Today my parents are going back home, after three very special weeks.

My parents took care of Nora during the week, so they really got to know her well. Nora, for her part, loved being read books by her Oma and always laughed at Opa's jokes. For Sasha and me it was great to spend time with them. We will miss them.

Yesterday was Jaap's birthday, and for the second time we celebrated it in Arlington. Nora gave her Opa two books.

My parents flight is around 3.00 pm from Reagan National Airport.

In a thrilling feat of engineering the Curiosity rover landed successfully on Mars this week. It is easy to be jaded about some of the technologies we see around us but landing a car-sized rover safely on Mars is extraordinary.

Here is an animation of the landing of Curiosity, and it shows the rover driving around on a different planet.

Hardware

The Curiosity is roughly the size of a car and weighs around 2,000 lbs. Its nuclear power source generates 125 watt of power initially but will slowly degrade. After 14 years it will deliver around 100 watt (the official mission of the rover takes two years).

The rover has 17 cameras and since the specs were created in 2004, the main cameras only have 2 MP sensors. Similarly, the processing hardware feels a little dated: the CPU runs at 200 Mhz, it has 256 MB memory and 2 GB flash solid state storage. It has two on-board computers, one is configured as backup, and will take over in the event of problems with the main one.

Software

One of the main engineering accomplishments in the project is the software.

With a total cost of around $1.2 billion and much scientific work on the line, a software mistake would be disastrous. The development and QA approach is very rigorous. I enjoyed reading the Coding Standards for the Jet Propulsion Laboratory. It is a very readable document, and the guidelines are obviously conservative. "Specifically the use of task delays has been the cause of race conditions that have jeopardized the safety of spacecraft." Rover has around 2.5 million lines of C-code.

Curiosity is running on Wind River's real-time operating system (RTOS), VxWorks. The software is similar to that of previous rover missions. There's a team of 30 developers and 10 testers working on the Curiosity rover. It runs over 130 threads.

A cool presentation has more details on the testing methodology. It emphasizes analyzing the logs that are generated. A Python-based high-level language helps with testing to see if the logs show the expected results.

Upgrade

Right now, the firmware on Curiosity is being upgraded. I have a lot of experience with remote firmware upgrades, and I know how scary this process can be. A senior flight software engineer speaking Computer World:

"It has to work. You don't want to be known as the guy doing the last activity on the rover before you lose contact."

Very cool to see a software upgrade being done 160 million miles away.

This morning my parents went to the Arlington Cemetery and in the afternoon I took them to the Great Falls.

We saw the Falls from the various overlooks and were planning to go for a hike. As we were watching a kayak going down the river, it started raining... and raining... and raining! We were soaked within moments.

On the picture you can get see the big clouds gathering above the river, and then Mieke running for (relative) cover under the tree were Jaap and I were hiding.

The last time my parents visited the Great Falls was in August 2005.

Nora spent another fun week with Opa and Oma.

It is amazing to see how fast she changes. Since a few days she is very interested in faces and tries to grab people's glasses. We played peekaboo with her today, it made her giggle.

Mr. Rudolf Bekink was formally accredited this week as the new Dutch Ambassador to the United States. He presented his Letters of Credence to President Obama on Monday.

In press release Mr. Bekink spoke of the historical ties between the two countries. "It's a great honor to represent the Netherlands in the United States. Our countries have a strong bond that spans more than four centuries and continues to thrive today. The Netherlands is the 3rd largest foreign investor in the U.S. and we have a vibrant partnership in many areas such as peace and security and economics. I look forward to strengthening our ties further,” said Ambassador Bekink.

His predecessor, Mrs. Renee Jones-Bos, returned to the Netherlands this summer and is now Secretary-General for the Ministry of Foreign Affairs.

A return to the United States

Ambassador Bekink's posting to Washington is a return to the U.S., where he served as the First Secretary to the Embassy's political department from 1982 to 1986. Prior to this new posting in Washington, Ambassador Bekink served as the Dutch Ambassador to three countries: the People's Republic of China (2008-2012); Belgium (2004-2008); and Sweden (2000-2004).

Throughout his 36-year diplomatic career, Ambassador Bekink has served as the Chargé d'Affaires in Ghana; Deputy Head of Division of the Ministry of Economic Affairs; Deputy Head of Mission to the Mission of the Dutch Permanent Representation to the Office for Economic Cooperation and Development (OECD) in Paris; and Director of Protocol for the Ministry of Foreign Affairs.

Mr. Bekink is married to Austin business woman Gabrielle de Kuyper Sheshunoff.

Nora and Oma Mieke are having an excellent time together. My parents brought her many books and Mieke reads her a new book every day.

During the week my parents looked after Nora but in the weekend they had time to explore the city. They know their way around so they have their favorite spots -- such as the Starbucks on Clarendon Blvd where they go almost every morning.

Saturday morning at 9.00 am they attended a wreath-laying ceremony at the Korean War Veterans Memorial and then spent time on the National Mall. We had home-made guacamole and tortilla chips for dinner. Yesterday Roosevelt Island and Georgetown were on the agenda and last night they went to a concert of Hawaii musicians and dancers here in Arlington.

From our correspondent Jaap Bosman.

With a wreath-laying ceremony in Washington, D.C. this Saturday, officials from South Korea and the Netherlands paid tribute to the Dutch soldiers who fought in the Korean War. Although the conflict has not been formally resolved to this day, an armistice was signed on July 27, 1953. The ceremony was held at the at the Korean War Veterans Memorial in Washington DC, in D.C.'s West Potomac Park, near the Lincoln Memorial and just south of the Reflecting Pool on the National Mall.

Freedom is not free

The Korean War Veterans Memorial dates from 1986 and honors members of the armed forces who served in the war.

"The words on this wall, 'Freedom Is Not Free', express gratitude for the service of members of the military," said Air Commodore Tom de Bok, the Netherlands Defense Attaché.

During the ceremony, a detachment of the Dutch 12th Infantry Battalion marched with the colors of the Dutch Korea veterans, the Nederlands Detachement Verenigde Naties (NDVN). The day before, a similar ceremony was held on Arlington Cemetery.

Rudolf Bekink, the new Ambassador Appointed, was present in one of his first public appearances in the United States. Mr. Bekink will present his formal credentials tomorrow, July 30th, to President Obama at the White House.

Frank Amaro of the Italian American War Veterans Department Of Illinois said that ceremony in 2013 will be larger, since it will mark the 60th anniversary of the armistice.

My parents are here! Jaap and Mieke arrived Monday evening. Their journey took a little longer than planned but they made it here safe and well.

Nora is getting a lot of love and attention from her Opa and Oma. Tuesday morning was the first time Oma and Nora met each other in person, and they both smiled a lot.

Jaap and Mieke took her for a walk today -- for the first time in the "big" stroller without the car seat. They brought several new Nijntje books, so Nora heard the story of "We hebben een orkest" today.