Mid November 2020

Introduction

By cosmic coincidence, seven planets are visible in the night sky this week. Mercury and Venus are visible in the early morning; Mars, Jupiter, Saturn and Neptune in the evening sky. Uranus is also visible, but only with the aid of a telescope.

The unusual planetary alignment caused me to think about exploration and discovery. It is sobering to realize how much more we know about the planets than my parents’ generation did. We are in a new age of discovery and it started when I was in my early high school years. It was certainly an exciting time for a kid interested in science. And it is continuing. Did you know that right now there is a probe named after an Italian mathematician headed to Mercury? And three, each from a different space agency, to Mars? Or that a NASA satellite is in orbit around Jupiter? I didn’t think so.

So here are some tidbits about the planets and some of their visitors.

Mercury

Mercury is visible low on the eastern horizon just before sunrise. It is near the star Spica and Venus.

Early Missions

Being close to the sun, Mercury is a difficult target for space craft. There have been two missions to Mercury; a third is on the way. Mariner 10, launched on November 1, 1973, attained solar orbit by mid-1975. It flew by Venus on its way into orbit. Mariner 10 flew by Mercury three times and mapped 45% of its surface. It also detected, in a bit of a surprise, a magetic field much like that of Earth.

The MESSENGER space craft was launched in August of 2004. It made gravitational slingshot flybys of Earth (February 2005), Venus twice (October 2006 and October 2007) and Mercury three times (January and October 2008 and September 2009) before achieving orbit around Mercury in 2011. Out of propellant, it crashed onto Mercury’s surface on April 30, 2016.

The spacecraft’s name shows NASA’s love of acronyms – the full name of the probe was MErcury Surface, Space Environment, GEochemistry and Ranging. Whatever its name, the mission was successful and returned about 10 terabytes of formatted data. Among its notable discoveries – water ice at Mercury’s north pole.

BepiColombo

The European Space Agency in cooperation with the Japan Aerospace Exploration Agency lauched the BepiColombo probe to Mercury on October 20, 2018. It will achieve orbiit around Mercury in December 2025 after gravitational slingshot flybys of Earth (once), Venus (twice) and Mercury (six times). It will then release two small satelittes, in different orbits, to study the planet.

By the way, the probe is named after Guissepe “Bepi” Colombo (1920 – 1984), a mathematician from the University of Padua. He proposed the slingshot flyby manuever as first successfully implemented by Mariner 10.

Venus

Like Mercury, Venus is visible low on the eastern horizon, just before dawn. It is a little higher than Mercury, and a bit to the right.

Early Missions

Venus has been the target for multiple space probes: 18 in the 1960s, 11 in the 1970s, seven in the 1980s, one in the 2000s and five in the 2010s. That is not to say all have been successful – during the 1960s, five missions were successful, and 13 failed for one reason or another – explosions on the launch pad, communications failures, etc.

The Russians had an early interest in Venus. The Venera 4 probe (launch June 1967) sampled Venus’s atmosphere; Venera 7 (August 1970 launch) was the first spacecraft to make a soft landing on another planet. The lander Venera 9 (June 1975) was the first to transmit images from the surface of another planet. Check here for a full list of missions and comments on their success/failure.

Surface Conditions

Venus, named for the Roman goddess of love, is anything but hospitable. The atmosphere (96.5 % carbon dioxide, 3.5 % nitrogen, traces of other gasses) is dense – surface pressure about 92 times that of earth, and hot – surface temperatures of 860 F. Venus is seismically active, with current volcanic activity. NASA and other enginners are beginning to design a Rover of some sort for a Venus landing. It is a daunting task – just keeping the thing cool enough for the electronics to function will be difficult.

Mars

Mars is visible in the evening sky. It will be near the waxing gibbous moon during the week of November 25.

Early Missions

There have been 46 missions to Mars – three more are on the way, all launched during the favorable July 2020 launch window. I’ll focus on those. Click here if you want to review the missions, with comments as to success and failure.

United Arab Emirates Space Agency (UAESA)

The United Arab Emirates created UAESA in 2014 to foster expertise in the space industry. In 2015, it established partnerships with the French and UK space agencies. It has overseen the launch of commercial communications satellites from EADS, Boeing, and others. On September 25, 2019, an Emeriti astronaut was lauched to the International Space Station from the Baikonar cosmodrome.

The 2020 mission to Mars is the USAEA’s first effort at exploring another planet. The Hope orbiter, built by a unit of the University of Colorado with several subcontractors, was launched on July 20, 2020 and will attain orbit in February of 2021. It is designed to study seasonal and localized weather patterns, and will make measurements to try to understand why the Martian atmosphere is losing oxygen and hydrogen to deep space.

