Polaris Dawn
 

It hasn’t received a lot of media attention, but on Tuesday, humans will travel further from earth than we in the past 52 years (Apollo 17)

@SpaceX will go for:

- The highest Earth orbit ever
- First ever commercial space walk
- Testing new EVA suit

The
@PolarisProgram
mission readiness review just finished and we are currently go for launch in just over 24 hours. Crew safety is absolutely paramount and this mission carries more risk than usual, as it will be the furthest humans have traveled from Earth since Apollo and the first commercial spacewalk! If any concerns arise, the launch will be postponed until those concerns are addressed.

https://cimg1.ibsrv.net/gimg/pprune....9fc1c35ac3.png
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Spacex:

”Due to unfavorable weather forecasted in Dragon’s splashdown areas off the coast of Florida, SpaceX is standing down from Falcon 9's launch opportunities of Polaris Dawn on Wednesday, August 28 and Thursday, August 29. Next attempt NET August 30.”

Crew:

”Our launch criteria are heavily constrained by forecasted splashdown weather conditions. With no ISS rendezvous and limited life support consumables, we must be absolutely sure of reentry weather before launching. As of now, conditions are not favorable tonight or tomorrow, so we’ll assess day by day.

“As Elon mentioned, Polaris Dawn is a challenging mission with critical objectives, so we’ll wait for the best opportunity to ensure success.

“Sometimes, the hardest journeys require the most patience, and we’re ready to wait for the right moment. We know many have traveled to see the launch, and we’re grateful for your support. Alongside @SpaceX, we’ll do our best to keep you updated.”

Obviously not grounded by the FAA any more....

SpaceX:

Latest forecasts continue to show unfavorable weather conditions in the areas along Florida’s coast where Dragon would splash down upon returning from space. Once teams identify the next best opportunity for launch and return of the Polaris Dawn mission, we’ll provide an update. Falcon 9 and Dragon remain healthy and vertical on the pad at 39A.

Next launch window:

WED, Sept 4: F9, Dragon - Polaris Dawn
3:38am EDT (0738 UTC)
LC-39A, KSC, FL
(Live webcast: ~3 1/2 hours before liftoff)

FYI: @SpaceX's spacewalk will happen on Sept 12th at 2:23 AM ET.

A backup opportunity is available on Friday, Sept 13th at the same time.

A live webcast on X via Starlink will begin about one hour prior to the beginning of the spacewalk.

Last time I looked it had been delayed until later this (Thursday) morning with the option of another attempt tomorrow.

From the Collectspace website a few hours back:


The start of the EVA has been delayed: The EVA is to start at 5:58 a.m. ET. If needed, a backup opportunity is available on Friday, September 13.

If I’ve got the sums right that’s 0958 UTC.

They are now (10:40 UTC) a few minutes away from opening the hatch. Very brave people!

Watching but I hate watching - in case something goes wrong.

The camera view from the capsule showing them with the earth as a back drop gave me the same feeling as looking over a cliff!!

Pretty brave I think :ok:

A bit of a round up of today’s events and also a potted history of Stand Up EVAs here:

Collectspace - First Commercial Stand up EVA

Standout thing here for me has been the testing of SpaceX independently designed EVA spacesuit.

As a reminder NASA has been spending $xxx to design a modern generation suit and one of their two selected companies has pulled out.

SpaceX has the advantage of being able to conduct actual tests rather than simulations…

https://spacenews.com/collins-aerosp...suit-contract/

Whilst SpaceX have done a good job on the suits I think it’s important to be aware that a short stand up EVA is a relatively benign test so what we saw today was a first step but an important one.

History shows that once astronauts start try to do meaningful tasks when geared up in zero-g air cooled suits struggle at best to handle the heat loads..

It will be interesting to see how the SpaceX suits evolve over the next few years.

Yes. And the recent problems with the ISS spacesuits were mostly caused by cooling water leaks of the ageing suits. If I understand the (little) information provided on the SpaceX site correctly, their EVA suits are cooled by additional oxygen pumped into the suit. We will see if this is sufficient for cooling an astronaut performing actual work in sunlight... Today they were mostly in the shadow without moving a lot and communicated suit temperatures around 33 degrees C, which is uncomfortably warm for most people.

First steps - but the important thing, like Falcon and `starship, is that its design is in house and will be incrementally upgraded . Unlike the ancient NASA suits…

To quote:

”“The goal of this suit is to be our first design of the EVA suit, and then, just like all over SpaceX products, we’re going to continue through block upgrades as we go forward and learn,” Keech said.”…

I recall that on several of the early Gemini program space walks where they tried performing some basic tasks, overheating was a huge issue - with visors fogging over and vision being impaired to the point where it was quite dangerous.
Although an impressive Space X effort, the jury is still out on if the spacesuits are up to the task of serious space activities.

