PRAGUE – European Space Agency Director-General Johann-Dietrich Woerner on May 9 expressed frustration with the equipment delays that forced a two-year slip in the launch of Europe’s ExoMars rover vehicle and said he would not write a blank check to keep the mission alive.

Addressing a briefing here, where he was attending ESA’s Living Planet Earth observation symposium, Woerner said he still did not fully understand why the project could not make its 2018 launch date. He wondered whether it is possible to have those responsible for the delay finance part of its cost.

“I was not only surprised, I was frustrated with this delay, which was for technical reasons on both the European and Russian sides,” Woerner said, adding that at first he did not accept it.

“I was fighting like hell” to keep the mission on schedule despite indications that multiple pieces of equipment would not make it in time for the launch, he said. “I’m very upset about it and I don’t understand it from a certain point of view.”

Woerner became ESA’s chief in July 2015. Before that he was head of the German Aerospace Center, DLR, which is Germany’s space agency. Germany has long resisted the mission creep of ExoMars – which began years ago has a technology-demonstration mission and has since grown into a telecommunications orbiter and landing demonstrator that launched in March, and the European rover and Euro-Russian surface-experiment package that was to have followed in 2018.

The Russian and European space agencies in March began hinting that the second mission – both launched by Russian Proton rockets – was having trouble meeting its deadlines for unspecified reasons. The two agencies later said they agreed to the two-year delay.

As the ExoMars mission has increased in sophistication and scientific value, its budget has about doubled, to as much as 1.3 billion euros ($1.5 billion). ESA has raised only about 1 billion euros. Before the latest delay, the agengy had expected to present its 22 member states in June with a plan to raise the remaining monies.

The two-year delay will add more costs, although ESA plans to reduce the increase by doing as much work as can be done soon, then storing the hardware until needed for prelaunch preparations in 2020.

ExoMars is ESA’s sole exploration mission. It also represents a substantial Euro-Russian collaboration that has already launched a telecommunications relay designed to beam the rover’s findings to Earth.

Given these elements, the program has taken on an inertia that would make it difficult to stop in the absence of a Russian admission of still more delays. But Woerner said he would not maintain ExoMars at all costs.

“We will have a discussion with the main member states involved with the program,” Woerner said. “Then we’ll see how we can manage, and whether we can manage. I am not saying we can manage it. There are cost increases with the delay and there were cost increases from a technical point of view. Again, I don’t fully understand it after all the discussions we had in the past. I thought we were finished with the numbers. Now we have new numbers and this does not make me happy.”

Woerner said some people want to delay a decision on fresh ExoMars funding until the telecommunications orbiter arrives in Mars orbit this autumn and is declared operational, and the experimental entry, descent and landing package is safely on the Mars surface.

“Then everybody is fascinated and ready to give more money,” Woerner said of this line of reasoning, which he rejected. “No: I am not like that. I would like to discuss it very openly, right now. I’ve got some numbers already and I am getting more [this week] and then we will discuss it.”

He said ESA would need to make a proposal its governments in June, and then to seek formal commitments in December at a meeting of ESA’s government ministers. The June meeting would free up monies needed for ExoMars for the balance of this year.

“I am not sitting here saying I will do everything to get ExoMars flown. For me it is very important that we first find out about the money and who we might ask for more money and is there some possibility of reducing the amount. We are not at a time when money is printed easily. The decision is not as simple as some people expect.”

Woerner said he did not like the idea of robbing other ESA programs, such as science missions, to finance ExoMars. “It’s difficult,” he said.

Peter B. de Selding was the Paris bureau chief for SpaceNews.