Electronic watch for space exploration and / or terrestrial exploration

Abstract

An electronic watch can be configured to have a function for space exploration and / or terrestrial planet surface exploration. The watch can include a time display device and a processor subsystem. The processor subsystem can be configured to maintain a coordinated planet time of a terrestrial planet, obtain longitude data representing a longitude of interest on the terrestrial planet, the longitude of interest being different from the prime meridian of the planet, determine a local true solar time, LTST, at the longitude of interest as a function of the coordinated planet time, and control the time display device of the electronic watch to display the LTST using a time equation that takes into account an orbital eccentricity and an axial tilt of the terrestrial planet.

Description

Technical Field

[0001] This invention relates to an electronic watch that has the function of space exploration and / or surface exploration on terrestrial planets. Background Technology

[0002] Clocks, used for telling time, are among humanity's oldest inventions. While earlier clocks were purely mechanical devices, modern clocks are typically at least partially electronically driven. For example, an electronic clock may include an electronic display and a processor configured to display certain information on that display. This information may include the time, but also other types of information such as the date, the time in another time zone, barometric pressure readings, etc. It is known that clocks exist that are partially mechanical and partially electronic; such clocks may, for example, include a clock face with physical hands that can be electronically controlled by a processor.

[0003] Timekeeping plays a crucial role in both space and surface exploration. For example, in space expeditions from Earth to Mars, a timekeeping function capable of accurately determining the time of certain events (such as rocket launch times, lander descent times, etc.) is essential. This timekeeping function is important not only on the destination terrestrial planet itself (e.g., on Mars) but also on Earth, for example, in mission control rooms. For surface exploration, the local time on the terrestrial planet constitutes vital information when exploring its surface; this could be, for example, on Mars, on Earth, or on another terrestrial body (e.g., the Moon, Mercury, Venus).

[0004] The expectation is to provide this functionality for space exploration and / or ground exploration in wearable timing devices, i.e., watches, so that the wearer can access this functionality no matter where she / he is.

[0005] The Omega Skywalker X-33 watch offers features for space exploration. For example, the watch claims to track Mission Time (MET) and Phase Time (PET). For space missions, Mission Time refers to the time elapsed since launch. Phase Time can be used to count down or track the duration of an event within the MET. For instance, Phase Time can be used to set a timer that counts down until a rover on the Martian surface begins scientific measurements.

[0006] It is also known to include features for ground exploration in portable electronic clocks. For example, a watch can be configured with a Global Positioning System (GPS) signal receiver to determine the wearer's geographical location. Summary of the Invention

[0007] The purpose of this invention is to provide an electronic watch with improved functionality for space exploration and / or surface exploration on terrestrial planets.

[0008] A first aspect of the present invention provides an electronic watch, comprising:

[0009] - A time display device for displaying time, wherein the time display device displays a defined time by electronic control;

[0010] - A processor subsystem, configured to communicate electronically with the time display device, and for:

[0011] - Maintaining Coordinated Planetary Time (UTC, MTC), which is defined by the prime meridian of the terrestrial planets;

[0012] - Obtain longitude data, which represents longitudes of interest on the terrestrial planets that differ from the prime meridian;

[0013] - The local true solar time, LTST, at the longitude of interest is determined as a function of the coordinating planetary time, using a time equation that takes into account the orbital eccentricity and rotational axis tilt of the terrestrial planet; and

[0014] - Control the time display device to display the LTST.

[0015] The electronic watch, as a wearable timekeeping device, includes a time display device for displaying time. The time display device is electronically controlled, wherein the watch's processor subsystem is capable of controlling the displayed time, or at least capable of setting the time to a specific point from which it can begin to increment outside the direct control of the processor subsystem. Such time display devices are known in various forms, such as an "analog" clock face with physical hour and minute hands, and an electronic display screen that can digitize the time, i.e., as a digital representation of a digital dial and / or as a digital representation of an analog clock face. The electronic watch may also include several time display devices, for example, including an electronically controlled analog clock face and one or more electronic displays.

[0016] The processor subsystem of an electronic watch may include one or more processors, which may also be referred to as "embedded" processors. The processors may be configured by software, or alternatively by a hardware implementation representing such software, to perform various functions, including at least, for example, controlling the time display device to display a specific time using an internal interface between the processor subsystem and the time display device.

[0017] According to the claimed invention, the processor subsystem can be configured to maintain Coordinated Planetary Time (UTC), defined by the prime meridian of a terrestrial planet. Such UTC is known for various terrestrial planets, but it can also be defined for those terrestrial planets for which a UTC is not yet defined. For example, for Earth, Coordinated Universal Time (UTC) is a UTC defined as the mean solar time (accurate to one second) at Earth's prime meridian, i.e., at 0° longitude (Greenwich Meridian). Another embodiment is, for Mars, Coordinated Martian Time (MTC), a Martian standard derived from Earth's UTC. MTC is defined as the mean solar time at the Martian prime meridian, which passes through the center of the Airy-0 crater in the Terra Meridiani. MTC is sometimes also referred to as Airy Mean Time (AMT).

[0018] The processor subsystem can maintain this coordinated planetary time in various ways, such as by setting the internal clock based on software and / or hardware to the coordinated planetary time, or by storing a time offset that allows the coordinated planetary time to be calculated at any point in time using an internal reference clock.

[0019] The processor subsystem can be further configured to acquire longitude data representing longitudes of interest on terrestrial planets that differ from the Prime Meridian. For example, this longitude data can define longitude coordinates, such as using degrees to represent the longitude of interest.

[0020] The processor subsystem can be further configured to determine the Local True Solar Time (LTST) at the longitude of interest as a function of Coordinated Planetary Time, using a time equation that takes into account the orbital eccentricity and rotational axis tilt of the terrestrial planet. Once the LTST is determined, it can be displayed using a time display device, for example, on a continuous basis or in response to a user's request (e.g., when selecting a corresponding function on a digital watch). Thus, the user can see the LTST at the longitude of interest on his / her digital watch.

[0021] Local true solar time (also known as apparent time or sundial time) is of particular significance for both space and surface exploration, as will be explained below. Clocks typically display mean solar time, which is the solar time measured if the sun were to move at a uniform apparent speed throughout the year. However, this is not the case in reality, as the sun moves at a slightly different apparent speed throughout the year due to the orbital eccentricity and tilted axes of rotation of terrestrial planets. For Earth, the Prime Meridian (0° longitude) passes through the Royal Observatory in Greenwich, London (UK), where UTC coincides with mean solar time. Time zones typically use a mean solar time, although mean solar time varies locally within a time zone. While such a time zone might ideally be defined as a repetition of longitude ranges, for example, a repetition of a longitude range exactly 15° wide, centered on consecutive longitudes that are multiples of 15° (such as 0°, 15°, 30°, etc.), this is not the case: Earth's time zones can have strange shapes, reflecting more commercial and political needs than astronomical common sense. For example, Spain, France, Belgium, the Netherlands, and Algeria should be in the same time zone as the United Kingdom. Furthermore, given Bolivia's meridian position, it is in the "correct" time zone, while Argentina and Uruguay are not. Therefore, mean solar time is inaccurate because it is an "average" time that does not take into account the seasonal variations in the apparent speed of the sun, and because mean solar time is typically used for an entire time zone, which includes a range of longitudes, and given the irregular shapes of many time zones, their longitude range is often related to latitude. For most work, using mean solar time and time zones for timekeeping is generally accepted and often sufficient.

