RU2820982C1 - Electronic clock for space and/or surface exploration - Google Patents

Abstract

FIELD: clocks and other time meters.

SUBSTANCE: invention relates to electronic clocks. Electronic clock has functionality for space exploration and/or surface exploration on a terrestrial planet. Clock comprises a time display facility and a processor subsystem. Processor subsystem is configured to support the coordinated planetary time of the earth-type planet, obtain longitudinal data representing the longitude of interest on the earth-type planet, which is different from the zero meridian of the planet, determining local true solar time, LTST, at longitude of interest depending on coordinated planetary time and using equation of time, which takes into account eccentricity of the orbit and inclination of the axis of rotation of the earth-type planet, and control of the electronic clock time display for displaying the LTST.

EFFECT: disclosed is an electronic clock for space and / or surface research.

15 cl, 9 dwg

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

The invention relates to an electronic watch having functionality for space exploration and/or surface exploration on a terrestrial planet.

BACKGROUND OF THE ART

Timekeeping watches are one of the oldest inventions of mankind. Clocks were previously purely mechanical devices, but modern watches are often at least partially powered electronically. For example, a digital watch may include an electronic display and a processor configured to display certain information on the display. Such information may include time and other types of information, such as date, time in another time zone, barometric data, etc. It is also known that there are part mechanical, part electronic watches which may, for example, comprise a dial with physical hands which may be electronically controlled by a processor.

Timing plays an important role in space exploration and surface exploration. For example, in a space mission from Earth to Mars, it is important to be able to accurately determine the time of occurrence of certain events, for example, the time of rocket launch, the time of landing of the lander, etc. Such timing is important not only on the Earth-type destination planet itself, for example, on Mars, but also on Earth, for example, at the mission control center. In relation to surface studies, the local time of day on a terrestrial planet constitutes important information for surface exploration of a terrestrial planet, which may be carried out, for example, on Mars, on Earth or on another space body with a solid surface (for example, the Moon, Mercury, Venus) .

It would be desirable to provide such functionality for space exploration and/or surface exploration in a wearable timekeeping device, i.e. in watches so that the wearer can always use such functionality regardless of his location.

The Omega Skywalker X-33 watch provides features for space exploration. For example, the watch is stated to track mission elapsed time (MET) and phase elapsed time (PET). Elapsed mission time, for a space mission, represents the elapsed time since launch. The elapsed time of a phase can be used to count down, or count forward, an elapsed time event in the MET. For example, the elapsed time of a phase can be used to set a timer that counts down until the rover begins scientific measurements on the surface of Mars.

It is also known to provide functions for surface testing in a portable electronic timepiece. For example, a digital watch may be equipped with a Global Positioning System (GPS) signal receiver to determine the geolocation of the wearer.

DISCLOSURE OF INVENTION

The objective of the invention is to create an electronic watch with improved functionality for space and/or surface exploration on a terrestrial planet.

The first aspect of the invention provides an electronic watch comprising:

- time display means for displaying time, wherein the time display means is electronically controllable for displaying a specific time;

- a processor subsystem configured to carry out electronic communication with a time display device and:

-- support for coordinated planetary time (UTC, MTC), which is set for the prime meridian of an terrestrial planet;

-- obtaining longitudinal data, wherein the longitudinal data represents a longitude of interest on a terrestrial planet that differs from the prime meridian;

-- determination of local true solar time, LTST, at the longitude of interest depending on coordinated planetary time and using the equation of time, which takes into account the eccentricity of the orbit and the inclination of the axis of rotation of the terrestrial planet; And

-- control the time display to display LTST.

An electronic watch, which is a wearable timekeeping device, includes a time display means for displaying the time. The time display means is electronically controlled by the clock processor subsystem having the ability to control the displayed time or at least being able to set the time to a specific time from which time can begin to count upward beyond the direct control of the processor subsystem. Such means of displaying time are known per se, and can take various forms, for example 'analogue' watch faces with physical hour hands and physical minute hands, as well as electronic displays which can display the time in digital format, i.e. in the form of numeric digits and/or through a digital representation of an analog watch face. An electronic watch may also contain multiple means of displaying time, such as an electronically controlled analog dial and one or more electronic displays.

The processor subsystem of a digital watch may contain one or more processors, which may also be referred to as 'embedded processor(s). The processor(s) may be implemented in software, or alternatively may be a hardware implementation of such software, for performing various functions, which at least includes controlling the time display means to display a specific time, for example, using an internal interface between the processor subsystem and a time display tool.

In accordance with the claimed invention, the processor subsystem can be configured to support coordinated planetary time, which is set for the prime meridian of an terrestrial planet. Such coordinated planetary time is known for various terrestrial planets, but can also be specified for terrestrial planets for which coordinated planetary time has not yet been assigned. For example, for the Earth, Coordinated Universal Time (UTC) is the coordinated planetary time, which is defined as the mean solar time (within about one second) at the Earth's prime meridian, i.e. at longitude 0° (Greenwich meridian). Another example is that for Mars, Martian Coordinated Time (MTC) is a proposed Martian standard similar to Earth's UTC. MTC is defined as the mean solar time at the prime meridian of Mars, which passes through the center of the crater Airy 0, in Meridian Earth. MTC is also sometimes referred to as Airy Mean Time (AMT).

The processor subsystem may support this coordinated planetary time in various ways, for example, by setting a software and/or hardware internal clock to the coordinated planetary time or by maintaining a time offset by which the coordinated planetary time can be calculated at any point in time from a reference internal clock .

The processing subsystem may be further configured to obtain longitudinal data that expresses a longitude of interest on an terrestrial planet that is different from the prime meridian. For example, such longitudinal data may specify a longitudinal coordinate, such as a number of degrees, that represents the longitude of interest.

The processing subsystem may be further configured to determine local true solar time (LTST) at a longitude of interest as a function of coordinated planetary time and using an equation of time that takes into account the orbital eccentricity and axis tilt of the terrestrial planet. Once the LTST is determined, the LTST may be displayed using a time display, for example, on a continuous basis or upon user request, such as by selecting an appropriate electronic clock function. Thus, the user is able to see the LTST at the desired longitude on his digital watch.