China National Space Administration (CNSA)

The CNSA used a Long March 5 heavy rocket to launch the ambitious Tianwen-1 to Mars from its Wenchang launch site, on July 23, 2020. The mission includes an orbiter, a lander, a rover, and a detachable camera. The orbiter should achieve orbit by mid-February 2021, the lander should reach the Martian surface by April, and the rover should begin its work shortly thereafter. It will study the Utopia Planita region, in an area near the 2003 Beagle mission (see the Mars map above). Click here for a well-done simulation of the mission.

NASA

The Mars 2020 Perserverance Rover launched from Cape Canaveral on July 30, 2020. It is now in its cruise phase. This is another in NASA’s on-going robotic explorations of Mars.

The Perservance rover is an impressive piece of technolgy. It is the size of a small car – it weighs about 2,260 Earth lbs, is about ten ft long, nine ft wide and seven ft high. This is quite an advance from the first Mars rover – the Sojourner (landed July 4, 1997) – which was about the size of a microwave oven. Click here for a NASA video showing the rover’s features.

Perserverance should land in the Jezero Crater on February 18, 2021. The crater, about 30 miles wide, is near the Martian equator in the Isidis Basin. The crater was apparently a lake at one time as there are inlet and outlet structures and what appears to be an alluvial fan within the crater. Mission scientists think this is an excellent place to find evidence of early life on Mars – in fact, astrobiology is the dominant theme of the whole Mars 2020 mission.

Helicopter on Mars?

And the Perservance is carrying a small helicopter, named Ingenuity. The 4 lb drone is a technology demonstrator – it carries no instruments. The goal is to see if and how it works in the thin Martian atmosphere.

NASA has an excellent website with all sorts of information about the mission. And you can sign up for Mars Newsletters, delivered via email. I wish, with apologies to Ray Bradbury, NASA had named them The Martian Chronicles. Another PR opportunity missed.

Jupiter and Saturn

The two giant planets are near each other, to the south west, in the evening sky, They are now near the waxing crescent moon.

Missions to Jupiter

There have been eight missions to Jupiter – six flybys and two orbital insertions – all managed by NASA. Pioneers 10 and 11 flew by Jupiter in the early 1970s, as did Voyager 1 and 2 in 1979. The Galileo orbiter, launched from the Space Shuttle Atlantis, attained orbit on December 8, 1995. The probe lasted for eight years, burning up in the Jovian atmosphere in September, 2003.

The Ulysses (1992) passed Jupiter on its way to a heliocentric orbit; the Cassini-Huygens (2000) on its way to Saturn. In 2007, the New Horizons passed nearby on its way to deep space.

The Juno orbiter, launched on August 5, 2011, entered orbit around Jupiter on July 4, 2016. Juno was suppossed to stay in the original orbit – with a period of 53 days – and then, after a course correction burn, move into an orbit with a 14 day period. However, NASA engineers, prior to the second burn, discovered faults in two helium valves. Mission scientists then decided to maintain Juno in the 53 day orbit.

The higher orbit means that Juno is in a less severe radiation environment., thus allowing the mission to be extended. It is now planned to end it in 2021, with a fatal dive into the Jovian atmosphere.

You can follow the Juno mission by visiting NASA’s Juno website here.

Missions to Saturn

I wrote about this in an earlier post. If you missed that example of erudition and wit, shame on you. You can make amends by clicking here now.

Uranus, Neptune, Pluto

Uranus will rise this afternoon on the horizon to the north-north west and will be best visible about 10 30 PM, here is San Juan. Neptune is visible low in the northwest sky, early in the evening.

By the way, click here for an excellent, interactive website that gives directions and best time to view objects in the sky.

Voyager 2 is the only spacecraft to visit both Uranus and Neptune.

Both Voyager 1 and 2, now in interstellar space, are still active. Click here for their current status.

Conclusion

We are living in an unprecedented era of planetary exploration – something we’ve begun to take for granted. I think it is good to get excited about some of this stuff – just like I was back in high school.

If you are interested in a telescope, consider this: sales of telescopes increased by 400 – 500 % over last year. This is undoubtedly due to the covid pandemic. Here’s my plan: wait a year or two and, as things get back to normal, I suspect there will be slightly used telescopes of all sorts for sale. Keep checking Craigslist or other such venues – I’m sure you’ll find a good deal.

Notes and Sources

The Mercury image and many others can be found here.

The image of the BepiColombo probe is from this site.

The BepiColombo image of Venus is from here.

See the desctiption of the twin Venus images here.

Click here for information about the Venus surface image.

Follow this link for more information about the UAE mission to Mars.

You can find more information on the Tianwhen-1 mission here.

The NASA website on the Mars 2020 Perservance mission is excellent, as is their website for the Juno mission.