[0022] However, mean solar time and time zones may not be suitable for timekeeping in space exploration and / or surface exploration. There are several reasons for this. One reason is that a standardized concept of time zones may not exist for missions on other terrestrial planets, such as Mars. Therefore, it may be necessary to determine the local solar time at a specific longitude of interest (e.g., the landing site of a Mars lander). Given this local solar time (LST), various mission events, such as landing and takeoff, can be timed based on the LST, for example, using times expressed in LST or daytime timing.

[0023] For surface exploration on Mars, Earth, or other terrestrial planets, determining the “true” solar time at a specific longitude of interest can also be of interest, as this aids in navigation on the surface. For example, it is known that a clock can be used as a solar compass by pointing the hour hand towards the sun, noting the angle between the hour hand and 12:00, and then finding approximately north-south at half an angle (i.e., between the hour hand and 12:00). By determining the local true solar time at a specific longitude of interest, such a solar compass provides greater accuracy in determining north-south direction than when using the average solar time of a time zone. This can improve navigation accuracy during surface exploration. In particular, this allows for navigation on terrestrial planets such as Mars, which lack a magnetic field, making compasses unusable, and also unsuitable for Galileo, GPS, and similar geolocation systems.

[0024] The above situation is explained in the instruction manual using the city of Leiden (Netherlands). A watch displaying UTC+1 (corresponding to LMST in the time zone) will show a direction 10° off from true south. This inaccuracy can be avoided by using an electronic watch displaying Leiden's longitude (4.50°E) at LTST.

[0025] Optionally, the electronic watch further includes:

[0026] - Electronic display screen;

[0027] - A user input subsystem for enabling users to input data, wherein the electronic display screen is configured to display feedback on the input data;

[0028] -The processor subsystem is configured to enable the user to indicate the longitude of interest using the user input subsystem.

[0029] The user can directly indicate the longitude of interest on the electronic watch itself, for example, by specifying longitude coordinates (e.g., 135.35°) using the user input subsystem. The electronic display screen can be, for example, a numeric display or an alphanumeric display. The user input subsystem may include, for example, one or more buttons, dials, touch-sensitive areas, etc.

[0030] Optionally, the processor subsystem is configured to receive the longitude of interest from a radio navigation system, such as a satellite-based navigation system (e.g., Galileo, GPS, GLONASS, etc.). For example, the watch may include a radio navigation receiver that can provide the processor subsystem with geographic location data indicating the current longitude of the watch and its wearer.

[0031] Optionally, the processor subsystem is configured to enable the user to specify the longitude coordinates with a precision of at least one or two decimal places.

[0032] Optionally, the time display device includes a clock face, wherein the clock face includes an hour hand and a minute hand, and wherein the processor subsystem is configured to control the time display device to display the LTST using the hour and minute hands. By using the clock face to display the LTST, a user can use the electronic watch as a solar compass, for example, by pointing the hour hand towards the sun as described above, noting the angle of the hour hand with 12:00, and then finding approximately north-south at half an angle. Therefore, a user can navigate more accurately on terrestrial planets such as Earth or Mars using only an electronic watch. If the LTST is displayed digitally only, the user must set another clock face to LTST and use that other clock face as a solar compass.

[0033] Optionally, the clock face includes physical hour and minute hands. Therefore, the electronic watch can have an analog clock face with physical hands, which is set to LTST, allowing the user to use it as a sun compass.

[0034] Optionally, the time display device includes a display screen for electronically displaying the clock face with hour and minute hands. The clock face can also be implemented digitally, for example, as a digital representation of an analog clock face. The digital clock face can also be used as a sun compass by setting the hands to LTST.

[0035] Optionally, the electronic watch also includes a bezel that is rotatable around the clock face and includes markings for basic directions. These basic directions include "North," "South," "East," and "West." The markings can take various forms, such as letters ('N', 'S', 'E', 'W') or symbols. Accordingly, the user can rotate the bezel so that the 'North' marking divides the angle between the hour hand and the 12 o'clock position on the watch in two. In the Northern Hemisphere, the 'North' marking now points approximately south, while in the Southern Hemisphere it points north.

[0036] Optionally, the processor subsystem is configured to perform at least one of the following:

[0037] - Maintaining Coordinated World Time (UTC) on Earth, and determining the Earth's Longitude (LTST) at the point of interest as a function of said UTC; and

[0038] - When maintaining coordination on Mars, MTC, and determining the Mars LTST at the longitude of interest as a function of the MTC.

[0039] The electronic watch can be configured specifically to determine the LTST of Earth or Mars, i.e., by maintaining (i.e., recording) the respective coordinating planetary time, and thus determining the respective (Earth or Mars) LTST based on this coordinating planetary time. In some embodiments, the electronic watch can be configured to determine the LTST of both planets and be able to switch between displaying the Earth-LTST and displaying the Mars-LTST. In this case, the user input subsystem allows the user to specify longitudes of interest on Earth and Mars.

[0040] Optionally, the processor subsystem is configured to enable a user to indicate the longitude of interest on Earth by specifying planetary geographic longitude coordinates on Earth. For example, the planetary geographic longitude coordinates can be represented as values ​​in the range of -180° to 180°, with the sign (- or +) indicating west or east respectively, and 0° corresponding to the Prime Meridian (Greenwich Mean Time).

[0041] Optionally, the processor subsystem is configured to enable a user to indicate the longitude of Mars by specifying the planetary center longitude coordinates on Mars. For example, the planetary center longitude coordinates can be expressed as values ​​in the range of 0° to 360°.

[0042] Optionally, the processor subsystem is configured to enable the user to indicate the number of leap seconds in the UTC. This can improve the accuracy of the Earth's LTST determined based on UTC.

[0043] Optionally, the processor subsystem is configured as follows:

[0044] - Enables users to use events on Mars as date and time indicators on Earth;

[0045] - Convert Earth's date and time to Martian date and time, where the Martian date and time is expressed as the Martian local solar time and Martian solar cycle date (Mars sol date) at the Martian longitude of interest; and

[0046] - Determine a relative date and time indicator, and optionally display the relative date and time indicator, wherein the relative date and time indicator represents the difference between the Martian date and time and the current Martian date and time.