Local true solar time, also referred to as apparent time or true solar time, is of particular interest to space exploration and surface exploration, as will be explained below. The clock usually displays mean solar time, which is the solar time that would be measured by observation if the Sun moved throughout the year at the same apparent speed rather than, as in fact occurs, with a slightly varying apparent speed due to orbital eccentricity and axis tilt. terrestrial planets. For Earth, the prime meridian (longitude 0є) passes through the Royal Observatory in Greenwich, London (UK), and UTC coincides with mean solar time there. Time zones generally use one mean solar time, although mean solar time will vary locally within a time zone. While such time zones can ideally be specified as a repeating range of longitudes, for example strictly 15° wide and centered on successive longitudes that are multiples of 15°, at 0°, 15°, 30°, etc., this is not the case: Earth time zones can have strange shapes that suit more commercial and political needs rather than astronomical common sense. For example, Spain, France, Belgium, the Netherlands and Algeria must be in the same time zone as the UK. Also, given its meridional position, Bolivia is in the ‘correct’ time zone, while Argentina and Uruguay are not. Thus, mean solar time is imprecise, being an 'average' time, due to its ignorance of seasonal variability in the apparent speed of the sun, and also due to the fact that mean solar time is generally used over an entire time zone, which includes a range of longitudes and often can be frequency dependent due to the irregular shape of many time zones. For most work, using mean solar time and time zones for timekeeping is accepted throughout the world and is usually sufficient.

However, for space exploration and/or surface exploration, mean solar time and time zones may not be suitable for timekeeping. There are various reasons for this. One is that for missions to other Earth-like planets, such as Mars, there may not be a standardized concept of time zones. Thus, there may be a need to determine local solar time at a particular longitude of interest, such as the Mars lander landing site. Given such local solar time, LST, various mission events, eg landing, take-off, etc., can be timed with respect to the LST, eg by time or time of day expressed in LST.

For surface exploration, whether on Mars or on Earth or another terrestrial planet, determining the 'true' solar time at a particular longitude of interest may also be of interest, as this may aid in surface navigation. For example, it is known that a watch can be used as a solar compass by pointing the hour hand at the Sun, marking the angle with the direction 12:00, with the approximate North-South direction being at the bisector of the angle, i.e. angle between the clock hand and 12:00. By determining local true solar time, LTST, at a particular longitude of interest, such a solar compass can provide greater accuracy in determining North-South direction than using mean solar time for a time zone. This can improve navigational accuracy during surface surveys. In particular, this makes it possible to navigate on terrestrial planets, such as Mars, which do not have a magnetic field and on which compasses cannot be used and on which Galileo, GPS and similar geolocation systems are not available.

The above is illustrated in the description of the invention using the example of the city of Leiden (NL), in which the use of a clock displaying UTC+1 (LMST for the relevant time zone) gives a direction that is 10 degrees different from true South. This inaccuracy can be avoided by using an electronic clock that displays the LTST for the longitude of Leiden (4.50єE).

If necessary, the electronic watch additionally contains:

- electronic display;

- a user input subsystem allowing the user to enter data, wherein the electronic display is configured to display a response to said data input;

wherein the processing subsystem is configured to allow the user to specify the longitude of interest using the user input subsystem.

The user has the opportunity to indicate the longitude of interest directly on the electronic watch itself, for example, by specifying a longitudinal coordinate, for example, 135.35º, using the user input subsystem. The electronic display may be, for example, a numeric or alphanumeric display. The user input subsystem may, for example, include one or more buttons, dials, touch zones, etc.

If necessary, the processor subsystem is configured to receive the desired longitude from a radio navigation system, for example, a satellite navigation system (for example, Galileo, GPS, GLONASS, etc.). For example, an electronic watch may contain a radio navigation receiver that can provide geolocation data to the processor subsystem indicating the current longitude of the electronic watch and its carrier.

If necessary, the processor subsystem is designed in such a way that the user can specify the longitudinal coordinate with an accuracy of at least 1 or 2 decimal places.

Optionally, the time display means includes a dial, wherein the dial includes an hour hand and a minute hand, and the processor subsystem is configured to control the time display means to display the LTST using the hour hand and the minute hand. By displaying the LTST using a dial, the user is able to use the digital watch as a sun compass, for example, by the aforementioned method of pointing the hour hand at the Sun, marking an angle with the direction of 12:00, with the approximate North-South direction being at the bisector of the angle. Thus, the user is able to more accurately navigate on a terrestrial planet, such as Earth or Mars, using only an electronic watch. If the LTST is only subject to numerical display, the user will need to install another dial for the LTST and use the other dial as the sun compass.

Optionally, the watch face contains a physical hour hand and a physical minute hand. Thus, an electronic watch may have an analog dial with physical hands that can be set to LTST and thus allow use as a sun compass.

Optionally, the time display means includes a display for electronically displaying a clock face using an hour hand and a minute hand. The watch face can also be implemented in a digital format, for example as a digital representation of an analog watch face. By setting the hands to LTST, the digital dial can also be used as a sun compass.

If necessary, the electronic watch additionally contains a edging, the edging being capable of rotating around the dial and containing marks for cardinal directions. Such cardinal points include 'north', 'south', 'east' and 'west'. Labels can take different forms, such as letters ('N', 'S', 'E', 'W') or symbols. Accordingly, the user can rotate the bezel so that the 'north' marker bisects the angle between the hour hand and the 12 o'clock direction. In the northern hemisphere, the 'north' label now points approximately due south, and in the southern hemisphere, due north.

If necessary, the processor subsystem is configured to at least one of:

- support for coordinated universal time, UTC, on Earth and determination of the Earth's LTST at the Earth's longitude of interest depending on UTC; And

- support for coordinated Martian time, MTC, on Mars and determination of the Martian LTST at the Martian longitude of interest depending on the MTC.

An electronic clock may be configured to specifically determine the LTST for Earth or Mars, namely by maintaining (i.e., appropriately timing) a corresponding coordinated planetary time and determining the corresponding LTST (Earth or Mars) based on that coordinated planetary time. In some embodiments, the electronic clock may be configured to determine the LTST for both planets and may switch between an Earth-LTST and a Mars-LTST display. In this case, the user input subsystem allows the user to specify the longitude of interest on Earth and Mars.

If necessary, the processor subsystem is designed in such a way that the user can specify the Earth's longitude of interest by indicating a planetographic longitude coordinate on the Earth. For example, a planetographic longitude coordinate can be expressed as a value ranging from -180° - 180°, where the sign (- or +) indicates west or east, respectively, and 0° corresponds to the prime meridian (Greenwich).

If necessary, the processor subsystem is designed in such a way that the user can specify the Martian longitude of interest by indicating the planet-centric longitude coordinate on Mars. For example, the planetocentric longitudinal coordinate can be expressed as a value ranging from 0°-360°.

If necessary, the processor subsystem is designed so that the user can specify the number of coordination seconds for UTC. This may improve the accuracy of UTC-based terrestrial LTST determination.

