# Ice formation in a cavity that was sealed at ambient condition and taken to space

I have a hardware with a cavity that was closed (welded) at ambient conditions (298K, 1 bar Pressure and 50% RH). The hardware was taken to space where the temperature can go down to near zero Kelvin. Will there be any ice formation? And will it be a hard ice or more like a snow?

I can imagine ice formation but I suspect it will not be like an ice crystal but more like snow. Can somebody explain this? Thank you.

• I would be concerned about your hardware being able to withstand the 14.7 psi of outward pressure from the air inside the cavity, as there's no atmospheric pressure in space to push back against it. – probably_someone Oct 23 '18 at 15:13
• @probably_someone And any additional pressure that could be brought on if exposed to the sun would make it worse. – JMac Oct 23 '18 at 15:16
• @JMac Exactly. It's hard to get rid of heat in space, as you can't exactly conduct or convect it away, and the Sun is just as strong of a heat source as it is on the ground. – probably_someone Oct 23 '18 at 15:18
• @probably_someone pressure is not the problem, the walls are thick enough for that. In fact, I am talking about a hardware that could withstand much higher pressure difference across the wall. My concern is a diaphragm inside the hardware which is effectively facing no pressure difference across it but if hard ice forms on one side, it might damage it. And regarding dissipating heat, what about radiation? – Manish Kumar Mishra Oct 23 '18 at 15:36
• @ManishKumarMishra It's not the thickness of the walls that matters, but rather the integrity of the weld/sealant. And of course there is radiation, but at low (i.e. not-visibly-glowing) temperatures, it doesn't transfer all that much heat away. Anyway, let's compare the two situations: on the ground, you can get rid of the Sun's heat through conduction, convection, and radiation. In space, you can only get rid of the Sun's heat by radiation. Therefore, you're going to heat up more from the Sun in space than you would in-atmosphere. – probably_someone Oct 23 '18 at 15:47