[0047] Therefore, the electronic watch can support space expeditions from Earth to Mars, where it can use Earth's daytime and Martian date and time. Specifically, events on Mars can be designated as Earth's date and time, i.e., date and time, and then converted to Martian date and time in the form of local solar time (i.e., local true solar time or local mean solar time) and Martian solar day. The electronic watch can then determine a relative date and time index that indicates the difference between the Martian date and time and the current Martian date and time, and can optionally display this relative date and time index. For example, the electronic watch can provide a countdown for future events or display the elapsed time of past events, the relative date and time index being Mars-related, indicating the difference between the current Martian date and time and the determined Martian date and time.

[0048] Optionally, the processor is configured to determine, as a relative date-time indicator or as part of the relative date-time indicator, the mission sol number, which represents the number of sols relative to the Martian solar cycle date. For example, the electronic watch could display the Martian solar cycle number relative to takeoff, landing, or the start of a rover exploration on Mars.

[0049] Optionally, the processor subsystem is configured to increment the mission solar cycle number at midnight local Martian time. Attached Figure Description

[0050] The above and other aspects of the invention will be apparent and will be illustrated with reference to the embodiments described below. In the accompanying drawings,

[0051] Figure 1 An electronic watch is shown, featuring: an electronic display screen, an analog clock face, several buttons, and a rotating bezel with basic orientation markings;

[0052] Figure 2 The operation of the electronic watch is illustrated in a schematic way;

[0053] Figure 3 This explains how to input the longitude of interest on the digital watch;

[0054] Figure 4 The various functions of the electronic watch are explained, including: displaying the number of solar cycles per year, mission time, longitude of interest, and mission solar cycle number;

[0055] Figure 5AThe time equation for the Earth is explained, showing the components caused by the tilt of the rotational axis and the components caused by orbital eccentricity, as well as their sum;

[0056] Figure 5B A map showing the Earth's daily trajectory with these two components is displayed;

[0057] Figure 6A The time equation for Mars is explained, showing the components caused by the tilt of the rotation axis and the components caused by the orbital eccentricity, as well as their sum;

[0058] Figure 6B A map showing the Martian daily trajectory with these two components is presented; and

[0059] Figure 7 This explains how an electronic watch can be used as a solar compass when displaying local real solar time using an analog clock face.

[0060] It should be noted that items with the same reference numbers in different figures have the same structural features and functions, or the same symbols. If the function and / or structure of an item has already been explained, there is no need to repeat it in the detailed description.

[0061] List of reference symbols and abbreviations

[0062] The following list of reference symbols and abbreviations is provided to facilitate understanding of the drawings and should not be construed as limiting the claims:

[0063] 100 electronic watches

[0064] 110 Simulated Clock Face

[0065] 120-124 Electronic Display Screen

[0066] Buttons 130-134

[0067] 140 bezel

[0068] 142 Basic Marker (North)

[0069] 200 Processor Subsystem

[0070] 210 User Input Subsystem

[0071] 220 User Input Interface

[0072] 230 User Input Elements

[0073] 240 Electronic Display Controller

[0074] 250 electronic display screen

[0075] 260 Analog Clock Controller

[0076] 270 Simulated Clock Face

[0077] 300 Longitudes of interest, edit mode

[0078] 310 Button press increment

[0079] 312 Confirm input, press the button to move to the next number / input area

[0080] 314 Decrease value of button press

[0081] 320 Adjusted longitude of interest

[0082] 400-year solar cycle (1-668)

[0083] 402 Select Mars time: M1 or M2

[0084] Task time in 404 24h mode

[0085] 410 Switch from page 1 to page 2 by pressing the button.

[0086] 420 Longitudes of interest

[0087] 422 Midweek Dates

[0088] 424 mission solar cycle number

[0089] 500 Earth's Time Equation

[0090] 510 Time (Sun)

[0091] 520 Time Difference (minutes)

[0092] 530 Due to the component of the tilt of the axis of rotation

[0093] 532 Due to the components of orbital eccentricity

[0094] 534 The sum of the components

[0095] 550 Earth's Solar Track Map

[0096] 560 Time Difference (minutes)

[0097] 570 degrees (True solar declination)

[0098] 580 Due to the component of the tilt of the axis of rotation

[0099] 582 Due to the components of orbital eccentricity

[0100] The sum of 584 components

[0101] 600 The Time Equation of Mars

[0102] 610 Time (Solar Cycle)

[0103] 620 Time difference (minutes)

[0104] 630 Due to the component of the tilt of the axis of rotation

[0105] 632 Due to the components of orbital eccentricity

[0106] The sum of 634 components

[0107] 650. Map of Mars's orbit around the Sun

[0108] 660 Time Difference (minutes)

[0109] 670 degrees is the true solar declination.

[0110] 680 Due to the component of the tilt of the axis of rotation

[0111] 682 Due to the components of orbital eccentricity

[0112] The sum of 684 components

[0113] 700 Suns

[0114] 710 The analog clock face is set to local real solar time.

[0115] 712 Basic markings on the rotating bezel

[0116] 720 Angle between the hour hand and 12 o'clock

[0117] 730 south (north) direction Detailed Implementation

[0118] Figure 1An electronic watch 100 according to some embodiments is shown. The electronic watch 100 is shown as including a time display device for displaying the time in the form of electronic displays 120, 124 and an analog clock face 110 having hour and minute hands. The electronic displays 120, 124 are shown as numeric displays, capable of displaying at least numbers. In some embodiments, one or more electronic displays 120, 124 may be alphanumeric displays capable of displaying letters, numbers, and / or other graphic symbols. The electronic watch 100 is further shown as including another electronic display 122, which may be an alphanumeric display for displaying the currently selected mode of the electronic watch 100. Typically, the time display device can be electronically controlled by a processor subsystem of the electronic watch 100 to display a specific time. For example, the hands of the clock face 110 can be controlled to carry a specific time, and one or more electronic displays 120, 124 can be controlled to display that specific time.

[0119] In some embodiments, the electronic watch 100 may include one or more electronic displays or analog clock faces. In some embodiments, the electronic watch 100 may include an electronic display on which the time may be displayed by a digital representation of an analog clock face and / or as a digital representation.

[0120] The electronic watch 100 is further shown to include several buttons 130, 132, and 134, through which a user can control several aspects of the operation of the electronic watch 100. These aspects of operation will be further explained below.

[0121] The electronic watch 100 is further shown to include a bezel 140, which may include one or more markers representing one or more basic directions. Figure 1 In one embodiment, the bezel 140 shown includes markings for each fundamental direction, namely "North," "South," "East," and "West," with the fundamental direction of "North" indicated by reference numeral 142. The bezel 140 can rotate around the clock face, which facilitates the use of the electronic watch 100 as a sun compass.