If necessary, the processor subsystem is configured to:

- providing the user with the ability to indicate an event on Mars as an earthly date and time;

- conversion of terrestrial date and time to Martian date and time, which are expressed as Martian local solar time and date in Martian sols at the Martian longitude of interest; And

- determining a relative date and time metric and selecting a relative date and time metric to display, the relative date and time metric indicating the difference between the Martian date and time and the current Martian date and time.

Thus, electronic watches could support a space mission from Earth to Mars that could use both Earth dates and times and Martian dates and times. In particular, an event on Mars can be indicated as an terrestrial date and time, i.e. date and time, which can then be converted to a Martian date and time in the form of local solar time, i.e. either local true solar time or local mean solar time, and dates in Martian sols. The electronic clock can then determine a relative date and time metric that can indicate the difference between the Martian date and time and the current Martian date and time, and allows the relative date and time metric to be selected for display. For example, an electronic clock may provide a countdown to an event that is to occur in the future, or show the time elapsed after an event that occurred in the past, in a relative date and time metric, which is related to Mars in that it indicates the difference between current and certain Martian dates and times.

Optionally, the processor is configured to determine, as a relative date and time metric or part thereof, the number of mission sols, which indicates the number of sols relative to the date in Martian sols. For example, a digital clock can show the number of Martian sols relative to takeoff, landing, or the start of rover exploration on Mars.

If necessary, the processor subsystem is configured to increase the number of mission sols at midnight Martian local true solar time.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention will be apparent from the embodiments described below and will be explained with reference to them. On the drawings:

in fig. 1 shows an electronic watch with electronic displays, an analogue dial, several buttons and a rotary edging with marks for the cardinal points;

fig. 2 schematically illustrates the operation of an electronic clock;

fig. 3 illustrates entering the desired longitude on an electronic watch;

fig. 4 illustrates various functions of the electronic clock, which include displaying the number of sols in a year, mission time, longitude of interest, and number of mission sols;

fig. 5A illustrates an Earth time equation illustrating the axis tilt component and the orbital eccentricity component and their sum;

fig. 5B illustrates the Earth analemma with both components;

fig. 6A illustrates the Mars equation of time illustrating the rotation axis tilt component and the orbital eccentricity component and their sum;

fig. 6B illustrates the Mars analemma with both components; And

fig. 7 illustrates the use of an electronic clock as a sun compass while displaying local true solar time using an analog dial.

It should be noted that elements designated by the same reference numerals in different drawings have the same structural features and the same functions, or are the same signals. Once the function and/or structure of such an element has already been explained, there is no need to explain it again in the detailed description.

List of symbols and abbreviations

The following list of symbols and abbreviations is provided to facilitate interpretation of the drawings and is not intended to limit the claims.

100 electronic watches

110 analog dial

120-124 electronic display

130-134 button

140 edging

142 cardinal point (north)

200 processor subsystem

210 user input subsystem

220 user input interface

230 user input elements

240 electronic display controller

250 electronic display(s)

260 analog dial controller

270 analog dial

300 longitude of interest, edit mode

310 increase value by pressing a button

312 confirm the entry, move to the next digit/input field by pressing the button

314 decrease value by pressing a button

320 adjust the desired longitude

Sol number 400 of the year (1-668)

402 selected Martian time: M1 or M2

404 mission time in 24 hour format

410 move from page 1 to page 2 by pressing a button

420 longitude of interest

422 day of the week

424 number of mission sols

500 equation of earth time

510 time (days)

520 time difference (min)

530 component due to the inclination of the rotation axis

532 component due to orbital eccentricity

534 sum of components

550 Earth analemma

560 time difference (min)

570 inclination of the true Sun (degrees)

580 component due to the inclination of the rotation axis

582 component due to orbital eccentricity

584 sum of components

600 equation of time of Mars

610 time (sols)

620 time difference (min)

630 component due to the inclination of the rotation axis

632 component due to orbital eccentricity

634 sum of components

650 analemma of Mars

660 time difference (min)

670 inclination of the true Sun (degrees)

680 component due to the inclination of the rotation axis

682 component due to orbital eccentricity

684 sum of components

700 Sun

710 analog dial set to local true solar time

712 cardinal marker on rotating edging

720 angle between the hour hand and the 12 o'clock direction

730 direction south (north)

Carrying out the invention

In FIG. 1 shows an electronic clock 100 according to some examples. The electronic clock 100 is shown to include time display means for displaying time in the form of electronic displays 120, 124 and in the form of an analog dial 110 having an hour hand and a minute hand. Electronic displays 120, 124 are shown to be numeric displays in that they are capable of displaying at least numbers. In some examples, one or more electronic displays 120, 124 may be alphanumeric displays that are capable of displaying both letters and numbers and/or other graphic symbols. Additionally, the electronic clock 100 is shown to further include an electronic display 122, which may be an alphanumeric display for displaying a currently selected mode of the electronic clock 100. In general, the time display means may be operated under electronic control by a processor subsystem of the electronic clock 100 to display certain time. For example, the hands of the dial 110 can be controlled to indicate a specific time, and one or more of the electronic displays 120, 124 can be controlled to display a specific time.

In some examples, electronic watch 100 may include either one or more electronic displays or an analog dial. In some examples, electronic watch 100 may include an electronic display on which time may be displayed via a digital representation of an analog dial and/or as a numeric representation.

Additionally, the electronic clock 100 is shown to include a plurality of buttons 130, 132, 134 through which a user can control aspects of the operation of the electronic clock 100. Several aspects of operation will be further explained below.

Additionally, the electronic watch 100 is shown to include a bezel 140 that may include one or more markers for one or more cardinal points. In the example shown in FIG. 1, the bezel 140 is shown to include marks for each of the cardinal directions, namely 'north', 'south', 'east', 'west', with the direction of 'north' being designated by reference numeral 142. The bezel 140 is rotatable about the dial. , which can help in using the electronic clock 100 as a sun compass.

Fig. 2 schematically illustrates the operation of an electronic clock. In particular, FIG. 2 illustrates an electronic clock processor subsystem 200. The processor subsystem 200 may include one or more microprocessors or microcontrollers (both not shown separately) that can execute appropriate software that implements at least some or all of the described electronic clock operations. In some examples, the electronic watch may include a memory for storing software (not shown in FIG. 2). In other examples, processor subsystem 200 may be implemented by programmable hardware, such as an FPGA, or non-programmable hardware, such as an ASIC or any other type of integrated circuit.

