It’s a lit­tle more dif­fi­cult in space...

Focus-Science and Technology - - LEAVING EARTH -

If we’re go­ing to suc­cess­fully leave Earth, we’ll need to fig­ure out how to con­ceive in space. One po­ten­tial hur­dle is the ef­fects of weight­less­ness on sperm – some­thing that’s cur­rently be­ing in­ves­ti­gated by NASA.

In April this year, the Mi­cro-11 pro­ject sent hu­man sperm to the ISS for the first time. Researchers are still await­ing the re­sults, but pre­vi­ous work from the same team has shown that bull and sea urchin sperm fare pretty well in space. The bull sperm move faster in mi­cro­grav­ity (a trait that’s gen­er­ally as­so­ci­ated with higher fer­til­ity), while, in sea urchin sperm, the chem­i­cals that get the sperm cells to start swim­ming also kick in faster.

“Given what we know from the pre­vi­ous data, our hy­poth­e­sis is that [hu­man] sperm are go­ing to be found to swim faster in mi­cro­grav­ity,” says Dr Joseph Tash at the Univer­sity of Kansas, leader of the Mi­cro-11 pro­ject. If this does hap­pen, he hopes the pro­ject will be able to fig­ure out why.

But sperm is only half of the equa­tion. Pre­vi­ous ex­per­i­ments on Space Shut­tle mis­sions with fe­male mice sug­gest that mi­cro­grav­ity de­lays the re­lease of ma­ture eggs from ovaries. Tash has got an­other ex­per­i­ment in the works to test whether this is a long-term ef­fect – if it is, it’ll be an­other bridge we need to cross.

An­other ob­sta­cle to mak­ing space ba­bies might be high-en­ergy cos­mic rays and the charged par­ti­cles stream­ing from the Sun. While ra­di­a­tion lev­els on the ISS are 10 times higher than on Earth’s sur­face, they’re noth­ing com­pared to lev­els out­side the pro­tec­tion of Earth’s mag­netic field, which acts as a de­flec­tive shield. Ra­di­a­tion can stop sperm and eggs from be­ing pro­duced, and can also cause mu­ta­tions, lead­ing to dam­aged foe­tuses. We’ll need to find ways to shield space trav­ellers from these ef­fects with ra­di­a­tion-proof habi­tats, or medicines that can help re­pair DNA dam­age.

Once we’ve got over these bi­o­log­i­cal hur­dles, we’ll also need to make sure that we send enough peo­ple to our new home to keep the gene pool healthy and avoid in­breed­ing. One hy­po­thet­i­cal plan for a 6,300-year trip to nearby ex­o­planet Prox­ima Cen­tauri b es­ti­mates as few as 98 peo­ple would be enough to pre­vent in­breed­ing. Oth­ers think a crew on the or­der of thou­sands is a bet­ter bet for such a long mis­sion, to cope with the pos­si­bil­ity of a cat­a­strophic event and keep the crew as healthy as pos­si­ble.


Any chil­dren born in space will grow up in a very dif­fer­ent world from our own Kelly Oakes is a sci­ence writer based in London.Colin Stu­art is an as­tron­omy au­thor. His lat­est book, How To Live In Space, is out on 4 Oc­to­ber (An­dre Deutsch, £16.99).

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