Jupiter’s Moon Europa Spectroscographymetroscophy

Index

Abstract

Introduction

Observations and Reduction

Conclusions

References

Abstract

This project’s objective is to determine the composition of the emissions from Jupiter’s moon Europa, in order to know the probability it has to sustain life forms. This spectra data was obtained from a 60” telescope, reduced and analyzed.

IntroductionJUPITER

The planet Jupiter is primarily composed of hydrogen with a small proportion of helium; it may also have a rocky core of heavier elements under high pressure. Because of its rapid rotation, Jupiter's shape is that of an oblate spheroid (it possesses a slight but noticeable bulge around the equator). The outer atmosphere is visibly segregated into several bands at different latitudes, resulting in turbulence and storms along their interacting boundaries. A prominent result is the Great Red Spot, a giant storm that is known to have existed since at least the seventeenth century. Surrounding the planet is a faint planetary ring system and a powerful magnetosphere. There are also at least 63 moons, including the four large moons called the Galilean moons that were first discovered by Galileo Galilei in 1610. Ganymede, the largest of these moons, has a diameter greater than that of the planet Mercury.

Jupiter has been explored on several occasions by robotic spacecraft, most notably during the early Pioneer and Voyager flyby missions and later by the Galileo orbiter. The latest probe to visit Jupiter was the Pluto-bound New Horizons spacecraft in late February 2007. The probe used the gravity from Jupiter to increase its speed and adjust its trajectory toward Pluto, thereby saving years of travel. Future targets for exploration include the possible ice-covered liquid ocean on the Jovian moon Europa

The atmosphere contains trace amounts of methane, water vapor, ammonia, and silicon-based compounds. There are also traces of carbon, ethane, hydrogen sulfide, neon, oxygen, phosphine, and sulfur. The outermost layer of the atmosphere contains crystals of frozen ammonia.[11][12] Through infrared and ultraviolet measurements, trace amounts of benzene and other hydrocarbons have also been found.

Europa Spectrum

Solar Spectrum

Overplotted Spectrum

Observations and Reduction

Spectra was obtained for the moon Europe of Jupiter, four expositions of 200 seconds, at a grading tilt of 11. The position of the moons at the day the data was obtained was as seen on the picture above.

Callisto

Ganymedes

Io

Europe

The data for the position of the moons (Jupiter ephemeris) can be looked up in the Astronomical Handbook 2008, or in the Sky and Telescope Website, article “Chasing the Moons of Jupiter”

Our observing procedure was pointing to the Planet Jupiter, and then moving to center the moon Europe in the spectral focus. The telescope is not aligned so we had to use a visual aid to center it that was pasted below the telescope.

RA: 19:21:47, DEC: -22 15 52.7, UT: 09:45:24

Afterwards, you need to select the desired wavelength, which is done by changing the angle of the CCD. We used a tilt of 11 so we could observe a green spectrum around 5000 Armostrongs. We took four 200 seconds exposures.

Jupiter’s Moon Positions at 06/27/2008, 09:00 UT

Reduction//Open Packages

onedspec

twodispec

apextract

epar campspec

*input europa_r4

*output europa_r4_spec.fit

*darksubs Yes

*darkim darks.fit

*display europa_4_ds.fit

//note: use same exposure time for images and dark current.

//Results from campspec start appearing. For almost all questions answer is YES, although some require you to do some stuff.

Y respond affirmatively to question

E on image

M to select main peaks, first one

M to select second main peak

Q Quit graph

//Wavelet Calibration: you center on the mark and type M, and type the value (calibration corresponding to graphs of HgNE Lamp Spectra, in Light section of you Binder).

M To do wavelength calibration

M Second wavelength calibration

M Third wavelength calibration

Q

E Extrapolate from that Fit.

F Calculate Fit. This plots the position of brightest pixels, looks 4 peaks of your spectrum

Q

//After you use E, you can select the strange data marks of the graphic in order to obtain better information by deleting it.

D Delete

F Fit again

Q

//SPECTRA Appears. It can be plotted

Splot europa_r4_spec.fit // plot the image that had all this done.

//On spectrum:

e //obtain contour image, Isofode.

Spacebar // Gives coordinates, the X is the wavelength

w e e // zoom in. e's must be done on corner DL and UR.

w a // zoom out

= // Print

//Combine the four images for Europe

epar scomb

*input europa_r1.spec, europa_r2.spec, ....

*output europa_rcombine

*logfile STDOUT

*apotres 2

*group aperture

*combine average

*reject sigikip

*First no

//Everything else the same

Results

From the resulting image, europa_rcombine, the Earth atmosphere needs to be divided. In this image, peaks are emissions and other are absorptions. You compare the depth to obtain data from this. On this image Europa doesn't seem to emit but rather to absorb.

Next steps: Print out in apollo, go online, look up absorption features, figure out based on wavelength what lines are.

References