# A spacecraft the size of Apollo 11's lunar module, composed of antimatter, around a normal star

After writing this question, I came up with a new question.

# Consideration

1. The considerations are mostly similar to the linked question (reading it is highly encouraged, as I am trying to post as little redundancy as possible)
2. The ship in question is comparable to Apollo 11 lunar module
3. The distance from the star is roughly the distance between Earth and the Sun

# The Questions

1. How long would an antimatter ship (not powered by antimatter, but composed of antimatter) survive with exposure to stellar winds?
2. How much energy is released during the exposure?
3. How long could the crew (consider human-like physiology and radiation resistance) survive the radiation before dying?
4. Related to number 2, would the radiation affect the planet or life on that planet in a way that's not negligible in effect? Consider the minimum unshielded distance from the planet's center to be around 1.2 times the radius of Earth, and away toward the moon.
• What specific type of antimatter? What atoms, molecules, chemical compounds, etc.? Commented Aug 29, 2015 at 16:48
• How would the spaceship protect itself from micrometeoroid impacts? Given the energy levels involved in matter/anti-matter annihilation even a tiny (sub-gramme) meteoroid collision would be catastrophic. Commented Aug 29, 2015 at 23:37
• @HDE226868 consider the spacecraft were built just like it's ordinary matter counterparts. Or consider the opposite, the spacecraft is normal, but the entire universe is composed of antimatter Commented Aug 30, 2015 at 5:35
• @SteveBird that is the exact question I am asking (or at least within the scope of my question) Commented Aug 30, 2015 at 5:37
• Especially considering that you tagged this hard-science: how did the antimatter ship arrive in this location?
– user
Commented Aug 30, 2015 at 17:21

The density of the solar wind (near earth) is approximately 6 atoms per cc. Essentially the craft would be “Sandblasted” away by the matter-antimatter annihilation occurring on the surface of the craft in whichever direction it was traveling.

The exact amount of time required to compromise the hull of the craft would be difficult to determine due to not knowing the density of the hull’s material, and relative direction of space craft travel in relation to the solar wind.

Think of a bicyclist traveling with a tail wind, he encounters much less force from the air resistance (in front of him) if the air in back of him is going in his direction (essentially causing fewer interactions of the air molecules against the rider).

The same concept would be applicable in your scenario. So calculating the time would be difficult due to the fact that there would be fewer anti-particles impacting the hull than if the craft were “Bucking” the solar wind.

The length of time for the crew to survive would also be difficult to determine for the same reason.

But since matter-antimatter annihilation produces gamma rays (which is ionizing radiation) and neutrinos. The crew would be at serious risk.

However, long before the effects of radiation sickness killed the crew, the craft would be compromised by loss of hull integrity.

As for the radiation hitting the planet and causing damage: that would probably not be an issue due to the protective effects of the planets magnetosphere and the thickness of the atmosphere; along with the fact that neutrino interactions with matter are somewhat rare, and not usually a source of concern health wise.

The energy released follows the E=mc2 equation, so again it depends on “with the solar wind”, or “bucking” the solar wind.

Density of solar wind - http://hypertextbook.com/facts/2005/RandyAbbas.shtml

Antimatter/Matter mass energy conversion - https://en.wikipedia.org/wiki/Antimatter

• hard-science $\implies$ citation needed Commented Aug 30, 2015 at 10:16
• Density of solar wind - hypertextbook.com/facts/2005/RandyAbbas.shtml Commented Aug 30, 2015 at 17:37
• Antimatter/Matter mass energy conversion - en.wikipedia.org/wiki/Antimatter Commented Aug 30, 2015 at 18:10
• The citations should be in the answer, not in the comments. Commented Aug 30, 2015 at 19:11