[0122] Figure 2 The operation of the digital watch is illustrated schematically. Specifically, Figure 2 A processor subsystem 200 of a digital watch is shown. The processor subsystem 200 may include one or more microprocessors or microcontrollers (neither shown separately), which can execute appropriate software to implement at least some or all of the operations described for the digital watch. In some embodiments, the digital watch may include memory for storing the software. Figure 2(Not shown in the image). In other embodiments, the processor subsystem 200 may be implemented using programmable hardware, such as an FPGA, or non-programmable hardware, such as an ASIC, or any other type of integrated circuit.

[0123] exist Figure 2 In some embodiments, the processor subsystem 200 is shown communicating with an electronic display controller 240 and an analog clock face controller 260, wherein the electronic display controller 240 is configured to control one or more electronic displays 250 via respective data communications, and the clock face controller 260 is configured to control an analog clock face 270 via respective data communications. In some embodiments, the electronic watch may include one or more electronic displays or one or more analog clock faces.

[0124] The electronic watch may further include a user input subsystem 210 for enabling a user to control at least a portion of the operation of the electronic watch. Figure 2 In this embodiment, the user input subsystem 210 is shown as including a user input interface 220 and one or more user input elements 230, which in this embodiment are Figure 1 Buttons 130, 132, and 134. Typically, user input element 230 can take any suitable form, such as one or more buttons, dials, touch-sensitive surfaces, microphones, cameras, etc. User input interface 220 can be, for example, an electronic interface built using a microcontroller, which can be matched to the type of user input device. For example, the electronic interface may include a data bus.

[0125] Figure 1 and Figure 2 The electronic watch can be configured to support space exploration and / or surface exploration on terrestrial planets. For this purpose, the processor subsystem 200 can be configured to communicate electronically with the time display devices 250, 270, and:

[0126] - Maintaining Coordinated Planetary Time (UTC, MTC), which is defined by the prime meridian of the terrestrial planets;

[0127] - Obtain longitude data, which represents longitudes of interest on terrestrial planets that differ from the prime meridian;

[0128] - The local true solar time (LTST) at the longitude of interest is determined as a function of coherent planetary time, using time equations that take into account the orbital eccentricity and rotational axis tilt of the terrestrial planets; and

[0129] - Control the time display device to display LTST.

[0130] The above operational arrangements will be further explained below.

[0131] Continue to refer to Figure 2 The processor subsystem 200 can be configured to enable a user to indicate the longitude of interest using the user input subsystem 210, and to display feedback of the input data on the electronic display screen 250. In an alternative embodiment, the electronic watch may obtain the longitude data from elsewhere, such as from a Galileo-based or GPS-based receiver. Figure 2 Data is obtained from (not shown in the image), and the receiver may be, but does not have to be, part of the electronic watch.

[0132] Typically, the electronic watch described in this specification may implement several astronomical functions in some embodiments to calculate and display timekeeping information that may be useful for Earth-Mars space missions. However, these functions can also be used for daily life on Earth and / or Mars or other terrestrial planets. While Mars is referred to below as an exemplary terrestrial planet, it is equally applicable to other terrestrial planets, such as Venus and Mercury, with appropriate modifications. In some embodiments, the electronic watch may implement several functions, including but not limited to:

[0133] For Earth: Coordinated Universal Time (UTC).

[0134] Local Mean Solar Time (LMST) of the time zone

[0135] Local True Solar Time (LTST) at the Earth's surface location / longitude

[0136] Task time in terrestrial (Earth) days

[0137] For Mars: Coordinated Mars Time (MTC)

[0138] LMST at the location (or time zone) on the ground

[0139] LTST at surface location / longitude

[0140] Mission duration in solar cycles (Mars day) and solar longitude (Mars orbital position).

[0141] Annual solar cycle number (Mars date)

[0142] In particular, in some embodiments, the electronic watch, especially through its processor subsystem, can provide the following functions related to or for keeping time on Mars, wherein the processor subsystem is configured to:

[0143] - Calculate and display MTC from UTC. For example, the processor subsystem of an electronic watch can calculate the corresponding Martian orbit and ephemeris based on Earth's UTC, which can then be used to calculate and display the MTC. This MTC can be displayed on the watch's electronic display or shown through the hands of the watch's analog clock face.

[0144] - Calculate and display the LMST for a specific location on Mars, using the planetary center longitude of that location as input. For example, the processor subsystem of a digital watch can use user-provided longitude coordinates to convert the MTC and LMST values ​​of the Martian Prime Meridian into the meridian for that specific location. The LMTS (also known as the Mars-LMTS) can be displayed on the watch's electronic display or through the hands of the watch's analog clock face.

[0145] - The Mars Time Equation is calculated to display the LTST, using the planetary center longitude of that location as input. For example, the processor subsystem of a digital watch can calculate the "Mars Time Equation" to determine the LTST at a previously calculated LMST location. This time equation can take into account the effects of variations in Mars' orbital eccentricity and rotational axis attitude (precession and nutation) on the time at a particular location throughout the Martian year. The LTST (also known as Mars-LTST) can be displayed on the watch's electronic display or via the hands of the watch's analog clock face.

[0146] - Calculates and displays the Martian solar longitude (orbital position around the sun). For example, the processor subsystem can track the orbital position of Mars throughout the year and display the information as a numerical value between 0° and 360°. With this information, users can track the evolution of typical seasons (spring, summer, autumn, and winter) and the evolution of statistically significant dust storm seasons.

[0147] - Calculates and displays the number of solar cycles in a Martian year (representing dates on Mars). For example, the processor subsystem of a digital watch can calculate and display the number of solar cycles in a Martian year (0-668). Since months are not yet defined on Mars, this may be equivalent to Earth dates on Mars.

[0148] - Calculate and display the number of solar cycles for the mission (post-landing solar cycles). For example, the processor subsystem can calculate and keep track of the number of solar cycles after the mission touches down at a designated Martian location.

[0149] - Calculate and display mission phase countdown timers and alarms based on Mars time. This can be an adaptation of the timer functions described in US 7,688,682 B2, making them usable on Mars time. Aspects of these timer functions are introduced here with reference to US 7,688,682 B2.

[0150] It will be understood that, based on this disclosure, the above-mentioned functions can also be provided for terrestrial planets other than Mars and Earth.

[0151] In some embodiments, the electronic watch may provide the following functions related to keeping time on Earth or for the purpose of keeping time on Earth, and in particular, the electronic watch is configured, through its processor subsystem, to:

[0152] The Earth Time Equation is calculated to display the LTST, taking the east-west longitude of that location as input. For example, the processor subsystem can compute the "Earth Time Equation" to determine the LTST at the meridian of a specific location using user-provided longitude coordinates. This time equation can take into account the effects of variations in the Earth's orbital eccentricity and rotational axis attitude (precession and nutation) on the time at that location throughout the Earth year. The LTST (also known as Earth-LTST) can be displayed on the watch's electronic display or via the hands of the watch's analog clock face.