In the example shown in FIG. 2, the processor subsystem 200 is shown to communicate with an electronic display controller 240, which is configured to control one or more electronic displays 250 through a corresponding communication, and with an analog dial controller 260, which is configured to control an analog dial 270 through a corresponding transmission. data. In some examples, an electronic watch may include either one or more electronic displays or one or more analog dials.

The electronic clock may further include a user input subsystem 210 allowing the user to control at least a portion of the operation of the electronic clock. In the example shown in FIG. 2, user input subsystem 210 is shown to include a user input interface 220 and one or more user input elements 230, which in this example are buttons 130, 132, 134 in FIG. 1. In general, user input elements 230 may take any suitable form, such as one or more buttons, dials, touch sensitive surfaces, microphone, camera, etc. The user input interface 220 may be an electronic interface, for example, installed using a microcontroller, which may be matched to the type of user input device. For example, the electronic interface may include a data bus.

The electronic clock shown in FIG. 1 and 2 may be configured to support space exploration and/or surface exploration on a terrestrial planet. To this end, the processor subsystem 200 may be configured to communicate electronically with the time display means 250, 270 and:

- support for coordinated planetary time (UTC, MTC), which is set for the prime meridian of an earth-type planet;

- obtaining longitudinal data, wherein the longitudinal data represents a longitude of interest on a terrestrial planet that differs from the prime meridian;

- determination of local true solar time, LTST, at the longitude of interest depending on coordinated planetary time and using the equation of time, which takes into account the eccentricity of the orbit and the inclination of the axis of rotation of the terrestrial planet; And

- control of the time display to display LTST.

The above-mentioned operating steps will be further explained below.

Referring again to FIG. 2, the processor subsystem 200 may be configured to allow a user to specify a longitude of interest using the user input subsystem 210 and display a response to the input on the electronic display 250. In an alternative example, the electronic clock may receive longitude data from another source, e.g. from a Galileo or GPS receiver (not shown in Fig. 2), which may, but does not have to, form part of an electronic clock.

In general, an electronic clock as described in this specification may, in some examples, implement several astronomical functions for calculating and displaying time control information that may be useful for conducting Earth-Mars space missions. However, these functions can also be used in everyday life on Earth and/or on Mars or another terrestrial planet. Although the following description applies to Mars as an illustrative terrestrial planet, it is equally applicable to other terrestrial planets, such as Venus and Mercury, mutatis mutandis. In some examples, a digital watch may implement multiple functions, which may include, but is not limited to:

for Earth: Coordinated Universal Time (UTC)

- local mean solar time (LMST) for time zones

- local true solar time (LTST) at surface location/longitude

- elapsed mission time in days of a terrestrial planet (Earth)

for Mars: Martian Coordinated Time (MTC)

- LMST at surface locations (or time zones)

- LTST at surface location(s)/longitudes

- elapsed mission time in sols (Martian days)

- solar longitude (orbital position of Mars)

- sol number in the year (Martian date)

Specifically, in some examples, the electronic clock may provide the following functionality with respect to timekeeping on or for Mars, particularly by having the electronic clock's processor subsystem configured to:

- calculation and display of MTC from UTC. For example, the processor subsystem of an electronic clock can calculate, based on Earth's UTC, the corresponding orbital and rotational ephemeris of Mars, which in turn can be used to calculate and display MTC. MTC may be provided on an electronic watch display and may also be indicated by the hands of an analog watch face.

- LMST calculations and displaysat a specific location on Marsusing as inputplanetocentric longitudelocations.For example, the electronic clock processor subsystem may translate the LMST MTC value for the prime meridian of Mars to the meridian of a specific location using a longitude coordinate provided by the user. LMTS (also called Mars LMTS) can be shown on an electronic watch display and can also be shown by the hands of an analog watch face.

- calculating the Martian time equation to display LTST using the planetocentric longitude of the location as input. For example, the electronic clock processor subsystem may calculate the 'Martian time equation' to determine the LTST at a location where the LMST was previously calculated. The equation of time can account for the effect that the eccentricity of Mars' orbit and changes in the position of the rotation axis (precession and nutation) have on time at a particular location throughout the Martian year. LTST (also called Mars LTST) can be shown on an electronic watch display and can also be shown by analog dial hands.

- calculation and display of the solar longitude of Mars (orbital position around the Sun ). For example, the processor subsystem can track the orbital position of Mars throughout the year and can display the information as a value from 0° to 360°. This information allows the user to follow the development of the canonical seasons (spring, summer, fall and winter) and the statistically specified dust storm season.

- calculation and display of the sol number in the Martian year (a substitute for the date on Mars). For example, the processor subsystem of an electronic clock can calculate and display the number of sols (0-668) in a Martian year. This may be the equivalent of the Earth date for Mars, for which the months have not yet been determined.

- calculation and display of the count of the number of mission sols (soles after landing) . For example, the processor subsystem could calculate and track the number of sols after a mission lands at a given location on Mars.

- calculation and display of several timers and mission phase countdown alarms based on Martian time bases. This may be an adaptation of the timer functions described in US 7,688,682 B2, allowing them to also be used with Martian time bases. US 7,688,682 B2 is hereby incorporated by reference in connection with these timer functions.

Obviously, the above-mentioned functions can also be provided for terrestrial planets other than Mars and Earth based on the present invention.

In some examples, the electronic clock may provide the following functionality with respect to timekeeping on or for the Earth, in particular due to the fact that the processor subsystem of the electronic clock is configured to:

calculating the earth time equation to display LTST using the east-west location longitude as input . For example, the processor subsystem may calculate the 'Earth Time Equation' to determine the LTST at the meridian of a particular location using a longitude coordinate provided by the user. The equation of time can account for the effect that orbital eccentricity and changes in the position of the Earth's rotation axis (precession and nutation) have on time at a particular location over the course of an Earth year. LTST (also called Earth LTST) can be shown on an electronic watch display, and can also be shown by the hands on an analog watch face.

The above and additional functions of digital watches are described in more detail below. These functions can be implemented in an electronic clock by the processor subsystem together with the user input subsystem and time display means. In some examples, the electronic watch may implement only some of these functions, such as a single function or a subset of functions.

Earth time zones (T1 and T2)

The electronic clock allows the user to set two time zones T1 and T2, which can trigger the electronic clock to keep time for those two time zones. Time zones T1 and T2 can be specified as time differences relative to UTC.

Coordination seconds for UTC

The electronic clock processor subsystem may be configured to allow a user to specify the number of leap seconds for UTC. For example, the user is given the opportunity to enter the total number of coordination seconds within the range of 0-255.

