Mars sol

Last updated
PIA25178-Mars-InSightLander-Sunrise-20220410.gif
Sunrise on Mars
PIA25178-Mars-InSightLander-Sunset-20220410.gif
Sunset on Mars
Images captured by InSight

Sol (borrowed from the Latin word for sun) is a solar day on Mars; that is, a Mars-day. A sol is the apparent interval between two successive returns of the Sun to the same meridian (sundial time) as seen by an observer on Mars. It is one of several units for timekeeping on Mars.

Contents

A sol is slightly longer than an Earth day. It is approximately 24 hours, 39 minutes, 35 seconds long. A Martian year is approximately 668.6 sols, equivalent to approximately 687 Earth days [1] or 1.88 Earth years.

The sol was adopted in 1976 during the Viking Lander missions and is a measure of time mainly used by NASA when, for example, scheduling the use of a Mars rover. [2] [3]

Length

The average duration of the day-night cycle on Mars — i.e., a Martian day — is 24 hours, 39 minutes and 35.244 seconds, [3] equivalent to 1.02749125 Earth days. [4] The sidereal rotational period of Mars—its rotation compared to the fixed stars—is 24 hours, 37 minutes and 22.66 seconds. [4] The solar day lasts longer because Mars's rotation is the same direction as its orbital motion. [5]

Usage in Mars lander timekeeping

Transit of Deimos from Mars, as captured by the Mars rover Perseverance on sol 1037 of its mission (20 January 2024 UTC).

When a NASA spacecraft lander begins operations on Mars, the passing Martian days (sols) have been tracked using a simple numerical count. The two Viking landers, Mars Phoenix, Mars Science Laboratory rover Curiosity, InSight, and Perseverance rover projects all counted the sol of touchdown as "Sol 0". Mars Pathfinder and the two Mars Exploration Rovers instead defined touchdown as "Sol 1". [6] Generally speaking, the choice between counting from Sol 0 or Sol 1 has been made so that Sol 1 would be the first sol with "meaningful" or "useful" lander operations. [3] Thus, landers that touched down late in the Martian day have begun their sol count at 0, while those that touch down early in the day began their count at 1.

Although NASA lander missions to Mars have twice occurred in pairs, no effort was made to synchronize the sol counts of the two landers within each pair. Thus, for example, although Spirit and Opportunity were sent to operate simultaneously on Mars, each counted its landing date as "Sol 1", putting their calendars approximately 21 sols out of sync.

Terminology

The word "yestersol" was coined by the NASA Mars operations team early during the MER mission to refer to the previous sol (the Mars version of "yesterday"), and came into fairly wide use within that organization during the Mars Exploration Rover Mission of 2003. [7] It was eventually picked up and used by the press. [8] Other neologisms include "tosol" (for "today" on Mars), as well as one of three Mars versions of "tomorrow": "nextersol", "morrowsol", or "solmorrow". [9] NASA planners coined the term "soliday" at least as far back as 2012 to refer to days off due to time phasing or the synching of planetary schedules. [10]

Conversion

Considering a possible colonization of Mars, one question that arose was "how does one convert a Sol to standard Earth time?" In the science fiction series Mars trilogy by Kim Stanley Robinson, the Mars settlers use traditional Earth watches that stop ticking at midnight for 39 minutes and 40 seconds before resuming their timekeeping. This creates something like a "witching hour" which compensates for the time difference between a Sol and an Earth day. This follows the method previously given by Philip K. Dick in his 1964 novel Martian Time-Slip .

For the Spirit mission, a small watchmaker's store created mechanical watches for the mission crew that kept Mars time with no more than 10 seconds difference per Earth-day. [11] In 2022, it was reported that the watchmaker Omega had begun to sell digital-analog hybrid watches to the public. [12]

Related Research Articles

<i>2001 Mars Odyssey</i> NASA orbiter for geology and hydrology

2001 Mars Odyssey is a robotic spacecraft orbiting the planet Mars. The project was developed by NASA, and contracted out to Lockheed Martin, with an expected cost for the entire mission of US$297 million. Its mission is to use spectrometers and a thermal imager to detect evidence of past or present water and ice, as well as study the planet's geology and radiation environment. It is hoped that the data Odyssey obtains will help answer the question of whether life existed on Mars and create a risk-assessment of the radiation that future astronauts on Mars might experience. It also acts as a relay for communications between the Curiosity rover, and previously the Mars Exploration Rovers and Phoenix lander, to Earth. The mission was named as a tribute to Arthur C. Clarke, evoking the name of his and Stanley Kubrick's 1968 film 2001: A Space Odyssey.

<i>Viking 1</i> Robotic spacecraft sent to Mars

Viking 1 was the first of two spacecraft, along with Viking 2, each consisting of an orbiter and a lander, sent to Mars as part of NASA's Viking program. The lander touched down on Mars on July 20, 1976, the first successful Mars lander in history. Viking 1 operated on Mars for 2,307 days or 2245 Martian solar days, the longest Mars surface mission until the record was broken by the Opportunity rover on May 19, 2010.

