Editor’s Note: The findings reported here are based on preliminary results that have not been shared formally with the scientific community via peer-reviewed publication.
Webb’s first near-infrared spectrum of Mars, captured by the Near-Infrared Spectrograph (NIRSpec) on September 5, 2022, reveals chemical and physical properties of Mars’ surface and atmosphere. Data are shown in white, with a best-fit model in purple.
The spectrum shows a combination of sunlight reflected from Mars’ surface and atmosphere, and light emitted by the planet as it gives off heat. Wavelengths between 1 and 3 microns are dominated by reflected light, while those between 3 and 5 microns are dominated by emitted light. Both the reflected and emitted light pass through Mars’ atmosphere, affecting the brightness of various wavelengths and the shape of the spectrum in various ways.
The deep valleys are absorption features caused when specific wavelengths are blocked by gases such as carbon dioxide, water, and carbon monoxide. Other details, like the broad shape of the spectrum and the slope of the curve at different points, reveal information about dust, clouds, and surface features.
The data were collected using six different high-resolution spectroscopy modes (grating modes), each of which covers a different wavelength range. (The white line is not continuous because there are small gaps in coverage.) The best-fit model takes into account the data as well as other known properties of Mars. Constructing a best-fit model using a tool such as the Planetary Spectrum Generator makes it possible to estimate abundances of given molecules in the atmosphere.
NIRSpec was built for the European Space Agency (ESA) by a consortium of European companies led by Airbus Defence and Space (ADS) with NASA’s Goddard Space Flight Centre providing its detector and micro-shutter subsystems.
See the Fast Facts below for additional technical details.
Credits
Image
NASA, ESA, CSA, STScI, Mars JWST/GTO Team
| About The Object | |
|---|---|
| Object Name | Mars |
| Object Description | Terrestrial (rocky) planet |
| Distance | On September 5, 2022, Mars was 0.92 astronomical unit (86 million miles or 140 million km) away from Earth. |
| About The Data | |
| Data Description | The spectra were taken on September 5th 2022 (23:30 UT) with the narrow NIRSpec slit and the fast readout with the SUBS200A2 mode. The shown spectra are a combination of data collected over 3 gratings (G140H, G235H, G395H) with 2 orders per grating (NRS1, NRS2). The planet was mapped with several slit positions. In this particular composite, only non-saturated spectra are shown; they sample different locations along the planet. At this preliminary stage, the data are not flux calibrated and for display purposes, the continuum fluxes have been scaled to a model spectrum (purple line) as computed with the Planetary Spectrum Generator (PSG, https://psg.gsfc.nasa.gov). These observations are part of the JWST Mars GTO (Guaranteed Time Observations) program (G. Villanueva). |
| Instrument | NIRSpec |
| Exposure Dates | September 5th 2022 (23:30 UT) |
| Filters | The shown spectra are a combination of data collected over 3 gratings (G140H, G235H, G395H) with 2 orders per grating (NRS1, NRS2). |
| About The Object | |
|---|---|
| Object Name | A name or catalog number that astronomers use to identify an astronomical object. |
| Object Description | The type of astronomical object. |
| R.A. Position | Right ascension – analogous to longitude – is one component of an object's position. |
| Dec. Position | Declination – analogous to latitude – is one component of an object's position. |
| Constellation | One of 88 recognized regions of the celestial sphere in which the object appears. |
| Distance | The physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs. |
| Dimensions | The physical size of the object or the apparent angle it subtends on the sky. |
| About The Data | |
| Data Description |
|
| Instrument | The science instrument used to produce the data. |
| Exposure Dates | The date(s) that the telescope made its observations and the total exposure time. |
| Filters | The camera filters that were used in the science observations. |
| About The Image | |
| Image Credit | The primary individuals and institutions responsible for the content. |
| Publication Date | The date and time the release content became public. |
| Color Info | A brief description of the methods used to convert telescope data into the color image being presented. |
| Orientation | The rotation of the image on the sky with respect to the north pole of the celestial sphere. |