Mars Coordinated Time (MTC)

Mars Coordinated Time (abbreviated MTC) is a proposed Martian standard similar to Earth's UTC. MTC is defined as the mean solar time at the prime meridian of Mars (longitude 0є), which passes through the center of the crater Airy-0, in Meridian Earth. MTC is also sometimes referred to as Airy Mean Time (AMT).

Currently, the axial tilt and rotation period of Mars are similar to those of Earth. The duration of a solar day on Mars (called a “sol”) is 24 hours 39 minutes 35.244 s (the corresponding value for Earth is 24 hours 00 minutes 00.002 s). Thus, a Martian sol is approximately 2.7% longer than an Earth day. Sol is divided into 24 Martian hours, each of which consists of 60 Martian minutes.

One can define 'Martian time zones', for example, to be 15° wide, centered on successive longitudes that are multiples of 15°, at 0°, 15°, 30°, etc. By knowing which Martian time zone a rover or landmark is located in, one can have an estimate of the approximate mean solar time at that location. For example, Mount Olympus, the highest volcano in the solar system, is located at 133.8°W. If 133.8° west divided by 15є, it turns out 8.9. Therefore, an astronaut standing on the rim of the Olympus Mons crater could set his watch to the Martian time zone MTC-9 (that is, nine hours ahead of MTC). MTC-based time zones are still used to keep Martian time, but this may change in the near future.

Another important piece of knowledge for Mars missions is data; or more precisely, the position of Mars in its orbit around the Sun. The Earth uses a well-known 365-day calendar, which consists of 12 months. However, the Martian year is 668.59 sols long. While the Earth year is divided into 52 seven-day weeks, the Martian year spans 95 seven-day weeks. Because Martian months are not yet agreed upon, scientists use solar longitude ( _Ls ) to mark the passage of time during the Martian year. For all planets, seasons begin at intervals of L _s 90є, at equinoxes and solstices:

Solar longitude (L _s ) North hemisphere Southern Hemisphere 0є the vernal equinox spring autumn equinox autumn 90є summer solstice summer winter solstice winter 180є autumn equinox autumn the vernal equinox spring 270є winter solstice winter summer solstice summer

Because Mars' orbit has a higher eccentricity than Earth's (it is more elliptical), the seasons are not of equal length. Aphelion, the point furthest from the Sun (249 million km), where Mars moves slowest, is at L _s =70є. Perihelion, the point closest to the Sun (207 million km) where Mars moves fastest, is at L _s =250є. The close coincidence of aphelion with the northern summer solstice causes a temperate climate in the northern hemisphere. On the other hand, summers in the southern hemisphere are usually short and relatively hot, but winters are long and very cold. The period during which Martian dust storms are most likely to occur begins at L _s =180º and ends near L _s =325º. This is a critical time for missions that generate electrical power from solar panels, as dust kicked up into the atmosphere during a storm can block sunlight for weeks. Global-scale dust storms are relatively rare, but their atmospheric effects can last for months; the last ones took place in 2001, 2007, 2018.

Using Mars Coordinated Time (MTC)

On Mars, the MTC function of an electronic clock can provide a useful overview of the orbital status of Mars. For this purpose, digital watches can display dates in sols, season (solar longitude) and time on the prime meridian. Although it is in principle possible to synchronize Martian activities using MTC, in reality, since most activities on or near Mars are controlled from Earth, the ground control complex typically uses UTC instead. However, the MTC may form a practical temporal basis for calculating mean solar time at different locations on the Martian surface. See also electronic clock functionality to maintain Martian time at two positions (M1 and M2) on the surface. On Earth, as with previous missions to the surface of Mars, the mission crew may also begin operations operating in 'Martian time'.

Local Mean Solar Time (LMST)

The electronic clock allows the user to set the Martian time at two positions on the surface, for example, at two longitudes, using the corresponding modes M1 and M2. The Mars missions have not yet set their clocks to time zones. Instead, 'Mars mission time' is usually specified as the mean solar time at the designated landing location, that is, local mean solar time (LMST or Mars-LMST). The LMST can be calculated for the designated landing location, or any other longitude of interest, as follows. At the same time, the Kisloye plateau, which has planetographic coordinates of 18.159°N, 24.334°W, is assumed to be the landing point. MTC is specified as the mean solar time at longitude 0є, i.e. prime meridian of Mars. Since the landing site is located at 24.334°W, mean solar time will increase relative to MTC; thus, a negative offset must be applied. Landmarks exactly east of the prime meridian require a positive offset.

LMST for a given planetographic longitude, L _pg , in degrees west longitude, is expressed as: LMST=MTC - L _pg (24 h/360º). Therefore, LMST _ExoMars =MTC - (24.334є x 24 h/360є)=MTC - 1.622 h=MTC - 1 h 37 min 20.1 s.

During use on Mars, the user can set M1 as the user's local Martian time, i.e. LMST at the user's longitude. M1 can be displayed using an analog watch face. M2 could be adjusted to show a second Martian time, for example, for another mission. On Earth, mission crew members can set M1 to follow the mission clock, but can leave the analog clock face displaying Earth time T1.

M1 and M2 can be used as actual Mars mission functions. To program these timers, the user can provide two input parameters: the longitude (or generally the latitude of interest) of the landing site and the landing date (or generally the date of the event). Electronic clocks allow the user to enter these and other types of input data.

Fig. 3 illustrates, by way of example, the entry of a longitude of interest on an electronic clock. As shown on the left side, in edit mode, the current longitude of interest, such as 335.6º, may be shown, with an underline indicating that the clock is in edit mode. The user can then increase the currently entered value by pressing the corresponding button indicated by reference numeral 310, decrease the currently entered value by pressing the corresponding button indicated by reference numeral 314, and confirm the entry by pressing the corresponding button indicated by reference numeral 312. In one For example, the user can edit the longitude of interest from digit to digit, i.e. first adjusting and confirming the first digit of the entered value, then adjusting and confirming the second digit of the entered value, then adjusting and confirming the third digit of the entered value, and finally adjusting and confirming the first decimal place of the entered value. In another example, the user can enter the longitude of interest by incrementing and decrementing and then confirming the full value. As shown on the right side of Fig. 3, this may result in adjustment 320 of the entered longitude of interest, for example, 240.3º. Obviously, in some examples, the user may also directly enter the longitude of interest without adjusting the previously entered longitude of interest, for example, starting with 0є or 'nothing'.