<i>Viking 2</i> Space orbiter and lander sent to Mars

The Viking 2 mission was part of the American Viking program to Mars, and consisted of an orbiter and a lander essentially identical to that of the Viking 1 mission. Viking 2 was operational on Mars for 1281 sols. The Viking 2 lander operated on the surface for 1,316 days, or 1281 sols, and was turned off on April 12, 1980, when its batteries failed. The orbiter worked until July 25, 1978, returning almost 16,000 images in 706 orbits around Mars.

<span class="mw-page-title-main">Mars 3</span> Soviet space probe launched in 1971, consisting of a Mars orbiter and lander

Mars 3 was a robotic space probe of the Soviet Mars program, launched May 28, 1971, nine days after its twin spacecraft Mars 2. The probes were identical robotic spacecraft launched by Proton-K rockets with a Blok D upper stage, each consisting of an orbiter and an attached lander. After the Mars 2 lander crashed on the Martian surface, the Mars 3 lander became the first spacecraft to attain a soft landing on Mars, on December 2, 1971. It failed 110 seconds after landing, having transmitted only a gray image with no details. The Mars 2 orbiter and Mars 3 orbiter continued to circle Mars and transmit images back to Earth for another eight months.

<i>Mars Pathfinder</i> Mission including first robotic rover to operate on Mars (1997)

Mars Pathfinder is an American robotic spacecraft that landed a base station with a roving probe on Mars in 1997. It consisted of a lander, renamed the Carl Sagan Memorial Station, and a lightweight, 10.6 kg (23 lb) wheeled robotic Mars rover named Sojourner, the first rover to operate outside the Earth–Moon system.

<span class="mw-page-title-main">Mars Exploration Rover</span> NASA mission to explore Mars via two rovers

NASA's Mars Exploration Rover (MER) mission was a robotic space mission involving two Mars rovers, Spirit and Opportunity, exploring the planet Mars. It began in 2003 with the launch of the two rovers to explore the Martian surface and geology; both landed on Mars at separate locations in January 2004. Both rovers far outlived their planned missions of 90 Martian solar days: MER-A Spirit was active until March 22, 2010, while MER-B Opportunity was active until June 10, 2018.

<i>Spirit</i> (rover) NASA Mars rover, active from 2004 to 2010

Spirit, also known as MER-A or MER-2, is a Mars robotic rover, active from 2004 to 2010. Spirit was operational on Mars for 2208 sols or 3.3 Martian years. It was one of two rovers of NASA's Mars Exploration Rover Mission managed by the Jet Propulsion Laboratory (JPL). Spirit landed successfully within the impact crater Gusev on Mars at 04:35 Ground UTC on January 4, 2004, three weeks before its twin, Opportunity (MER-B), which landed on the other side of the planet. Its name was chosen through a NASA-sponsored student essay competition. The rover got stuck in a "sand trap" in late 2009 at an angle that hampered recharging of its batteries; its last communication with Earth was on March 22, 2010.

<span class="mw-page-title-main">Mars rover</span> Robotic vehicle for Mars surface exploration

A Mars rover is a remote-controlled motor vehicle designed to travel on the surface of Mars. Rovers have several advantages over stationary landers: they examine more territory, they can be directed to interesting features, they can place themselves in sunny positions to weather winter months, and they can advance the knowledge of how to perform very remote robotic vehicle control. They serve a different purpose than orbital spacecraft like Mars Reconnaissance Orbiter. A more recent development is the Mars helicopter.

<span class="mw-page-title-main">Mars Science Laboratory</span> Robotic mission that deployed the Curiosity rover to Mars in 2012

Mars Science Laboratory (MSL) is a robotic space probe mission to Mars launched by NASA on November 26, 2011, which successfully landed Curiosity, a Mars rover, in Gale Crater on August 6, 2012. The overall objectives include investigating Mars' habitability, studying its climate and geology, and collecting data for a human mission to Mars. The rover carries a variety of scientific instruments designed by an international team.

<span class="mw-page-title-main">Timekeeping on Mars</span> Proposed approaches to tracking date and time on the planet Mars

Though no standard exists, numerous calendars and other timekeeping approaches have been proposed for the planet Mars. The most commonly seen in the scientific literature denotes the time of year as the number of degrees on its orbit from the northward equinox, and increasingly there is use of numbering the Martian years beginning at the equinox that occurred April 11, 1955.

<span class="mw-page-title-main">Mars landing</span> Landing of a spacecraft on the surface of Mars

A Mars landing is a landing of a spacecraft on the surface of Mars. Of multiple attempted Mars landings by robotic, uncrewed spacecraft, ten have had successful soft landings. There have also been studies for a possible human mission to Mars including a landing, but none have been attempted. Soviet Union’s Mars 3, which landed in 1971, was the first successful Mars landing. As of 2023, the Soviet Union, United States and China have conducted Mars landings successfully.

<span class="mw-page-title-main">Martian dust devils</span> Weather phenomenon on Mars

Martian dust devils are convective atmospheric vortices that occur on the surface of Mars. They were discovered from data reported by NASA's Viking probes, and have been photographed by orbiting satellites and surface rovers in subsequent missions.

