orion MPCV capsule. The overall mission duration is expected to be some 42 days.
This first flight – which will also mark the first use of the European-built Orion service module (Orion’s flight in 2014 didn’t require a service module) – is to be one of only three launches of the SLS Block 1 rocket. This uses what is called the Interim Cryogenic Propulsion Stage (ICPS) – essentially the upper stage of a Delta IV rocket. From Artemis 4 onwards, launches will use the more powerful Exploration Upper Stage (EUS) in what is termed the Block 1B SLS variant, and which will also be used in the Block 2 cargo variant (if this eventually flies).
The ICPS will be used to insert Orion into its trajectory to the Moon prior to separating from the capsule and its service module and performing one further crucial mission task. It will then pretty much parallel Orion to the Moon before using the latter’s gravity to slingshot itself away into a highly elliptical orbit of its own.
As well as being used to check-out SLS and Orion, Artemis 1 has a number of science goals, and the Orion MPCV is not the only payload for the mission. Shortly after Orion separates from the ICPS, the latter – in that other crucial aspect of the mission mentioned above – will deploy multiple cubesats on trajectories to the Moon. These will carry out an range of scientific tasks, including:
- Detecting, measuring, and comparing the impact of deep space radiation on living organisms (yeast in this instance) over long durations.
- Studying the dynamic particles and magnetic fields that stream from the Sun and as a proof of concept for the feasibility of a network of stations to track space weather.
- Imaging Earth’s plasmasphere to study the radiation environment around the Earth.
- Searching for additional evidence of lunar water ice from a low lunar orbit.
- Mapping hydrogen within craters near the lunar south pole, tracking depth and distribution of hydrogen-rich compounds like water over a 60-day, 141 lunar orbit mission.
- Flying by the Moon to collect surface spectroscopy and thermograph and return the results to Earth for analysis.
In addition, some of the cubesat missions will be technology demonstrators, including a further solar sail demonstrator; using very small automated vehicles to operate in close proximity to large vehicles and image them / look for potential damage; using small, low thrust gas motors for trajectory control in the space between Earth and the Moon.
Nor is that all; Orion itself will be carrying a number of experiments within the capsule, with a focus on gaining a better understanding of the radiation regime between the Earth and Moon and within cislunar space.
The most evident of the onboard experiments is “Commander Moonikin Campos”, a mannequin dressed in the Orion Crew Survival System Suit. Sharing (OCSSS). Sharing same iconic orange colour as the survival suits used on shuttle missions, the OCSSS is a much more advanced version, designed to be worn continuously for periods of up to 6 days at a time (so whilst en route to the Moon, whilst in lunar orbit and during a return to Earth), to offer enhanced radiation protection for the wearer whilst aboard Orion. To this end the mannequin – named for Apollo 13 electrical subsystems engineer Arturo Campos, who played a major role in bringing that crew back to Earth alive – is equipped with a plethora of radiation sensors to test the effectiveness of the suit.
The “Moonikin” is joined by two torso-only mannequins, referred to as the “phantoms” (and individually named Helga and Zohar). These are constructed from materials that mimic human bone and tissue, as well as organs unique to adult females, such as breast tissue and ovaries, which are susceptible to radiation damage. Each is equipped with over 6,000 passive radiation detectors and 34 active detectors, and form the core element of the international Matroshka AstroRad Radiation Experiment (MARE), led by the German Aerospace Centre.
As well as being used to gather data on how radiation in space beyond Earth’s orbit affect human tissues, bone and organs, the phantoms will be used to determine how effective different materials and materials combinations used in the construction of the “AstroRad” vests they are wearing are at helping to mitigate the effects of radiation exposure.
And if that’s not enough, Orion itself is equipped with multiple radiation detectors intended to gather data on radiation exposure in different parts f the vehicle, and under changing conditions of sunlight and vehicle orientation throughout the flight. Finally, Orion also carries Biology Experiment-1, comprising four investigations to study the effects of radiation on plants and fungi. The focus of the experiment is on changes in the nutritional value of seeds, how fungi repair their DNA, yeast adaptability, and algal gene expression, with the aim of help to develop future countermeasures and identify strategies to develop sustainable crops, and in scientific advancements that will ensure crew health and productivity.
The following is an approximate timeline for the flight of Artemis 1 – all times approximate and based on a 12:33 UTC lift-off:
- August 29th:
- 12:33 UTC: engine ignition and lift-off from Pad 39B, Kennedy Space Centre.
- 12:35:12 UTC: Artemis 1’s two strap-on solid rocket boosters will separate and fall toward the Atlantic Ocean.
- 12:36:10 UTC: Orion jettisons its emergency launch-abort system and the protective fairing that covers its European-built service module.
- 12:41 UTC: Artemis 1 core engines shut-down.
- 12:14:12 UTC: Core stage separation from ICPS / Orion.
- 12:51 UTC: Orion commences solar array deployment (12 minutes).
- 13:22 UTC: ICPS performs a 22-second engine burn to stabilise orbit.
- 14:11 UTC: ICPS performs 18-minute trans-lunar injection (TLI) burn, break Earth orbit and starting Orion on its way to the Moon.
- 15:39 UTC: Orion separates from ICPS.
- 16:13 UTC: ICPS commences periodic deployment of cubesats (deployment lasting some 5 hours in total).
- September 3rd: Orion completes Outward Powered Flyby Burn”, passing around the Moon at some 92 km above the lunar surface
- September 7th: Orion completes DRO stabilisation burn, placing it in an orbit by which is can “follow” the Moon as it tracks around the Earth..
- September 8th: Orion exceeds the furthest distance for Earth achieved by any crew-rated vehicle (400170 km, set in 1970 by Apollo 13).
- September 21st: Orion completes a “departure burn” in readiness to start its long return to Earth.
- September 23rd: Orion reaches its maximum distance from Earth – 450,600 km – as it swings back towards the Moon.
- October 3rd: Orion completes a “Return Flyby Burn”, looping around the Moon some 800 km from the surface and then heading back towards Earth.
- October 10th: splashdown in the Pacific Ocean off the coats of San Diego, California.