In general, the processing subsystem may be configured to allow a user to specify a longitude of interest by specifying a longitudinal coordinate using a user input subsystem. For example, the processor subsystem may be configured to allow a user to specify a longitudinal coordinate with an accuracy of at least 1 or 2 decimal places. In general, the processor subsystem may be configured to allow the user to indicate the Earth's longitude of interest by specifying a planetographic longitude coordinate on Earth, for example, in the range -180° to +180°, or specifically in degrees west longitude (-180° to 0° ) or eastern longitude (from 0є to +180є) relative to the prime meridian. The processor subsystem is also designed so that the user can specify the Martian longitude of interest by specifying a planet-centric longitude coordinate on Mars. In 1970, the International Astronomical Union (IAU) agreed that longitude should increase in the direction of rotation. For prograde-rotating planets like Mars, this means that longitude is measured from 0° to 360° east of the prime meridian.

Referring again to FIG. 3, the user can be asked, to set the mission time, to enter the planetocentric longitude, L _pc , landing site in degrees east longitude. Setting local time using position longitude provides significant operational flexibility. For example, if the ground control complex allows the mission clock to be adjusted, for example as a result of the actual landing point being at a different location than originally planned, the user can simply enter the new longitude and the electronic clock can calculate the correct mean solar time for the new landing location .

In the case where the user wishes to program M1 or M2 to operate in a given Martian time zone rather than a specific longitude of interest, the user can specify the central longitude of the appropriate time zone. It's easy to calculate. Below are two examples, one exactly west of the prime meridian, the other exactly east.

In the first example, M1 can be programmed for the Mount Olympus time zone. Mount Olympus was previously shown to be located on MTC-9. Since each time zone can be centered on its corresponding 15° meridional strip, the central longitude of MTC-9 is expressed as L _pc =360є - 9×15є=225єE. In the second example, M2 can be programmed for the time zone of the Curiosity rover. The landing took place at a location of 4.59°N, 137.44°E. If the user wishes to program the clock to operate during a mission, the user can enter 137.44°E. If the user wishes to program the watch to operate in the appropriate time zone, 137.44°E can be calculated as before. / 15є = 9.16, which can be rounded down to 9. Thus, the Curiosity landing site is in the MTC+9 time zone. For MTC+9, the correct longitude of the band is 9×15є E. Therefore, Lpc _MTC+9 =135.00є east.

Note that the electronic clock may allow the user to check the longitude assigned to M1 or M2 by entering the mode shown in FIG. 3.

Referring again to input data entry, to set the number of mission sols, the user can set the UTC landing date using the user interface subsystem. The processor subsystem may designate the corresponding sol on Mars as 'mission sol 1', regardless of the local landing time, and may treat sol 2 as the start of the mean solar time of the landing site at 00:00:00 on the next sol. Note that alternatively, landing sol can be thought of as ‘mission sol 0’. In such cases, the UTC landing date programmed in M1 (or M2) may be increased by one day. The user may also choose not to enter the UTC landing date, in which case the electronic clock may report solar time at the programmed longitude.

Fig. 4 illustrates various functions of the electronic clock, which include displaying the number of sols in a year, mission time, longitude of interest and number of mission sols, as well as various other types of information. In particular, an electronic watch may be configured to display different types of information on different “pages” where the electronic display(s) display different information elements. The user has the ability to switch between these pages using the user input subsystem. For example, as shown on the left side of FIG. 4, the electronic clock can display the sol number of the year as a value from 1 to 668 (reference numeral 400), particularly '451', the selected Martian time (reference numeral 402), particularly 'M1', and the mission time in 24h format (reference 404), specifically '12:37:00'. The user can move from page 1 to page 2 by pressing a button (reference numeral 410). On page 2, the electronic clock may display the longitude of interest (reference numeral 420), specifically '335.6º', the day of the week (reference numeral 422), particularly 'Fri(day)', and the number of mission sols (reference numeral 424) , specifically '2327'.

Other electronic clock functionality may relate to timing events on Mars, or more generally on a terrestrial planet other than Earth. For example, the processor subsystem of an electronic clock may be configured to:

- providing the user with the ability to indicate an event on Mars as an earthly date and time;

- conversion of terrestrial date and time to Martian date and time, which are expressed as Martian local solar time and date in Martian sols at the Martian longitude of interest; And

- determining a relative date and time metric and selecting a relative date and time metric to display, the relative date and time metric indicating the difference between the Martian date and time and the current Martian date and time.

For example, the processor subsystem may be configured to determine, as or part of a relative date and time metric, a mission sols number that indicates the number of sols relative to a date in Martian sols. The processor subsystem may be configured to increase the number of mission sols at midnight Martian local true solar time.

Aspects of the above functionality are explained below in more detail with reference to the 'Mission Elapsed Time' and 'Phase Elapsed Time' functions. In this regard, note that references to 'time' include date and time. Thus, elapsed or remaining time can be expressed in hours, seconds, etc., as well as in days or sols.

Mission Elapsed Time (MET)

The MET function can display the time remaining before, or time elapsed after, the start of an event and, in particular, the start of a mission. The remaining time can be identified by the prefix '-' for time, and the elapsed time can be identified by the prefix '+' for time. MET can be expressed in Earth days and time, and can be specified using UTC, T1 or T2. In some cases, electronic watches can emit a warning signal when an event occurs. The warning signal may be, for example, a visual warning signal and/or an audible warning signal, which may be generated by a piezoelectric speaker or similar sound generating element that may be included in the electronic watch.

The MET function can be used on Earth to continue to track time before and after the start of an (important) event. This could be, for example, the initiation and subsequent development of a journey, the submission of a destination and the period before receiving a reaction, etc. The user can typically select T1 (local time) as the reference time against which the remaining and/or elapsed time is calculated. MET can play a fundamental role for space missions, which are typically protocolized regarding their launch. Since the project team may work in three shifts to integrate spacecraft elements, test all systems, complete launch campaign tasks, and refuel the rocket, the clock is ticking: T-20 days, T-6 days, ... immediately after launch, mission checkpoints (e.g. deployment of solar panels, orbital activation of the propulsion engine and entry into the interplanetary trajectory) can be recorded as T+ h, min, s. During a cruise flight, the mission duration can be summarized as T+XX days from launch using UTC as the timestamp.

The MET function can be used on Mars so that, in addition to the M1 (and M2) functions, which can be performed with the ability to continue to track the number of mission sols and additionally track the mission in Earth days. Thus, for Mars missions, the MET can be programmed with UTC as a reference to feed useful and additional information to M1.

Phase Elapsed Time (PET)

The PET function may provide a special type of timing, and in some cases corresponding alarm functionality. When PET is selected, the electronic clock can display the remaining time (-) before, or the elapsed time (+) after the event. PET can be programmed either according to MET (indicating the interval in days and hours) or according to a user-defined date and time (in UTC, T1, T2, MTC, M1, M2 or MLs).

