What's Up in the Night Sky?

July 2021 - Vol. 25, No. 7

Astra's Star Gate

This Month's Night Sky - NOTE: The next paragraph describes the sky as it appears at 10 pm EST (11 pm EDT) near mid- month. The sky also looks this way at 11 pm EST (midnight EDT) during the beginning of the month and at 9 pm EST (10 pm EDT) by month's end.

Bright blue-white Vega (Lyra) shines high overhead as it "leads" the Summer Triangle across the night sky. The "Triangle" is the summer’s most prominent asterism and is made up of three stars: Vega, the brightest, Deneb (Cygnus) and Altair (Aquila). In the SW, Arcturus (Bootes) is dropping towards the horizon as Spica (Virgo) vanishes from sight below. Also look for Antares (Scorpius) low in the SW. The stars of constellations Scorpius and Sagittarius, embedded in the "Milky Way" (part of one of the spiral “arms” of our galaxy), are at their best this month. Look for another famous asterism, "the teapot" (Sagittarius). The "Great Square of Pegasus" asterism, now appears on the E horizon just before the onset of morning twilight. These are the stars of autumn that will take over when the northern summer wanes!

MERCURY in the morning sky favors southern observers as it approaches superior conjunction on August 1 . VENUS favors the southern hemisphere, joining up with Mars for a close conjunction on the 13th. MARS in the evening sky reaches its faintest magnitude (1.8) while joining Venus and Regulus (Alpha Leonis) this month. JUPITER rises before midnight, traveling retrograde in Aquarius this month. SATURN rises earlier each night, ruling the dim stars in the constellation of Capricornus. URANUS is in the morning sky among the stars of Aries. NEPTUNE rises with the stars of Aquarius.

Review how to determine Angular Measurement.

Calendar of Events

NOTE: For those observers not in the ET zone, convert the calendar times to your zone's time by subtracting one hour for CT, two for MT and three for PT. Don't forget to adjust for Daylight Savings Time when necessary by subtracting one hour from your planisphere's time. Dawn and dusk times must also be corrected. See your local newspaper, TV news, or cable TV's Weather Channel for sunrise and sunset times or check with the U.S. Naval observatory. Unfortunately some of these events may occur during daylight hours in your area.

DATE EVENT
04 Venus at greatest heliocentric lat. N.
Uranus 2 deg. N of Moon.
Mercury at greatest elongation W. (22 deg.)
05 Earth at aphelion.
Moon at apogee.
08 Mercury 4 deg. S. of Moon.
12 Venus 3 deg. S. of Moon.
Mars 4 deg S. of Moon.
13 Mars at aphelion.
Venus .5 deg N. of Mars.
17 Pluto at opposition.
19 Mercury at ascending node.
21 Moon at perigee.
Venus 1.2 deg. N. of Regulus.
24 Mercury at perihelion.
Saturn 4 deg. N. of Moon.
26 Jupiter 4 deg. N. of Moon.
29 S. Delta Aquariid meteors peak, this shower produces up to 20 meteors at its peak.
Mars 0.7 deg N. of Regulus.

Lunar Almanac for July 2021

Phases of the Moon Phase and Date(s) Best viewed before local midnight
new moon New
10
Deep Space Objects
first quarter moon 1st. Qtr
17
Planets & Moon
full moon Full
24
Moon
last quarter moon Last Qtr
1, 31
Deep Space & Planets

Topic of the month: Mars 2021 Explorers

NASA Mars2020 Mission update

NASA's Mars 2020 mission continues on the surface of Mars. As of July 1, the Rover has been on the surface for 130 Sols or martian days. Mars Perseverance was NASA's 5th rover to land successfully on Mars. Meanwhile, Mars Rover Curiosity has been exploring the Gale crater for 3165 sols. It has driven over 16 miles (~24 km) and sent back over 800,000 images of Mars.

Mars Perseverance took a self with the Ingenuity Helicopter on April 6, 2021
Perseverance selfie with Ingenuity

The Mars 2020 rover, Perseverance, also called Persy, has traveled 350 meters on Mars. It is being prepared to take its first core sample. The sample will be picked up by a later mission to the red planet. Persy also carried a small helicopter in its belly. This helicopter is named, Ingenuity and has proved for the first time that flight is possible on another planet in the solar system, specifically, Mars! The helicopter carries with it a piece of the original Wright Brothers Flyer. Ingenuity's launch and landing site has been named, Wright Brother's Field by the Mars Helicopter Team.

Here is a close up selfie that Persy took with Ingenuity on April 6, 2021. NASA released this image and all of the others that are here in this article. Some of them have been modified (i.e. cropped and shrunk) to fit the web pages here at Astra's. There are many images available from NASA with more appearing regularly. NASA's original image of Perseverance’s selfie with Ingenuity is made up of 62 individual images stitched together once they are sent back to Earth. This image is taken with Perseverance's WATSON (Wide Angle Topographic Sensor for Operations and eNgineering) camera at the end of the rover's robotic arm.

