BTS#18: Growing Space Lettuce Amid Tense NASA-Russian Relations

Show Notes

The International Space Station plants a garden

On the 18th of April 2014, a Dragon capsule was launched aboard a Falcon 9 rocket towards the International Space Station. Launched by the private company SpaceX, this capsule carried, among other things, a new gardening experiment aimed at determining the best way to grow plants in space for consumption. The experiment is called the Veggie Hardware Validation tet (Veg-01) or ‘Veggie’ for short and will be testing a new set of hardware called ‘Plant Pillows’ designed to distribute water and hold soil. The first crop (a mix of lettuces called outredgeous) is expected to be ready in late May, but the astronauts won’t be allowed to test the food. It will be sent home for analysis. Suggested Reading: Science @ NASA, Press Release, Veggie mission page.


The ESO has measured the length of an exoplanet’s day

Using the Very Large Telescope (VLT), astronomers from the Netherlands have measured the rotation rate of an exoplanet. The exoplanet in question is Beta Pictoris b, which has a day that lasts 8 hours; for reference, the shortest day in our Solar System is Jupiter’s at 9.9 hours to complete a rotation. Coupled with the fact that Beta Pictoris b is a larger planet than Jupiter, this short day indicates the equator of the planet is rotating at 100 000 km/h (much faster than Jupiter’s 47 000 km/h, and Earth’s 1700 km/h). The astronomers were able to measure this using a very high resolution spectrograph to detect absorption features in the atmosphere of the planet. Then using the principles of Doppler shift, were able to measure the rotation speed.

Suggested Reading: ESO Press Release, Nature paper, VLT wiki, The Doppler Effect (also this, hehe).


Nearby brown dwarf discovered at 7.2 light-years

The closest system to the Sun is the Alpha Centauri system at 4.4 light-years away; the next closest system is Barnard’s Star at 6.0 light-years away. After that is a binary Brown Dwarf duo called Luhman 16, at 5.69 light-years. Those two were discovered in 2013 using data from WISE and are the closest Brown Dwarfs ever discovered. Now, using data from the the same telescope, astronomer Kevin Luhman (of the aforementioned discovery) announced the fourth closest system to the Sun: WISE 0855-0714, at 7.2 light-years away.

Not only is this new Brown Dwarf very close to the Sun (relative to the size of the Milky Way, that is), it is also very very cold: the surface temperature is -48 < T < -13 degrees Celsius, or as cold as the North Pole on Earth. The Brown Dwarf was found as a result of its high proper motion, which is the motion of the object relative to the Sun. Objects that are far from the Sun (like distant stars) will move relatively slowly across the sky; objects that are very close will move much faster. By taking multiple images of the same location on the sky and then comparing them, its possible to locate an object that is moving, and measure its velocity and distance. As Brown Dwarfs do not shine like stars, these discoveries require the use of an infrared telescope; hence WISE.

How exactly to categorize Brown Dwarfs is a topic of much debate in the community. They are definitely not stars, because they haven’t ignited fusion of hydrogen in their core. Fusion is started when enough mass has accreted onto an object such that the pressure and temperature at the core of the object reaches levels high enough to overcome the Coulomb barrier, and fuse two protons together. Brown Dwarfs simply aren’t massive enough to sustain this reaction. However, classifying them as giant planets is also up for debate. They are much bigger than most of the planets we have discovered in other star systems, and they also occur on their own (i.e., not orbiting a star).  What’s interesting is WISE 0855-0714 has a mass between 3 and 10 times that of Jupiter, making it more likely to be a gas giant planet that was (most likely) ejected from its own star system.

Suggested Reading: Science @ NASA, Bad Astronomy article, List of Nearest Stars.