The PET function provides significant flexibility in specifying events. The following table summarizes the possible input parameters.

PET mode Programming data PET MET Earth date and time offset from mission time (MET) PET UTC Earth: counting before and after UTC date and time PET T1 Earth: counting before and after date and time T1 PET T2 Earth: counting before and after T2 date and time PET MTC Mars: countdown before and after sol number and MTC time PET M1 Mars: countdown before and after sol number and time M1 PET M2 Mars: countdown before and after sol number and time M2 PET MLs Mars: countdown before and after the solar longitude of Mars

The PET function can be used on Earth to issue a warning signal at a specific time after the start of an event programmed in MET. In this case, the PET function may behave as a warning signal relative to another warning signal. For example, if the user needs to prepare a test sample and deliver it to an industrial partner on a given date, the user can program an alarm and time against this event using the MET function. The user can also be reminded to check that the sample arrives safely a week later by setting a seven-day countdown using the PET functions relative to the MET date and time.

For space missions, the PET function can be used to count down to and/or from events specified in relation to the mission's elapsed time since launch. On Mars itself, PET can be set to the time before and/or after the event using the Martian time base.

Electronic watches can additionally provide MLs (Mars solar longitude) mode. The beginning of the statistical season of dust storms begins at L _s =180є and ends near L _s =325є. The PET function can be used in MLs mode to count the number of sols before the start of the statistical dust storm season. For example, the PET function can be used to determine when a rover will be able to operate on the surface of Mars.

In general, the user can program the PET timer relative to the date and time programmed for the MET, but also relative to the individually entered date and time.

Local True Solar Time (LTST)

As described elsewhere, an electronic clock can calculate local true solar time (LTST) and, in some examples, can also display LTST using an analog dial so that the user can use the electronic clock as a sun compass.

The background to LTST is described below: The length of the solar day is not constant. As mechanical clocks begin to replace the timekeeping field of sundials that have served people for centuries, the difference between clock time and true solar time becomes a problem for everyday life. True solar time (also called apparent solar time) can be given as the time indicated by the Sun on a sundial (or as measured by its half-day passage through the preferred local meridian), while mean solar time can be given as its average, which is usually displayed by a well-regulated clock.

The equation of time describes the difference between true solar time and mean solar time throughout the year. Its shape can be understood as the sum of two sinusoids, the first of which has a period of one year (its amplitude is a function of the eccentricity of the planet's orbit) and the other of which has a period of half a year (the amplitude of which depends on the inclination of the axis of rotation). The equation of time will only be constant for a planet with a perfectly circular orbit and zero axial tilt. Another interesting way to look at this effect is to consider the planetary analemma. This graph describes the annual development of the sun's position in the sky, as seen if a stationary camera is set up to take several pictures every day at the same mean solar time.

Below with reference to FIG. 5A-6B discusses the equation of time and analemma for Earth and Mars. Fig. 5A illustrates Earth time equation 500, where horizontal axis 510 represents time in days and vertical axis 520 represents time difference in minutes. Fig. 5A further illustrates a first component 530 due to axis tilt, a second component 532 due to orbital eccentricity, and the sum 534 of both components. Fig. 5B illustrates the Earth analemma 550, where the horizontal axis 560 illustrates the time difference in minutes, and the vertical axis 570 illustrates the inclination of the true Sun in degrees. Fig. 5B further illustrates a first component 580 due to axis tilt, a second component 582 due to orbital eccentricity, and the sum 584 of both components. Fig. 6A and 6B represent FIGS. 5A and 5B, but apply to Mars, where the horizontal axis 610 in FIG. 6A the time is given in sols instead of days.

As can be seen from Earth time equation 500 in FIG. 5A, true solar time can be about 14 minutes 6 seconds behind mean solar time (around February 12) or ahead of it by 16 minutes 33 seconds (around November 3). The equation of time has zeros (dates when true solar time and mean solar time are the same) near April 15, June 13, September 1, and December 25. On Mars, whose orbit has a significantly higher eccentricity than the Earth's orbit, the difference between true solar time and mean solar time can be up to 50 minutes, as can be seen in Fig. 6A.

Given these differences, it can be understood that an accurate solar compass can only be ensured if the clock hands reflect true solar time at the wearer's location.

Note that the equation of time is known on its own, for example, from the document “ A Post-Pathfinder Evaluation of Areocentric Solar Coordinates with Improved Timing Recipes for Mars Seasonal/Diurnal Climate Studies ” by Allison, Michael et al., 1999. Namely, the equation of time can be derived by properly combining the expansions into a series of equations (4) and (5) in the paper, according to the formula EOT=Alpha(FMS) - Alpha(s), which is shown in the second paragraph of page 219. The equation of Martian time is given by Eq. (20), while equation (23) specifies how to calculate local true solar time (LTST) for a given location based on its longitude. The document is hereby incorporated by reference to the extent that it relates to the calculation of the equation of time and, in particular, to the extent that it relates to the equations given.

Fig. 7 illustrates the use of an electronic clock as a sun compass while displaying local true solar time using an analog dial. Namely, as shown on the left side of FIG. 7, an electronic clock can display LTST using an analog dial 710, in this example 10:15, in a mode called 'STE' (Local True Solar Time Earth). As shown on the right side of Fig. 7, the user can then rotate the electronic watch so that the hour hand points toward the Sun 700. This can create an angle of 720 between the hour hand and the 12 o'clock direction (1 o'clock, in daylight saving time). The user can then rotate the bezel so that the north cardinal marker 712 bisects the previous angle 720 (ie, midway between the hour hand and 12 o'clock). Then in the northern hemisphere, the 712 cardinal point points approximately south, and in the southern hemisphere, approximately north.

In order for the electronic clock to be used as a sun compass, the processor subsystem of the electronic clock may be configured to control the time display means to display the LTST, i.e. true solar time at the specified longitude of interest, using the hour hand and minute hand. The LTST may be determined and displayed for Earth and/or for Mars and/or for another terrestrial planet. In the case where the LTST is determined for multiple planets or for multiple longitudes on the same planet, the electronic clock may provide different modes for displaying the corresponding LTST. To determine the terrestrial LTST, the processor subsystem may be configured to support coordinated universal time, UTC, on Earth and determine the terrestrial LTST at the terrestrial longitude of interest as a function of UTC. To determine the Martian LTST, the processor subsystem may be configured to support Martian coordinated time, MTC, on Mars and determine the Martian LTST at a Martian longitude of interest depending on the MTC.

