This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

ad. With a sense of urgency, because it is very important.

ad. Importantly. Often used with more in this sense.

ad. With enthusiasm. With friendly encouragement.

In a pressing manner; with force or urgency; closely.

ad. in a pressing manner

"Translated into scientific research, the overall goal of the campaign then becomes most pressingly to map Mars for methane and water, and to see where they coincide."

half-heartedly    apathetically