[0153] The above and other functions of the electronic watch will be described in more detail below. These functions can be implemented by the electronic watch through a processor subsystem, a user input subsystem, and a time display device. In some embodiments, the electronic watch may implement only a portion of these functions, for example, a single function or a subset of the functions.

[0154] Earth time zones (T1 & T2)

[0155] The electronic watch allows the user to configure two time zones, T1 and T2, which triggers the watch to keep time in both time zones. Time zones T1 and T2 can be defined by their time difference relative to UTC.

[0156] UTC leap seconds

[0157] The processor subsystem of the electronic watch can be configured to enable the user to indicate the number of leap seconds in the UTC. For example, the user can input the total number of leap seconds in the range of 0 to 255.

[0158] Coordinated Mars Time (MTC)

[0159] Coordinated Martian Time (MTC) is a Martian standard proposed to simulate Earth's UTC. MTC is defined as the mean solar time at the Martian prime meridian (0° longitude), which passes through the center of the Airy-0 crater in the Meridian Mesa. MTC is sometimes also expressed as Airy Mean Time (AMT).

[0160] Currently, Mars' axial tilt and rotation period are similar to Earth's. The length of a Martian solar day (called a "solar cycle") is 24 hours, 39 minutes, and 35.244 seconds (the corresponding Earth time is 24 hours, 00 minutes, and 00.002 seconds). Therefore, the Martian solar cycle is approximately 2.7% longer than an Earth day. One solar cycle is divided into 24 Martian hours, and each Martian hour is divided into 60 Martian minutes.

[0161] A "Mars time zone" can be defined, for example, as 15° wide, centered on consecutive longitudes that are multiples of 15° (such as 0°, 15°, 30°, etc.). By knowing which Martian time zone a rover or landmark is located in, one can determine the approximate average solar time there. For example, Olympus Mons, the largest volcano in the solar system, is located at 133.8°W. Dividing 133.8°W by 15° gives 8.9. Therefore, an astronaut standing on the rim of Olympus Mons' crater can set his or her watch to Martian time zone MTC-9 (i.e., 9 hours ahead of MTC). MTC-based time zones are not yet used for timekeeping on Mars, but this may change in the near future.

[0162] Another crucial piece of knowledge for a Mars mission is the date; or more precisely, Mars' position in its orbit around the Sun. On Earth, we use the well-known 365-day calendar consisting of 12 months. However, a Martian year is 668.59 solar cycles long. An Earth year can be divided into 52 seven-day weeks, while a Martian year spans 95 seven-solar-cycles. Since a Martian month has not yet been agreed upon, scientists use solar longitude (L... s The seasons are marked by intervals of 90°L to indicate the passage of time within a Martian year. For all planets, seasons begin at intervals of 90°L. s Starting from the dividing point and the terminating point:

[0163]

[0164] Because Mars' orbit has a higher eccentricity than Earth's (i.e., it's more elliptical), the lengths of its seasons are not equal. At aphelion, the point at which Mars is farthest from the Sun (249 million kilometers), its motion is slowest. This aphelion occurs at L... s =70°. Perihelion, the point closest to the Sun (207 million kilometers), is when Mars moves the fastest. This perihelion occurs at L... s =250°. The aphelion almost coincides with the summer solstice in the Northern Hemisphere, resulting in a mild climate in the Northern Hemisphere. On the other hand, the Southern Hemisphere has a relatively short, hot summer, but long and very cold winters. Martian dust storms are most likely to occur from L... s =180°, ending at L s= Around 325°C. This is a critical period for missions that rely on solar panels to generate electricity, as dust storms can block sunlight for weeks. Global-scale dust storms are relatively rare, but their atmospheric effects can last for months; the most recent global-scale dust storms occurred in 2001, 2007, and 2018.

[0165] Uses of Coordinated Mars Time (MTC)

[0166] On Mars, the MTC function of the electronic watch can provide a useful overview of the Martian orbital status. For this purpose, the watch can display the solar cycle date, season (solar longitude), and time at the prime meridian. Although MTC can theoretically be used to synchronize Martian activities, in reality, since most operations performed on or near Mars are directed from Earth, ground control typically uses UTC. However, MTC can form the practical time basis for calculating the mean solar time at different locations on the Martian surface. See the function of the watch maintaining Martian time at two surface locations (M1 and M2). On Earth, as with previous Martian surface missions, mission teams can also begin their activities using "Mars time."

[0167] Local Mean Solar Time (LMST)

[0168] The electronic watch allows users to configure Mars time at two surface locations, for example, at two different longitudes, using separate modes M1 and M2. The Mars mission has not yet set its clocks to time zones. Instead, the usual practice is to define "Mars mission time" as the mean solar time at the intended touchdown location, i.e., the local mean solar time (LMST or Mars-LMST). As shown below, the LMST can be calculated for the intended touchdown location or for any other longitude of interest. Here, we assume the Oxia Planum as the landing site, with planetary geographic coordinates of 18.159°N, 24.334°W. The MTC is defined as the mean solar time at 0° longitude (i.e., the Prime Meridian of Mars). Since the landing site is located at 24.334°W, the mean solar time here is earlier than the MTC; therefore, a negative offset will be used. Landmarks east of the Prime Meridian require a positive offset.

[0169] For a given planetary longitude Λ pg Using west longitude as the unit, LMST is: LMST = MTC - Λ pg (24h / 360°). Therefore, LMST ExoMars =MTC-(24.334°x24h / 360°)=MTC-1.622h=MTC-1h 37m 20.1s.

[0170] While on Mars, users can set M1 to their local Martian time, i.e., LMST at their longitude. M1 can be displayed using an analog clock face. M2 can be configured to show a second Martian time, for example, the time of another mission. On Earth, mission team members can set M1 to follow the mission clock but can keep the analog clock face displaying Earth time T1.

[0171] M1 and M2 can be used as actual Mars mission functions. To program these timers, users can provide two input parameters: landing site longitude (or latitude of interest in general) and landing date (or event date in general). The electronic clock allows users to input this and other types of input data.