Ingenuity's purpose is to test powered flight in Mars' thin atmosphere, operate autonomously, and test miniaturized flying technology (i.e., computers and electronics). In April 2021, Ingenuity proved itself by making 4 powered flights that month. The first flight came on April 19, 2021. The helicopter rose 10 feet or 3 meters, it hovered, rotated and landed successfully. The whole flight sequence took only 39 seconds, but Ingenuity proved itself expertly. Ingenuity took a picture of its own shadow while it was performing its first flight. Ingenuity's second flight occurred on April 22 , 2021. It rose up 16 feet (4.9 m)in a vertical takeoff and then stopped. It flew .5 meters per second during this flight that lasted 51.9 seconds. Ingenuity proved that the atmosphere on Mars could be used to lift and navigate the small helicopter. It returned the first color image of the Martian surface taken by an aerial vehicle while it was aloft. On April 25, 2021 the third flight lasted 80-seconds. It rose 17 feet (just over 5 meters) and flew at .2 meters per second. Ingenuity's 4th flight occurred on April 30, it lasted 117 seconds and the helicopter took many more images than it had on previous flights.

Ingenuity took an image of its shadow on Mars
Ingenuity's Shadow on Mars

The fifth flight of Ingenuity helicopter took place on May 7, 2021. It moved from Wright Brothers Field to a location 423 feet (129 meters) away toward the south. Ingenuity rose 33 feet (10m) setting a new record. The flight began at 3:26 p.m. EDT and lasted 108 seconds. Ingenuity is officially moving into an unplanned operations demonstration phase. During this phase, NASA will discover what new capabilities a helicopter might achieve on Mars. The helicopter may prove that tasks like scouting or making aerial observations of areas that a rover can explore directly will assist in the exploration of Mars and other worlds.

Ingenuity's sixth flight on May 22, 2021 was not uneventful. Taking off on May 22, 2021, the helicopter rose from its new airfield. It rose an altitude of 33 feet (10 meters) and moved 492 feet (150 meters) to the southwest at 9 mph (4 meters per second.) At the end of the flight the helicopter began to pitch and roll uncontrollable and use a lot of energy to stop and land. Ingenuity uses an onboard inertial measurement unit (IMU)to keep track of its accelerations and rotational rates. This system is aided by images of the surface that are taken by navcams at the rate 30 pictures per second. The images are used by the helicopter’s navigation system that makes adjustments while the vehicle is in flight. One of these images was lost and the timestamps on the images were jumbled causing the system to adjust the flight pattern. Fail-safes written into the navigation system enabled Ingenuity to maintain flight and land safely on the surface within 16 feet (5 meters) of its intended landing site. Now NASA can analyze the flight data and possible improve the helicopter’s performance for future flights and also future missions to the red planet. In any case, Ingenuity has already exceeded expectations.

Ingenuity helicopter took its 7th flight on June 8, without experiencing any of the difficulties that it had on the previous flight. Ingenuity made its 8th flight on June 21, 2021. It traveled about 525 feet (160 meters) to a new airfield. This was the third flight in the helicopter's Operations Demonstration Phase.

CNSA Tianwen-1 mission

Tianwen Lander image from CNSA
Tianwen Lander (image from CNSA)

The China National Space Administration (CSNA) Mars mission rover Zhurong rover landed safely on Mars surface on May 14, 2021. Before exploring the surface, Zhurong was subjected to the usual "seven minutes of terror" experience by spacecraft landing at Mars. The terror comes because earthlings are not able to monitor the entire process because of time delay from Mars. Mars landers must make their descent autonomously. Zhurong's entry, descent and landing sequence began ~ 7:04 EDT when the lander and rover hit the Martian atmosphere traveling about 4,800 meters per second. A heatshield kept the spacecraft safe from heating. It landed at 25.1 N 109.9 E in the Utopia Planitia region on the red planet.

The rover is named after the ancient Chinese god of fire Zhurong. (The Chinese name for Mars is Huoxing, the planet of fire.) The rover was built to last at least 90 Sols on the Martian surface conducting geological and mineralogy investigations. Zhurong is 1.85 m tall and weighs ~ 240 kilograms. It can move up to 200 meters an hour on the Martian surface and is equipped with ground penetrating radar. On May 22, 2021, Zhurong drove off its landing platform and rolled onto the surface of Mars.

The success of the Zhurong rover makes China only the second nation to land a rover on the surface of the red planet. Even though today's technology is a vast improvement over the early explorers, this is a wonderful accomplishment as Mars is very far away and landings are difficult to achieve. The Zhurong rover builds on the expertise gained from the successful rovers that have recently launched to the lunar surface.

For more information on Mars robotic explorers, check out Astra's Mars Exploration page. This page includes a section on the Tianwen mission.

Don't forget to check at NASA for the latest details and images on Ingenuity and Perseverance rover!

--See You Under the Stars!
Astra for Astra's Almanac

This installment of "What's Up?" is ©2021 by Dawn Jenkins for Astra's Stargate. View Ron Leeseburg's Farewell Issue for information on where to find information such as is presented in this almanac.