<span class="mw-page-title-main">Mars Astrobiology Explorer-Cacher</span> Cancelled NASA Mars rover concept

The Mars Astrobiology Explorer-Cacher (MAX-C), also known as Mars 2018 mission, was a NASA concept for a Mars rover mission, proposed to be launched in 2018 together with the European ExoMars rover. The MAX-C rover concept was cancelled in April 2011 due to budget cuts.

<span class="mw-page-title-main">Mars atmospheric entry</span> Entry into the atmosphere of Mars

Mars atmospheric entry is the entry into the atmosphere of Mars. High velocity entry into Martian air creates a CO2-N2 plasma, as opposed to O2-N2 for Earth air. Mars entry is affected by the radiative effects of hot CO2 gas and Martian dust suspended in the air. Flight regimes for entry, descent, and landing systems include aerocapture, hypersonic, supersonic, and subsonic.

<i>Curiosity</i> (rover) NASA robotic rover exploring Gale crater on Mars

Curiosity is a car-sized Mars rover exploring Gale crater and Mount Sharp on Mars as part of NASA's Mars Science Laboratory (MSL) mission. Curiosity was launched from Cape Canaveral (CCAFS) on November 26, 2011, at 15:02:00 UTC and landed on Aeolis Palus inside Gale crater on Mars on August 6, 2012, 05:17:57 UTC. The Bradbury Landing site was less than 2.4 km (1.5 mi) from the center of the rover's touchdown target after a 560 million km (350 million mi) journey.

<i>Sojourner</i> (rover) First NASA Mars rover on Mars Pathfinder mission

Sojourner is a robotic Mars rover that landed in the Ares Vallis channel in the Chryse Planitia region of the Oxia Palus quadrangle on July 4, 1997. Sojourner was operational on Mars for 92 sols. It was the first wheeled vehicle to rove on a planet other than Earth and formed part of the Mars Pathfinder mission.

Timeline of <i>Opportunity</i> Robotic rover that was active on the planet Mars from 2004 to 2018

Opportunity is a robotic rover that was active on the planet Mars from 2004 to 2018. Launched on July 7, 2003, Opportunity landed on Mars' Meridiani Planum on January 25, 2004, at 05:05 Ground UTC, three weeks after its twin Spirit (MER-A), also part of NASA's Mars Exploration Rover Mission, touched down on the other side of the planet. While Spirit became immobile in 2009 and ceased communications in 2010, Opportunity exceeded its planned 90 sol duration of activity by 14 years 46 days. Opportunity continued to move, gather scientific observations, and report back to Earth until 2018. What follows is a summary of events during its continuing mission.

The following outline is provided as an overview of and topical guide to Mars:

References

  1. ↑ "Mars' Calendar".
  2. ↑ Snyder, Conway W. (1979). "The extended mission of Viking". Journal of Geophysical Research. 84 (B14): 7917–7933. Bibcode:1979JGR....84.7917S. doi:10.1029/JB084iB14p07917.
  3. 1 2 3 Allison, Michael; Schmunk, Robert (30 June 2015). "Technical Notes on Mars Solar Time as Adopted by the Mars24 Sunclock". Goddard Institute for Space Studies . National Aeronautics and Space Administration . Retrieved 13 June 2018.
  4. 1 2 Allison, Michael (15 August 1997). "Accurate analytic representations of solar time and seasons on Mars with applications to the Pathfinder/Surveyor missions". Geophysical Research Letters . 24 (16): 1967–1970. doi: 10.1029/97GL01950 .
  5. ↑ Belloni, Mario; Timberlake, Todd (2014). "Sidereal and Solar Day JS Model". compadre.org. American Association of Physics Teachers.
  6. ↑ "Phoenix Mars Mission - Mission - Mission Phases - On Mars". Phoenix.lpl.arizona.edu. 29 February 2008. Retrieved 13 July 2012.
  7. ↑ Rusch, Elizabeth (2012). The Mighty Mars Rovers: The Incredible Adventures of Spirit and Opportunity. ISBN   978-0547822808.
  8. ↑ Chang, Alicia (3 August 2012). "MSL? EDL? A guide to NASA's Mars rover lingo". The Christian Science Monitor . Retrieved 19 June 2020. Yesterday on Mars is yestersol.
  9. ↑ Martínez-Frías, Jesús (28 September 2002). "Marte: 'yestersol', 'tosol' y 'solmorrow'" [Mars: 'yestersol', 'tosol', and 'solmorrow']. El Mundo (in Spanish). Madrid, Spain: Unidad Editorial S.A. Retrieved 23 April 2014.
  10. ↑ "MSL abbreviations and acronyms". an.rsl.wustl.edu. 31 October 2012. Retrieved 19 December 2015.
  11. ↑ "Watchmaker With Time to Lose". JPL Mars Exploration Rovers. 2014. Retrieved 22 January 2015.
  12. ↑ Pearlman, Robert Z. (2022). "New Omega Marstimer watch keeps time on Earth and the Red Planet". Space.com. Retrieved 3 October 2022.

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.