[0172] Figure 3 The following example illustrates how to input a longitude of interest on a digital watch. As shown on the left, in edit mode, the currently interested longitude, such as 335.6°, is displayed, with an underline indicating that the watch is in edit mode. The user can then increment the input value by pressing the button indicated by reference number 310, decrement it by pressing the button indicated by reference number 314, and confirm the input by pressing the button indicated by reference number 312. In one embodiment, the user can edit the longitude of interest digit by digit, first adjusting and confirming the first digit, then the second, then the third, and finally the first decimal place. In another embodiment, the user can input the longitude of interest by incrementing and decrementing, and then confirming the entire value. Figure 3 As shown on the right-hand side, this results in the input of an adjusted longitude of interest, such as 320, for example, 240.3°. It will be understood that in some embodiments, the user may also directly input the longitude of interest, rather than adjusting a previously input longitude of interest, for example, starting from 0° or "none".

[0173] Typically, the processor subsystem can be configured to allow a user to specify longitude coordinates by using a user input subsystem, thereby indicating the longitude of interest. For example, the processor subsystem can be configured to allow a user to specify longitude coordinates with at least one or two decimal places of precision. Typically, the processor subsystem can be configured to allow a user to indicate the longitude of interest on Earth by specifying the planet's geographic longitude coordinates on Earth, for example, coordinates in the range of -180° to +180°, or specifically, west longitude (-180° to 0°) or east longitude (0° to +180°) relative to the Prime Meridian. The processor subsystem can also be configured to allow a user to indicate the longitude of interest on Mars by specifying the planet's central longitude coordinates. In 1970, the International Astronomical Union (IAU) adopted the convention that longitude should increase along the direction of rotation. For directly rotating planets like Mars, this results in longitude being measured from 0° to 360° east of the Prime Meridian.

[0174] Continue to refer to Figure 3 To set the mission time, users can be prompted to enter the planetary center longitude, Λpc, of the landing site in east longitude. Configuring the local time using the longitude of a location provides significant operational flexibility. For example, if ground control needs to adjust the mission clock because, for instance, the actual touchdown point is not the originally planned location, the user can simply enter the new longitude, and the electronic clock can calculate the correct mean solar time for that new landing location.

[0175] If a user wishes to program M1 or M2 to work for a given Martian time zone, rather than for a specific longitude of interest, the user can specify the central longitude of the corresponding time zone. This can be easily calculated. Two examples are provided below, one west of the Prime Meridian and the other east of the Prime Meridian.

[0176] In the first embodiment, M1 can be programmed as the Olympus time zone. As previously shown, Olympus is located in MTC-9. Since each time zone is centered on its respective 15° meridian band, the central longitude of MTC-9 is Λ. pc =360° - 9 x 15° = 225°E. In the second embodiment, M2 can be programmed to the time zone of the Curiosity rover. The touchdown occurred at 4.59°N, 137.44°E. If the user wants to program the watch to work for the mission time, the user can input 137.44°E. However, if the user wants to program the watch to work for the corresponding time zone, it can be calculated as before: 137.44°E / 15° = 9.16, which can be rounded to 9. Therefore, Curiosity's landing point is in the MTC+9 time zone. For MTC+9, the correct longitude zone is 9 x 15°E. Therefore, Λ pcMTC+9 =135.00°E.

[0177] It should be noted that by entering Figure 3 As shown in the diagram, the digital watch allows users to check the longitude assigned to M1 or M2.

[0178] Continuing with the input data: To establish the mission solar cycle number, the user can set the UTC landing date using the user interface subsystem. The processor subsystem can assign the corresponding solar cycle on Mars as "Mission Solar Cycle 1," independent of the local landing time, and can assume that Solar Cycle 2 in subsequent solar cycles begins at the mean solar time of the landing site, 00:00:00. Alternatively, it should be noted that the touchdown solar cycle can be considered as "Mission Solar Cycle 0." In this case, the UTC landing date programmed into M1 (or M2) can be incremented by one day. The user can also choose not to enter a UTC landing date, in which case the electronic clock can report the solar time programmed into the longitude.

[0179] Figure 4 The various functions of the electronic watch are described, including displaying the annual solar cycle number, mission time, longitude of interest, mission solar cycle number, and various other types of information. Specifically, the electronic watch can be configured to display different information on different "pages," with the electronic display showing different information items. Users can switch between these pages using a user input subsystem. For example, as... Figure 4 As shown on the left, the digital watch displays the annual solar cycle number (reference number 400) as a value from 1 to 668, here '451', the selected Mars time (reference number 402) as 'M1', and the mission time in 24-hour mode (reference number 404) as '12:37:00'. The user can switch from page 1 to page 2 by pressing a button (reference number 410). On page 2, the digital watch displays the longitude of interest (reference number 420) as '335.6°', the weekday date (reference number 422) as 'Friday', and the mission solar cycle number (reference number 424) as '2327'.

[0180] Other functions of the electronic watch may relate to the timing of events on Mars, or generally to another terrestrial planet beyond Earth. For example, the electronic watch's processor subsystem could be configured to:

[0181] - Enables users to display events on Mars as Earth dates and times;

[0182] - Convert Earth's date and time to Martian date and time, where the Martian date and time is expressed as Martian local solar time and Martian solar cycle date at the Martian longitude of interest; and

[0183] - Determine a relative date and time indicator, and optionally display the relative date and time indicator, wherein the relative date and time indicator represents the difference between the Martian date and time and the current Martian date and time.

[0184] For example, the processor subsystem can be configured to determine, as a relative date-time indicator or as part of the relative date-time indicator, the mission solar cycle number, which represents the number of solar cycles relative to the Martian solar cycle date. The processor subsystem can be configured to increment the mission solar cycle number at midnight at the Martian local true sun time.

[0185] The following sections refer to the "Task Time" and "Stage Time" functions to explain the various aspects of the above functions in more detail. In this regard, it should be noted that references to "Time" include date and time. Therefore, elapsed or remaining time can be expressed in hours, seconds, etc., or in days or solar cycles.

[0186] Task time (MET)

[0187] The MET function can display the remaining time until the start of an event, or the elapsed time since the start of the event, more specifically, the start of a task. The remaining time may be indicated by a time prefix "-", while the elapsed time may be indicated by a time prefix "+". MET can be expressed in Earth Day and Time, and can be specified using UTC, T1, or T2. In some embodiments, the watch can sound an alarm when the event is reached. The alarm can be, for example, a visual alarm and / or an audible alarm, and can be generated by a piezoelectric speaker or similar sound-generating element, which may be part of the watch.

[0188] On Earth, the MET (Mean Time Shift) function can be used to track time up to and from the start of a (significant) event. This event could be, for example, the start of a journey and its subsequent development, mission submission, and the period until feedback is received. Users typically select T1 (local time) as the reference time and calculate remaining time and / or elapsed time accordingly. MET is fundamentally important for space missions, which are typically logged for their launch. As the mission team works in shifts, integrating spacecraft components, validating all systems, completing launch activities, and fueling the rocket, the clock ticks: T-20 days, T-6 days, ... Immediately after launch, mission milestones (e.g., solar panel deployment, main engine orbital burn, and release into interplanetary orbit) can be recorded as T+h, m, s. During cruise, mission duration, using UTC as the time reference, can be calculated as T+XX days after launch.