Obviously, the LTST display, unlike the LMST using an analog dial, provides increased navigational accuracy, can be illustrated as follows: the city of Leiden (NL) is located at 4.50°E, in the UTC+1 time zone. All locations in UTC+1 are assigned mean solar time corresponding to longitude 15°E. Thus, from a solar point of view, the time shown by the clock in Leiden is behind.

Divergence of LMTS for UTC+1 relative to LTST for the city of Leiden (NL), i.e. at 4.50°E, can be calculated as follows:

Lv. (1): LMST for a given planetographic longitude, L _pg , in degrees west longitude, expressed as: LMST=UTC - L _pg (24 h/360º).

Lv. (2): LMST for a given planetographic longitude, L _pg , in degrees east longitude, expressed as: LMST=UTC+L _pg (24 h/360º).

Using equation 2, it can be determined that the clock in Leiden should show:

LMST _Leiden =UTC+4.50є x 24 h/360є=UTC+0.3 h, or UTC+20 min.

Instead, traditional clocks display UTC+60 min. This allows us to conclude that to correctly track LMST, the clock in Leiden must be set back 60 min - 20 min = 40 min. If someone wants to use the watch as an accurate sun compass, they may need to understand what effect this 40 min offset will have on the hour hand, which most people fail to account for. This can be explained as follows: the hour hand makes a full revolution (360°) in 12 hours. In one hour, the hour hand sweeps an angle of 360°/12=30°. Therefore, 40 minutes corresponds to 40 minutes x 30°/60 minutes = 20° clockwise movement. This is not a small correction, but a large one. If you use a traditional clock as a sun compass in Leiden using the above method, i.e. By dividing in half the angle formed between the hour hand (pointed at the Sun) and the 12 o'clock direction, the direction will differ from true south by 10 degrees. Such errors can be avoided by displaying true solar time at the longitude of interest.

It should be noted that the above embodiments illustrate and do not limit the invention, and that those skilled in the art will be able to develop many alternative embodiments without departing from the scope of the following claims.

In the claims, any reference numerals enclosed in parentheses should not be construed as limiting the claim. The use of the verb “comprise” and its conjugations does not exclude the presence of elements or steps other than those specified in the claim. The use of the name of an element does not exclude the presence of many such elements. Expressions such as "at least one of" preceding a list or group of items represent a selection from all or any subset of the items in the list or group. For example, the expression "at least one of A, B, and C" should be understood to include only A, only B, only C, both A and B, both A and C, both B and C, or all of A. B and C. The invention may be implemented by means of hardware comprising several separate elements and by means of a suitably programmed computer. In a device claim that lists multiple features, multiple features may be implemented by the same piece of hardware. The mere fact that certain agents are mentioned in different dependent claims does not indicate that a combination of these agents cannot be used to advantage.

Claims (30)

1. Electronic watch (100), containing: - time display means (110, 120, 122) for displaying time, wherein the time display means is electronically controllable for displaying a specific time; - processor subsystem (200), configured to - implementation of electronic communication with a time display device and - support for coordinated planetary time (UTC, MTC), which is set for the prime meridian of an earth-type planet; - obtaining longitudinal data, wherein the longitudinal data represents a longitude of interest on a terrestrial planet that differs from the prime meridian; - determination of local true solar time, LTST, at the longitude of interest depending on coordinated planetary time and using the equation of time, which takes into account the eccentricity of the orbit and the inclination of the axis of rotation of the terrestrial planet; And - control of the time display to display LTST. 2. Electronic watch (100) according to claim 1, additionally containing: - electronic display (120, 122); - a user input subsystem (210) allowing the user to enter data, wherein the electronic display is configured to display a response to said data input; wherein the processing subsystem (200) is configured to allow the user to specify a longitude of interest using the user input subsystem. 3. The electronic watch (100) of claim 2, wherein the processing subsystem (200) is configured to allow a user to specify a longitude of interest by specifying a longitudinal coordinate using a user input subsystem (210). 4. Electronic watch (100) according to claim 3, in which the processor subsystem (200) is configured to allow the user to indicate a longitudinal coordinate with an accuracy of at least 1 or 2 decimal places. 5. Electronic watch (100) according to any one of paragraphs. 1-4, wherein the time display means includes a dial (110), the dial including an hour hand and a minute hand, and the processor subsystem (200) is configured to control the time display to display the LTST using the hour hand and the minute hand. 6. The electronic watch (100) of claim 5, wherein the dial (110) includes a physical hour hand and a physical minute hand. 7. An electronic watch (100) according to claim 5, wherein the time display means comprises a display for electronically displaying a dial. 8. Electronic watch (100) according to any one of paragraphs. 5-7, further comprising a edging (140), the edging being rotatable around the dial and containing markers for cardinal directions (142). 9. Electronic watch (100) according to any one of paragraphs. 1-8, in which the processor subsystem (200) is configured to at least one of: - support for coordinated universal time, UTC, on Earth and determination of the Earth's LTST at the Earth's longitude of interest depending on UTC; And - support for coordinated Martian time, MTC, on Mars and determination of the Martian LTST at the Martian longitude of interest depending on the MTC. 10. The electronic watch (100) of claim 9, wherein the processor subsystem (200) is configured to allow the user to indicate the Earth's longitude of interest by indicating a planetographic longitude coordinate on the Earth. 11. The electronic watch (100) of claim 9 or 10, wherein the processor subsystem (200) is configured to allow the user to indicate a Martian longitude of interest by indicating a planet-centric longitude coordinate on Mars. 12. Electronic watch (100) according to any one of paragraphs. 9-11, in which the processor subsystem (200) is configured to allow the user to specify the number of coordination seconds for UTC. 13. Electronic watch (100) according to any one of paragraphs. 9-12, in which the processor subsystem (200) is configured to: - providing the user with the ability to indicate an event on Mars as an earthly date and time; - conversion of terrestrial date and time to Martian date and time, which are expressed as Martian local solar time and date in Martian sols at the Martian longitude of interest; And - determining a relative date and time metric and selecting a relative date and time metric to display, the relative date and time metric indicating the difference between the Martian date and time and the current Martian date and time. 14. The electronic clock (100) of claim 13, wherein the processor is a subsystem (200) configured to determine, as a relative date and time metric or as part thereof, a number of mission sols that indicates the number of sols relative to a date in Martian sols. 15. Electronic clock (100) according to claim 13 or 14, in which the processor subsystem (200) is configured to increase the number of mission sols at midnight Martian local true solar time.

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