Staying on the suits: I wonder if the degree of movement testing - which seemed to be the majority of the excursion - is for how a cooling/plumbing system can be integrated into the future suits, obviously keeping (what seems to be), an ideal suit for maneuverability and small size.

However, what an experience to look outside onto the planet with only a helmet visor in the way.

Let's all hope for a safe return.

While the effort and risk in this event are tremendous and worthy of note, it was so underwhelming that the first comparison that came to mind was those people who stand up on the seats of a limo and wave at the passersby from the open sun roof. Weeee!

The suits seemed almost entirely unsuitable for movement outside of the spacecraft, but it did give me an idea that I have not seen in space suits before.

The problem for inflated suits is the pressure inside causes the suit to distend. Bending reduces the volume inside the suit, this requires mechanical work in the amount of pressure times delta-volume and keeping the bend requires continuous muscle contraction to resist the loads from the pressure trying to re-extend. It looked to me that the orbital crew was getting exhausted from just a few minutes of movement.

I think the way to go is to create an exoskeleton that manages that force. While powered exoskeletons have been seen as a way to augment factory workers and soldiers to lift and carry excessive loads, the needs for a space suit are significantly reduced. Small actuators with cable-in-tube connections along the arms and legs can perform that task, or inflatable bladders that add counter force. There are several approaches to pick up the desired motion directly from the suit wearer, but even something as simple as a switch in the glove that told the system to hold a position would be a help to let the wearer hold position and rest. Counterbalancing the fingers would be a bonus. Since it is used to counterbalance the pressure, which the wearer should already be able to do, over powering them in case of malfunction isn't a particular risk.

Anyway, WEEEEEEEE!

.

Yep, Ed White’s EVA (first by an American) was fairly straightforward and didn’t really reveal the potential pitfalls so NASA charged into planning some complex activities for those that followed and as you say rightly say ran into major problems.

At least one astronaut of that era has said that NASA were very lucky not to lose somebody due to heat exhaustion and extreme fatigue on at least one of the later Gemini EVAs.

The quick fix was to change the training, simplify the tasks, provide lots of foot and hand holds and take lots of breaks - that allowed Buzz Aldrin to perform a couple of successful EVAs on the last Gemini flight (something he often doesn’t get credit for).

Long term solution was liquid cooled undergarments as seen on Apollo and subsequent missions various.

BTW of course when I said air cooled in a post upthread I mention oxygen flow cooled.

What do you wear to work?

Serious question. For some its suit and tie. Manual workers, perhaps a one-piece overall or maybe cargo-pants and a hi-viz. Maybe the job needs ear/eye protection and a hard-hat. If the environment and protocol permit, shorts and a tee is comfy. We dress for the occcasion.

Until now, whatever the space-job, the choice was largely a one-design-fits-all with the same protection, dexterity, mobility, bulk and cost. I'm pretty sure that the current Spacex IVA and EVA suits are not yet a finished product. I'm also pretty sure that product may not be suitable for every environment and task, but why would you want to have the same level of protection, security and dexterity on every job? It is also demonstrating innovation, and trialling new technologies, materials and fabrics and it was, above all, a test flight.

The suits are perhaps indicating what Spacex demonstrates every day; the normalisation of space, and it being just another workplace.

(They also look pretty cool don't they?).

This is not entirely true I'm afraid. During 60 years of crewed spaceflight a number of spacesuits for different uses have been developed. All different and specifically taylored (literally...) for the task. There are the "simple but quite comfortable" pressure suits that are worn inside a spacecraft during critical phases of the mission. Their main task is to offer protection against depressurisation. They have no life-support of their own and no cooling.
Then there are EVA suits for "free space" like those on the ISS. They must be little spacecraft of their own providing life support and climate control for many hours. Some even came with their own attitude control and thrusting system (like the MMU of the early Shuttle days and SAFER systems - that must have been an astronauts dream to freely fly around with a MMU - the mother of all EVAs!). Size and mass and bulk do not matter much with this kind of suit, the astronauts mainly use their hands at work and the overall package must be safe and comfortrable to wear and work inside for a whole day.
And then there are the suits for lunar and planetary exploration. They are like EVA suits in many respects (life support, heating/cooling, communications) but they must be lightweigt and flexible enough to wear with gravity present. To this day there is not yet a good solution of how to build such a suit. The lunar suits of Apollo for example are much too heavy to be worn on Mars with it's higher gravity. But the demands on the life support on Mars (no atmosphere, extreme temperatures) are the same, so the backpack must contain the same stuff as those from the
time of Apollo. A difficult task!
And then of course, for longer stays on Moon and Mars, protection from ionising radiation will become an important task for the suits as well. Even more difficult to ensure.

Mars suit.

​​​​​​​https://en.wikipedia.org/wiki/Mars_s...ion%20sickness.

So all safely back on the ground. On to IFT5….