[0189] In addition to the M1 (and M2) functions configured to track the mission's solar cycle number, the MET function can be used to further track the mission in Earth days. Therefore, for a Mars mission, the MET can be programmed with UTC as a reference to provide useful and complementary information to the M1.

[0190] Stage Duration (PET)

[0191] The PET function can provide special types of timing and, in some cases, related alarm functions. When PET is selected, the watch can display the remaining time (-) until a certain event, or the time elapsed since a certain event (+). PET can be programmed according to MET (specifying intervals in days and hours) or according to user-defined dates and times (in UTC, T1, T2, MTC, M1, M2, or MLs).

[0192] The PET function can allow considerable flexibility in how events are assigned. The table below summarizes the possible input parameters.

[0193]

[0194]

[0195] The PET function can be used on Earth to trigger an alarm at a specific time after an event is programmed into the MET (Mean Time of Event). In this case, the PET function can behave as an alarm relative to another alarm. For example, if a user needs to prepare a test sample and ship it to an industry partner on a specified date, the user can use the MET function to program an alarm and timing program relative to this event. Alternatively, the PET function can be used to set a seven-day countdown relative to the MET date and time to remind the user to check a week later to see if the test sample has arrived safely.

[0196] For space missions, the PET function can be used to time events to and / or from the start of an event, particularly for timing mission duration from launch. On Mars itself, PET can be configured to use Martian time as the basis for timing events to and / or from the start of an event.

[0197] The digital display can further provide MLs (Mars Solar Longitude) models. Statistically, dust storm seasons begin at Ls = 180° and end around Ls = 325°. The PET function can be used in the MLs model to calculate the solar cycle number from the start of the statistically significant dust storm season. For example, the PET function can be used to determine when a rover can operate on the Martian surface.

[0198] Typically, users can program the PET timer relative to a date and time programmed to MET, but it can also be programmed relative to a separate input date and time.

[0199] Local True Solar Time (LTST)

[0200] As described elsewhere, the electronic watch can calculate Local True Solar Time (LTST) and in some embodiments, it can also display the LTST using an analog clock face, which allows the user to use the electronic watch as a solar compass.

[0201] The following provides background for LTST: The length of a solar day is not constant. When mechanical clocks began to replace sundials, which had served humanity for centuries, the difference between clock time and sundial time became a problem in daily life. True solar time (also known as apparent solar time) can be defined as the time indicated by the sun on a sundial (or the time measured when the sun crosses a preferred local meridian at its noon), while mean solar time can be defined as the average of said true solar time, which is usually displayed by a standard clock.

[0202] The time equation describes the difference between actual solar time and mean solar time throughout the year. Its shape can be understood as the sum of two sine curves: the first with a period of one year (its amplitude is a function of the planet's orbital eccentricity), and the second with a period of half a year (its amplitude depends on the tilt of the rotational axis). This time equation is constant only for planets with perfectly circular orbits and zero axial tilt. Another interesting way to observe this effect is to consider planetary track maps. These maps depict the annual evolution of the sun's position in the sky, much like the maps formed if one sets up a fixed camera and takes multiple exposures daily at the same mean solar time.

[0203] The following text refers to Figures 5A to 6B The discussion covers the time equations and solar trajectory maps for Earth and Mars. Figure 5A The Earth's time equation 500 is shown, with the horizontal axis 510 showing time in days and the vertical axis 520 showing time differences in minutes. Figure 5A The diagram further illustrates the first component 530 caused by the tilt of the rotation axis, the second component 532 caused by the orbital eccentricity, and the sum of the two components 534. Figure 5B The Earth's orbital path is shown in diagram 550, with the horizontal axis 560 showing the time difference in minutes and the vertical axis 570 showing the actual solar declination in degrees. Figure 5B The diagram further illustrates the first component 580 caused by the tilt of the rotation axis, the second component 582 caused by the eccentricity of the track, and the sum of the two components 584. Figure 6A and 6BIndicates applicability to Mars Figure 5A and 5B ,but Figure 6A The horizontal axis 610 shows time in units of solar cycles, not days.

[0204] from Figure 5A As can be seen from the Earth time equation 500, true solar time can lag behind mean solar time by 14 minutes and 6 seconds (around February 12th) or advance by 16 minutes and 33 seconds (around November 3rd). The time equation has a zero point near April 15th, June 13th, September 1st, and December 25th (i.e., the dates when true solar time coincides with mean solar time). On Mars, due to its much higher orbital eccentricity than Earth's, as... Figure 6A As can be seen, the difference between actual solar time and mean solar time can reach 50 minutes.

[0205] Given these differences, it is understandable that an accurate solar compass can only be provided when the watch's hands display the true sun at the wearer's location.

[0206] It should be noted that the time equation itself is known, for example, from the paper “A Post-Pathfinder Evaluation of Areocentric Solar Coordinates with Improved Timing Recipes for Mars Seasonal / Diurnal Climate Studies” by Allison, Michael, et al., 1999. That is, the time equation can be derived by suitably combining an extended series of equations (4) and (5) from the paper, as shown in the formula EOT = Alpha(FMS) - Alpha(s) in the second paragraph on page 219. The Martian time equation is given as equation (20), while equation (23) specifies how to calculate the local true solar time (LTST) for a given location based on its longitude. The parts of the paper relating to the calculation of the time equation, particularly those relating to the cited equations, are incorporated herein by reference.

[0207] Figure 7 This explains how to use a digital watch as a solar compass when displaying local real solar time using an analog clock face. That is, as... Figure 7 As shown on the left, in a mode called 'STE' (Local True Solar Time), the digital watch can display LTST using an analog clock face 710, which in this embodiment is 10:15. Figure 7As shown on the right side, the user can then rotate the watch so that the hour hand points to the sun at 700. This creates an angle of 720 between the hour hand and the 12 o'clock position (1 o'clock during daylight saving time). The user can then rotate the bezel so that the fundamental mark 712, representing north, bisects the previous angle 720 (i.e., it is located exactly in the middle between the hour hand and the 12 o'clock mark). In the Northern Hemisphere, the fundamental mark 712 now points approximately south, while in the Southern Hemisphere, it points approximately north.

[0208] To enable the electronic watch to function as a solar compass, its processor subsystem can be configured to control the time display to show LTST, i.e., to display the true solar time at a specified longitude of interest using hour and minute hands. LTST can be determined and displayed for Earth and / or Mars and / or other terrestrial planets. In cases where LTST is determined for multiple planets, or for multiple longitudes of a single planet, the electronic watch can provide different modes to display the respective LTSTs. For determining Earth's LTST, the processor subsystem can be configured to maintain Coordinated Universal Time (UTC) on Earth and determine the Earth LTST at the Earth longitude of interest as a function of UTC. For determining Mars' LTST, the processor subsystem can be configured to maintain Coordinated Martian Time (MTC) on Mars and determine the Martian LTST at the Martian longitude of interest as a function of MTC.

[0209] It will be understood that using an analog clock face to display LTST instead of LMST improves navigation accuracy, as can be explained below: Leiden (NL) is located at 4.50°E, in the UTC+1 time zone. All locations in UTC+1 are assigned the mean solar time corresponding to longitude 15°E. Therefore, from the sun's perspective, the time deviation shown by a clock in Leiden is...

[0210] The difference between the LMTS at UTC+1 and the LMTS at Leiden (Netherlands) (i.e., 4.50°E) can be calculated as follows:

[0211] Eq.(1): For planetary longitudes Λ given in west longitude units pg LMST is: LMST = UTC - Λ pg (24h / 360°).

[0212] Eq.(2): For planetary longitudes Λ given in east longitude units pg LMST is: LMST = UTC + Λ pg (24h / 360°).

[0213] Using Formula 2, the reading of the Leiden watch can be determined as follows:

[0214] LMSTLeiden =UTC+4.50°x 24h / 360°=UTC+0.3h, or UTC+

[0215] 20m.

[0216] Alternatively, a traditional watch displays UTC+60m, so one would conclude that to correctly track LMST, a Leiden watch must be adjusted backwards by 60m - 20m = 40m. If one wishes to use the watch as an accurate solar compass, one might need to understand the effect of this 40m compensation on the hour hand, something most people don't consider. This phenomenon can be explained as follows: the hour hand completes a full circle (360°) in 12 hours, and in one hour, the angle swept by the hour hand is 360° / 12 = 30°. Therefore, 40m corresponds to 40m x 30° / 60m = 20° of hour hand movement. This is not a small correction; it's a large one. If one uses a traditional Leiden watch as a solar compass, using the previously described method—that is, dividing the angle formed between the hour hand (pointing to the sun) and the direction of 12 o'clock by 2—the direction will be 10° off from true south. This inaccuracy can be avoided by displaying the true sun at the longitude of interest.

[0217] It should be noted that the embodiments described above illustrate the invention, but are not intended to limit it, and those skilled in the art can devise many alternative embodiments without departing from the scope of the appended claims.

[0218] In the claims, any reference numerals enclosed in parentheses should not be construed as limiting the claims. The use of the verb "comprising" and its conjunctions does not exclude the presence of elements or stages not stated in the claims. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. Expressions such as "at least one," when preceding a list or group of elements, indicate the selection of all elements or any subset of elements from that list or group. For example, expressions such as "at least one of A, B, and C" should be understood to include only A, only B, only C, including A and B, including A and C, including B and C, or including all of A, B, and C. The invention can be implemented by means of hardware comprising several different elements, and by means of a suitably programmed computer. In device claims enumerating several means, several of these means can be implemented by the same hardware. The mere fact that certain measures are referenced in different dependent claims does not indicate that a combination of these measures cannot be used to exert an advantage.

Claims

1. An electronic watch (100), comprising: - A time display device for displaying time, wherein the time display device displays a defined time by electronic control; - The processor subsystem (200) is configured to communicate electronically with the time display device and is used for: - When maintaining a coordinating planetary time, the coordinating planetary time is defined by the prime meridian of the terrestrial planet; - Obtain longitude data, which represents longitudes of interest on the terrestrial planets that differ from the prime meridian; - The local true solar time (LTST) at the longitude of interest is determined as a function of the coordinating planetary time, using a time equation that takes into account the orbital eccentricity and rotational axis tilt of the terrestrial planet. as well as - Control the time display device to display the LTST.

2. The electronic watch (100) according to claim 1 further includes: - Electronic display screens (120, 122); - User input subsystem (210) for enabling a user to input data, wherein the electronic display screen is configured to display feedback on the input data; The processor subsystem (200) is configured to enable a user to use the user input subsystem to indicate the longitude of interest.

3. The electronic watch (100) according to claim 2, wherein the processor subsystem (200) is configured to enable a user to specify longitude coordinates by using the user input subsystem (210) to indicate the longitude of interest.

4. The electronic watch (100) according to claim 3, wherein the processor subsystem (200) is configured to enable a user to specify the longitude coordinates with a precision of at least one decimal place.

5. The electronic watch (100) according to any one of claims 1 to 4, wherein the time display device includes a clock face (110), wherein the clock face includes an hour hand and a minute hand, and wherein the processor subsystem (200) is configured to control the time display device to display the LTST with the hour hand and minute hand.

6. The electronic watch (100) according to claim 5, wherein the clock face (110) comprises a physical hour hand and a physical minute hand.

7. The electronic watch (100) according to claim 5, wherein the time display device includes a display screen for electronically displaying the clock face.

8. The electronic watch (100) of claim 5 further includes a bezel (140), wherein the bezel is rotatable about the clock face and includes markings for basic orientation.

9. The electronic watch (100) according to any one of claims 1 to 4, wherein the processor subsystem (200) is configured to perform at least one of the following: - Maintain Coordinated Universal Time (UTC) on Earth, and determine Earth's Longitude (LTST) at the Earth's longitude of interest as a function of said UTC; and - Maintain the coordinated Martian time MTC on Mars, and determine the Martian longitude LTST at the longitude of interest as a function of the MTC.

10. The electronic watch (100) of claim 9, wherein the processor subsystem (200) is configured to enable a user to indicate the longitude of interest on Earth by specifying planetary geographic longitude coordinates on Earth.

11. The electronic watch (100) of claim 9, wherein the processor subsystem (200) is configured to enable a user to indicate the longitude of Mars of interest by specifying the longitude coordinates of the planetary center on Mars.

12. The electronic watch (100) of claim 9, wherein the processor subsystem (200) is configured to enable a user to indicate the number of leap seconds in the UTC.

13. The electronic watch (100) according to claim 9, wherein the processor subsystem (200) is configured to: - Allows users to use events on Mars as Earth date and time indicators; - Convert Earth's date and time to Martian date and time, where the Martian date and time is expressed as Martian local solar time and Martian solar cycle date at the Martian longitude of interest; and - Determine a relative date and time indicator, and optionally display the relative date and time indicator, wherein the relative date and time indicator represents the difference between the Martian date and time and the current Martian date and time.

14. The electronic watch (100) of claim 13, wherein the processor subsystem (200) is configured to determine, as a relative date-time indicator or as part of the relative date-time indicator, the mission solar cycle number representing the number of solar cycles relative to the Martian solar cycle date.

15. The electronic watch (100) of claim 14, wherein the processor subsystem (200) is configured to increment the mission solar cycle number at midnight local Martian time.

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